Originally posted by homer1
One question I still have is about the tilting of the yagi? I wonder since my general location is low lyeing, would there be any benefit in a slight angle upwards?

Some people have reported better results with tilting. I think this is more likely to be caused by moving the antenna into "hot spots" than anything else, but I haven't tested it personally.

If you use a rotor, you'll either need to invest in a remote tilter or you'll be pointed into the ground when you point in some directions.

If you've got hills that are more than 2-3 degrees above level, tilting might help. Otherwise, I'd go with a level install.

Hi MAX HD, that combiner that I used was a one in & two outs
splitter that I reversed. As I said before, I will try the antennas
again, And I will let you know how it turns out. Also, I checked the
Excel document that someone else posted, and am trying to figure out
what the NEC is that the document refers to. Is that an independent
testing organization? If anybody knows, let me know.
--ALSO--I have found a great FCC web site that will let you know everything that did or did not want to know about a tv station,
including footprint & location maps. I tryed to post it yesterday,
but this forum would not let me because I don't have 5 posts yet.
When I do, I will post it then.
fay28301

Here is that FCC site:

http://www.fcc.gov/fcc-bin/audio/tvq.html

I have used it with pretty good luck on finding out everything you did & did not want to know about a tv station, including its footprint and maps of where it is located. All I ever do is plug in the city & state, and where it asks for the channel you want to look up, I always put ch. 2 into the lower as the upper already has ch. 69 in it. When I do it like that, it always gives me all of the stations in that city. Then I click on the one I am interested in.
fay28301

Originally posted by cpcat
That's probably a pretty good preamp. I'm not sure you'd see much improvement with the CM 777x series, but you might. My 7777 gave me a small but significant improvement over a Blonder Tongue Vaulter III plus. If you decide on a new preamp, I'd get the 7777 just to have VHF capability as it's about the same cost. The performance on UHF will be the same. If your current preamp has a 300 ohm input, that may be a small advantage in not having to use a balun. The 777x series has 75 ohm inputs so you'll likely incur some minimal loss through the conversion which may offset any improvement the new preamp might give you.

What channel is giving you the problem? The Winegard 8-bay has a rep for not being very good in the upper UHF range. It's also possible the channel in question is still at low power or you have co-channel interference from an analog. Here's a computer simulated comparison of various antennas including the Winegard 8800:http://www.hdtvprimer.com/ANTENNAS/comparing.html

Assuming you're not using a rotor, the CM 4228 is pretty hard to beat for flat response up and down the UHF range. It can be hard on a rotor, though.

Thank for the reply. The channel that's giving me the biggest problem is 16-1, but it is as very low power. It did come in strong Friday and Saturday but it is raining today, so it's not coming in at all. The Blonder Tongue uses 300 ohm inputs so I might not gain with the Channel Master
(it came last Thursday but I haven't had a chance to do anything with it-CM 7775--all my local digitals are UHF--I have a cable feed for the analogs).
I was going to add another length of mast but the store was out of the 5 ft lengths. Increasing the height may help more than the new pre amp. If the 8 bay doesn't do the job (most of the towers are 40-50 miles from me in the same direction). One is full power and two are a little less than full power but I can get their signals with an indoor antenna (with some problems on one channel). The fourth channel I am trying to get is very low power (FOX). Our CBS station will finally be on the air this spring
(supposed to start up at full power).
.

Have you had practical experence at eliminating or at least reducing the effects of CCI between a digital and an analog signal?

Ch. 13 digital due North at 50 mi. and analog 60+ mi. at SSE
Digital nearly wipes analog out completely.

I'm an avid NFL football fan, thinking I'm now going through withdrawal shock! I'm already thinking about next season. I very much miss my analog 13 for Steelers games.

I'm thinking of a dedicated hi-band vhf or cut-to-channel 13 antenna on the south side of my house.

Any ideas?

Thanks

Originally posted by bruschi88
I'm thinking of a dedicated hi-band vhf or cut-to-channel 13 antenna on the south side of my house.
http://community-2.webtv.net/GregBarker/UltraHighGain/

Thanks Rack!

Yes,one of these strategically placed to optimize the reception of the analog station should work nicely.The reflector design may help some too,to null out the DT station.

Have some left,ready to ship!

http://community-2.webtv.net/GregBarker/UltraHighGain/

Originally posted by bruschi88
Have you had practical experence at eliminating or at least reducing the effects of CCI between a digital and an analog signal?

Ch. 13 digital due North at 50 mi. and analog 60+ mi. at SSE
Digital nearly wipes analog out completely.

...Any ideas?

The trick is to point one antenna directly at the analog source, pad it down so that its output matches that of the main antenna, and couple the two leads so that they are 180 degrees out of phase with one another.

There isn't much point in me trying to explain how one goes about balancing the two signals and coupling them out of phase with one another because you surely do not have the signal measuring equipment needed to do so, but if you really have to solve this problem, that is what you should have a local antenna expert do.

I have a high-band (7-13) adjustable phase shifter I bought from Microwave Filter Company that I could sell you that makes the job easier to do, if you are intent on giving it a shot. I think paid about $500 for it, but I could let it go for $300.

Oops. I now see that you are trying to preserve the analog source while canceling the digital, so do the opposite of what the above post recommends.

Originally posted by bruschi88
Have you had practical experence at eliminating or at least reducing the effects of CCI between a digital and an analog signal?

Ch. 13 digital due North at 50 mi. and analog 60+ mi. at SSE
Digital nearly wipes analog out completely.

I'm an avid NFL football fan, thinking I'm now going through withdrawal shock! I'm already thinking about next season. I very much miss my analog 13 for Steelers games.

I'm thinking of a dedicated hi-band vhf or cut-to-channel 13 antenna on the south side of my house.

Any ideas?

Thanks

It's also possible to null unwanted channels by the use of horizontal stacking. I've done this with some measure of success. See http://www.kyes.com/antenna/sca/scaint1.html and
http://www.kyes.com/antenna/sca/scaint2.html

The spacing required at channel 13 for increased gain is fairly wide, but I think you'll find the spacing for nulling should be more manageable. You may have to experiment with different widths to see what works best.

I once significantly improved the front-to-back ratio of a highband antenna, receiving channel 7 in a hostile reception environment, by placing a second, identical highband antenna exactly one quarter wave length below it (around 29", as I recall). The front-to-back ratio increased without even electrically connecting the second antenna.

Actually, I found this by accident. I was removing and throwing away abandoned antennas on a highrise condominium with four masts, and noticed that the channel 7 got sucky when I removed the abandoned channel 9 antenna on the same mast, but improved when I clamped it back on, and then the rear rejection improved even more when I replaced the obsolete channel 9 antenna with a matching YA-1713.

Okay, I have a CM 4228 on order, and will also need a VHF antenna. One of the signals is just 5 of so miles away(channel 4) but the other VHFs (channel 2, 7,10) are around 50 miles. What VHF only antenna that is still being made would be good for this purpose?
Thank you

Originally posted by VMsat
Okay, I have a CM 4228 on order, and will also need a VHF antenna. One of the signals is just 5 of so miles away(channel 4) but the other VHFs (channel 2, 7,10) are around 50 miles. What VHF only antenna that is still being made would be good for this purpose?

What market has 4 VHF digital signals? I suspect you're using analog channel equivalents, unless you're near Salt Lake City.

If you really need a VHF-only, this is a good one:
http://www.winegard.com/offair/pdf/hd4053p.pdf

They are not all digital, the channel 7 and 2 are digital but the others are not. But I need to get the analog 4 as well.

Originally posted by VMsat
Okay, I have a CM 4228 on order, and will also need a VHF antenna. One of the signals is just 5 of so miles away(channel 4) but the other VHFs (channel 2, 7,10) are around 50 miles. What VHF only antenna that is still being made would be good for this purpose?
Thank you

Others to consider:
Antennacraft 3bg17:http://www.antennacraft-tdp.com/pdfs/3bg17_.pdf
3bg22:http://www.antennacraft-tdp.com/pdfs/3bg22_.pdf
cs900:http://www.antennacraft-tdp.com/pdfs/CS900.pdf
Delhi VIP 304 or 305: http://wade-antenna.com/VHF-FMantennas.htm

Thanks. I have another question. My parents like in the country and have a 35 foot antenna mast which is mounted in the ground about 50 feet from their house. The main tv is another 100 feet or more to the other side of the house. I think the CM 4228 is a good choice for UHF since some of the stations are atleast 50 miles or so away. However, one of the stations is only about 5 miles away from their house. My question is if a CM 7777 preamp is used, as the cabale will likely have to be atleast 150 feet, do you think it will degrade the signal from this closer station as some people have said that for close stations a preamp will make the signal worse. If so what can be done?

Originally posted by VMsat
Thanks. I have another question. My parents like in the country and have a 35 foot antenna mast which is mounted in the ground about 50 feet from their house. The main tv is another 100 feet or more to the other side of the house. I think the CM 4228 is a good choice for UHF since some of the stations are atleast 50 miles or so away. However, one of the stations is only about 5 miles away from their house. My question is if a CM 7777 preamp is used, as the cabale will likely have to be atleast 150 feet, do you think it will degrade the signal from this closer station as some people have said that for close stations a preamp will make the signal worse. If so what can be done?

If they are truly "in the country" then this station is likely a low-power station, in which case it isn't a problem. If it's a full-power station, it may overload the preamp in which case you'll need to notch it out or attenuate it. Fixed filters of this type can be had at http://www.tinlee.com/
Blonder Tongue makes adjustable notch filters (very expensive) as does Winegard (for uhf only). The adjustable filters require time and effort as well as at least an analog TV without a mute circuit.

If you use a notch filter, you will most likely attenuate at least a channel above and below as well, depending on the slope of the filter.

Where do I go to find out if this is a low power station. I just went to antennaweb.org and it does not show the power.

Okay i found it on tvradioworld, it is 12.9 kW. Is this considered low power?

How accurate, generally, are AntennaWeb's projections. I know they say they're somewhat conservative, but for me they say I can receive UHF transmissions from 120 miles away with a Violet Antenna (LD with Preamp). I read that to basically say CM 4228 + CM 7777. I can receive my local stations fine all of them. This is more basically a curiousity to me, that "conservatively" I could get 5 stations from 120 Miles away and 1 station in Reno from 140 Miles away (all Violet, not Pink). (They're analogs, but still I'm curious as it might also put me outside of some blackout areas...not that I'd ever consider that as a reason to go outside my DMA). Right now I'm have with a CM 4221 no Preamp or Amp, and do just fine for locals.

Originally posted by VMsat
Okay i found it on tvradioworld, it is 12.9 kW. Is this considered low power?

Depends on whether that's lo-VHF (channels 2-6), hi-VHF (channels 7-13) or UHF.

If it's UHF, it's low power. If it's lo-VHF, that's pretty hot. Hi-VHF is in between.

It's channel 4 so I might need an attenuator i guess if i use a preamp. I live in west texas in the middle of almost nowhere and none of the so called local stations i get, ( although they are from a larger city about 50 miled away Midland /Odessa area) broadcast in HD although they are in digital. Lubbock, a larger city 100 miles to the north on the other hand has three stations in HD, channel 9-1 (NBC), 5-1 (PBS), and 35-1( another network not sure if CBS or ABC). Right now with my sensar II antenna mounted on a twenty foot mast on the roof with rotor, I get some of the Lubbock stations some of the time. I never get any of the Midland/Odessa stations which is only 50 miles away, probably because of a hill between my house and that city. The terrain between my house and lubbock (100 miles away) is 100% completely flat. Probably the flattest 100 mile strtch in the whole country. Now when I get my new CM 4228 and CM 7777 preamp I'm hoping to get these HD stations out of Lubbock. The problem is the 4228 is UHF and channel 7-1 and 5-1 are not UHF stations, but I understand that that antenna is also good with higher VHF stations. What do you think, might I be able to bring in these stations?

Originally posted by VMsat
It's channel 4 so I might need an attenuator i guess if i use a preamp. I live in west texas in the middle of almost nowhere and none of the so called local stations i get, ( although they are from a larger city about 50 miled away Midland /Odessa area) broadcast in HD although they are in digital. Lubbock, a larger city 100 miles to the north on the other hand has three stations in HD, channel 9-1 (NBC), 5-1 (PBS), and 35-1( another network not sure if CBS or ABC). Right now with my sensar II antenna mounted on a twenty foot mast on the roof with rotor, I get some of the Lubbock stations some of the time. I never get any of the Midland/Odessa stations which is only 50 miles away, probably because of a hill between my house and that city. The terrain between my house and lubbock (100 miles away) is 100% completely flat. Probably the flattest 100 mile strtch in the whole country. Now when I get my new CM 4228 and CM 7777 preamp I'm hoping to get these HD stations out of Lubbock. The problem is the 4228 is UHF and channel 7-1 and 5-1 are not UHF stations, but I understand that that antenna is also good with higher VHF stations. What do you think, might I be able to bring in these stations?

As far as I can tell, in the Midland/Odessa as well as Lubbock area, the only VHF digital you have is on ch. 9 from Lubbock. The channel 4 you are referring to is an analog NBC from Big Springs. You should do fine with the 7777 and the CM 4228. Hook to the "combined" input and be sure the internal switches are set to "combined" and the FM trap "in". The 4228 should do a very nice job of attenuating channel 4 as it's gain is minimal there. It should do pretty well for channel 9 but if you need more add an Antennacraft Y10 7-13 or equivalent high band antenna which still will not likely have enough channel 4 gain to overload the preamp.

Thanks for the information, I will try the 4228 with the 7777 first and then upgrade if needed.

Many thanks to all who replied to my post about ch.13 cci from a couple days ago. The information was very helpful and much appreciated!

I'm leaning toward trying one PSP.1922 initially and then perhaps two horizontally stacked.

I've been waiting for the ch.13 analog in question (WOWK-DT47, Huntington,WV.) to improve the quality of their digital signal. I can receive their digital, but to say they're not passing HD would be a gross understatement, as all the folks in the Charleston,WV section can attest. I'd rather watch a semi-noisey analog!

Thanks again!

I hate doing this, but I'm driving myself nuts trying to get a local CBS station and have had zero luck. I'm trying to pick up WWMT, a CBS out of Kalamazoo/Grand Rapids. I'm 31 miles southeast of the antenna. I'm also in a southeast facing apartment meaning I have several walls to go through. I am on the 2nd floor however. I've tried a folded dipole with little luck. The station is on the frequency assignment 2, but is channel 3.1. Anyway, I went to Menards, a lowe's/home depot style store and bought a Magnavox outdoor antenna (I think they call it yagi-style). Granted it was only 30 bucks and probably about 60" in length, I was still able to pull in somewhat decent analog signals without too much trouble. But when I try to pull in the digital signal, I max out at 41%. That's the same I maxed out at with the folded dipole. It's the same across several other VHF channels, where I can get a somewhat decent analog signal, but max out at 41% when I try to pull in the digital signal. Am I doing anything wrong? Do I need a pre-amp or something (not even sure what a pre-amp does)? Would I be better off contacting the stations engineer to see if he knows of any reason I'd be having so much trouble?

Originally posted by SteveMSU
I hate doing this, but I'm driving myself nuts trying to get a local CBS station and have had zero luck. [...]I was still able to pull in somewhat decent analog signals without too much trouble. But when I try to pull in the digital signal, I max out at 41%. That's the same I maxed out at with the folded dipole.

If you haven't tried it yet, this page has some good information on building your own specific frequency antenna: http://www.wfu.edu/~matthews/misc/dipole.html If you add his recommended improvements at the bottom of the page, you should have a far better antenna than the VHF/UHF combo you picked up at Menard's. You might find that a stack of two of these home-built antennas is necessary for best results.

Digital VHF signals can be tricky because most areas of the country were already "saturated" with analog signals. The FCC has tried to squeeze some digital stations into the mix, but the fact is that co-channel (meaning the same channel) interference is going to be a problem for most people outside of the Grade A contours. Given the difficulty of your local environment, you've got at least two strikes against you at the get-go.

You may not be able to get better reception no matter what you do. I doubt signal strength is your real problem. You probably have more interference and ghosting than weak signal problems. (Weak signals look like "snow" on analog.) Thus a preamplifier is not going to help. All I can suggest beyond the antenna above is to use the latest tuners, with the advanced chipsets. Good luck.

I need a antenna that will go at least 100 miles. for 250.00$ or less. Any Suggestions? ZIP 32456

Originally posted by Audioman1
I need a antenna that will go at least 100 miles. for 250.00$ or less. Any Suggestions?

Depending where you are it can be done. If you are low in between mountains forget it. If your relatively flat like in Texas may not be a problem. Give us a zip and see if one of us can help you.

Originally posted by j_buckingham80
How accurate, generally, are AntennaWeb's projections. I know they say they're somewhat conservative, but for me they say I can receive UHF transmissions from 120 miles away with a Violet Antenna (LD with Preamp). I read that to basically say CM 4228 + CM 7777. I can receive my local stations fine all of them. This is more basically a curiousity to me, that "conservatively" I could get 5 stations from 120 Miles away and 1 station in Reno from 140 Miles away (all Violet, not Pink). (They're analogs, but still I'm curious as it might also put me outside of some blackout areas...not that I'd ever consider that as a reason to go outside my DMA). Right now I'm have with a CM 4221 no Preamp or Amp, and do just fine for locals.

Antennaweb is usually accurate with analogs but very conservative with digital. Have you tried getting a signal from that direction with the 4221?
If you do get a signal then the 4228 with the 7777 will probably bring them in. 140 miles is a haul for any antenna. The natural curve of the earth is the killer. I can get ground reception late night digital out to about 200 miles but not reliable enough to watch. I do have mountains and other geographical problems here not to mention 2 digital channel 7's and soon to be a third.

In my case here antennaweb says I should get 2 digitals with a violet antenna and booster. I get reliable 14 digitals with a 7777 or 12 without any amp. If they say you can get digital reception from that far I'd bet money you can.

Originally posted by jimc705
Depending where you are it can be done. If you are low in between mountains forget it. If your relatively flat like in Texas may not be a problem. Give us a zip and see if one of us can help you.

I need a antenna that will go at least 100 miles. for 250.00$ or less. Any Suggestions? ZIP 32456

Audioman1, if you decide to use the Triax Unix 100A, I just bought 4 (2 extras because shipping was same) on cpcat's recomendation (http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=481958). This antenna only covers UHF channels 14-38 (which is why it has such good gain), so it should only be considered if you don't care about channels above 40. You would have to get a separate VHF antenna if you have VHF stations.

I don't have enough experience to feel comfortable making a recomendation. I just wanted to give you a heads up and cut your shipping costs from Great Britain in half.

doublepost - forum was misbehaving, i swear :rolleyes:

triple post - :confused:

Originally posted by Audioman1
I need a antenna that will go at least 100 miles. for 250.00$ or less. Any Suggestions? ZIP 32456

The best performance is separate VHF and UHF antennas. The biggest thing especially for you is antenna height. At or close to sea level, it's critical to get as much height as possible. A starting recommendation would be the XG91 for UHF on a rotor with a separate VHF antenna depending on your needs below. Even then, consistent reception much beyond 60-70 miles is often impossible. Get as much height as you can. You do live in a tropo prone area (weather conditions often allow propagation of signals over long distances) which I'm sure allows you to receive distant signals at times, but you just can't cheat the laws of physics.

I have reliably received a signal from both PBS (KIXE-DT) and ABC (KRCR-DT) in Redding from Chico. Those stations are 67 miles away at low power (<26kW) Both locked solidly tonight showing HD. I bought an AntennasDirect DB4. I haven't put it in a permanent location yet, its currently propped up next to the TV, sitting on the floor of my living room. Signal strength was solidly in the 60's on my HR10-250. Interestingly, I can receive all of our digital stations without redirecting the antenna even though some are 90 degrees apart. My next move will be to install it in the attic and try it out. If I point it towards the southwest I am even able to pick up KFTY-DT out of Santa Rosa which is 88 miles away. I guess there is something to just trying. Once its mounted higher, I wonder if I'd be able to get Sacramento (110 miles). I doubt it though.

Chris

Question Regarding the Silver Sensor. I have two Silver Sensors hooked up to two separate TV's. I am using a Samsung TS-360 HD receiver on both. Would having the two silver sensors in the same room about 4 inches apart, affect their reception? I am experiencing picture break up on one particular channel. I got the searching for signal message.

Background:

I live in town, and my towers are in all different directions from me. This causes series issues with multipath. There are two towers, about 90° apart from one another from my location, that give me a lot of headaches: one on Ch. 39, the other on ch. 43. Both of these towers are only about a mile away. 39 is closer to the same direction of many of my other towers as 43, and I'm able to pretty much get all my stations from one antenna aimed at a compromise between them. To get 43, I had to get a second antenna, placed in my attic, aimed specifically at that tower, with the signal combined with a Jointenna specifically tuned for ch. 43. The problem is, ch. 39 and 43 are close enough frequency-wise that the filters in the jointenna don't quite have enough attenuation to keep them from interfering: I'm getting multipath on ch. 39 that is being received by the antenna aimed at 43, and not filtered enough by the jointenna to prevent disruption of my signal. I had tried a variable attenuator on the second antenna, hoping to be able to attenuate the signal enough to prevent the secondary 39 signal interfering with the primary signal, while still allowing enough of the 43 signal to get through, but I could never get a sweet spot that made both reliable: too much attenuation, and 43 came in and out, too little, and 39 came in & out due to multipath.

Last year, I swapped out my Samsung TS160 receiver with an HD-TiVo, and suddenly the problem went away. I had to move the variable attenuator to the input of the HD-TiVo, because it was getting overloaded in general (not just on 43), but it SEEMED that I was suddenly getting perfect reception on both 43 and 39. I just assumed the tuners in the TiVo just handled multipath a little better than the Samsung.

A month or two ago, the problem re-appeared. Since I got the TiVo around June or so, I'm now thinking my sudden ability to get both at the same time may have at least been partially due to leaves on the trees partially attenuating the multipath signal from 39 to the second antenna. Since DirecTV will be carrying HD locals via sat, possibly this year, I don't want to sink much more money into my antenna set-up. But I would like to do what I can to improve the situation.

Question:

Since channel 39's tower is so close to me (I'd have line of sight from the secondary antenna if it wasn't for my roof, and possibly some trees), could I just get some aluminum screening, staple it up in my attic in a position that would disrupt line of sight from the secondary antenna, and ground it? Would that significantly reduce the signal being received by that antenna from that tower? Since the two towers are 90° apart, I'd have no problem locating the screen in such a way that it would completely block LOS from the one tower, while not coming close to obstructing LOS from the other. But since the antenna is in the attic, I'm not sure how "direct" reception is. I don't know if radio waves continue in a direct manner to the antenna, or if passing through the roofing causes significant scattering, thereby causing the signal to come in from many different directions (therefore, getting around my screen). And I don't know how effective a grounded screen would be at attenuating a signal from a certain direction.

Any suggestions are appreciated! :)

Originally posted by elove
Would having the two silver sensors in the same room about 4 inches apart, affect their reception?

Yes, and probably negatively. You should maintain a minimum of 36" between your UHF antennas.

Originally posted by cpcat
The best performance is separate VHF and UHF antennas. The biggest thing especially for you is antenna height. At or close to sea level, it's critical to get as much height as possible. A starting recommendation would be the XG91 for UHF on a rotor with a separate VHF antenna depending on your needs below. Even then, consistent reception much beyond 60-70 miles is often impossible. Get as much height as you can. You do live in a tropo prone area (weather conditions often allow propagation of signals over long distances) which I'm sure allows you to receive distant signals at times, but you just can't cheat the laws of physics.

Quick Question: Say you had the XG91 and wanted to pair it up with a VHF antenna, would you have to use a VHF-only antenna to pair up with? In other words, do you loose some of the UHF reception benefits of a very high-quality UHF only antenna when pairing it with a so-so U/V/FM antenna?

The reason i ask is because I am interested in a bay-style antenna since they seem to perform the best with the channels I am looking to get (all under 30), but I still want VHF SD signals. Seeing that there aren't any bay plus VHF combos out there I see the need to combine the signals. Would it be silly to attach a NICE Winegard or CM UHF (or AntennasDirect) bay-style antenna with a cheap-o Radio Shack U/V/FM antenna?

Darin,

Yes, it is theoretically possible to make a shield just as you described. However, in the real world, it will be harder than you would think, especially in an attic. In your specific case, maybe impossible, because you live so close to the antennas you wish to block. Living that close to the antennas, you experience a significant reduction in received signal level.

If you paste the link below into your web browser, you will find two posts where I tried to explain this to the Houston OTA crowd on this forum.

www.avsforum.com/avs-vb/showthread.php?postid=4792867#post4792867

When you are closer in than 10 miles, the signal strength begins to decline significantly. In areas that are populated near the towers, broadcasters will use a trick called null fill to help those viewers out. If they didn't do that, there would be areas of NO reception (nulls).

The 1st post's PDF shows the angle of reception for the beam as you get closer to the tower. (At one mile the signal is coming down to you at about 11 degrees above the horizon for a 2000' tall tower.)

The 2nd PDF shows the beam's relative strength for a given depression angle. For my antenna, it's about one tenth of the main beam that is over your home but this antenna HAS null fill. This antenna also has a very small area where the beam just falls apart due to differential gain. That's the areas where the signal strength lines "break apart" like a string unraveling and then come back together at 10 or 11 degrees depression. Other antennas have huge areas, close in, where the diff. gain falls apart.

I don't know how the 43 and 39 antennas are built or how high they are above you. I do know that there is a very good chance that reflected signals (multi-path) are actually stronger than the direct signal from the antenna. I know that this is hard for a consumer to comprehend but it is true. At my transmitter site, I can receive ALL the other stations better than our own. Our station comes in best if I aim a directional antenna at one of the other towers. (We are all within a mile of each other in Houston.)

Attics attenuate the signal about 20 dB which means that you are receiving 1/100th of the signal in the attic as you would with the same antenna outside. The attic loss coupled with the low signal strength from the antenna puts you between a rock and a very, very, hard place.

If you can borrow a Wiengard Square Shooter (SS1000) from someone, it might be worth your while to see if a roof mounted antenna would get both stations for you. The Square Shooter is about the size of a Direct TV sat dish. In fact, it comes with an adapter pipe to allow it to be mounted on the same mount. Few homeowner associations complain about this antenna.

Another suggestion would be to talk to the Director of Engineering at WATL. He is a very sharp guy and will have the "local" knowledge that few on the forum will have.

Bob Chase
KHWB

Thanks Bob for the detailed explanation. I understand completely what you are talking bout. It makes perfect sense that my location may cause my signal to be coming in from directions besides directly from the tower, so I can see that making such a shield could prove fruitless. FWIW, the "43" antenna is the only one that is in the attic. It is a simple Radio Shack "double bowtie" indoor antenna. The a antenna that I use to pick up "39", and all of the other UHF stations, is a Wineguard PR4400, mounted to a mast on my roof. The PR4400 is aimed due north: there are several towers about three miles away north of me, "39" which is a mile away NW, and another that is less than a mile, ENE. The "43" station, however, is SW of me, and I got NOTHING from it with the PR4400, which is why I added the other antenna & Jointenna. Throughout the summer, I've had excellent reception with this setup: 90s or more on most of my stations (with the exception of the ENE station, which is in the 60s-70s, but it's mostly good enough). In fact, both 39 and 43 were very consistently 92 or better. But now, 39 ranges from being fine, around 90 at some times of the day, to having wild fluctuations, sometimes dipping to 0. It's clear that multipath through the second (indoor) antenna is the culprit, as all I have to do is unplug it's input from the jointenna, and 39 jumps back up to a solid 92-95.

So at this point, based on your input, I'm not going to try the shield, at least not yet. I'm going to get another rat-shack variable attenuator to put on the 2nd antenna, to see if I can find a balance point that reduces it's signal enough that 39's signal through that path isn't strong enough to interfere with the signal through the main antenna, yet still let enough signal through for 43 to still be received. As I said, I had tried that before with little luck, but that was with the previous receiver. Things DID seem to improve when I got the TiVo, so perhaps I'll have better luck finding a balance point. I can't help but wonder if a second jointenna, tuned to the same channel, and wired in series, wouldn't help, as I would think that it would cause more attenuation of 39 than 43, that's really more money than I want to spend at this point, since it's really a temp solution now anyway. If I could home-build a high pass filter that would attenuate 39 more than 43, that might also be a good solution, though I've not found any good guides on doing so.

So now that I'm totally hooked on HDTV, I've been trying like heck to get FOX - Channel 6 to come in. I do have a conventional antenna that was working OK. Was able to get all the stations except Channel 6.

So I went out and purchased a Zenith "HDTV antenna" from a local Big Box retailer. That helped get me Chaneel 6 but signal still very weak, drops out. Also, I now can not pick up Channel 58. So, I tried using the antennas in parallel. I know bad idea, don't laugh.

I do have a RCA 25dB amplifier to bost the single from the antenna.

BTW, the antennas are in the garage attic, east side of house. I live Nothwest of the stations, about 20-25 miles. So, antennas have a straight line of sight to TV stations. Area is very flat with no obstructions.

HDTV receiver is the one from DISH network.

Help!!! Thanks!!

Here in Las Vegas, we have 5 VHF digitals, the most in the country. In fact, the entire high VHF band is on the air with analog and digital signals! It sucks!

Originally posted by nuevo_eph
Would it be silly to attach a NICE Winegard or CM UHF (or AntennasDirect) bay-style antenna with a cheap-o Radio Shack U/V/FM antenna?

No. Not at all. Separate them by at least 48 inches if you can (even more if you have VHF channels in 2-6 range).

Originally posted by Darin
Background:

I live in town, and my towers are in all different directions from me. This causes series issues with multipath. There are two towers, about 90° apart from one another from my location, that give me a lot of headaches: one on Ch. 39, the other on ch. 43. Both of these towers are only about a mile away. 39 is closer to the same direction of many of my other towers as 43, and I'm able to pretty much get all my stations from one antenna aimed at a compromise between them. To get 43, I had to get a second antenna, placed in my attic, aimed specifically at that tower, with the signal combined with a Jointenna specifically tuned for ch. 43. The problem is, ch. 39 and 43 are close enough frequency-wise that the filters in the jointenna don't quite have enough attenuation to keep them from interfering: I'm getting multipath on ch. 39 that is being received by the antenna aimed at 43, and not filtered enough by the jointenna to prevent disruption of my signal. I had tried a variable attenuator on the second antenna, hoping to be able to attenuate the signal enough to prevent the secondary 39 signal interfering with the primary signal, while still allowing enough of the 43 signal to get through, but I could never get a sweet spot that made both reliable: too much attenuation, and 43 came in and out, too little, and 39 came in & out due to multipath.

Last year, I swapped out my Samsung TS160 receiver with an HD-TiVo, and suddenly the problem went away. I had to move the variable attenuator to the input of the HD-TiVo, because it was getting overloaded in general (not just on 43), but it SEEMED that I was suddenly getting perfect reception on both 43 and 39. I just assumed the tuners in the TiVo just handled multipath a little better than the Samsung.

A month or two ago, the problem re-appeared. Since I got the TiVo around June or so, I'm now thinking my sudden ability to get both at the same time may have at least been partially due to leaves on the trees partially attenuating the multipath signal from 39 to the second antenna. Since DirecTV will be carrying HD locals via sat, possibly this year, I don't want to sink much more money into my antenna set-up. But I would like to do what I can to improve the situation.

Question:

Since channel 39's tower is so close to me (I'd have line of sight from the secondary antenna if it wasn't for my roof, and possibly some trees), could I just get some aluminum screening, staple it up in my attic in a position that would disrupt line of sight from the secondary antenna, and ground it? Would that significantly reduce the signal being received by that antenna from that tower? Since the two towers are 90° apart, I'd have no problem locating the screen in such a way that it would completely block LOS from the one tower, while not coming close to obstructing LOS from the other. But since the antenna is in the attic, I'm not sure how "direct" reception is. I don't know if radio waves continue in a direct manner to the antenna, or if passing through the roofing causes significant scattering, thereby causing the signal to come in from many different directions (therefore, getting around my screen). And I don't know how effective a grounded screen would be at attenuating a signal from a certain direction.

Any suggestions are appreciated! :)

I'd suggest a rotor as the easiest solution and going back to one antenna.

Assuming you don't want to do that you could also get an adjustable notch filter to notch out the undesired signal. Winegard makes one as does Blonder Tongue (expensive). There are also fixed filters available for specified channels at http://www.tinlee.com/

The other thing you could do is get another identical Jointenna and run one or both in series to increase the depth of the notch on the undesired signal.

Thanks for the info cpcat. A rotor is out of the question, as it's no use with a TiVo. I didn't realize that Winegard made such filters... I see they have an adjustable one, but it's $50+. As I mentioned, I don't really want to spend much on this, as I should have the option of getting HD locals from DirecTV sometime this year. The tinlee site is great... all kinds of good stuff there, but I couldn't find any prices. Since much of that is custom, I have to assume it's at LEAST as much as the Winegard adjustable filter. I thought about doing the dual jointennas in series (see my previous post), but again, that's just a little more than I want to spend. The two channels in question are: ABC, and UPN (the one on the seperate antenna). The only thing I record off UPN is Star Trek, and that's getting cancelled anyway. Just seems kind of silly going through TOO much expense just to get the last few episodes. At this point, unless anyone has any other suggestions, it seems the most cost effective solution is to try the adjustable attenuator on my second antenna input. If I CAN'T find an attenuation level that cuts enough of 39, without reducing 43 too much, then I still have several options: take it back (rat shack is pretty good about that stuff), and simply disconnect my second antenna except on friday nights when I need to record enterprise (or until the leaves come back and the problem goes away), or leave the attenuator there, and adjust it back and forth on friday nights to shift the bias towards a stable UPN, and a stable ABC. And I suppose the other reason I'm leaning towards that is because there's a rat-shack a mile from my office. It's a relatively easy, low cost thing to try. :)

Originally posted by cheeseman
So now that I'm totally hooked on HDTV, I've been trying like heck to get FOX - Channel 6 to come in. I do have a conventional antenna that was working OK. Was able to get all the stations except Channel 6.

So I went out and purchased a Zenith "HDTV antenna" from a local Big Box retailer. That helped get me Chaneel 6 but signal still very weak, drops out. Also, I now can not pick up Channel 58. So, I tried using the antennas in parallel. I know bad idea, don't laugh.

I do have a RCA 25dB amplifier to bost the single from the antenna.

BTW, the antennas are in the garage attic, east side of house. I live Nothwest of the stations, about 20-25 miles. So, antennas have a straight line of sight to TV stations. Area is very flat with no obstructions.

HDTV receiver is the one from DISH network.

Help!!! Thanks!!

This post just merged in.

Originally posted by cheeseman
So now that I'm totally hooked on HDTV, I've been trying like heck to get FOX - Channel 6 to come in. I do have a conventional antenna that was working OK. Was able to get all the stations except Channel 6.

So I went out and purchased a Zenith "HDTV antenna" from a local Big Box retailer. That helped get me Chaneel 6 but signal still very weak, drops out. Also, I now can not pick up Channel 58. So, I tried using the antennas in parallel. I know bad idea, don't laugh.

I do have a RCA 25dB amplifier to bost the single from the antenna.

BTW, the antennas are in the garage attic, east side of house. I live Nothwest of the stations, about 20-25 miles. So, antennas have a straight line of sight to TV stations. Area is very flat with no obstructions.


First thing I'd try is get rid of the RCA amplifier. It's probably causing more problems for you than it solves. If that doesn't help, read on...

You probably need to get a "real" antenna, and not a gimmicky or gadget antenna. Most people here have had a lot of success with 4-bay and 8-bay bowtie style antennas like the Channel Master 3021, 4228, Winegard PR4400 and PR8800 and the Antennas Direct DB4 and DB8. Any of these should beat any antenna you purchase at Best Buy.

Indoor placement of antennas is generally bad. You should be able to get away with it as close as you are to the stations, but just know that part of your problem is that the antenna isn't "free and clear" of man-made structures.

Originally posted by cpcat
No. Not at all. Separate them by at least 48 inches if you can (even more if you have VHF channels in 2-6 range).

How will my performance w/ the UHF channels change going from just a great UHF to a bay UHF plus the UHF signal in the Radio Shack combo antennas? Will it be worse or better?

I should just ask all the EE's I work with (we design and run the VLA, seen in Contact). I guess if they can design equipment to receive and decipher radio signals from space, this shouldn't be too hard ;)

I finally got my new antenna, CM 4228 and CM 7777 preamp. I have a question on how I should hook up the preamp. I have voom (atleast for now it may shut down soon) and my reciever powers some antennas. I have a diplexer on the roof, then one coax coing into the house, then another diplexer in the house which splits the signal back into antenna and satellite signals. My question is where do I put the power supply for the preamp. I originally had it between the coax from the second diplexer from the ant jack then into the tv. Then I changed it to before the diplexer (I had the single coax coming into the house plugged into the power supply then out of the power supply into the second diplexer). This gave me the best ant picture but I could not get any satellite channels at all. So where do I put the power supply? Someone told me that the sat reciever should power the preamp since the diplexers are power passing, but I don't know if this is as good as the power supply that came with the preamp.

Originally posted by nuevo_eph
How will my performance w/ the UHF channels change going from just a great UHF to a bay UHF plus the UHF signal in the Radio Shack combo antennas? Will it be worse or better?

You need to use an antenna joiner/combiner that has separate UHF and VHF inputs. The Channel Master 7777 preamplifier is one such combiner, but if you don't need amplification, part number #0549 is the one you need. It filters out the UHF from the combo antenna, and filters out the VHF (yes, there is some) from the UHF antenna.

wow, that is the best solution I could have asked for. Thanks.

Originally posted by VMsat
I finally got my new antenna, CM 4228 and CM 7777 preamp. I have a question on how I should hook up the preamp. I have voom (atleast for now it may shut down soon) and my reciever powers some antennas. I have a diplexer on the roof, then one coax coing into the house, then another diplexer in the house which splits the signal back into antenna and satellite signals. My question is where do I put the power supply for the preamp. I originally had it between the coax from the second diplexer from the ant jack then into the tv. Then I changed it to before the diplexer (I had the single coax coming into the house plugged into the power supply then out of the power supply into the second diplexer). This gave me the best ant picture but I could not get any satellite channels at all. So where do I put the power supply? Someone told me that the sat reciever should power the preamp since the diplexers are power passing, but I don't know if this is as good as the power supply that came with the preamp.
The DC power to the antenna can't be sent through a line shared with a satellite signal since it will interfere with the DC voltage sent by the receiver to control the LNB.

There are amplifiers intended to be powered by the DC power of the satellite receiver -- I'd really not try this unless it explicitly said it was usable this way; I don't know how much current is available from the satellite receiver, and the receiver itself will vary the voltage between 13vDC and 18vDC which some preamps may not handle properly.

But the way you would do it is use a diplexer at the antenna which passes DC voltage on both sides. The Terk diplexers do it; others are available too, though the more common variety blocks DC voltage on the antenna side.

For your setup you need to get the power inserter connected inline between the antenna and that diplexer you have outside; which generally means you need to find a way to loop that run into the attic or somewhere else in the house where you can place the power inserter, since it's not weatherproof.

Originally posted by nuevo_eph
How will my performance w/ the UHF channels change going from just a great UHF to a bay UHF plus the UHF signal in the Radio Shack combo antennas? Will it be worse or better?

I should just ask all the EE's I work with (we design and run the VLA, seen in Contact). I guess if they can design equipment to receive and decipher radio signals from space, this shouldn't be too hard ;)

None of the UHF signals from the combo antenna will be present if your system is properly diplexed. The CM 7777 preamp has an internal diplexer and most any uhf/vhf preamp with separate inputs should have one. You can also diplex the signal separately before amplification if you need to with a diplexer such as the CM 0549: http://www.starkelectronic.com/cmjoiner.htm
or pico makes a good one as well:
http://www.picomacom.com/specs/pico/C/C24.pdf

Getting the separate diplexer should only be necessary if you are using a preamp with a single uhf/vhf input.

Originally posted by VMsat
I finally got my new antenna, CM 4228 and CM 7777 preamp. I have a question on how I should hook up the preamp. I have voom (atleast for now it may shut down soon) and my reciever powers some antennas. I have a diplexer on the roof, then one coax coing into the house, then another diplexer in the house which splits the signal back into antenna and satellite signals. My question is where do I put the power supply for the preamp. I originally had it between the coax from the second diplexer from the ant jack then into the tv. Then I changed it to before the diplexer (I had the single coax coming into the house plugged into the power supply then out of the power supply into the second diplexer). This gave me the best ant picture but I could not get any satellite channels at all. So where do I put the power supply? Someone told me that the sat reciever should power the preamp since the diplexers are power passing, but I don't know if this is as good as the power supply that came with the preamp.

The CM 7777 runs on +18V DC. Get a voltmeter and measure what's being supplied by your VOOM receiver. If it's between +12 to +24 Volts DC you should be fine to use the power from the receiver. I've used 12 volts on the CM 7777 and it works fine. I've also powered two 7777's simultaneously from a single power supply and it works fine.

If it's not too much trouble, you might consider running a separate downlead for the antenna to bypass the satellite diplexer completely. In this case, the CM power supply would go inside next to the receiver.

Does anybody have experience with this antenna? I put it up recently and
am having problems with one channel--51. I read a comparison of antennas and this antenna was rated highly, but with a caveat--it is a dog on channels above 50. There is another channel in my area coming on line
at 55 (the other channels are all 14,16, and 27 and they come in fine).
Since I am having problem with 51 and will have 55 to deal with in a month or so I am thinking I may need to try another antenna. My zip code is
36092 and antenna web shows I need a medium directional antenna.
I have the Channel Master 7775 pre amp that I am currently using and will be using on a new antenna if I go that direction (all my digitals are UHF--if any migrate to VHF in a few years I'll deal with that then). What is considered the best yagi or yagi style antenna for my situation? The area is fairly flat and there are no big obstructions between me and the towers
(the closest is about 14 miles away and the furtherest is about 50 miles away--that station is full power and I can get it indoors with the silver sensor antenna--but I need an outdoor antenna to get all the channels).
What about the antennas on antennas direct?

The 7777 runs on 24VDC.

At what length cable run should I expect to need a preamp? I just bought a DB4. When it is connected to a 30 ft piece of coax and sitting in the window of my living room I'm able to pull in all my stations, including the two low power ones 67 miles away. These are the ones I want to receive. When I move the antenna to where the diplexer is located outside I get almost nothing on the signal strength meter. The cable run is about 100-120' (I think) The antenna is pointed the same direction and the closer stations still come in. Will a preamp help me?

Chris

Whenever a diplexer is added into the mix and signal is lost, the first thing I suspect is a bad diplexer. I'd try bypassing the diplexers and check antenna signal with the dish temporarily disconnected first. Bad diplexers occur all too frequently.

Originally posted by greywolf
The 7777 runs on 24VDC.

I assume you mean it *will* run on +24V DC. The power supply that come with it is +18V DC. See http://www.channelmaster.com/home.htm
and go to "products", then "amplifiers", then "Titan" and look at the last bulletted item.

I've measured it as well, and it's right on +18 V or pretty close.

Then something happened. I remember the one I had a couple of years ago registered 24VDC on my voltmeter. I went through a whole rigamarole trying to find out if the Terk BMS-58 actually output the correct voltage with sufficient power from its UHF/VHF connector to power a multiswitch. That included measuring the voltage on my 7777's power supply to see if it matched the Terk's 24VDC spec and amp capacity. It did, but the Terk didn't output anything.

On the other hand, I must admit that the number of experiments I've done with stuff has exceeded my capacity to remember them all and I've been dead sure about things before that I've been dead wrong about. The published specs on the 7777 at other url's I've seen do not include voltage. I've got to wonder if the power supplies have varied.

Originally posted by greywolf
Then something happened. I remember the one I had a couple of years ago registered 24VDC on my voltmeter. I went through a whole rigamarole trying to find out if the Terk BMS-58 actually output the correct voltage with sufficient power from its UHF/VHF connector to power a multiswitch. That included measuring the voltage on my 7777's power supply to see if it matched the Terk's 24VDC spec and amp capacity. It did, but the Terk didn't output anything.

On the other hand, I must admit that the number of experiments I've done with stuff has exceeded my capacity to remember them all and I've been dead sure about things before that I've been dead wrong about. The published specs on the 7777 at other url's I've seen do not include voltage. I've got to wonder if the power supplies have varied.
It could just be the classic unregulated power adapter, requiring a load in order to actually see the real voltage it's going to put out. I just checked my power inserter and if it's labeled, it's on the underside and I have it screwed to a rafter so I'd have to unscrew it to confirm.

I did notice the Terk BMS-58 power adapter is labeled as 24VDC, so perhaps you're just remembering that.

Originally posted by cmassa
At what length cable run should I expect to need a preamp? I just bought a DB4. When it is connected to a 30 ft piece of coax and sitting in the window of my living room I'm able to pull in all my stations, including the two low power ones 67 miles away. These are the ones I want to receive. When I move the antenna to where the diplexer is located outside I get almost nothing on the signal strength meter. The cable run is about 100-120' (I think) The antenna is pointed the same direction and the closer stations still come in. Will a preamp help me?

Chris

Yes, most likely. The only way it could hurt is if you have a full power station within 30 miles or so which might overload it. Multipath problems can be made worse with a preamp as well, but likely at greater distances that won't be the major problem. UHF attenuates much quicker than VHF but over 100 ft of cable run it should help both. Can't beat the CM 7777 but if you have concerns with overload from a close station you might consider one with less gain.

Originally posted by dswallow
It could just be the classic unregulated power adapter, requiring a load in order to actually see the real voltage it's going to put out. Bingo! It was unloaded when I checked it. It's not the dumbest thing I've ever done but it's not far off. It's not like I didn't know voltage needs to be measured under load. It's kind of comforting to have an explanation though.

My CM7777 power supply gives me 23V. Does anyone make a UHF/VHF combiner with DC pass on 2 ports? I want to couple my Research Communications UHF-only amp with a 7777 for VHF using seperate VHF and UHF antennas and only one downlead.

Originally posted by gfgray
Does anyone make a UHF/VHF combiner with DC pass on 2 ports?
I don't know if that's possible, or at least practical. DC pass on both ports would mean that the two ports are electrically tied. That makes having the two ports RF separated more difficult.

Why not use the CM7777 for both UHF and VHF? It's a perfect fit for a 2 antenna system..

I have a Square Shooter for my OTA stations. As you are aware it is a
UHF antenna. Question? If I split the RG6 at the receiver and use it
for FM radio frequencies will the Fm stations be received from the
UHF antenna. I am presently not using my tuner but would like to set
it up. My HT is in the basement and naturally the shot wire antenna sent with the Yamaha won't receive but a couple of ststions. The square shooter
is mounted on the roof of the house.

The Research Comms preamp has a 0.4 dB noise figure compared to 7777's 2.0 dB nf. I may just have to run another cable or build my own filter.

Originally posted by gfgray
My CM7777 power supply gives me 23V. Does anyone make a UHF/VHF combiner with DC pass on 2 ports? I want to couple my Research Communications UHF-only amp with a 7777 for VHF using seperate VHF and UHF antennas and only one downlead.

Yes.
http://www.tinlee.com/
You'll have to specify when you order that you want DC pass on both.
DC is 0 Hz so I don't think it's that big of a deal to do.
I have a low band vhf/high band + uhf diplexer from them which passes DC on both legs and it works well.

You'll not see any improvement using the RC amp though, or at least that's my experience. The CM 7777 is slightly better for both VHF and UHF. The RC amp is very prone to FM overload so you may need an FM trap as well if you're going to try it. Also, the RC amp will amplify both vhf and uhf, although it's advertised only for uhf. This is likely why it's so sensitive to FM.

Both the 7777 and the RC amp will work fine off the CM power supply. The RC is actually spec'd to work from between +7.5 to +30 V DC.

Originally posted by citico
I have a Square Shooter for my OTA stations. As you are aware it is a
UHF antenna. Question? If I split the RG6 at the receiver and use it
for FM radio frequencies will the Fm stations be received from the
UHF antenna. I am presently not using my tuner but would like to set
it up. My HT is in the basement and naturally the shot wire antenna sent with the Yamaha won't receive but a couple of ststions. The square shooter
is mounted on the roof of the house.

Yes, the square shooter will probably pass enough of the FM signal to give you good FM reception.

Alternatively, you could use a Wiengard CA-8800 to separate out the FM signals from the VHF/UHF signals and save 3 dB. The CA-8800 looks like a splitter but all the FM is directed to one output port and all of the TV band is directed to the other port.

Bob Chase

Originally posted by bobchase
Yes, the square shooter will probably pass enough of the FM signal to give you good FM reception.

Alternatively, you could use a Wiengard CA-8800 to separate out the FM signals from the VHF/UHF signals and save 3 dB. The CA-8800 looks like a splitter but all the FM is directed to one output port and all of the TV band is directed to the other port.

Bob Chase

Pretty cool. Here's a link to info on this device: http://www.winegard.com/offair/separatorsjoiners.htm
it's at the bottom of the page.

You want long distance UHF reception? Does 65 miles sound
too restrictive for you? How about DX'ing for *470,000 miles*?

http://internal.physics.uwa.edu.au/~agm/eme.html

That, folks, is DX!!!

Gilbert

Bob and CpCat: Thanks for the information. Will order one this week.
I knew that someone would be able to help me. Exactly what I was looking
for.

Thanks Again,

It isn't so much a matter of an antenna "passing" an out of band signal as it is a matter of "developing" it. The elements in a Square Shooter are not tuned for reception in the FM band. That will be one major impediment to it developing an FM signal. If there is any kind if an internal highpass filter in the Square shooter, that would be another impediment.

Before you buy a CA-8800 diplexer, you might as well try connecting the Square Shooter antenna downlead directly to the FM tuner input to see whether you are satisfied with that reception.

You can buy either of two Winegard FM antennas that would be substantially superior to whatever FM comes out of a Square Shooter for about $20. If you are restricted to using the single coax downlead, you could combine that FM antenna lead with the Suqare Shooer lead using a hi-lo signal joiner, commonly designated as HLSJ. For that matter, anyone who wants to effieciently separate FM from UHF and VHF highband could use that same part and save about ten bucks.

AntAltMike: I followed your suggestion and hooked up the antenna from the square shooter to the receiver(don't know why I did not do this before)
but it involved moving equipment etc. Any way the FM reception was terrific.
Will also check out the HLSJ.

Thanks to All

Ed

how much of a difference could i possibly see in quality and stability in the winegard AP- series antenna pre-amps compared to my radio shack mast mount pre-amp inside power amp setup? the noise factor on my radio shack setup is 4.5 db the winegard that i'm looking at says it's 2.9db.

thanks in advance

sony 46" hdtv
samsung T451 HD receiver
radio shack VU-90 antenna ( 25 ft in the air )
radio shack mast mount pre amp and matching indoor power amp
GI 2750 c/Ku satellite receiver
dsr 905 sidecar DC2 satellite receiver

oh,and alot of headaches cause wife can't watch some of her shows without breakup of hdtv video :o(

Originally posted by AntAltMike

You can buy either of two Winegard FM antennas that would be substantially superior to whatever FM comes out of a Square Shooter for about $20. If you are restricted to using the single coax downlead, you could combine that FM antenna lead with the Suqare Shooer lead using a hi-lo signal joiner, commonly designated as HLSJ. For that matter, anyone who wants to effieciently separate FM from UHF and VHF highband could use that same part and save about ten bucks.

Are you sure a hi-lo diplexer passes UHF through the hi port? I thought it passed hi band vhf but filtered out uhf.

The one I have from Pico also seems to filter at least some of the FM band through the low port.

Originally posted by dapack5
how much of a difference could i possibly see in quality and stability in the winegard AP- series antenna pre-amps compared to my radio shack mast mount pre-amp inside power amp setup? the noise factor on my radio shack setup is 4.5 db the winegard that i'm looking at says it's 2.9db.

thanks in advance

sony 46" hdtv
samsung T451 HD receiver
radio shack VU-90 antenna ( 25 ft in the air )
radio shack mast mount pre amp and matching indoor power amp
GI 2750 c/Ku satellite receiver
dsr 905 sidecar DC2 satellite receiver

oh,and alot of headaches cause wife can't watch some of her shows without breakup of hdtv video :o(

Noise is the enemy. The CM 7777 has 2.0 db noise on the UHF and should be a noticeable difference. Check link under noise.
http://www.hdtvprimer.com/ANTENNAS/basics.html

I`ve had a big antenna and a Wine-guard antenna and I can only pick one ota channel. I`ve did the antenna-web thing and that didn`t help. My zip-code is 39465. I did get 4 of them before. I haven`t try-ed any with a amplifier though. Which antenna or amplifier would you recommend? I`m thinking about trying the square-shooter antenna. The furtherest tower away is I think about 70 miles away.

Originally posted by gjp33usa
I`ve had a big antenna and a Wine-guard antenna and I can only pick one ota channel. I`ve did the antenna-web thing and that didn`t help. My zip-code is 39465. I did get 4 of them before. I haven`t try-ed any with a amplifier though. Which antenna or amplifier would you recommend? I`m thinking about trying the square-shooter antenna. The furtherest tower away is I think about 70 miles away.

You said you got 4 channels before. Before what? What changed?
To have a shot at the furtherest signals you are going to need a pre-amp on a large (medium for most) directional antenna. What antenna do you presently have? If you have the right antenna, try it with a pre-amp such as the Channel Master 7777. (It is very doubtful that the Square Shooter will pull in a signal from 70 miles away). If you need a new antenna you could go with something like the Channel Master or Winegard 8 bay or
one of the antennas from antennasdirect.com. I'm not an expert at all, so
I'm sure some other will offer more antenna choices. But, you may have all you need except for the pre-amp (according to antennaweb.org you should be able to receive several channels without a pre amp).

Originally posted by gjp33usa
I haven`t try-ed any with a amplifier though. Which antenna or amplifier would you recommend?

You're too close to some of the stations (the zip code return says 4 miles to two UHF stations) to be able to use an amplifier effectively unless you filter out the local stations. I'd recommend against an amplifier.

The SquareShooter is not a good long-range antenna. It's good for 25-35 miles under normal conditions, but then it's just not a strong performer. It's an "urban/suburban" antenna.

For long range reception, either an 8-bay bowtie antenna (CM4228) or a very big yagi (AntennasDirect91XG) is a good idea. You can read my results here:
www.geocities.com/figbert/antennasdirect91xg.html

Originally posted by gjp33usa
I`ve had a big antenna and a Wine-guard antenna and I can only pick one ota channel. I`ve did the antenna-web thing and that didn`t help. My zip-code is 39465. I did get 4 of them before. I haven`t try-ed any with a amplifier though. Which antenna or amplifier would you recommend? I`m thinking about trying the square-shooter antenna. The furtherest tower away is I think about 70 miles away.

Assuming you gace the correct zip here's the digital only stations in your area.
* yellow - uhf WHLT-DT 58 CBS HATTIESBURG MS Currently Not Available 337° 4.0 58
* yellow - uhf WDAM-DT 7.1 NBC LAUREL MS 328° 8.3 28
* blue - uhf WLOX-DT 13.1 ABC BILOXI MS 170° 44.0 39
* violet - uhf WMAH-DT 16.1 PBS BILOXI MS 159° 44.1 16
Note:
Looks like no FOX but all the major networks shouldn't be a problem. If you are going only for the digitals the furtherest is 44 miles WMAH and WLOX. If antenna web says you can get these then they should be easy. I'd start from scratch run new cable etc. As serenger said no booster for you're too close to other stations. You may have a bad connection broken wire etc. If you have received these before then something else has gone wrong. You said you tried other antennas . Did you use the same lead in? I assume you have a rotor for the direction of each station is different. DT 16 and 39 is S to SE and DT 28 and 58 are almost 180 degrees the other direction.

i see most all the recommendations in here are for the cm 7777,and from all i have read on the specs on the web,it seems to be highly recommended.
now,my question is this, ( since i have a chance to pick one up for next to nothing ) how do these compare with the CM-7777

1: CM 3041DSB
2: Winegard AP-8275
3: Winegard AP-8283
an out of business local shop owner says he has a couple of these,never gave me a price yet,but,said he would let them go cheap says these still list for $59.00 to $89.00 and then the line but of course that isn't what you would pay for it.
i'm looking for something better than my radio shack model that just isn't up to snuff,works but not very well

Without factoring in terrain, buildings, etc. What is considered a powerful station and how does station power relate to signal reception? The station I am having trouble receiving transmits at 37. kw according to the FCC site. I am 15 miles from transmitter, but do not have line of sight with the tower.

Thanks

I am in 33327. To the north 32 miles is West Palm Beach, to the south east at 16 miles is Miami/Fort Lauderdale. The angle between each antenna farm is about 95 degrees. There are two VHF-high (8 and 13) channels in the Miami farm. I want to do an attic install so I don't lose it during hurricane season.

I've noticed that the more powerful the antenna, the narrower the beamwidth. I don't want to connect a rotor (not wife-friendly) so two antennas might be a possibility or else something like the CM2001 which is LD plus a pre-amp.

I would appreciate any pointers from people who have a similar setup. I have an RS 15-1880 right now which is omni but I have to point towards multipath to get the VHF stations so this solution is only temporary.

Cheers,
Tony

Originally posted by shajoe44
Without factoring in terrain, buildings, etc. What is considered a powerful station and how does station power relate to signal reception? The station I am having trouble receiving transmits at 37. kw according to the FCC site. I am 15 miles from transmitter, but do not have line of sight with the tower.

For low VHF (2-6), 12.5kw is full power.
For high VHF (7-13), about 60kw is full power.
For UHF (14+), 1000kw is full power.

At 15 miles, you should be able to get a 37kw station, though I doubt you'd get a .37kw station, even without line-of-sight.

I get a 6kw station at 40 miles, with no line-of-sight, though it isn't always there. (Sometimes the lock comes and goes.)

Originally posted by dapack5
how do these compare with the CM-7777

1: CM 3041DSB
2: Winegard AP-8275
3: Winegard AP-8283


Not familiar with item #1 above.

#2 and #3 are identical except for their inputs - the 8283 takes 300-Ohm (twin-lead) wire, and the 8275 takes 75-Ohm (coax) in.

The Winegards probably have a little bit more noise. I've read that they are less prone to overload than the Channel Master. I use a Winegard, and am very satisfied with it.

If you get a low-noise-figure (<3db) preamp, which I know the Winegards are, you should see a difference from your Radio Shack preamp.

The CM 3041DSB is the one sold at our local Fry's (http://www.channelmaster.com/Pages/TVS/SpartanAmp.htm). They don't have the CM7777. It looks like it's not as good (http://www.channelmaster.com/Pages/TVS/SpartanAmp.htm) as the 7777 (http://www.channelmaster.com/Pages/TVS/TitanAmp.htm), but would it be worth it (I'd like to be able to take it back if it doesn't help)?

Xesdeeni

Originally posted by Xesdeeni
...but would it be worth it (I'd like to be able to take it back if it doesn't help)?
[/B]

Honestly, .2db of noise isn't going to make or break you, which appears to be the difference between the two CM models on UHF.

As to whether or not a preamp would help you, that's a complicated question made even more complicated by the fact that I don't know your location or your situation. But hey, if you can take it back if it doesn't work, what do you have to lose besides a couple of hours time?

I didn't want to go into the details and bore you :-)

I get good reception most of the time, but on some days, on some channels, I get breakups. I just want to max out my signal strength. Two different amps, I've now discovered are really distribution amps, didn't make a difference, although I've left them in because the antenna feeds multiple tuners. (At one point, a month or so back, I lost one channel, like a select few viewers in my area (DFW), but the station was able to finally isolate the problem and fix it--but it was a S:N issue, that I might have avoided with an amp?)

Ideally I'd add a 7777, but since I have to mailorder, if it doesn't help, it'd be a pain to return. The 3041DSB is returnable, but installation will be a PITA, so I wanted be sure I could reasonably expect something, before I went to the trouble.

Xesdeeni

Originally posted by Xesdeeni
I get good reception most of the time, but on some days, on some channels, I get breakups. I just want to max out my signal strength.

You still haven't told me how far you are from the stations. As a general rule, if you're less than 25 miles, an amplifier is a bad idea. If you're over 25 miles away from all of your television stations, it's worth trying.

If you have a 300 ohm antenna (and most of them are), then the 300 ohm input models (i.e. CM Spartan) are 1-2 dB better than the 75 ohm input models (i.e. CM Titan CM777).

The Spartan models specify a 2.2 dB Noise Figure, which includes the loss in the internal balun transformer. The Titan models specify a 2.0 dB Noise Figure, which will be degraded by the external balun transformer (about 1-2 dB in the CM Balun).

Originally posted by sregener
You still haven't told me how far you are from the stations. As a general rule, if you're less than 25 miles, an amplifier is a bad idea. If you're over 25 miles away from all of your television stations, it's worth trying. 35.9-38.2 miles, but the (CM3018) antenna is inside the attic.Originally posted by holl_ands
If you have a 300 ohm antenna (and most of them are), then the 300 ohm input models (i.e. CM Spartan) are 1-2 dB better than the 75 ohm input models (i.e. CM Titan CM777).

The Spartan models specify a 2.2 dB Noise Figure, which includes the loss in the internal balun transformer. The Titan models specify a 2.0 dB Noise Figure, which will be degraded by the external balun transformer (about 1-2 dB in the CM Balun). So since my antenna is a 300-ohm, the CM3041DSB is really the same or better than the 7777? Sweet!

Thanks for the great help!

Xesdeeni

Originally posted by AntAltMike
It isn't so much a matter of an antenna "passing" an out of band signal as it is a matter of "developing" it. The elements in a Square Shooter are not tuned for reception in the FM band. That will be one major impediment to it developing an FM signal. If there is any kind if an internal highpass filter in the Square shooter, that would be another impediment.

Before you buy a CA-8800 diplexer, you might as well try connecting the Square Shooter antenna downlead directly to the FM tuner input to see whether you are satisfied with that reception.

You can buy either of two Winegard FM antennas that would be substantially superior to whatever FM comes out of a Square Shooter for about $20. If you are restricted to using the single coax downlead, you could combine that FM antenna lead with the Suqare Shooer lead using a hi-lo signal joiner, commonly designated as HLSJ. For that matter, anyone who wants to effieciently separate FM from UHF and VHF highband could use that same part and save about ten bucks.

Whether on a mast or in the attic, the square shooter "develops" FM stations as good as it does the high-band TV signals. Additionally an FM receiver requires significantly less signal for full quieting than a TV receiver does. What that means is, the square shooter makes a good FM antenna for the stations it is aimed at.

In fact, compared to the Houston digital TV stations I have measured with the square shooter, the FM station levels are right in the middle of the UHF levels.

Bob Chase
KHWB-TV

Originally posted by Xesdeeni
35.9-38.2 miles, but the (CM3018) antenna is inside the attic.So since my antenna is a 300-ohm, the CM3041DSB is really the same or better than the 7777? Sweet!

Thanks for the great help!

Xesdeeni

The other advantage (maybe even more important) is that the CM 3041 has less gain on both vhf and uhf and at your distance that's probably good as you'll be less likely to run into any overload problems. It also has just a single combined uhf'vhf input whereas the CM 7777 has both combined and separate. Doesn't sound like you need separate inputs with the combo antenna.

Originally posted by bobchase
Whether on a mast or in the attic, the square shooter "develops" FM stations as good as it does the high-band TV signals.

Just looking at the frequency maps, wouldn't the Square Shooter 'develop' FM stations as well as it does the low-band TV signals? Channel 6 ends at 88Mhz, the start of the FM range. Channel 7 starts at 175 Mhz, well above the top of the FM broadcast range.

I could use some expert advice. I live in a very bad reception area: tall trees to the SW and S of me (towards most of the towers), and the distance of the towers range from 2-49 miles (with hills in the way). I have no direct line of sight to any of the towers (due to trees and high hills). Directions range about 160 degrees to the several towers.
Do I have a prayer for getting any OTA reception? And if so, what kind of equipment do I need?

Thanks,
Mike52

Originally posted by Mike52
I could use some expert advice. I live in a very bad reception area: tall trees to the SW and S of me (towards most of the towers), and the distance of the towers range from 2-49 miles (with hills in the way). I have no direct line of sight to any of the towers (due to trees and high hills). Directions range about 160 degrees to the several towers.
Do I have a prayer for getting any OTA reception? And if so, what kind of equipment do I need?

Yes, you have a prayer. It may not be much more than that, or it may be a lot more than that. But you'll definitely need a rotor - no antenna covers 160 degrees very well.

If you haven't read my 91XG story yet, it's probably a good place to start. I have line-of-sight to towers that are about 30 miles away. I don't have line-of-sight to stations any further than that, yet I get reception from over 80 miles away, given the right conditions.
http://www.geocities.com/figbert/antennasdirect91xg.html

Depending on how close those hills are and how tall they are, you'll either be fine or in a heap of trouble.

Just to clear up a possible misconception regarding preamps. The preamp is placed at or as near as practical to the antenna itself. It's purpose is raise the amplitude of weak signals to make up for the signal loss due to the length of the cable from the antenna to the receiver. The first RF stage in any receiver is beset by thermal noise. Desired signals must be strong enough to overcome this unavoidable phenomenon. The preamp simply brings weak signals up to a level that, after the loss in the antenna cable, is at a level sufficient to overcome the receiver's inherent noise. It is not noise picked up by the cable itself. Coax is well shielded, thus doesn't pick up significant noise normally. One caveat: if the signals at the antenna are particularly strong use of a preamp to further strengthen them could overload the receiver. In that case a preamp would not be used. What I do not know is if the power supply for the preamp failes or is purposly disconnected, will the preamp pass signals without significant loss. Can anyone answer that??

When the power is turned off, the preamps that I've used no longer pass any signals, except whatever may leak across at a much, much lower signal level.

The overall tuner sensitivity is measured by the Noise Factor (NF), which indicates how strong the minimum "acceptable" signal level is relative to the Thermal Noise Floor.

A typical Tuner has a NF of perhaps 7 dB (per ATSC recommendation) and a maximum NF of 14 dB (per FCC regulation). Any cable and RF Splitter loss between the Tuner and the antenna directly adds to the overall Noise Figure. So without a preamp, the overall system NF may be 10-20 dB.

When you add a preamp, the cable, RF Splitter and Tuner NF still contribute to the overall system NF, but the contribution is reduced by the amount of gain in the preamp. In most systems, this contribution is therefore reduced to only 1 or 2 dB. So with a preamp, the overall NF may be on the order of only 3-6 dB (1.5 dB if use external Balun, 2.0 dB if use CM7777, 1-2 dB after preamp). This is why a preamp is so important, unless nearby signals (less than about 5 miles) are expected to be a problem.

Originally posted by Tony Nx
One caveat: if the signals at the antenna are particularly strong use of a preamp to further strengthen them could overload the receiver. In that case a preamp would not be used. What I do not know is if the power supply for the preamp failes or is purposly disconnected, will the preamp pass signals without significant loss. Can anyone answer that??

Most preamps either won't pass a signal when unpowered or will severely attenuate it. If comparing between preamp and no preamp, always take the preamp/power supply completely out of the signal path.

*Preamp* overload is probably the more common problem with strong signals, although I have had receiver overload/interference occur especially with FM. Lower gain (<20db) preamps are less susceptible to overload (and would be less likely to overload the receiver) and can usually be used with long cable runs in medium signal strength areas, i.e. 30-40 mile range.

Originally posted by Tony Nx
What I do not know is if the power supply for the preamp failes or is purposly disconnected, will the preamp pass signals without significant loss. Can anyone answer that??

I contacted Channel Master a few weeks ago to ask this question. None of the Channel Master preamps pass signal when the power is removed.

i

Can an amplifier or pre-amp work around all signal-loss in a long cable run/splitter? Or will their always be loss. Can you buy a big enough amp to split a cable 4 ways with no problems? For example, I have a 50 ft. RG-6 cable that runs to my TV directly from the antenna. If I run that cable to the Television Box (where all the inhouse wires run in and out of, the total cabling will be about 125 ft. with a 4-way splitter (7db loss). Will an amplifier or pre-amplifier prevent that cable and splitter loss from being an issue or can noise overtake the signal even if amplified at the mast or directly after the mast (for a dist. amp)?

Originally posted by j_buckingham80
Can an amplifier or pre-amp work around all signal-loss in a long cable run/splitter? Or will their always be loss. Can you buy a big enough amp to split a cable 4 ways with no problems? For example, I have a 50 ft. RG-6 cable that runs to my TV directly from the antenna. If I run that cable to the Television Box (where all the inhouse wires run in and out of, the total cabling will be about 125 ft. with a 4-way splitter (7db loss). Will an amplifier or pre-amplifier prevent that cable and splitter loss from being an issue or can noise overtake the signal even if amplified at the mast or directly after the mast (for a dist. amp)?

If your signal is good at the distribution point already, just use a distribution amp placed in-line at that point. If you are > 35 miles from your closest full power station, consider using a preamp on the antenna and most likely it will provide the gain for distribution as well. Those of us who are in the fringe >65 miles out might actually require both if distributing to multiple sets, but I'd always use a preamp on the antenna first and then add the dist. amp only if needed.

Originally posted by j_buckingham80
Can an amplifier or pre-amp work around all signal-loss in a long cable run/splitter?

No, but it can offset a lot of it. If you have strong signals to begin with, you'll be fine. But if you're dealing with weak signals, even splitting the signal once could be enough to drop you below the noise floor.

I used to use a three-way splitter and some of my weaker stations wouldn't come in. I switched to a direct connection and they were much better. Granted, closer stations were just fine, no matter how many times I split the signal.

after much debating i decided to give this amplifier a try,needless to say i was less than impressed! i tried it with several different antennas and my radio shack unit out performed this one ( on all antennas ). so it's a trip back to the store and return it for a full refund! with my radio shack unit i can lock and hold channel 29 from west palm beach and i am 99 miles ( via driving ) from west palm and i also get cbs-4 from miami ( 149 miles away )
not all the time but just about all evening and into the late morning hours.

i may tru the 7777 unit after i get a little more cash flow.

how do i post a picture of my antenna so if anyone has one or more info on it,it can be passed along?

Originally posted by dapack5
how do i post a picture of my antenna so if anyone has one or more info on it,it can be passed along?You can post a picture by following the below specific directions.


Adding Images

To include a picture or graphic within the body of your message, you can simply surround the address of the image as shown here:

http://www.avsforum.com/avs-vb/images/avsforum-logo.jpg

Note that the http:// part of the image URL is required for the code.

You can even create a thumbnail-type hyperlink by surrounding your [img] code with a [url] code like this:

[img]http://www.avsforum.com/avs-vb/images/vb_bullet.gif (http://www.avsforum.com/avs-vb/images/avsforum-logo.jpg)

I did not successfully cut and paste in my previous post, so for complete directions you need to cursor down this page and click on IMG in box at lower left.

I had a chance to look today at my antenna( Channel Master 4228 8-Bay Bowtie UHF Antenna )installation that I had done in Feb. Coming from my antenna he has RG-59 inside to my (Channel Master 7777 VHF/UHF Preamplifier) than into a spliter to one TV using RG6 that is a short run and another that runs around 120 FT using RG-6 and on that run there is a double male connecting the cable. Why I don't Know. My question is going to effect any recption using two different types of cables and that he used a double male to connect one going to the other cable going to my other TV?

Thank You

Hi guys,

I got a new Pio plasma and hooked it up to the attic antenna (condo) I had installed when it was built about 15 yrs ago. I don't know what it is and haven't been up there yet to look.

I get from the high 70s to low 90s on sig strength screen, which is not easy to monitor when watching. I've seen some dropouts or freezes for up to a few seconds which I think *may* be associated with rain or possibly wind or fog(!)? When conditions are right for this, the signal goes down to 40 or 50 briefly. (Is it likely that this is multipath?)

This is what antennaweb shows:

DTV Antenna

* red - uhf WWJ-DT 62.1 CBS DETROIT MI 200° 14.1 44
* red - uhf WTVS-DT 43.1 PBS DETROIT MI 200° 14.1 43
* red - uhf WXYZ-DT 7.1 ABC DETROIT MI 218° 14.1 41
* red - uhf WKBD-DT 50.1 UPN DETROIT MI 230° 15.3 14
* red - uhf WDWB-DT 20.1 WB DETROIT MI 200° 14.1 21
* red - uhf WJBK-DT 2.1 FOX DETROIT MI 210° 13.9 58
* red - uhf WDIV-DT 4.1 NBC DETROIT MI 210° 12.3 45
* red - uhf WADL-DT 39.1 IND MOUNT CLEMENS MI 126° 12.9 39

From what I've read here, I get the impression that:

1. Multipath may be my problem vs. signal "strength".
2. An amp may cause a problem instead of solve it.

I haven't seen much about how directional antennas are and I wonder if I don't have a highly directional one, would one be likely to solve my problem since these stations that I'm interested in are within 30 deg?
(Any recommendations, assuming I can fit it in.)

Is there any easy way to verify the coax and connectors are good? (With ohm meter etc?)

Would it be foolish to try a preamp halfway between the antenna and TV, where I have a coupling for the coax already?

Thanks for any comments.

John

Originally posted by firemantom26
I had a chance to look today at my antenna( Channel Master 4228 8-Bay Bowtie UHF Antenna )installation that I had done in Feb. Coming from my antenna he has RG-59 inside to my (Channel Master 7777 VHF/UHF Preamplifier) than into a spliter to one TV using RG6 that is a short run and another that runs around 120 FT using RG-6 and on that run there is a double male connecting the cable. Why I don't Know. My question is going to effect any recption using two different types of cables and that he used a double male to connect one going to the other cable going to my other TV?I'm not sure if I'm envisioning this setup but if your reception has no problems I believe you're OK. If it were me, I'd change out that RG-59 to QS RG-6 but that's just me. The splitter is probably power passive on only one port so that amplification is just serving one tv, the long run one. The installer must have not had a long piece of cable so he spliced two with a double male. This will cause some signal loss but may be overcome by the pre-amp. Now perhaps an expert can chime in.

Originally posted by JLaamanen
1. Is it likely that this is multipath?

2. I haven't seen much about how directional antennas are and I wonder if I don't have a highly directional one, would one be likely to solve my problem since these stations that I'm interested in are within 30 deg?

3. Is there any easy way to verify the coax and connectors are good? (With ohm meter etc?)

4. Would it be foolish to try a preamp halfway between the antenna and TV, where I have a coupling for the coax already?


1. Probably. But diagnosing reception problems with digital meters is never easy. If you have UHF analog stations broadcasting from the same towers at the same relative power (take digital and multiply by 5 for analog equivalent) then watching them can tell you what the problem is. Does the picture get very snowy? Or do you get moving ghosts? The answer to that question will tell you the answer to your problem. Snow = weak signals. Ghosts = multipath.

2. 30 degrees is not a directional antenna. A directional antenna should have an acceptance angle of less than 10 degrees. Examples include the Channel Master 4228 and the Antennas Direct 91XG. Either of these would probably require a rotor.

3. If you're getting signals that are routinely in the 70s+, your coax is most probably good. If you consistently had problems above or below a certain frequency, things would be different.

4. Foolish? If you've got snow on the analog test in answer #1 above, no. If you've got any ghosting now or when you have issues, yes.

Originally posted by JLaamanen
Hi guys,

I got a new Pio plasma and hooked it up to the attic antenna (condo) I had installed when it was built about 15 yrs ago. I don't know what it is and haven't been up there yet to look.

I get from the high 70s to low 90s on sig strength screen, which is not easy to monitor when watching. I've seen some dropouts or freezes for up to a few seconds which I think *may* be associated with rain or possibly wind or fog(!)? When conditions are right for this, the signal goes down to 40 or 50 briefly. (Is it likely that this is multipath?)

This is what antennaweb shows:

DTV Antenna

* red - uhf WWJ-DT 62.1 CBS DETROIT MI 200° 14.1 44
* red - uhf WTVS-DT 43.1 PBS DETROIT MI 200° 14.1 43
* red - uhf WXYZ-DT 7.1 ABC DETROIT MI 218° 14.1 41
* red - uhf WKBD-DT 50.1 UPN DETROIT MI 230° 15.3 14
* red - uhf WDWB-DT 20.1 WB DETROIT MI 200° 14.1 21
* red - uhf WJBK-DT 2.1 FOX DETROIT MI 210° 13.9 58
* red - uhf WDIV-DT 4.1 NBC DETROIT MI 210° 12.3 45
* red - uhf WADL-DT 39.1 IND MOUNT CLEMENS MI 126° 12.9 39

From what I've read here, I get the impression that:

1. Multipath may be my problem vs. signal "strength".
2. An amp may cause a problem instead of solve it.

I haven't seen much about how directional antennas are and I wonder if I don't have a highly directional one, would one be likely to solve my problem since these stations that I'm interested in are within 30 deg?
(Any recommendations, assuming I can fit it in.)

Is there any easy way to verify the coax and connectors are good? (With ohm meter etc?)

Would it be foolish to try a preamp halfway between the antenna and TV, where I have a coupling for the coax already?

Thanks for any comments.

John

You need to get up there and take a picture of the antenna and post it here. At your distance, a CM 4221 should work and has a beamwidth of around 60 degrees. If you're already using something equivalent though, you'll have to go bigger. Sometimes attics can really block the signals. If you can't get the pic at least desribe what it looks like.

Thanks guys,

Good ideas.

I really should go up there and look, see and take a pic. Also setting up second tv for seeing ghosts vs. snow when it acts up.

(Or get cable :)

Thanks for ideas.

John

What do you think of the XG91 antenna for my situation?
WPXS 13 PAX MOUNT VERNON IL 351° 15.0 13
* lt green - uhf WSIU-DT 40.1 PBS CARBONDALE IL 233° 25.4 40
* blue - uhf WSIL-DT 3.1 ABC HARRISBURG IL 181° 49.5 34
blue - vhf WSIU 8 PBS CARBONDALE IL 233° 25.4 8
* violet - uhf WPXS-DT 21 PAX MOUNT VERNON IL TBD 296° 36.1 21
violet - vhf WSIL 3 ABC HARRISBURG IL 181° 49.5 3
violet - vhf KFVS 12 CBS CAPE GIRARDEAU MO 210° 71.0 12
violet - uhf KBSI 23 FOX CAPE GIRARDEAU MO 212° 73.9 23
violet - vhf KSDK 5 NBC ST. LOUIS MO 283° 80.5 5
violet - vhf WPSD 6 NBC PADUCAH KY 185° 78.8 6
violet - uhf WDKA 49 WB PADUCAH KY 184° 64.7 49
violet - vhf KTVI 2 FOX ST. LOUIS MO 281° 82.3 2
violet - uhf KDNL 30 ABC ST. LOUIS MO 284° 80.5 30
violet - vhf KPLR 11 WB ST. LOUIS MO 282° 78.2 11
violet - vhf KMOV 4 CBS ST. LOUIS MO 282° 78.2 4

Since I had Voom installed with their Winegard batwing antenna I always get ABC and PBS. The ABC station I get is 50 miles away.

A few times I've gotten FOx and CBS to come in, and they're 71 and 73.9 miles away. Would it be worth my effort to try the XG91 with an amplifier? I'd probably also find a way to mount it higher, too, since the Winegard is on a low part of the roof of my guest house (only about 10' high).

Finally, if I did use the XG91 and an amp, could I use the diplexor supplied by Voom to power the amp? The diplexor is made by Winegard and is 12V. Or should I just run a separate line?

Mainly I'm just wondering if it's worth my while to even try to pull in these distant locals. I'd really love to get them, though.

Thanks

Originally posted by sregener
2. 30 degrees is not a directional antenna. A directional antenna should have an acceptance angle of less than 10 degrees.
Wow, you have a high standard for what you consider a directional antenna!
Would you consider the Winegard PR-4400 to be not directional from this
plot (even though the beamwidth is around 30 degrees)?

http://www.hdtvprimer.com/ANTENNAS/w4400.html

Ron

Originally posted by ChrisDuncan
A few times I've gotten FOx and CBS to come in, and they're 71 and 73.9 miles away. Would it be worth my effort to try the XG91 with an amplifier? I'd probably also find a way to mount it higher, too, since the Winegard is on a low part of the roof of my guest house (only about 10' high).

Finally, if I did use the XG91 and an amp, could I use the diplexor supplied by Voom to power the amp? The diplexor is made by Winegard and is 12V. Or should I just run a separate line?

If you've gotten locks on Fox and CBS at 71 and 73.9 miles away with the "batwing" antenna, you've got an excellent chance of getting solid reception with the AntennasDirect 91XG under similar circumstances. (Note: Whenever receiving signals over the horizon, too many factors to list, including weather and humidity, tree foliage, topography, etc. come into play. One should never expect perfect, 100% reliable reception in such situations, but must take a "beating the laws of physics" approach, being grateful for what comes in.) If you were only getting those signals during strong tropospheric events, you might not be able to get them with any antenna.

If you haven't read my review of the 91XG, I strongly advise you to do so:
www.geocities.com/figbert/antennasdirect91xg.html

For what it's worth, I have gotten locks on stations as far as 89 miles away (reliable and consistent) with my 91XG, with no line-of-sight, and the transmitting station was only at 500kw. My terrain is hostile to reception, and this antenna still performs like a champ. I do not, however, get that station every time I point my antenna in that direction, and it does sometimes suffer from breakups and dropouts. My experience is not "normal" and no one should expect to get similar performance from this or any antenna due to the large variety of factors involved in reception.

I'd run a separate cable. Diplexers cost you some signal, even if they're "perfect", so if your goal is to get the best you can, you'll need that extra oomph of performance.

You'll also probably need a rotor, as the 91XG is very directional, unless all your channels that you want are within 20 degrees or so.

Originally posted by dr1394
Wow, you have a high standard for what you consider a directional antenna!
Would you consider the Winegard PR-4400 to be not directional from this
plot (even though the beamwidth is around 30 degrees)?

I do not consider the PR-4400 to be very directional. All antennas are "somewhat" directional, but when you're trying to eliminate multipath problems, you need a very narrow acceptance angle.

I get discernable differences in reception strength on local signals when I move my antenna 10 degrees. I get discernable differences in reception strength on distant (75 mile) signals with changes of 2 degrees. *THAT* is directional.

Originally posted by ChrisDuncan
What do you think of the XG91 antenna for my situation?
WPXS 13 PAX MOUNT VERNON IL 351° 15.0 13
* lt green - uhf WSIU-DT 40.1 PBS CARBONDALE IL 233° 25.4 40
* blue - uhf WSIL-DT 3.1 ABC HARRISBURG IL 181° 49.5 34
blue - vhf WSIU 8 PBS CARBONDALE IL 233° 25.4 8
* violet - uhf WPXS-DT 21 PAX MOUNT VERNON IL TBD 296° 36.1 21
violet - vhf WSIL 3 ABC HARRISBURG IL 181° 49.5 3
violet - vhf KFVS 12 CBS CAPE GIRARDEAU MO 210° 71.0 12
violet - uhf KBSI 23 FOX CAPE GIRARDEAU MO 212° 73.9 23
violet - vhf KSDK 5 NBC ST. LOUIS MO 283° 80.5 5
violet - vhf WPSD 6 NBC PADUCAH KY 185° 78.8 6
violet - uhf WDKA 49 WB PADUCAH KY 184° 64.7 49
violet - vhf KTVI 2 FOX ST. LOUIS MO 281° 82.3 2
violet - uhf KDNL 30 ABC ST. LOUIS MO 284° 80.5 30
violet - vhf KPLR 11 WB ST. LOUIS MO 282° 78.2 11
violet - vhf KMOV 4 CBS ST. LOUIS MO 282° 78.2 4

Since I had Voom installed with their Winegard batwing antenna I always get ABC and PBS. The ABC station I get is 50 miles away.

A few times I've gotten FOx and CBS to come in, and they're 71 and 73.9 miles away. Would it be worth my effort to try the XG91 with an amplifier? I'd probably also find a way to mount it higher, too, since the Winegard is on a low part of the roof of my guest house (only about 10' high).

Finally, if I did use the XG91 and an amp, could I use the diplexor supplied by Voom to power the amp? The diplexor is made by Winegard and is 12V. Or should I just run a separate line?

Mainly I'm just wondering if it's worth my while to even try to pull in these distant locals. I'd really love to get them, though.

Thanks

I also got VOOM installed and have both their Bat wing antenna and the 91 XG. The batwing did suprizingly well. It picked up out to 70 miles with a full power digital station and no weather issues. The big difference is the hard to get channels. I get 14 digitals here with the 91XG. 7 are very hard to get but lock with no drops using the 91xg. The Batwing got only the 5 strongest. So you stand a good chance with the 91xg. The VOOM receiver is fickle though and I get one signal in the 92 range it refuses to lock on. My old Dish 811 had no problem and did a smidget better the the Motorola. I just had to have more HD,analog is very unexciting anymore.

Finally, if I did use the XG91 and an amp, could I use the diplexor supplied by Voom to power the amp?

Opps forgot ! Yes the Moto will supply voltage through the their diplexer. However since I have several digitals very close to not getting I removed their diplexer and ran a seperate antenna coax. You can always try it with their diplexer first and then run a seperate line if needed. Be sure you have a DC pass diplexer at the satellite end also. If you had their Batwing then you should have the DC pass diplexer.

I know the 4228 has been beat to death on AVS for years now but one poster in our local forum insists that it is NOT directional, does NOT do well in trees and has nothing to recommend it over the 4248 or others. Here is a sample post:

"The 4228 is NOT directional, really. A meter will prove it. At first you might think that, but if you saw what's on the meters scope, and how it's reacting to the small movements, it would show a classic case of Nulling, or one half partially cancelling the other half. The 4228 is two horizontally stacked 4221's. Each has a very wide path, but because they're side by side, and you are going through a bunch of trees, one half is getting a slightly different waveshape than the other. The trees are most likely blocking some of the signal, a little differently, to each half. Not much, but enough to cause the sensitivity to direction. It may be multipath, too, but signal gets more blockage from trees than bounce. That's one reason I'm not fond of the 4228 in the trees, and haven't needed or used one in 7 years. The 4221 by its self doesn't have this problem, and can out perform it in the trees. BUT, the 4248 still does better than either in trees and weaker areas."

What do you experts think of this? Is the 4228 overrated? Does the theory about trees affecting each half differently make sense?

Are there any installers here that have experience with 4228, 4248 and others? Does the 4228 ever outshine another antenna in an A-B test? Does the 4228 NOT work well close in (<20 miles)?

Originally posted by quarque
I know the 4228 has been beat to death on AVS for years now but one poster in our local forum insists that it is NOT directional, does NOT do well in trees and has nothing to recommend it over the 4248 or others. Here is a sample post:

"The 4228 is NOT directional, really. A meter will prove it. At first you might think that, but if you saw what's on the meters scope, and how it's reacting to the small movements, it would show a classic case of Nulling, or one half partially cancelling the other half. The 4228 is two horizontally stacked 4221's. Each has a very wide path, but because they're side by side, and you are going through a bunch of trees, one half is getting a slightly different waveshape than the other. The trees are most likely blocking some of the signal, a little differently, to each half. Not much, but enough to cause the sensitivity to direction. It may be multipath, too, but signal gets more blockage from trees than bounce. That's one reason I'm not fond of the 4228 in the trees, and haven't needed or used one in 7 years. The 4221 by its self doesn't have this problem, and can out perform it in the trees. BUT, the 4248 still does better than either in trees and weaker areas."

What do you experts think of this? Is the 4228 overrated? Does the theory about trees affecting each half differently make sense?

Are there any installers here that have experience with 4228, 4248 and others? Does the 4228 ever outshine another antenna in an A-B test? Does the 4228 NOT work well close in (<20 miles)?

Large forward lobe with deep nulls to both sides = highly directional and high performance. It doesn't matter how you get it. Stacking (horizontal) does tend to produce sidelobes but the advantages still outweigh the disadvantages. The 4228 is probably the best overall commonly available single antenna across the uhf band. The 4248 will have slightly more gain in the higher ranges say >ch. 40 and lower gain below and will have similar or probably even wider beamwidth.

The best thing for multipath is high directionality and high front to back ratio.

The 4228 performs fine close in, just don't use a preamp if you're that close.
The narrower beamwidth must be a consideration, though, and may require a rotor if you have > 30 degrees of spread for your desired
stations.

For an explanation on how stacking narrows beamwidth: http://www.kyes.com/antenna/stackluge.html

cpcat - I think you missed my point. You see, I'm already a huge fan of the 4228 and know all about it. But this guy keeps bad-mouthing it - which I think is a disservice to other members if it is universally accepted as "one of the best". I am looking for feedback on his specific theories about why it is "not good in trees" etc. He does not consider it directional because "paper specs are one thing but the meter don't lie". He is an installer and tried one a few times many years ago with mixed results. It is now collecting dust in his garage. Every time I recommend a 4228 he shoots it down with his "not directional" and "not good in trees" etc. All this seems totally counter to 5 years of AVS experience by dozens of members. How do you tell a "know-it-all" that he doesn't...

I just switched to a plasma set and a DISH 811 receiver. Now I need a better antenna for UHF. Since I already have a DISH antenna and feedline, can I add a UHF antenna nearby and then diplex that signal down the existing feedline and then split it near the monitor and feed it into the set that way?

Quarque,

I have put up one of my own, know another guy 1 mile east of me who
has done so. We live 30 miles southeast of Rockford, IL...or 65 miles
west of Chicago. Yet, we can both lock WHA-DT from Madison, WI.
Consistently. Oh, yeah, we're roughly 85 miles away from their 100 kw
ERP transmitter. We both have our antennas in attics, and we're both
rather low in elevation, close to a river.

To have that kind of reception requires:

1. An antenna with high front-to-back gain
2. High directionality, knocking down or eliminating multipath ("ghosts")
3. A very good preamp (such as the ChannelMaster 7777)
4. Carefully pointing it in the right direction
5. RG-6 or RG-11 lead-in cable, preferably the latter
6. Very good to excellent connectors AND connections

If ANY of these are missing, great reception doesn't happen. Period.
Physics says so. End of story. On a side note, I still say the 4228
does best at general UHF reception, but you may have a case for
slightly better UHF reception at or below channel 32 on the
AntennasDirect 91XG, since that part of the UHF dial uses the
seemingly great quality reflector screen on it. Just a guess on my part.
The XG-91 will outperform a 4228, my guess again, if you are in an
area requiring a long-distance reception of channels, and you are
subject to multipath.

Originally posted by sebenste
On a side note, I still say the 4228
does best at general UHF reception, but you may have a case for
slightly better UHF reception at or below channel 32 on the
AntennasDirect 91XG, since that part of the UHF dial uses the
seemingly great quality reflector screen on it. Just a guess on my part.
The XG-91 will outperform a 4228, my guess again, if you are in an
area requiring a long-distance reception of channels, and you are
subject to multipath.

The 4228 will most likely better the XG91 slightly on the lower channels while the XG91 will be best in the upper ranges. The lower you go, the less gain the Yagi/Corner reflector has as it's typically designed for gain in the upper range (if designed for wideband uhf). The "corner reflector" increases the gain on the lower channels to some extent, but not enough to keep the gain curve from dropping off below the range at which the yagi part is optimized for. See http://www.hdtvprimer.com/ANTENNAS/comparing.html

Originally posted by quarque
cpcat - I think you missed my point. You see, I'm already a huge fan of the 4228 and know all about it. But this guy keeps bad-mouthing it - which I think is a disservice to other members if it is universally accepted as "one of the best". I am looking for feedback on his specific theories about why it is "not good in trees" etc. He does not consider it directional because "paper specs are one thing but the meter don't lie". He is an installer and tried one a few times many years ago with mixed results. It is now collecting dust in his garage. Every time I recommend a 4228 he shoots it down with his "not directional" and "not good in trees" etc. All this seems totally counter to 5 years of AVS experience by dozens of members. How do you tell a "know-it-all" that he doesn't...

Trees cause multipath. Horizontal stacking (as in stacking two 4221's i.e. the 4228) narrows horizontal beamwidth, increases forward gain, increases front to back ratio and rejects multipath. The "nulling" he's referring to is simply the intended result of stacking. Read the link I gave and it will help you.

Also, you may just need to learn to ignore this guy.

Originally posted by Jim1348
I just switched to a plasma set and a DISH 811 receiver. Now I need a better antenna for UHF. Since I already have a DISH antenna and feedline, can I add a UHF antenna nearby and then diplex that signal down the existing feedline and then split it near the monitor and feed it into the set that way?

Jim,
The quick answer is YES! Depending how close and how strong the UHF digitals are in your area. Diplexers will decrease reception a little and can cause other reception problems. Usually if the signals are strong and steady you can diplex with no problems.

Originally posted by jimc705
Finally, if I did use the XG91 and an amp, could I use the diplexor supplied by Voom to power the amp?

Opps forgot ! Yes the Moto will supply voltage through the their diplexer. However since I have several digitals very close to not getting I removed their diplexer and ran a seperate antenna coax. You can always try it with their diplexer first and then run a seperate line if needed. Be sure you have a DC pass diplexer at the satellite end also. If you had their Batwing then you should have the DC pass diplexer.

Thank you very much for the info.

I'm now trying to decide between the XG91 and the CM4228. There's a place that sells the 4228 right down the road from me so I wouldn't have to order it, and could get it right away. Money isn't the issue, I just want whichever one is best.

Specifically, I want to get CBS and Fox (71 & 73 miles away). If I could get NBC at 78 miles away that would be great too, but not all that important to me (I need abc, cbs, and fox for sports).

The local dealer also has everything I need for mounting the antenna. I'm thinking of buying a 30' telescoping mast and maybe a rotor..

sregener, I read your review and it was very informative!

Thanks again for all the responses.

Originally posted by ChrisDuncan
I'm now trying to decide between the XG91 and the CM4228.

The wind load on the 4228 makes it a poor choice for use with a rotor. That should make your decision easier.

Originally posted by quarque
I am looking for feedback on his specific theories about why it is "not good in trees" etc. He does not consider it directional because "paper specs are one thing but the meter don't lie". ...Every time I recommend a 4228 he shoots it down with his "not directional" and "not good in trees" etc. All this seems totally counter to 5 years of AVS experience by dozens of members. How do you tell a "know-it-all" that he doesn't...

The fact is that if you are not receiving a signal "dead-on" on any stack, the signal will be weaker for the directions that stack is designed to reject. Thus, if you're trying to receive scatter, extreme directionality isn't a good thing - that's why people right under transmitters get better results with a single bowtie than they do with a yagi - the bowtie will accept the signal from more directions (especially vertically) than the yagi will.

All antennas pick up signals from the sides and rear. No antenna has a perfect reflector in the back. No antenna can reject all signals that hit it. The 4228 is an excellent long-range antenna because it will "hone in" on the direction it's pointed and reject the significantly weaker signals from the sides. But this "rejection" is little more than a 3db boost of the signal in the direction it's aimed. If the side reflections are strong, that may not be enough to clear the "signal from the trees."

Every situation is different, and different antennas have strong points and weak points. I would challenge any assumption this guy has that the 4228 is not directional. It's not "perfect" but no antenna is. In some circumstances, you'll get better results from a less directional antenna. That's not a fault of any design, it's just a fact. The 4228 is what it is - a great long-distance performer that is fairly resistant to multipath.

What is curious is his recommendation of the 4248. I had a vertical stack of these and found that they performed about the same as my single Winegard HD-7084P's UHF section. And when you get below channel 35 or so, they are most decidedly "not directional" as they are basically corner reflectors which have a 60 degree beamwidth. I eventually sold my two 4248s because they were such poor performers for long-distance reception.

But how do you tell someone who thinks they know it all that they don't? You don't. You supply good information in a reasoned and rational way, and hope that your readers can see who is the extremist and who understands what is really going on. Some people may take his advice. It's a free world.

Can ham radios cause interference problems? I have a friend who is 5 miles away from the tower farm and his neighbor with the ham radio tower is directly between him and the tower farm.

Originally posted by HiDefSooner
Can ham radios cause interference problems? I have a friend who is 5 miles away from the tower farm and his neighbor with the ham radio tower is directly between him and the tower farm.

Ham radio shouldn't cause interference. If it does, it's because the operator has a malfunctioning piece of equipment. The operator would no doubt want to be made aware of that.

Originally posted by cpcat
...
Also, you may just need to learn to ignore this guy.
Thanks cpcat & sregener for your input.

You were mostly "preaching to the choir" but it is still good info. It is hard to ignore someone who critiques EVERY post you make and contradicts about half of them. Most of my advice to people comes from reading this thread and keeping track of what has worked and what has not.

I use a topo program to assist people in our area because of all the hills. Many people rely on antennaweb but don't realize that they don't take hills into account. So I do a profile from their location to the various towers and tell them if they have anything in the way. So far I have been very successful at predicting their chances at reception.

I used to recommend the 4228 for anything > 20 miles and a 4221 for closer in. Until this person came along and said the 4228 was no good and he uses 4248 all over because it "gets through the trees" (we do have a LOT of trees here). I can see that if you plop a 4228 5 miles from a tower that you will think it is not directional because there is enough gain even 45 degrees off axis to get a signal. He does not seem to understand that.

I think I will just keep reminding the other readers that the 4228 works very very well for many many people and should not be disregarded so easily.

Originally posted by fay28301
This is for MAX HD from fay28301. Thanks for the link on where I can find a CM 4251, I am going to send them an email when I get off of here. I found an old one that is rather oxidized for next to nothing, but I would rather use a new one than go through the trouble of cleaning the old one up. As far as that goes, I don't even know what to use to get the oxidation off of it, so I figured that I would sand & polyurathane it, unless someone can tell me something better to clean it with. The reason I was looking for one, is that I stay near Fayetteville, N.C., (Hope Mills) which is about 70mi from any of the major networks which come out of Raleigh, N.C. I can get all of them except the WB & UPN stations, which come & go. No trouble with any of them on analog. I used to have a CM4251 until it got destroyed in a house fire. As I said, for sheer gain it was the best UHF antenna ever made---but---(always one of them, ain't it) it suffered mightily from multipath interference due to the way the reflector was made. The feed would pick up any nearby adjacent stations through the screen while trying to pickup the far off ones through the front. I don't know how much this will affect digital reception with this antenna, but it is worth a try. Now I have a CM4228A and a CM7775 preamp about 40ft. up, with RG-11 coax downlead. I have a U.S. Digital STB which seems to have an excellent tuner in it. I didn't really want to go any higher (aggravation of have to buy & install a tower), so I figured on a better antenna. I tried 2 DAT75's which had a combined gain comparable to one 4228. They are stored in my attic now. Sorry for being late on the reply to you.
fay28301

Ive read that salt and lemon juice will take the oxidation off of anything...
Id be intrested in the used antenna by the way if you were looking to sell it... leave me a instant message on my yahoo ID if you are intrested...

Originally posted by sregener
Ham radio shouldn't cause interference. If it does, it's because the operator has a malfunctioning piece of equipment. The operator would no doubt want to be made aware of that.
Very true. On another note, we had a guy with a hotrod in our area and every time he fired it up the HD would go crazy. He finally replaced the solid spark plug wires with the noise-suppression carbon type and the problem went away.

Originally posted by quarque

I used to recommend the 4228 for anything > 20 miles and a 4221 for closer in. Until this person came along and said the 4228 was no good and he uses 4248 all over because it "gets through the trees" (we do have a LOT of trees here). ...I think I will just keep reminding the other readers that the 4228 works very very well for many many people and should not be disregarded so easily.

Just to let you know, I live about 25 miles from the antennas and get everything solid with a 4221 in the attic. Also there are lots of trees however I just recently set it up and being winter there are no leaves yet.

Originally posted by quarque

I used to recommend the 4228 for anything > 20 miles and a 4221 for closer in. Until this person came along and said the 4228 was no good and he uses 4248 all over because it "gets through the trees" (we do have a LOT of trees here). I can see that if you plop a 4228 5 miles from a tower that you will think it is not directional because there is enough gain even 45 degrees off axis to get a signal. He does not seem to understand that.



You could liberalize that a little. The 4221 is probably good to at least 35 miles or so if mounted outside, particularly if you've found a favorable topographic profile at the location in question. Inside an attic it will be more unpredictable.

What topo program do you use?

I'm 35-40 from the towers where I'm at. 4221 works wonderfully in my attic. In fact, I was able to split it once with no appreciable loss in signal. The area I live in though is pretty flat from here to the tower so of course, YMMV. I do think the 4221 is a great inexpensive antenna for your AntennaWeb Yellow-Lt. Green stations, especially if, they all broadcast from the same area.

Originally posted by ChrisDuncan
What do you think of the XG91 antenna for my situation?
WPXS 13 PAX MOUNT VERNON IL 351° 15.0 13
* lt green - uhf WSIU-DT 40.1 PBS CARBONDALE IL 233° 25.4 40
* blue - uhf WSIL-DT 3.1 ABC HARRISBURG IL 181° 49.5 34
blue - vhf WSIU 8 PBS CARBONDALE IL 233° 25.4 8
* violet - uhf WPXS-DT 21 PAX MOUNT VERNON IL TBD 296° 36.1 21
violet - vhf WSIL 3 ABC HARRISBURG IL 181° 49.5 3
violet - vhf KFVS 12 CBS CAPE GIRARDEAU MO 210° 71.0 12
violet - uhf KBSI 23 FOX CAPE GIRARDEAU MO 212° 73.9 23
violet - vhf KSDK 5 NBC ST. LOUIS MO 283° 80.5 5
violet - vhf WPSD 6 NBC PADUCAH KY 185° 78.8 6
violet - uhf WDKA 49 WB PADUCAH KY 184° 64.7 49
violet - vhf KTVI 2 FOX ST. LOUIS MO 281° 82.3 2
violet - uhf KDNL 30 ABC ST. LOUIS MO 284° 80.5 30
violet - vhf KPLR 11 WB ST. LOUIS MO 282° 78.2 11
violet - vhf KMOV 4 CBS ST. LOUIS MO 282° 78.2 4

Since I had Voom installed with their Winegard batwing antenna I always get ABC and PBS. The ABC station I get is 50 miles away.

A few times I've gotten FOx and CBS to come in, and they're 71 and 73.9 miles away. Would it be worth my effort to try the XG91 with an amplifier? I'd probably also find a way to mount it higher, too, since the Winegard is on a low part of the roof of my guest house (only about 10' high).

Finally, if I did use the XG91 and an amp, could I use the diplexor supplied by Voom to power the amp? The diplexor is made by Winegard and is 12V. Or should I just run a separate line?

Mainly I'm just wondering if it's worth my while to even try to pull in these distant locals. I'd really love to get them, though.

Thanks

Being the impatient person that I am, I went ahead and bought a 4228 yesterday with a 7777 amp. I mounted the antenna in the exact spot my batwing antenna was at, which isn't a good spot--it's only about 15' high and facing some trees. I also ran it through the diplexor instead of running a straight line.

Immediately I was able to pick up Fox from 73.9 miles away, and it hasn't went out since.

NBC and CBS would not show a picture until it got dark, and then they didn't go out at all. My signal strength (during the afternoon) would jump up well past 80 then all of a sudden down to around 40 for both. But as soon as it started to get dark, they stabilized and worked fine.

I'm also getting WB and UPN which are substations of my local CBS and Fox.

Tomorrow I'm going to actually mount the antenna on top of my house which is 2 stories and sits sort of on a hill. My backyard slopes and my guest house is pretty low, so this should improve things. ALso, I won't be shooting into the trees anymore.

THe only bad part is that it's going to be a very long run. I bought the mounting hardware for mounting it on the peek of my house and a 10' mast along with 200' of RG6. I'll now run a straight line and use the power supply that came with the CM7777 and bypass the diplexor to see if that helps.

2 questions:
1. Will having such a long run (maybe close to 200'; it's a long way to my guest house) affect signal strength.
2. If I wanted to split the line at some point and run it under my house so I could get OTA in my living room (I have a D* HD box), where would I put the power supply for the amp, and what kind of splitter would I use?
Ideally, I'd like to receive OTA in 3 places: 2 in the house and 1 in the guest house where I have my theater set up.

So far I'm pretty excited about the new antenna. No doubt it's a big improvement over the batwing, and I believe that mounting it higher and away from trees will improve things even more. It should be around 35' to 40' high once it's mounted since my house is pretty tall. I'm not looking foward to walking around on my roof since it's fairly steep but once it's all done I believe it'll be worth it.

Thanks

Chris

200' is a long way. As this author shows

http://www.hdtvprimer.com/ANTENNAS/basics.html

Scroll down to transmission basics

you'll lose almost 10 db of gain running a 200' Rg-6 cable that's a gain factor of 10. Anything you can do to shorten up the cable would help.

I walked off the distance a little bit ago and it looks like I can get by with around 150' to the guest house.

If I add a splitter in there will I need a distribution amplifier?

Originally posted by ChrisDuncan
1. Will having such a long run (maybe close to 200'; it's a long way to my guest house) affect signal strength.
2. If I wanted to split the line at some point and run it under my house so I could get OTA in my living room (I have a D* HD box), where would I put the power supply for the amp, and what kind of splitter would I use?

1. Yes. You'll lose a fair bit of signal over that length, however the preamplifier should eliminate most or all of that loss. If you're really concerned, get RG-11 - the loss factor is much lower for RG-11. You'll need special connectors to reduce the cable thickness for attaching it to things like your preamp.

2. Split after the power supply. If your signals are marginal, you'll lose them by splitting the signal. I had a 3-way splitter, and stations broke up terribly. I switched to a 2-way and things improved. A direct connection ended up working the best.

With a 200 ft. cable run or even a 150' run from 80 miles out, I wouldn't be surprised if you needed a pre-amp and a distribution amp if you wanted to split the signal. I agree with sregener that the preamp should eliminate most of the loss in the long run.

However, A splitter 3-4 way is going to cut your signal another 6-7 db (a 2-way split is a minimum of 3db a 3 way split about 5-6 db and a 4 way split about 7 and that's assuming a pretty efficient splitter).

I'd think your best bet is to run the long cable with just your pre-amp...If you get a good signal, then try splitting it however many ways you like...if it doesn't work, well you'll need a dist amp.

One other possiblity...say you have a "preferred" tv...you can have a single split to that tv and the rest of the house, then split the rest of the house line. That will preserve a better signal for your preferred tv. The rest of the house's signal will suffer, but if you don't want to buy a dist. amp that can reduce the problem.

Hmmm. I was thinking of putting the power supply by my Voom box out in the guest house. So if I wanted OTA in 2 rooms in my regular house, I'd have to run more cable back from the guest house to the house? Seems like a lot of cable.

Maybe I could put the power supply in my living room, and go from there since that will be closer to the antenna if it's on my roof.

One more thing: why is reception so much better at night? I've lost CBS and UPN now during the day (signal keeps going up and down) but I suspect, like last night, it'll be okay after dark.

Well, after much hesitation I went ahead and installed a CM 4228 on the roof out here in rural MD (21620). Tried the Silver Sensor route for a while,but obviously it just can't do the job a roof mounted antenna can.

I have a very sloped roof here so it was pretty hairy getting up there, I recommend hiring someone but at quotes of 400 or so, I was going to do it myself!

I strapped it to the chimney and after scraping my knuckles and dropping a few key parts over the side and having to retreive them,I went inside and was expecting digital HD nirvana. Did a channel scan and came up with only three stations! None that I remember with the SS pulling in. All frantic I checked my connections and swore up and down this must be a defective
antenna! Took a look at the instructions and D'OH I had it up backwards!
Aiming it right into some tress I was pulling in Philadelphia stations! I'm like 75-80 miles away! But that's not what I wanted so turned it around and now get all the Baltimore stations and even a couple of DC stations! Fantastic! No more dropouts or searching for signal!

So for anyone wanting to know how far this 4228 can pick up without a preamp,pretty darn far!
Do you guys think adding one would let me get the rest of DC channels?
Doesn't really matter,though, just curious.

Thanks to all who recommended this antenna a few weeks ago when I asked for advice on here!
Thank you again.

One explanation for why reception changes with the time of day.

http://www.hdtvprimer.com/ANTENNAS/GlossaryA.html#fading

Originally posted by cpcat
You could liberalize that a little. The 4221 is probably good to at least 35 miles or so if mounted outside, particularly if you've found a favorable topographic profile at the location in question. Inside an attic it will be more unpredictable.

What topo program do you use?
I agree it works well to 35 miles or beyond in clear terrain but I tend to play it safe when recommending stuff. I hate to see people waste $$ and time trying 4 and 5 different antennas. With all the hills and trees here you often need every dB you can get.

I use DeLorme TOPO USA. It is very user friendly and pretty accurate. You can get a nice profile (slice) from any location to another within the US. It will even give you a profile of a river or road if you click on it. I used it to find the best vantage point at Hell's Canyon last summer. I do a fair amount of photography and I wanted the longest stretch of visible canyon I could get to by road. Much of the canyon twists and turns so you rarely see more than a mile or two at a time. Using the 3D mode I was able to sight down the canyon from various forest service roads to find the best spot. It worked very well. The "overlook" that is advertized in the brochures is a joke. You only see the top few hundred feet because the "overlook" is one ridge away from the actual canyon edge.
Anywaaaaay, the program is very handy for lots of things.

Hi,
I have been having pixelazation issues with some of my OTA channels and need some advice. I get slight one or two second dropouts every few minutes on my OTA hdtv channels. I live near DC, about 10 miles from the towers, and should be in the yellow. I have a Radio shack UHF only antenna (15-2160) chimney mounted. I have a 25ft cable run to an Eagle-Aspen 5x8 multi switch, then a 100ft cable run to my hr-10 250 HD Tivo box, where the signal is split between one of my satellite inputs and my ota antenna input (didn't want to add a third cable run to my box). What is the most likely cause of the dropouts? I could shorten the cable runs by 40ft maybe, or add a pre-amp to my antenna. If I add a powered pre-amp, can I power it around the multiswitch (i.e. the preamp is connected at the antenna, but the power coax runs through the multi switch? The multiswitch is already powered). Thanks in advance for any help!

I don't suppose one could connect 2 "outdoor balun kits" to the 4228 and just run two lines off it as one would do a dish?

Probably a stupid question, but in my case that could give me two "straight" runs from the antenna. I could just buy another CM7777. One for the house, one for the guest house.

j_buckingham80, thanks for posting that about reception changes.

Originally posted by cpcat
Trees cause multipath.

I'm not sure I buy that. First off, trees are not nearly as good at reflecting UHF as a hard surface like a building. Secondly, large flat surfaces can create a reflection with a coherent wavefront that would appear to a receiver like a strong signal that could be locked on to. But a stand of trees would create a multitude of weak signals of all differing phases. This would look to the receiver like background noise which is more easily rejected than a single strong reflected signal that is out of phase with the main line-of-sight signal. So I think trees can *partially block* signals but I seriously doubt they can create a reflection that any receiver could lock on to or be seriously bothered by.

Originally posted by roland77
Hi,
I have been having pixelazation issues with some of my OTA channels and need some advice. I get slight one or two second dropouts every few minutes on my OTA hdtv channels. I live near DC, about 10 miles from the towers, and should be in the yellow. I have a Radio shack UHF only antenna (15-2160) chimney mounted. I have a 25ft cable run to an Eagle-Aspen 5x8 multi switch, then a 100ft cable run to my hr-10 250 HD Tivo box, where the signal is split between one of my satellite inputs and my ota antenna input (didn't want to add a third cable run to my box). What is the most likely cause of the dropouts? I could shorten the cable runs by 40ft maybe, or add a pre-amp to my antenna. If I add a powered pre-amp, can I power it around the multiswitch (i.e. the preamp is connected at the antenna, but the power coax runs through the multi switch? The multiswitch is already powered). Thanks in advance for any help!
At only 10 miles you may actually have TOO MUCH signal. The 2160 is also not highly directional so you could be getting a lot of multipath. Dropouts and bouncing signal levels are often an indication of strong multipath. The first thing I would try is the Rat Shack variable attenuator since it is cheap and easy to put inline at your receiver. The next step is relocating and re-aiming your antenna. Changes as small as 6" or 5 degrees can have a big effect. If that fails you may want to consider a different antenna. The HD Tivo is not known for its fantastic tuner so that is not helping you. Shorter cable runs are always better than longer ones. Cut out whatever you can. If you run the 2160 direct to the Tivo do you get an change in reception?

Originally posted by ChrisDuncan
One more thing: why is reception so much better at night? I've lost CBS and UPN now during the day (signal keeps going up and down) but I suspect, like last night, it'll be okay after dark.

Long distance reception (i.e. no line-of-sight) does seem to benefit from nighttime conditions. I find that nights are almost always better than days, and the good "daytimes" are few and far between. I've heard dozens of theories about this, but I've come to the conclusion that wind and sun are the two biggest factors.

When it is windy, long-distance reception suffers during the day. When it is calm, reception is better.

The higher the sun is in the sky, the worse the reception is. Thus, you should expect summertime reception to be far worse than winter.

I've also found that snow cover improves reception dramatically. It probably increases ground bounce.

Originally posted by slapshot
Do you guys think adding one would let me get the rest of DC channels?
Doesn't really matter,though, just curious.


I'd definitely recommend a CM7777 preamplifier for your situation. It shouldn't negatively impact the Baltimore stations (over 30 miles away, according to Antennaweb) and it should positively impact D.C. stations. It's impossible to say how much improvement you'll get, and not all the D.C. stations are on the same tower, so you might get into aiming problems (and I strongly advise against a rotor with the 4228) at that distance. Close in, pointing the antenna a little off doesn't really hurt you. At long distances, just a few degrees can make the difference between getting a rock-solid signal and getting nothing.

Originally posted by ChrisDuncan
I don't suppose one could connect 2 "outdoor balun kits" to the 4228 and just run two lines off it as one would do a dish?

You could, but the impact would be the same as a splitter.

If you're willing to put up two antennas, that would be the better route, IMO.

quarque-
Thanks for the input. After doing more checking last night, I think it has to do with my HD Tivo box. The dropouts seem worse on taped materials versus live TV, and there seem to be a lot of issues with the HR10 250. I figured out how to check my signal strength and I am getting around 90 for my locals. I will try some of your suggestions though. Thanks.

Originally posted by roland77
quarque-
Thanks for the input. After doing more checking last night, I think it has to do with my HD Tivo box. The dropouts seem worse on taped materials versus live TV, and there seem to be a lot of issues with the HR10 250. I figured out how to check my signal strength and I am getting around 90 for my locals. I will try some of your suggestions though. Thanks.
If your signal levels are steady for very long periods of time then the Tivo is most likely the culprit. Sounds like the Tivo hiccups during recording. Other HD recorders have had similar issues when trying to do more than one thing at a time (not enough horsepower/speed in the hardware).

I have been using the Winegard 8 bay for several weeks. I was having problems with a staion on a higher UHF frequency (51). I read that this particular antenna is not good on higher UHF frequencies (above 50). Since I will be having a channel coming on the air at 55 in a month or so I decided to try the AntennasDirect 43XG (corner reflector yagi). I installed the antenna this morning. I had checked my signal strength with the old antenna prior to putting up the 43XG. After installation the signal strength on 51 was rock solid (it fluctuated wildly with the Winegard). There was some improvement in signal strength on my other channels. The only thing I changed was the antenna. Everything else (pre-amp, cabling, antenna heigth) stayed the same. Whether the 43XG is better at multipath or whatever, in my situation, it does a much better job than the Winegard.
I realize that due to the many variables that affect antenna performance, my results can't be extrapolated to someone else's situation but I am very happy with the antenna.

Originally posted by SD4934
Since I will be having a channel coming on the air at 55 in a month or so I decided to try the AntennasDirect MX43 (corner reflector yagi).

Do you mean the 43XG? I searched their site and couldn't find any antenna with an MX designation.

I'm sure the 43XG is a better performer on higher channel numbers than the PR-8800. And if the corner reflector on the 43XG is as good as the one on the 91XG, it's a solid performer on the lower channels, too.

Originally posted by sregener
Do you mean the 43XG? I searched their site and couldn't find any antenna with an MX designation.

I'm sure the 43XG is a better performer on higher channel numbers than the PR-8800. And if the corner reflector on the 43XG is as good as the one on the 91XG, it's a solid performer on the lower channels, too.

Yes, it is the 43XG. On the shipping invoice the SKU # is listed as UE-MX43. That's what I was looking at when I typed my post. I didn't go with the 91XG becuase I thought that would be overkill in my situation (even the
medium range yagi would probably work). It appears to be a better perfomer for me even in the lower ranges (consistently better and on one channel-27-significantly better performance). For the few hours I've had the antenna up I am very happy with it.

I put my antenna up today on the house and have decide just to go with the two antenna idea so I'll also have one for the guest house. My reception didn't improve all that much, about the same as at the other location even though it's much higher. When I try to add a splitter with it being such a long run I lose channels completely. Perhaps if it was a shorter run it'd be okay to split it but not in my case.

So... sometime next week I'll add another antenna. Kind of disappointing.

OK gang, I need some advice here. Due to terrain in my section of Nashville, I have not been able to pick up all the stations I'd like to. In fact, all I can get is ABC, PBS and sometimes NBC. After talking with Voom, they are going to send out a team to install a different antenna on my roof. I will pay for the antenna, boom and mounting equipment and Voom will pick up the install charge.

I need advice on just what antenna to try next. Given the gain problems I have here, here's what I'm thinking the short list is including gain measurements from either manufacturers data or SolidSignal:

Channelmaster:
4248 8-bay bowtie (I've tried this before), 10.8 db max
3023 Yagi, 11.5 db max

Wineguard:
HD9095P Yagi, 14.2 db (ch 14), 16 db (ch 32), 15.5 db (ch 50) 12.2 db (ch 69)
PR8800 8-bay bowtie, 10.7 db (ch 14), 12 db (ch 32), 11 db (ch 50) 12.5 db (ch 69)

AntennasDirect:
91XG Yagi, 16.7 db max
DB8 8-bay bowtie, 15.8 db max


Since one of my problem channels is the local NBC affiliate at VHF-10, the 8 bays would have an advantage of bringing in an upper VHF signal. But it appears the Yagis rule having the ability to squeeze out more signal from a bad situation. And are ChannelMaster antennas really behind the curve as opposed to some of these other designs?

All of the problem stations are fortunately on the the same vector so I don't think I'll need a rotor. The stations are on UHF channels 15, 21, 23 and 56, as well as VHF 10 I mentioned earlier. The VHF channel is 6 miles away, all others are 16 miles away.

And yes, I'm already using a pre-amp (CM7777). I'm noticing some loss between the multiswitch that was installed (Wineguard) some of my rooms that is preventing me from seeing the weak NBC affiliate on two of my three televisions. Do I need a indoor distribution amps to boost the signal or another tactic? Right now, the power module for the 7777 is sitting right before the multiswitch in the chain in my garage.

Originally posted by Sevenfeet
91XG Yagi, 16.7 db max

Since one of my problem channels is the local NBC affiliate at VHF-10, the 8 bays would have an advantage of bringing in an upper VHF signal. But it appears the Yagis rule having the ability to squeeze out more signal from a bad situation. And are ChannelMaster antennas really behind the curve as opposed to some of these other designs?

I can speak from experience that the 91XG does an excellent job on VHF channel 10. I receive a perfect picture from KTTC, and they're over 20 miles away. I do use a preamp (19db VHF gain), but I suspect it isn't doing much to boost the picture.

I haven't personally tried the 4228, but I know the 4248 was an underperformer for me. The 91XG is by far the best antenna I've tried.

Originally posted by ChrisDuncan
I put my antenna up today on the house and have decide just to go with the two antenna idea so I'll also have one for the guest house. My reception didn't improve all that much, about the same as at the other location even though it's much higher.

I'd give the 91XG a try. I think it might impress you. Since you're already trying a second antenna, try something that might be better (a different design family altogether) and see if it makes a difference. AntennasDirect has a liberal return policy if you find the 4228 is a better antenna. Also, you don't mention a preamplifier, but I assume you used one with that monstrous cable run?

OK, I'll order the 91XG. Thanks guys.

Originally posted by sregener
I'd give the 91XG a try. I think it might impress you. Since you're already trying a second antenna, try something that might be better (a different design family altogether) and see if it makes a difference. AntennasDirect has a liberal return policy if you find the 4228 is a better antenna. Also, you don't mention a preamplifier, but I assume you used one with that monstrous cable run?

Yeah, I'm using the CM7777 amp. YOu know, I was just thinking the same thing, that I should order the 91XG and give that a try. Especially since I'm going to end up with 2 antennas anyway. I could also put a rotor on the 91XG which I didn't do with the 4228.

Today was kind of a letdown after going to all that trouble to roofmount it. It's at least 35' high now since the mast is 10'. But maybe the 91XG will improve things some more.

At least I'm getting Fox and WB all the time now, whereas before I couldn't get them at all. CBS will come in sporadically but keeps breaking up. I'm assuming that NBC and CBS will be okay again tonight at least.

I guess if I can watch The Tonight Show in HD then the effort was worth it.

I'm wondering why adding a short cable to the splitter doesn't make my channels go out, but adding a long one (150') makes them go out immediately. I added the short cable, like 10' or so, just to experiment and it didn't affect reception, but simply adding the long cable to the splitter makes all my channels go out.

I suppose I could at least get OTA in my upstairs bedroom using the same antenna since it would be a very short run, but the long run is out of the question.

I'm off to order the 91XG. :)

Just a quick disclaimer, I'm no antenna guru, but hey...FWIW, height's not necessarily as useful on UHF as it would be on VHF, if anything, it might be worth attempting to adjust the antenna up on down along the mast to see if a particular height is better than another.

http://www.hdtvprimer.com/ANTENNAS/siting.html

If you go here and read some of the issues related to site mounting, you can see how complex (especially for UHF) it becomes.

I have a Channel master amp 7777 and found this amp and was wondering how much it would improve reception, if any over the 7777 model. http://www.researchcomms.com/hdtv.html It has a UHF NOISE FIGURE UHF 0.4 dB. UHF 20 db GAIN vs the Channel master 7777 UHF NOISE FIGURE 2.0 dB UHF Gain: 26 dB:)

Originally posted by firemantom26
I have a Channel master amp 7777 and found this amp and was wondering how much it would improve reception, if any over the 7777 model. http://www.researchcomms.com/hdtv.html It has a UHF NOISE FIGURE UHF 0.4 dB. UHF 20 db GAIN vs the Channel master 7777 UHF NOISE FIGURE 2.0 dB UHF Gain: 26 dB:)

Send "cpcat" a PM...he has one that's for sale.Should be the very best preamp money can buy.

Originally posted by MAX HD
Send "cpcat" a PM...he has one that's for sale.Should be the very best preamp money can buy.


How much better reception do you think it will make. I did gave him a PM.


Thank you

Currently, I am using the 4228 and 7777. The antenna is mounted on the roof ~ 35 feet above ground. Generally, the reception is decent. But I am noticing a few things. The channels I am trying to receive are 17,25,47, and 54.

1. On overcast days the reception is better.
2. The reception is better in the evenings/night and early morning.
3. On sunny days, late morning and afternoon channels 47 and 54 become very difficult to receive.

Q: Does anyone have any experience in ganging two 4228's ? Would this improve this situation ?

I was thinking of purchasing either a 91XG or DAT75 to see if it were any better. If anyone has a DAT75 for sale please let me know.

cjhrph@yahoo.com

For the Pre-Amp with a noise figure of .4...Effectively, you are getting back 1.6 dB of Signal from your antenna. Signal that you normally lose. Theoretically, by cutting out that 1.6 dB of noise you are increasing your gain by 1.6dB or about 40%.

Originally posted by j_buckingham80
For the Pre-Amp with a noise figure of .4...Effectively, you are getting back 1.6 dB of Signal from your antenna. Signal that you normally lose. Theoretically, by cutting out that 1.6 dB of noise you are increasing your gain by 1.6dB or about 40%.
I believe the gain remains the same but the s/n ratio improves by 40% - not quite the same thing. You're not getting 40% more signal just 40% less noise mixed in with the same level of signal. If 0.4 is a real number (not advertising dept. #) then it is very impressive.

Hello all,

I have two channels I'd like to get that are consistently just below
signal acquisition levels on my tuner. The CM 4228 UHF antenna
is hooked up to the CM 7777 preamp, then 75' down the cable
to the powered part of the preamp, then another 15' to my TV.

Question: would replacing the RG-6 quad shielded length of cable with
RG-11 get me any improvement, or does the 7777 adjust the power
so that you do get an effective 26 dB gain out of the back end no
matter what? I can't move the antenna.

Originally posted by j_buckingham80
Just a quick disclaimer, I'm no antenna guru, but hey...FWIW, height's not necessarily as useful on UHF as it would be on VHF...

Actually, once you're beyond line-of-sight, this is blatently false. VHF "bends" much more readily than UHF. Thus, it is reasonable to get VHF reception from 100 miles away over average terrain. UHF is pretty much hard to do after 60 miles. (Assuming normal broadcast antenna height.) I had an antenna on my roof (about 20') and then switched to a 54' tower (and I'm married - I know, I know. Lucky guy...) Reception on UHF improved dramatically - I received UHF stations I'd never seen before. VHF improved, but not so much.

Originally posted by cjhrph
Q: Does anyone have any experience in ganging two 4228's ? Would this improve this situation ?

I was thinking of purchasing either a 91XG or DAT75 to see if it were any better. If anyone has a DAT75 for sale please let me know.


There was a guy in California who tried 2 and 4 4228s in a stack. He found 2 were better than 1, but 4 wasn't much better at all and the wind load became a major factor.

I'd strongly advise the 91XG. It may not be better than the 4228 in all situations, but it isn't nearly so heavy, doesn't have the same windload, and is a different style antenna. Where yagis have failed, bowties have worked, and vice versa.

Originally posted by sebenste
Question: would replacing the RG-6 quad shielded length of cable with
RG-11 get me any improvement, or does the 7777 adjust the power
so that you do get an effective 26 dB gain out of the back end no
matter what? I can't move the antenna.

Experts have told me that if you use a preamp, QS RG-6 is just as good as RG-11.

Sreg- No doubt height is going to help if you're trying to get around the curvature of the Earth. But in the average installation (which granted Chris is not) it doesn't take much to get an UHF antenna 4 wavelengths off the ground. I agree height is much more useful in situations like Chris's to clear obstructions, the Earth being his principal one. (basically extending his horizon) But, how much height it would take to do that is a different story. It did look like though, some of the stations he was attempting to pull in were VHF stations, so height would probably help anyways.

My more point was, that on a 10' mast, it might be worth his while to see if moving his antenna up and down along the mast might help, it's unlikely, but it's hard to know ahead of time. Also, he may be fortunate enough to be on a ridge or something similar so that his horizon is already substantially distant, in which case he might be getting reflections that reduce his signal. His day reception already significantly varies from his night reception, so it does appear that ground reflections may be having some influence.

Originally posted by sebenste

Question: would replacing the RG-6 quad shielded length of cable with
RG-11 get me any improvement, or does the 7777 adjust the power
so that you do get an effective 26 dB gain out of the back end no
matter what? I can't move the antenna.
I know folks get that glazed over look when I break out the math, but it's
the only way to precisely answer this question.

The noise temperature Tn of two amplifiers in cascade is the noise
temperature of the first plus the noise temperature of the second
divided by the gain of the first:

Tn = T1 + T2/G1.

To convert Noise Figure(f) to noise temperature (Tn):

Tn = 290(10^(f/10) - 1)

So a 2.0 dB preamp has a noise temperature of 169.6K

Let's say that the Noise Figure of your receiver is 10 dB and your RG6 cable
loss is 5.0 dB for a total Noise Figure of 15.0 dB. The receiver noise
temperature is 8880K.

Then the system noise temperature is 169.6 + 8880/400 (26 dB) = 191.8K

To convert from noise temperature back to Noise Figure:

NF = 10 log(1 + Tn/290)

So the system Noise Figure is 2.2 dB. The gain of the preamp "washes out"
the noise of the receiver and connecting coax.

Now let's plug in a different value of coax loss. Your rich uncle buys you
some 7/8" Heliax ($6 a foot) and your coax loss goes down to 1.0 dB,
making your receiver noise figure 11.0 dB or 3361K.

169.6 + 3361/400 = 178K or 2.08 dB

Your rich uncle's $600 was the wrong place to put the money since it only
buys you an undetectable 0.12 dB of signal to noise ratio. You should have
spent it on a taller tower or mast, a bigger antenna or a better preamp
(in that order).

Now for something counter-intuitive. Let's say the gain of the preamp is
13 dB instead of 26 dB at the same 2.0 dB Noise Figure. Then the system
noise temperature (with the 5.0 dB loss RG-6) is 169.6 + 8880/20 (13 dB) =
613.6K or a system Noise Figure of 4.9 dB. In this case, 13 dB less preamp
gain only causes the loss of 2.7 dB of signal to noise ratio.

Ron

Ron - I love it. No glaze here. So a high gain preamp with a noise figure of 0.4 really does make a difference in the total noise figure, but *may* not be as significant as it looks because of the other elements in the system. Sorta reminds me of a physics professor I had who constantly wrote "Sig Fig" on everyone's homework. Your calculations are dominated by the element with the least precision in the chain. If it only had 3 significant figures in its value then you better not use 10-digit precision in the result. "Siggy" finally became our friend at some point...

Ron,

Thank you for that answer...exactly what I was looking for. And
thank you Serenger...your experts are right. OK, no rewiring job
for me.

Some of the speculation here regarding the likely effect of increasing antenna height is based on a "perfect sphere" topograpical assumption. It is entirely possible, and in fact quite common, to be faced with a situation where someone is so far from the transmitter that they would not have line of sight over a sphere, and whose curved reception path is also blocked by a somewhat taller building that is fairly close by. In these instances, raising a UHF antenna a reasonable amount can often dramatically improve reception.

On the other hand, when one is in a metropolitan environment and suffering from hard multipath reflections, quite often the ideal height is below the maximum height, as lowering the antenna may reduce the multipath signal strength more than it reduces the desired signal strength.

I service a headend that supplies antenna signal to 400 drops. This campground is on low ground and the signal strength of reflections off Byrd Stadium in College Park, Maryland are nearly as strong as the signals from the transmitter azimuth direction. I get a clearer analog picture on all channels with the antenna about twenty feet LOWER than the previous technician had located it.

I ran your calculations for the Research Comms preamp with (0.4dB NF).

Tnamp = 290 * (10^(0.4/10) - 1)
= 27.98K

Tnsys = 27.98 + 8880 / 100 (20dB)
= 116.78K

NFsys = 10log(1 + 116.78/290)
= 1.47dB

So compared to the CM7777 system with NF 2.2dB, the Research Comms lowers the system NF by .7dB or .85 times or 15%. Incidentally, with the lower gain of this expensive amp, your $6/ft cable would lower the NF of the system to 0.84dB, which is 1.36dB lower or .73 times or 27% compared to CM7777. So the cable is a much bigger factor. I have this preamp and didn't notice a significant improvement. But it is at the end of a 150ft RG-6 cable run. I am still playing with it though.

So the cable is a much bigger factor.
Good observation. If anyone is interested in Heliax, here's a few links:

http://www.andrew.com/catalog38/Cat38Viewer.aspx?PageNum=580

http://www.andrew.com/catalog38/Cat38Viewer.aspx?PageNum=578

http://www.xmantennas.com/catalog38/PriceList/11191_Sept04_Price%20List.pdf

However, the effect of the feedline can be mitigated by placing another
preamp at the receiver.

The equation is extended for multiple stages like this:

Tn = T1 + T2/G1 + T3/G1G2 + T4/G1G2G3 .....

Coax is modeled as a "stage" with gain less than 1 and Noise Figure equal to
the cable loss (for instance, a cable with 6 dB of loss is an amplifier with a
gain of 0.25 and a noise temperature of 864.5K).

Ron

Dr et al,

Great observations. I have tried putting an in-line amplifier in after
my CM 7777 and all I got was extreme noise on every station,
despite haveing less than strong signals. I figured the amp was just
bringing the noise levels up too high. At some point, as others have
pointed out and as I have seen first hand, you can only amplify signal
so much before you start amplifying noise above desirable levels.

Gfgray...spot on with the calculations. But, because the CM 7777
puts out 6 dB more than your amp, despite the 1.6 db added noise
compared to yours, you're still getting 4 db more from the 7777
than the other. Just a thought.

Also, it would be interesting to do calculation on a 13 dB amp with
5 dB noise, which cheapy stores sell (or inflict) unwittingly to their
customers.

Gilbert,

Yes, it's a balancing act. Too much gain causes other problems. Armed with
the equations, one can select the minimum gain required of a preamp (or
preamps in a multi-stage configuration) for a given system.

gfgray's system is a good case study. He's bought an expensive GaAsFet
preamp and want's to take advantage of the low Noise Figure, but he's
got a 150 foot RG-6 run (about 7.5 dB loss). Let's add a 1 dB NF 10 dB
gain preamp at the 10 dB NF receiver.

Tn = T1 + T2/G1 + T3/G1G2 + T4/G1G2G3

Tn = 27.98 + 1341/100 + 75.1/(0.178)(100) + 2610/(100)(0.178)(10)
Tn = 27.98 + 1341/100 + 75.1/17.8 + 2610/178
Tn = 27.98 + 13.41 + 4.2 + 14.66
Tn = 60.25K or 0.82 dB Noise Figure

The overall added gain is 20 - 7.5 + 10 or 22.5 dB.

You can juggle the numbers. In fact, this stuff is perfect for an Excel spread-
sheet. Probably the more difficult part is finding preamps that meet your
specifications (that is, a 1 dB NF 10 dB gain preamp may not be "off the
shelf").

Another thing to consider is what is the value of the S/N improvement?
Adding the 1 dB NF 10 dB gain preamp buys about 1.35 dB S/N ratio. If
the long distance or weak station has a 5 dB or more variation due to
propagation effects (tropospheric enhancements and degradations due
to time of day and weather or changes in the local noise level), then the
1.35 dB improvement won't really be noticeable if you're looking for error
free viewing. If you're into DTV DX'ing and are thrilled with moments of
reception, then the 1.35 dB improvement means longer periods of time
between breakups.

Ron

Ron, good point on adding another amp to overcome the receiver NF. I'll give that a try with a CM7777 behind my TV or something. Or maybe I'll get a splitter to split my power signal at the antenna and run a CM7777 in series with the 9250 amp. This would also solve the problem of the 9250 being UHF only. I'll probably have to add an atenuator between the two amps.

Research Communications latest model uses pHEMT technology which I think is based on GaAs. But, it is also way cheaper than their older $700 GaAs based amp. The pHEMT preamp is 75GBP (~$150) plus 25GBP shipping.

Originally posted by dr1394
... Too much gain causes other problems...

Another thing to consider is what is the value of the S/N improvement? Adding the 1 dB NF 10 dB gain preamp buys about 1.35 dB S/N ratio. If the long distance or weak station has a 5 dB or more variation due to propagation effects (tropospheric enhancements and degradations due to time of day and weather or changes in the local noise level), then the 1.35 dB improvement won't really be noticeable if you're looking for error free viewing. If you're into DTV DX'ing and are thrilled with moments of reception, then the 1.35 dB improvement means longer periods of time between breakups.

These caveats must not be overlooked. In most real world situations, adding the second preamp will not improve system performance and may make it worse. Cascaded amplifiers develop intermodulation artifacts that tend to degrade signal quality. Furthermore, any signal so anemic that it theoretically is calculably enhanced through multiple stages of amplification is probably impure to begin with. The biggest remaining problem with a signal that has already been preamplified may not be S/N ratio and further increasing it may contribute nothing to system reliability while the efforts to do so may make it worse.

I didn't see how the calculations in dr1394's last post take into account the effect of the ambient signal level. To use more primitive methodology, suppose an antenna develops an output level of -20dBmV. For ease of calculation, we call the thermal noise floor -60dBmV, then the S/N at the antenna is 40dB. Say we lose 10dB of signal strength over the length of the coax, and so the signal strength at the tuner is -30dBmV, but since the tuner has a noise figure of 10dB, the tuner degrades the S/N to 20dB. We can live with that, but, according to the manufacturer's specs, it gives us no cushion.

Now, if we have a 13dB gain preamp with a 3dB noise figure, then the preamplifier output is -7dBmV, the system noise floor is up to -44dBmV (-60dBmv noise floor + 13 amp gain + 3dB) and the S/N ratio has dropped by 3dB to 37dB. After we lose 10dB of signal along the coax, the input signal has a signal strength of -17dBmV, and the power of the noise impressed upon that signal is -54dBmV (-44dBmV -10dB).

The noise figure of the tuner, 10dB, is added to the thermal noise floor and effectively develops a noise power level of -50dBmV, so when you convert -50dBmV to watts, add it to -54dBmv converted to watts and convert back to dBmV, you wind up with system noise of about -48dBmV, which means the S/N ratio will be about 31dB. That's pretty good. In fact, that's as good as you need. Uncle siggy says that more precise calculations are not warranted because of the range of the variables involved.

Now someone with more time on his hands than I have (and with either the innate ability to convert dBmV to watts and back in his head or through some more reliable means!) can redo these seat-of-the-pants calculations with weaker antenna input numbers and see that when input signal levels are really, really anemic, there will be an extremely narrow range of circumstances where the S/N ratio was acceptable coming off the antenna but where the output of one single 23/26dB gain, <3dB NF Channel Master preamp or one single 28/30dB gain, <3dB NF Winegard preamp, diminished by the downlead coax loss, barely nudges the tuner S/N ratio across the perceived magic 20dB S/N threshold, and where adding a second, low noise preamp at the tuner input will slightly improve that ratio, but those circumstances are few and far between. And in fact, if you compare using a second, cheap 3dB preamp in place of an expensive, <1 dB preamp just in front of the tuner, you will be astounded at how small a difference in calculated S/N ratio will be developed. It will only be a fraction of a dB difference between using a 3dB second stage amp versus a <1 dB second stage amp.

In nearly all instances, once you have installed a 23-30dB gain, 3dB or lower NF preamp, your time and money will be better spent on antenna improvements.

Originally posted by sregener
Actually, once you're beyond line-of-sight, this is blatantly false. VHF "bends" much more readily than UHF. Thus, it is reasonable to get VHF reception from 100 miles away over average terrain. UHF is pretty much hard to do after 60 miles. (Assuming normal broadcast antenna height.)

I agree about the difficulty of UHF after 60 miles . . . but, for some reason, I get a Richmond, Va., station (FOX-35) at 90+ air miles from here, solid all the time, with a ChannelMaster 4248 and 7777 preamp. This is the most recent of the Richmond stations to go to full power, with new equipment. The other Richmond stations are good more than 50 percent of the time, but certainly not always.

My puzzle is why I can get that Richmond station so well, all the time . . . at well beyond 60 miles. My experience with the other stations is more what I'd expect at this range.

willie

Originally posted by wildwillie6
I agree about the difficulty of UHF after 60 miles . . . but, for some reason, I get a Richmond, Va., station (FOX-35) at 90+ air miles from here, solid all the time, with a ChannelMaster 4248 and 7777 preamp. This is the most recent of the Richmond stations to go to full power, with new equipment. The other Richmond stations are good more than 50 percent of the time, but certainly not always.

My puzzle is why I can get that Richmond station so well, all the time . . . at well beyond 60 miles. My experience with the other stations is more what I'd expect at this range.

willie

Line of sight can easily extend to 100 miles or more depending on the elevation of the transmit and receive sites. What's not taken into account is intervening terrain. You need a topo program for that. Most likely you have favorable intervening topography between you and Richmond. A line of sight calculator can be found at http://www.vwlowen.demon.co.uk/java/horizon.htm but keep in mind this just assumes two theoretical points on a smooth sphere and doesn't account for intervening terrain.

Originally posted by wildwillie6
I agree about the difficulty of UHF after 60 miles . . . but, for some reason, I get a Richmond, Va., station (FOX-35) at 90+ air miles from here, solid all the time, with a ChannelMaster 4248 and 7777 preamp.

My puzzle is why I can get that Richmond station so well, all the time . . . at well beyond 60 miles. My experience with the other stations is more what I'd expect at this range.


There are a couple of things to consider. First, WRLH (call letters are always better than channel numbers for those of us not in your local area) has a higher tower than a lot of the other digital stations - over 100 meters higher in some cases. The exception seems to be WTVR, which is about at the same height. *BUT* receiving antenna characteristics come into play, too. You're using a yagi/corner-reflector antenna (and not the best, IMO) which means that there is a crossover point where the corner-reflector becomes the dominant reception design. Generally, speaking the low-to-mid 30s is where both halves are approximately equal. Thus, for very weak signals, this is the strongest part of the antenna.

I have a similar situation with WCCO-DT (UHF channel 32) for me - while every other digital station from the exact same tower (and relatively identical antenna heights, as well) gives me fits, WCCO-DT seems to be solid. Since every frequency propogates differently, there's going to be "hot spots" well beyond the predicted contours. Probably, you're experiencing the same thing I am - that frequency is just tending to hit your location stronger.

Of course, if you also have co-channel interference on other frequencies (a very real possibility at 90 miles) that could also make the one "clean" channel better than the others.

Originally posted by sregener
You're using a yagi/corner-reflector antenna (and not the best, IMO) which means that there is a crossover point where the corner-reflector becomes the dominant reception design. Generally, speaking the low-to-mid 30s is where both halves are approximately equal. Thus, for very weak signals, this is the strongest part of the antenna.

. . .

Of course, if you also have co-channel interference on other frequencies (a very real possibility at 90 miles) that could also make the one "clean" channel better than the others. [/B]

Good points, and I agree about antenna design. Looked long and hard at the CM 4228, but went with the yagi/corner-reflector 4248 because of concern about the wind load. Clearly I have some kind of sweet spot for WRLH -- but it's actually at UHF channel 26, their digital assignment. I don't get WTVR quite as well, and that's on UHF 25.

Thanks for the thoughts, and also for sharing your experience.

Originally posted by wildwillie6
Looked long and hard at the CM 4228, but went with the yagi/corner-reflector 4248 because of concern about the wind load.

If you haven't considered or looked at the AntennasDirect 91XG, my experience seems to indicate that there is a marked improvement in reception with the 91XG. I found the 4248 to be an underperformer in my situation. It wasn't noticably better than the UHF section of my Winegard HD7084P, even when used in a vertical stack of 2. YMMV.

http://www.geocities.com/figbert/antennasdirect91xg.html

I'm deliriously satisfied with the 4228 which by all common sense should not be doing for me what it is; but if I had any issues at all with long range beyond the envelope OTA, I'd be tempted to try the 91XG. Don't know how I'd get it into the attic, but that baby even looks like it would be extremely effective at pulling in UHF digital stations at the great distances I have -- to say nothing of the impressive specs it carries.

Just thought I would throw this out to you all:

For the past 3 years I have been doing line-of-sight checks for people in my area using a topographical program. Where I live (Seattle) the hills play a major factor in who get DT and who doesn't. Since things have quieted down a lot I have more time now. If you live in a hilly area and want a plot check just PM me your lat/lon or address and the call letters of the station(s) you are interested in. I will try to respond within 24 hours. If you know the locations of the towers that will save me the time of looking them up on the FCC site. If I am inundated with requests I will let you know the ETA on your plot. Each one takes about 20 minutes to do for say 6-7 stations.

What topographical program are you using? Does it do signal levels?

I started to do some propagation predictions for LA and San Diego area,
first using RFPROP, then some published SPLAT! curves for LA and now
RADIO MOBILE (incorporates the Longley-Rice Irregular Terrain Model).

Next on my agenda is to finish up a spread sheet calculator that includes
calculation for antenna gain, cable loss, etc at each channel frequency,
as well as effect of cascaded Noise Figure (Preamp/DistibutionAmp/HGTV).

Examples and setup info for RADIO MOBILE can be found here:
http://hdtv.forsandiego.com/messages/1/2846.html

Originally posted by holl_ands
What topographical program are you using? Does it do signal levels?

I started to do some propagation predictions for LA and San Diego area,
first using RFPROP, then some published SPLAT! curves for LA and now
RADIO MOBILE (incorporates the Longley-Rice Irregular Terrain Model).

Next on my agenda is to finish up a spread sheet calculator that includes
calculation for antenna gain, cable loss, etc at each channel frequency,
as well as effect of cascaded Noise Figure (Preamp/DistibutionAmp/HGTV).

Examples and setup info for RADIO MOBILE can be found here:
http://hdtv.forsandiego.com/messages/1/2846.html

I'm just using a map program called DeLorme Topo USA. It has topo data for the entire US and lets you do a profile from any point to another (among other things). This lets me see any intervening hills which is what we are mainly fighting in our area. If there is no line of sight from a tower to a receiving antenna then DT reception goes way down (duh).

The program has nothing to do with antennas or propagation. It is mainly aimed at recreational types looking for terrain info. It does have a 3D mode that lets you view a section in 3D projection that you can rotate - can be very handy sometimes.

I appreciate the info you told me about my location and line of sight enviroment. Do you get to see a map with your program? Maybe something in 3d, that could be pretty neat to see!

Originally posted by homer1
I appreciate the info you told me about my location and line of sight enviroment. Do you get to see a map with your program? Maybe something in 3d, that could be pretty neat to see!

Here's an example which was sent to me from a fellow AVS'er. On the right is Lexington, KY and on the left is somewhere in southern Ohio. The big dip is the Ohio river. The program does will do 3D representations as well.

Originally posted by cpcat
Here's an example which was sent to me from a fellow AVS'er. On the right is Lexington, KY and on the left is somewhere in southern Ohio. The big dip is the Ohio river. The program does will do 3D representations as well.At first glance, the attached map looks pretty impressive, but looking closer I'm afraid the map is out of proportion. The average depth of the Ohio River is only about 25 ft. and at its widest point it's only about 1 mile wide -- neither of which is supported by the map. I don't know about the foothills' measurements, but perhaps the maps aren't intended to be to scale, among other things. And if that's the case then -- borrowing a military phrase -- as you were.

Originally posted by Bill Johnson
At first glance, the attached map looks pretty impressive, but looking closer I'm afraid the map is out of proportion. The average depth of the Ohio River is only about 25 ft. and at its widest point it's only about 1 mile wide -- neither of which is supported by the map. I don't know about the foothills' measurements, but perhaps the maps aren't intended to be to scale, among other things. And if that's the case then -- borrowing a military phrase -- as you were.

I can't vouge for the accuracy of the program but that part doesn't seem that misrepresented to me. Regardless of the depth/width of the Ohio river, the gorge it has cut over millenia is much wider and deeper. At least at Covington going north on I-75 this is certainly true.

Originally posted by homer1
I appreciate the info you told me about my location and line of sight enviroment. Do you get to see a map with your program? Maybe something in 3d, that could be pretty neat to see!
You see a terrain map from above that is very detailed and you can zoom in so that your full CRT is viewing about a 200' x 200' chunk. You can also pull up a second panel that shows the enclosed area in 3D and viewed from an angle of 15 degrees to about 75 degrees and from any point on the compass. You can zoom in and out on both panels at the same time. Very good for sighting down canyons - see my post from a few days ago about Hells Canyon.

cpcat - your image looks very much like the DeLorme plots/profiles I see. From the little bit of testing I've done in Washington state, they appear to be very accurate. I know I have been surprised a few times at what the profile looked like from one point to another.

did you mean vouch?

vouge -
n : a kind of pike used by foot soldiers in the 14th century

for mounting antennas in the 21st century...

Originally posted by quarque
.

did you mean vouch?

vouge -
n : a kind of pike used by foot soldiers in the 14th century

for mounting antennas in the 21st century...

Yes, thanks. That Ohio river gorch is perty deep though isn't it?;)

I've been fascinated with topo maps for a number of years now and cp is providing really useful & intriguing info here for many of us. Nevertheless, on an X/Y axis layout having vastly different distances (miles compared to feet), I know of no way to make it look proportional. If there are any geographical features resembling those on the map anywhere on an 80 mile stretch of this earth, I desperately want to go there immediately and see them in person.

Still, the map within its limitations represents graphically actual terrain and I'm glad to see it on this forum. Kudos to cp and the fellow AVS'r forwarding it.

Bill - I think they are using a special algorithm to exaggerate the "edges" much like sharpening routines do for graphics. Otherwise the narrow features would disappear altogether because of the resolution limit of PC displays. The plots look much more realistic for a 5-mile stretch in my experience. The main thing we're interested in are the high spots between point A and point B. If one of those spikes is in the way it is trouble. Those seem to show up reliably even if they are not scaled properly.

Que- What you just indicated sounds reasonable and I'm glad we're now pretty much in agreement about this fascinating map.

Originally posted by Bill Johnson
I'm deliriously satisfied with the 4228 which by all common sense should not be doing for me what it is; but if I had any issues at all with long range beyond the envelope OTA, I'd be tempted to try the 91XG. Don't know how I'd get it into the attic, but that baby even looks like it would be extremely effective at pulling in UHF digital stations at the great distances I have -- to say nothing of the impressive specs it carries.


I use the cm-4228 7777 amp and I have had good luck with it. I am always looking to improve reception, Is the 91XG a better antenna or is 4228 better?
antenna?

Originally posted by firemantom26
I use the cm-4228 7777 amp and I have good luck with it. I am always looking to improve reception Is the 91XG a better antenna or is 4228 better
antenna?

If you're having good luck with an antenna, I don't recommend changing it for something that is "technically" better. Once you've got perfect reception, stop fussing.

Yagi/corner-reflector hybrids do better at some things than stacked-bowtie designs. Stacked bowtie designs do better at other things than yagi/corner-reflectors. I usually recommend that people having problems with the 4228 switch to a yagi/corner-reflector. I also usually recommend people having trouble with yagi/corner-reflectors switch to stacked bowties. Since they have different strengths, they offer a much better chance of success if one design is failing than a similar family antenna with just slightly better characteristics.

The 91XG is a better choice if you're using a rotor. It should outperform the CM4228 on channels above 42 or so. It may be weaker on channels below 30. There are too many variables to be sure one will be better than the other.

If your curiosity is killing you, AntennasDirect has an excellent return policy, costing you only shipping to try it out.

Originally posted by Bill Johnson
At first glance, the attached map looks pretty impressive, but looking closer I'm afraid the map is out of proportion. The average depth of the Ohio River is only about 25 ft. and at its widest point it's only about 1 mile wide -- neither of which is supported by the map. I don't know about the foothills' measurements, but perhaps the maps aren't intended to be to scale, among other things. And if that's the case then -- borrowing a military phrase -- as you were.

Its squeezing 106 miles of terrain data along the plotted path into a few inches of space. Some of the "spikes" you see are actually more rolling hills. But, the profile is to scale, and the data is quite accurate from what I have seen. It does not of course take curvature of Earth into account.

How deep the water in the river is has nothing to do with it. The bed of Ohio river at Cincinnati sits at about 459FT above sea level. Paul Brown Stadium on the Banks is at about 480FT. The tops of some of the hills(within less than a mile of the center of the river, Price Hill, Mt Adams/etc) right along the River at Cincinnati are at 800FT+ ASL. In some places it's flat along the banks(such as right at Downtown Cincinnati), In some places there are hills(not necessarily right at the banks of the river, but in some cases that is the case), this profile is only showing the terrain along a "direct line" path from ay location about 36 Miles North of Ohio River~Cincinnati to a TV tower in Lexington, KY at right.

Update: This might help. Attached is a portion of the topo map(just a 2D view from above in this case) within a few miles of Ohio river concerning where the profile Cpcat provided above crosses the Ohio river, which happens to occur a few Miles SE of Downtown Cincinnati. The Red line is what was used for the elevation profile cpcat provided. Scale bar is at right(had to "move it" a bit given the limitations on attached graphics), the lat/long coordinates+elevation is for the point of red line at about middle of river. I would have liked to "zoom it in" to show 20FT intervals instead of 100FT for the contour lines, but that would have taken quite a large graphic for you to see everything and fit in a couple miles on either side of Ohio River where the profile "line" crosses the river.

I recently bought and installed my CM 4228. When it arrived I noticed that two of the elements on two of the bowties were missing. The missing ones were on the second bowtie down on the right and te third bowtie down on the left, so it looked symmetrical, and I thought maybe it was suppose to be like this. But I have seen pictures and all eight bowties had all four elements. Do you think this is messing up the antenna reception. I only get channels some of the time, but I also live in an area which is notoriously hard to recieve signals.

VMsat - well it certainly is not helping matters. Can you see any obvious signs of damage where the elements attach (i.e. evidence of forceful removal)? I'd exchange it for a "complete" antenna.

I would send it back too.


Originally posted by VMsat
I recently bought and installed my CM 4228. When it arrived I noticed that two of the elements on two of the bowties were missing. The missing ones were on the second bowtie down on the right and te third bowtie down on the left, so it looked symmetrical, and I thought maybe it was suppose to be like this. But I have seen pictures and all eight bowties had all four elements. Do you think this is messing up the antenna reception. I only get channels some of the time, but I also live in an area which is notoriously hard to recieve signals.

According to antennaweb.org, I live about 12 miles from the closest station and 15.5 miles from the farthest one, at ground level, with no obstructions of importance. All stations come from the same quadrant (50-52 degrees). With a non-amplified Terk HDTVi (http://www.buy.com/retail/product.asp?sku=90130391&spf=1&sp=1) indoor antenna we only get one station (at about 12 miles) reliably and with good signal strength; the rest are either not received at all or very rarely. I would like to stick to an indoor antenna if possible. Would switching to an amplified Terk TV5 (http://www.buy.com/retail/product.asp?sku=90105138&loc=111&sp=1) or Radio Shack 15-1880 (http://www.radioshack.com/product.asp?catalog_name=CTLG&product_id=15-1880) solve my problem? What about adding an amplifier to my current antenna?

Thanks,

Val

For a good small indoor antenna, I don't know that you can beat antennas direct DB2. I think they're currently on back order though, excellent little UHF antenna, (most likely) outperform the Terk antennaes and the Radio Shack.

http://www.antennasdirect.com/db2_bowtie_antenna.htm

Of course both the HDTVi and this one are directional, so, if you're in the middle of a couple stations you'd want something multi-directional.

Originally posted by vdorta
According to antennaweb.org, I live about 12 miles from the closest station and 15.5 miles from the farthest one, at ground level, with no obstructions of importance. All stations come from the same quadrant (50-52 degrees). With a non-amplified Terk HDTVi (http://www.buy.com/retail/product.asp?sku=90130391&spf=1&sp=1) indoor antenna we only get one station (at about 12 miles) reliably and with good signal strength; the rest are either not received at all or very rarely. I would like to stick to an indoor antenna if possible. Would switching to an amplified Terk TV5 (http://www.buy.com/retail/product.asp?sku=90105138&loc=111&sp=1) or Radio Shack 15-1880 (http://www.radioshack.com/product.asp?catalog_name=CTLG&product_id=15-1880) solve my problem? What about adding an amplifier to my current antenna?

Thanks,

Val
At that distance you do not want any amplifiers. In fact you may need an attenuator if anything. Radio Shack has a cheap variable one. One of the best indoor antennas is the Zenith Silver Sensor (sold by Sears and others). It is somewhat directional. You do NOT want a "multi-directional" or "omni-directional" antenna. All they do is pick up reflected signals and cause the receiver to bounce around trying to lock on to one of them (unsuccessfully). Terk is not highly rated around AVS. Also, indoor antennas in general are problematic. You have to contend with your house and all nearby house's effects on signals. One of the best indoor setups is a CM 4221 in the attic. Works very well for many even if it is a little big and ugly for the living room. Although some have stuck them in a window behind a curtain. It certainly wouldn't hurt to try the 15-1880 since you can easily return it.

Hi guys, I'm back :)

I've got a couple more Qs.

Here's some pics from my attic. Can anybody ID or give opinion?
(Note: My first time posting pics and making my webpage, plus I changed a handful of burned out light bulbs while I had the ladder out! You guys are slave drivers :)

Here's the UHF, looks like it's not a CM 4221 remember that it's from 1990.

http://hometown.aol.com/newsgroupjohn/images/uhf.jpg

http://hometown.aol.com/newsgroupjohn/images/combo.jpg

VHF is good except chn 9 CBET from Windsor, Ontario eh?
It's in different direction and farther than others, but no hockey now :(

http://hometown.aol.com/newsgroupjohn/images/vhf.jpg

http://hometown.aol.com/newsgroupjohn/images/vhfvjobs.jpg

These are combined in attic (no or minimal loses???)
I gave the UHF a twist based on compass. I went a long time w/o dropouts/freezes but lately some on chn 4 (45), WDIV @210deg. Didn't troubleshoot a lot, because I was watching another channel that was rock steady. Now, I have a plan to check analog UHF if possible when it acts up.

Have read in Detroit thread that when I had DOs, cable AND satellite also did. This had led me to wonder if problems may not be OTA reception:(

Also have noticed UHF analog appears to me to be more ghosty than snowy, even if ghosts are weak, stable and generally look "OK" although I've heard "static" in sound even when picture is quite good (analog). Does this imply MP or weakness, or does it depend?

If I knew I could use a 4228 to solve problems I think I'd try it. Might have to do some disassembly to get it thru opening and it would be a pain to add a rotor, I'm not sure what the consensus is w/ or w/o rotor. This would be under the assumption I could cut down MP, and still have strength, but maybe I'd be fooling myself.

Thanks
John

Original post>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
I got a new Pio plasma and hooked it up to the attic antenna (condo) I had installed when it was built about 15 yrs ago. I don't know what it is and haven't been up there yet to look.

I get from the high 70s to low 90s on sig strength screen, which is not easy to monitor when watching. I've seen some dropouts or freezes for up to a few seconds which I think *may* be associated with rain or possibly wind or fog(!)? When conditions are right for this, the signal goes down to 40 or 50 briefly. (Is it likely that this is multipath?)

This is what antennaweb shows:

DTV Antenna

* red - uhf WWJ-DT 62.1 CBS DETROIT MI 200° 14.1 44
* red - uhf WTVS-DT 43.1 PBS DETROIT MI 200° 14.1 43
* red - uhf WXYZ-DT 7.1 ABC DETROIT MI 218° 14.1 41
* red - uhf WKBD-DT 50.1 UPN DETROIT MI 230° 15.3 14
* red - uhf WDWB-DT 20.1 WB DETROIT MI 200° 14.1 21
* red - uhf WJBK-DT 2.1 FOX DETROIT MI 210° 13.9 58
* red - uhf WDIV-DT 4.1 NBC DETROIT MI 210° 12.3 45
* red - uhf WADL-DT 39.1 IND MOUNT CLEMENS MI 126° 12.9 39

From what I've read here, I get the impression that:

1. Multipath may be my problem vs. signal "strength".
2. An amp may cause a problem instead of solve it.

I haven't seen much about how directional antennas are and I wonder if I don't have a highly directional one, would one be likely to solve my problem since these stations that I'm interested in are within 30 deg?
(Any recommendations, assuming I can fit it in.)

Is there any easy way to verify the coax and connectors are good? (With ohm meter etc?)

Would it be foolish to try a preamp halfway between the antenna and TV, where I have a coupling for the coax already?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

From sregner)

1. Probably. But diagnosing reception problems with digital meters is never easy. If you have UHF analog stations broadcasting from the same towers at the same relative power (take digital and multiply by 5 for analog equivalent) then watching them can tell you what the problem is. Does the picture get very snowy? Or do you get moving ghosts? The answer to that question will tell you the answer to your problem. Snow = weak signals. Ghosts = multipath.

2. 30 degrees is not a directional antenna. A directional antenna should have an acceptance angle of less than 10 degrees. Examples include the Channel Master 4228 and the Antennas Direct 91XG. Either of these would probably require a rotor.

3. If you're getting signals that are routinely in the 70s+, your coax is most probably good. If you consistently had problems above or below a certain frequency, things would be different.

4. Foolish? If you've got snow on the analog test in answer #1 above, no. If you've got any ghosting now or when you have issues, yes.

(From cpcat)
You need to get up there and take a picture of the antenna and post it here. At your distance, a CM 4221 should work and has a beamwidth of around 60 degrees. If you're already using something equivalent though, you'll have to go bigger. Sometimes attics can really block the signals. If you can't get the pic at least desribe what it looks like.

Originally posted by JLaamanen

Here's some pics from my attic. Can anybody ID or give opinion?
(Note: My first time posting pics and making my webpage, plus I changed a handful of burned out light bulbs while I had the ladder out! You guys are slave drivers :)

Here's the UHF, looks like it's not a CM 4221 remember that it's from 1990.
-----------------------------------------------------------------------


Whether it is a CM or not is moot. The design is similar to the 4221. Have you tried an attenuator? If not, go to Rat Shack and buy their cheap variable attenuator and stick it right behind your receiver so you can adjust it while watching the screen. You are so close to the towers that you may have *too much* signal (not to mention reflections). The attenuator will reduce all of them and hopefully just the main signal will get through.

i was just curious if the antenna direct db2 is better then the silver sensor indoors? I live about 45 miles from the stations and want to pull in cbs hd which is 21.6 kw.

sf49 - impossible to say. Each will work better than the other in certain circumstances. Each antenna has its own gain profile with high & low gain areas going around the compass points. These lobes & nulls can be "skinny" or "wide" in shape as well as differing in number. So each accepts and rejects signals a little different from the other. In your living room it is impossible to know beforehand which combination will work best. The best one can do is guess at a good starting point based on anecdotal data, design data and user's experiences. Eventually you find that the SS works well more often than others like Terk. That is not to say that Terk never works, just statistically it is less likely when starting from scratch. The DB2 is a proven double-bowtie design and works well in some places, I'm sure.

At 45 miles it will be tough to pull in a 21.6 kW signal indoors, but anything is possible! All of the major networks in our area are at 600kW or more. I certainly hope that CBS station is planning to boost power soon - what are the call letters?

quarque,

I picked up one of those antenna-u-ators and hooked it up on the DTV input. Was surprised how low I could dial "signal strength" down and maintain pic (at least in a short test, but will do more investigation). What I need now is a channel acting up. What concerns me a little is the report that cable and satellite was having problems w/ "West Wing" when I saw them too. I hope I'm not trying to fix network feed problems. Maybe I should move it to work on the analog input too, hmmmm.

Thanks,
John

Originally posted by quarque

Whether it is a CM or not is moot. The design is similar to the 4221. Have you tried an attenuator? If not, go to Rat Shack and buy their cheap variable attenuator and stick it right behind your receiver so you can adjust it while watching the screen. You are so close to the towers that you may have *too much* signal (not to mention reflections). The attenuator will reduce all of them and hopefully just the main signal will get through.

Originally posted by sf49ersnfl
i was just curious if the antenna direct db2 is better then the silver sensor indoors? I live about 45 miles from the stations and want to pull in cbs hd which is 21.6 kw.

In general an outdoor is always better then an indoor antenna. 45 miles you'll need a mid size outdoor for reliable DT reception.

I am now without HD having ditched my RS 15-1880 indoor beastie. I am now looking at either the CM3016 or RS 15-2152 to reach two antenna farms, one about 16 miles away and the other at 34 miles.

As I live in an area susceptible to hurriances I don't want an outdoor mount so would be looking for an attic install. I can accomodate an 80" boom (just) with about 45 degrees of turning radius for adjustments. The two antenna farms are about 100 degrees apart.

My question is about expected attenuation due to the attic root. It is a clay-tile roof with felt underneath then plywood on the inside. I will mount high enough to clear the A/C ducting but still expect some attenuation but don't know how much.

On a similar vein what attenuation would one expect from 50' of RG-6 ?

Any insight from people with similar experience appreciated.

Cheers,
Tony

how does anyone go about stacking 2 uhf antennas? i.e. using a combiner or ? does it serve to boost a signal or just try to gather more signal? i am about 90 air miles from the towers of the stations i would like to try to receive and i can get 1 of them about 65% of the time but it breaks up and one of them about 45% of the time but one i can get almost all the time. i am currently trying 2 different antennas 1: is the winegard i have asked questions about ( dedicated UHF ) and 1: is the radioshack VU90XR. i have also thought about getting the xg91 but haven't quite decided if it's worth it or not! i live in Lehigh Acres,Florida 33936 and the stations are in Miami and West Palm Beach. last weekend i had approximately 13 HDTV channels but now only 2.

any info on the possibility of stacking antennas (if it would help) is greatly appreciated. :)

no hills or mountains to interfere with reception

Originally posted by dapack5
i am about 90 air miles from the towers of the stations i would like to try to receive...

any info on the possibility of stacking antennas (if it would help) is greatly appreciated. :)

no hills or mountains to interfere with reception

At 90 miles, it isn't the hills or mountains that get in the way - it's the earth itself! The earth is curved and for an antenna mounted about 330 meters above average terrain, UHF signals run "aground" at 60 miles.

Whatever signal you are getting is a result of the troposphere helping you out. You're lucky in that Florida often gets a lot of tropospheric help, but it's not the kind of thing you can count on.

Stacking theoretically increases gain by 3db. While that doesn't sound like much, 3db is a doubling of the signal received by the receiver (this will not mean that you get an increase of 50% on your signal strength meter.) Stacking also increases directionality of your antenna, which is useful if multipath is the problem.

In my experience, one really good antenna is the ideal for long-distance reception. But nothing can overcome a bad location or extreme distances. AntennasDirect has a good return policy, so it may be worth a shot. But otherwise, I'd skip the stacking.

(For stacking, you need two identical antennas, connected to a splitter using cables of exactly the same length. If you use coax, you have to make sure the baluns also are "in phase" or you'll cancel the antennas out. For maximum gain, they should be stacked one above the other, at somewhere between 36" and 48".)

Re: Indoor and Attic UHF Signal Attenuation.

I've been doing some searching for information on this subject.

If your house is made of RF shielding material, such as a mylar aluminum "heat shield" or foil backed insulation material or aluminum siding, then the signal leaks in via windows and may be attenuated by 20 dB. People walking in front of the antenna may cause another 3-6 dB of attenuation.

During an on-the-air statistical gathering test of the Brazilian ATSC system, the MEDIAN indoor attenuation was 12.5 dB, which means that some homes have a lot more attenuation to make up for those of more typical tropical open construction.

So far in my search, I haven't seen much information wrt real-world attic attenuation, but I did run across a laboratory test that measured attenuation for basic building materials:
http://fire.nist.gov/bfrlpubs/build97/art123.html

A few germaine measurements:
500 MHz, 10000 MHz
0.4 dB, 2.6 dB, Double thickness, wood planking
0.35 dB, 0.75 dB, Single thickness, 3/4 in Plywood
0.2 dB, 0.8 dB, Single thickness, 1/4 in Glass

It appears that the roofing material attenuation for UHF is about 1 dB for low channels and 2 dB for high channels.
Of course, in a real attic there are metal nailing plates, wood struts and other objects that can perturb the antenna gain pattern and generate multipath reflections.
So the total reduction is probably 2-3 dB.

Re: RG-6 Attenuation.

Depends on the part number.
Belden makes over a dozen different part numbers with attenuation per 100 feet of cable
ranging from 4 to 9 dB for the high UHF channels and 3.5 to 6 for the low UHF channels.
The Quad Shield products tend to be in the middle of this range.
Of course, cable from your local home outlet may be different....

All the more reason to use a preamp, which does several things to improve the overall sensitivity:
1) replaces the HDTV's tuner with the much more sensitive (5-10 dB) preamplifier,
2) overcomes the reduction in sensitivity due to the cable downlead and RF splitters (another 5-10+ dB)
and 3) minimizes the DTV signal degradation due to VSWR reflections (another 2-6 dB).

If signal levels are high enough to overload a preamp, an attenuator may need to be used prior to the preamp, such as is integrated into the R-S model, which should yield a considerable portion of the above improvements.

Originally posted by holl_ands
So far in my search, I haven't seen much information wrt real-world attic attenuation


In document at link below which among other things describes results of 2600 field tests(some indoors, all in U.S.) of ATSC reception : They found typical outdoor to indoor signal attenuation to be in the range of about -9~-13db ... see table 7 in section 5.3 and paragraph immediately below table 7 on page 20 of PDF file at link below :

http://www.atscforum.org/doc/FieldTestReport.pdf

Originally posted by dapack5
any info on the possibility of stacking antennas (if it would help) is greatly appreciated. :)


In addition to srenger's excellent info, here is an excellent article on stacking antennas :

http://pages.cthome.net/fmdx/stackant.html

Originally posted by holl_ands
3) minimizes the DTV signal degradation due to VSWR reflections (another 2-6 dB).
VSWR doesn't cause that much loss. The formula for attenuation due to VSWR is:

K = (VSWR - 1) / (VSWR + 1)

attenuation in dB = 10 log (1 - K^2)

A very high VSWR of 6:1 only causes 3 dB of attenuation. A more typical VSWR
of 2:1 causes 0.5 dB of attenuation.

Ron

Originally posted by Nitewatchman
In addition to srenger's excellent info, here is an excellent article on stacking antennas :

http://pages.cthome.net/fmdx/stackant.html

i just revisited antennaweb and added my address and info,according to what was found for my location,with the right antenna it's showing that i can receive stations from 68 miles to 84.2 miles away. keep in mind it doesn't say digital,just gives a list of stations that can be received. one of those station ( 84.2 miles away ) i do get the digital feed occassionally.
the other i can get analog only reception.

i went to antennaweb typed in this info

121 highview ave
lehigh acres,fl
33936
no towers
no tall buildings
click on submit
and it returns the info i spoke of

Originally posted by tpalik
My question is about expected attenuation due to the attic...
Tony,
Attics take a huge toll on the signal you get. The few that I have measured so far have been in the 20 dB range of attenuation. Those attics are made of standard asphalt shingles, over roofing felt, over plywood type construction. I have not been in an attic like yours.

Attics also cause reflections that the HDTV tuner has to equalize out and there is only so much equalization that is available. So that means there is less equalization available for the 'real world' multipath that is arriving over your house.

Some folks have good luck with the Channel Master CM7777 preamp. Inside the attic it is pretty hard to overload the front end of that particular amp. (Outside it can happen quite easily.) Given the right conditions, preamp will not overload but the output of the amp can overload the HDTV tuner . That is just one of the good reasons for using an attenuator at the receiver.

RG6 cable has a loss of about 4 dB per 50 ft in the UHF band. That 4 dB loss is one of the few planing factors the FCC got right when they made the table of allocations for HDTV.

I've attached a PDF of the measurements I did in my attic. All of the outside antenna gains are referenced to a Scala log-periodic antennas performance. The attic measurements are referenced to each antennas' own outside performance. So if you look at the green lines, the upper one is how the CM4221 compared to the Scala outside. The lower green line is what the attic did to the antenna. The difference between them is the loss that the attic caused.

Bob Chase
KHWB-TV

Originally posted by dr1394
VSWR doesn't cause that much loss....A more typical VSWR
of 2:1 causes 0.5 dB of attenuation.
Ron
Ron,
You are correct if you only look at attenuation as a factor of 'degradation'. No argument there. You are also right about 2:1 VSWR being typical. In fact, you might even be too generous, as antennas have worse VSWR characteristics than tuners.

VSWR also causes reflections. A tuner with a VSWR of 2:1 will reflect a signal that is -10 dB compared to the original signal back to the antenna. If the antenna also has a VSWR of 2:1, then it will reflect the 'reflection' back at the tuner. Assuming that there is 4 dB of cable loss, the reflection caused by tuner VSWR will arrive back at the tuner about 28 dB down (-28 dB) from the original and a little bit later than the original. To the tuner, it will look like a VERY strong multipath signal and the tuner will expend some of its equalizer on removing it, leaving less equalization available for the real signal.

VSWR reduction is one the reasons that attenuators help HDTV tuners improve reception. A 3 dB pad attenuates the VSWR reflection by 6 dB, a 10 dB pad attenuates the reflection 20 dB, and so on. Many people attribute the affect the attenuator has on reception only to the reduction of strong signals. I see time after time folks writing to say that "The attenuator worked, there must be a really strong signal that was killing me". While it is often really the weak, time delayed, signals that kill reception.

How VSWR affects TV reception is also one of the least understood things in the broadcast industry. See Dr. Charlie Rhodes articles on the TV Technology website for an in depth look HDTV reception. He is a huge proponent of attenuators, preamps, and wide-band AGC in tuners.

Bob Chase
KHWB-TV

Hi,
I've had the Silver Sensor for a few months now and for the most part, its been great. Recently, however, a few channels have started to drop in and out. Namely FOX and NBC and PBS (WTTW where I live). The tuner is having a hard time "latching" onto the signal - sometimes after a few minutes, it'll find it and the strength will go from 40% to 80-90% - but sometimes if just stays at 40-50% and therefore can't lock in.

Funny thing is, up until a few weeks ago, FOX and NBC were the strongest signals (and CBS was weak). Now, I get CBS OTA (at about 80%) and I have the aforementioned FOX/NBC issues!

Even weirder is that I haven't moved my antenna at all from the general area its been at for the last few months (which at the time, I found to be the "sweet spot" in my condo). I've also rescanned many times, manually added the channels, and scooted the antenna a tad to the left/right.

So... question: how can I improve the my signal strength (for FOX/NBC)? I can pick it up at times so I know I can get it, but how can I keep it consistent? Any suggestions? Amp, pre-amp, etc? (btw, I'm sort of new in the antenna world).

I live in CHicago about 5 miles from the towers according to antennaweb.

THANKS!!!

Re. Receive Antenna VSWR Degradation to DTV Receiver Sensitivity
(frequently expressed as an increase in the Noise Figure):

The issue is not the signal loss due to VSWR, but the degradation to the DTV signal (mostly envelope delay) due to delayed reflections up and down a long antenna cable.
Some DTV transmitters reportedly compensate for this degradation by pre-distorting the transmit waveform in accordance to information from a local feedback receiver.
At the receive end, connecting a preamp via a short cable greatly minimizes this not so well known problem.

The issue of DTV signal degradation due to antenna VSWR has been discussed in Doug Lung's TV Technology on-line column:
http://www.tvtechnology.com/features/On-RF/f-dl-ieee2.shtml
http://www.tvtechnology.com/features/On-RF/f-DL-receive.shtml
http://www.tvtechnology.com/features/On-RF/antennas.shtml

A more complete description is found on pg 63+ in the fol. ATSC Report: "Performance Assessment of the ATSC Transmission System, Equipment and Future Directions", Rev. 1.0, 12 April 2001 available from:
http://www.atsc.org/news_information/papers.html

And Dielectric's website has O. Bendov's paper: "On the Validity of the Longley-Rice Propagation Model for HDTV Coverage and Interference Analysis":
http://www.dielectric.com/broadcast/longley-rice.asp


So we should all hope that the antenna manufacturers are trying to reduce VSWR in order to claim that they are especially "For DTV".
Unfortunately, very few of them mention VSWR in their spec sheets (SquareShooter is exception).


A paper presented by Kerry Cozad at Oct04 IEEE Broadcast Technology Society re. DTV antenna VSWR and Gain measurements is cited in the fol., but I have not yet seen it. I would appreciate a copy if anyone has it.
http://www.tvtechnology.com/features/On-RF/Lung_features.shtml


Anyone know of any DTV Antenna VSWR measurements....or NEC simulation results?

Bob: Thanks for the valuable "real world" measurement re attic loss.
I'm surprised as how much more you measured for your attic compared to the statistical numbers found for a large number of lower, indoor locations in the above ATSC Field Test Report.

Could you remark on construction materials, esp roof and proximity of foil backed insulation either in the line of fire or below the antenna as well as any other nearby metal objects?
Also, how did you measure signal strength?

I'm surprised by how well the mast mounted CM4221 4-Bay performed compared to ANY of the presumably higher gain models....and how poorly the CM4248 Yagi performed both outside and in the attic.

And why did the Scala 1469 Log Periodic have 7+ dB less attenuation at mid to high frequencies in the attic than ALL of the other antennas, but was right in the middle of the pack outdoors? Very strange....

Originally posted by phatboykim
So... question: how can I improve the my signal strength (for FOX/NBC)? I can pick it up at times so I know I can get it, but how can I keep it consistent? Any suggestions? Amp, pre-amp, etc? (btw, I'm sort of new in the antenna world).


An amplifier is never a good idea inside of 10 miles from the transmitters, and rarely a good idea even 20 miles away. You might want to try a variable attenuator (Radio Shack sells one) and see if that makes a difference.

Your location, as I'm sure you know, is less than ideal for today's receiver technology. You probably have plenty of signal strength, but lots of multipath.

I am also thinking of a Channel Master 4228 8-Bay Bowtie UHF Antenna. I entered my information at www.antennaweb.org and it indicated that the channels that I am interested in are either 19.8 or 20.1 miles from me at either 355 or 357 degrees. The antenna will be in the attic above the garage. Do you guys think that this antenna will be adequate without an amplifier or should I just get an amplifier right away? I am thinking of just ordering from www.solidsignal.com Does anyone know if they are a good dealer to buy from?

Originally posted by bobchase
VSWR also causes reflections. A tuner with a VSWR of 2:1 will reflect a signal that is -10 dB compared to the original signal back to the antenna. If the antenna also has a VSWR of 2:1, then it will reflect the 'reflection' back at the tuner. Assuming that there is 4 dB of cable loss, the reflection caused by tuner VSWR will arrive back at the tuner about 28 dB down (-28 dB) from the original and a little bit later than the original. To the tuner, it will look like a VERY strong multipath signal and the tuner will expend some of its equalizer on removing it, leaving less equalization available for the real signal.
From Figure 23 in the reference that holl_ands cited:

http://www.atsc.org/news_information/papers/2001_8vsb_performance/Performance_Assessment.pdf

It would appear that a -28 dB echo doesn't have much effect (especially
considering the it would take about 350 feet of feedline to generate a 1
microsecond VSWR induced echo).

Ron

Originally posted by Jim1348
Do you guys think that this antenna will be adequate without an amplifier or should I just get an amplifier right away? I am thinking of just ordering from www.solidsignal.com Does anyone know if they are a good dealer to buy from?

Twenty miles is well within the 4228's capabilities. Of course, if you've followed the attic discussions much, you know that those aren't the best places to put your antenna. Nevertheless, I don't recommend anyone purchase a preamplifier until they've determined that their reception problems are related to weak signal strength rather than multipath.

I haven't personally done business with Solid Signal, but others here have spoken highly of them. You can read independent reviews here:
http://www.resellerratings.com/seller8101.html

Originally posted by holl_ands
I'm surprised as how much more you measured for your attic compared to the statistical numbers found for a large number of lower, indoor locations in the above ATSC Field Test Report.


I expect windows allowing for less attenuation in the lower(1st floor) indoor locations in the field tests may have something to do with it.

Originally posted by phatboykim
Hi,
I've had the Silver Sensor for a few months now and for the most part, its been great. Recently, however, a few channels have started to drop in and out. Namely FOX and NBC and PBS (WTTW where I live). The tuner is having a hard time "latching" onto the signal - sometimes after a few minutes, it'll find it and the strength will go from 40% to 80-90% - but sometimes if just stays at 40-50% and therefore can't lock in.

Funny thing is, up until a few weeks ago, FOX and NBC were the strongest signals (and CBS was weak). Now, I get CBS OTA (at about 80%) and I have the aforementioned FOX/NBC issues!

Even weirder is that I haven't moved my antenna at all from the general area its been at for the last few months (which at the time, I found to be the "sweet spot" in my condo). I've also rescanned many times, manually added the channels, and scooted the antenna a tad to the left/right.

So... question: how can I improve the my signal strength (for FOX/NBC)? I can pick it up at times so I know I can get it, but how can I keep it consistent? Any suggestions? Amp, pre-amp, etc? (btw, I'm sort of new in the antenna world).

I live in CHicago about 5 miles from the towers according to antennaweb.

THANKS!!!

I'm in a somewhat similar reception situation like you, and also new to HD OTA reception and antennas. The difference here is I'm further way, 30 miles west of the Boston antenna farms but like you using a Silver Sensor.

I was shocked to discover that I could actually receive anything at all from my distance with the SS. But I got virtually every (network) channel that I had interest in with decent lock when I hooked it up to my HR10-250 in mid February.

Over the last two weeks I've noticed problems with losing Fox WFXT and NBC WHDH. PBS along with ABC, CBS, UPN, and WB, are solid in the lower 90's.

My fear is my problem may be related to the coming Spring season and loss of snow cover. I'm prepared to move the SS outside if necessary and even put up an XG91 if needed. Just when I'll need to do this I'm not sure.

Originally posted by sregener
An amplifier is never a good idea inside of 10 miles from the transmitters, and rarely a good idea even 20 miles away. You might want to try a variable attenuator (Radio Shack sells one) and see if that makes a difference.

Anyone know if the Rat Shack attenuator is 0-10dB or 0-20dB or ???

Edit: nevermind, I found it...

it's:

Attenuation: 0-20 dB
Return Loss:
5-500 MHz: 10 dB Min.
501-1000 MHz: 8 dB Min.

If you aren't too far away and are hoping to use your UHF antenna for VHF, the fol. claims that the Silver Sensor (indoor LPDA) did a "relatively good job" on Ch11, although the max gain was perpendicular to the UHF max gain direction:
http://www.tvtechnology.com/features/On-RF/Lung_features.shtml

There is a Polish Dipol antenna website that provides a gain figure of about 6+ dBi (4 dBp, relative to dipole) for their Model ASP-8A, a typical 4-Bay Bowtie with reflector (no preamp):
http://www.dipol.com.pl/esklep/a0033.htm
[Note that Polish TV channels use 8 MHz spacing, so PolCh6-12 is our Ch7-13 and PolCh21-62 is our Ch14-69.]

Dipol also makes an ASP-8W Version 3 (about 10 Euros) that adds "whiskers", extending the length for some of the elements in a 4-Bay Bowtie in order to improve coverage in VHF band, plus a snap-in preamp module in place of the balun transformer (so the antenna gain numbers now cleverly incude the Preamp gain).
Unfortunately, they don't provide a curve for this improved model.
Go to fol and Click on the pdf catalog for TV Antenna and Channel info:
http://www.dipol.com.pl/e01.htm
and english entry point to website:
http://www.dipol.com.pl/eindex.htm

As you can see, all they did was turn one of the bow-tie elements into a dipole that resonates at a much lower frequency.
And since the VSWR for a wideband UHF antenna is never going to be all that good to begin with....what the heck, perturb away....
So I've got my bailing wire "extenders" ready to go for my CM-4221 when they fire up VHF DTV in our area...

I added the 3041 pre-amp to my attic antenna, and my reception when to pot. I removed the distribution amplifier, and things were very good. But I don't really get any better digital reception than before. I'm about 38 miles from the antennas, and I have a 3018 antenna. So some questions...

1. I may have turned the antenna a bit during installation of the pre-amp. Is there an easy way to adjust the direction based on signal strength? I don't have a field strength meter, but just trying to adjust for analog look or digital bit rate error (reported as pseudo signal strength) seems very unscientific, on top of the fact that none of those displays is in the attic :-|

2. Does the angle of the boom matter much? Should it be level? Tilted down or up?

3. I had to run a length of twin-lead between the antenna and the pre-amp. It is about 3 feet long or so (pre-fab). Is this a problem?

4. Why am I seeing almost no signal with the distribution amp in the circuit? I have the antenna feeding potentially 10 tuners, so I figured the distribution amp would be appropriate. Without it, it seems OK feeding 5 tuners right now, but I worry about further distribution.

5. Should I switch in the FM trap? It was on when I bought it, so I left it, but I don't know if that's a problem or a benefit.

Xesdeeni

Originally posted by Xesdeeni
1.Is there an easy way to adjust the direction based on signal strength?

2. Does the angle of the boom matter much? Should it be level? Tilted down or up?

3. I had to run a length of twin-lead between the antenna and the pre-amp. It is about 3 feet long or so (pre-fab). Is this a problem?

4. Why am I seeing almost no signal with the distribution amp in the circuit?

5. Should I switch in the FM trap? It was on when I bought it, so I left it, but I don't know if that's a problem or a benefit.

1. The signal meter, tuned to the weakest station you get, is probably the best method, short of a dB meter.

2. The angle matters, and how much depends on how directional your antenna is. Generally speaking, they all work about the same +/- a few degrees. If you have a lot of airplanes, pointing down benefits some, and if you're in a valley or shooting over the horizon, pointing up benefits some.

3. There's no reason that this should be a problem, but if you could get the preamp closer, that would be better.

4. Distribution amplifiers usually insert a lot of noise into the picture. They can also overload. (This assumes that you had it wired correctly and the preamplifier was receiving power properly - distribution amps will not pass DC, so if you had the distribution amp between your preamp's indoor and outdoor units, it wouldn't work right.) Generally speaking, you're better off not using one unless you have to.

5. The FM trap blocks FM signals. This is beneficial if you don't want to receive FM signals through your antenna, and your amplifier amplifies VHF signals. FM resides just above Channel 6 on the broadcast spectrum, and if your amplifier tries to amplify that, it will take some of the power that could be used for television broadcasts. Add to this the fact that FM signals can be quite strong, and you've got a couple of good reasons to use the FM trap.

thanks all -- I'll look into getting an attenuator.

I've been reading for almost a week on this board and can't seem to make a decision. I'm in the 70714 zip code and have used antennaweb.org and checkhd.com to check my data. It looks like most of my HD channels are all in one direction. I had a spare RG6 available from the TV to the attic so for kicks I put one of those TV top RCA UHF/VHF amplified antannas in the attic. To my suprise I picked up several HD channels. My Hitachi TV has the built in QAM tuner and I can pick up UPN, WB, ABC, FOX, CBS, NBC, and PBS in HD with my basic cable subscription but I find the OTA channels to have better quality. The OTA's I picked up are 2-1, 9-1, and 25-1 (including their subchannels). These are in the 80's of signal strength.

Now my TV can find the following channels but can not lock in: 17-1, 23-1, 36-1, and 40-1. I've even tried the same antenna on top of the house but I guess I need a real antenna to pick them up. I don't have a problem with an outside mount antenna so what should I get? I really worried about buying the wrong thing and not being able to return it. Should I get an amp with the antenna?

Do I just order the antenna and go to the hardware store and get some piping to mount on the side of the house? I'm currently living in a typical one-story brick home. The neighborhood is pretty much covered with very large oaks in everyones front yard.

It seems I get conflicting info from the two above websites? Does anyone have another website that I can find out about the HD channels in my area?

Thanks for all the help guys!

digiblur - PM your address to me and I will try to help you sort it out. We need to first find out if there are any topograhical problems (you can't move a hill). Could you also send the call letters of the stations you want so I can easily look up their coordinates? If you know your lat/lon you can go to: http://www.2150.com/broadcast/default.asp
But none of the online sites account for topography. That is a killer in my area.