Congrats on a successful installation!

Thanks,

Frank.

I went with the more expensive Samy converter at this time because of possible problems with the multipathing of several UHF stations in analog, however, with a large directional combo antenna, that too seriously helped negate multipath effects for signal lock.

The tuner is a little slow to change (lock) at times, but, once it grabs, it's there and stays!:rolleyes:

I'll be fine tuning and making notes the next few days out for direction station, etc.:cool:

I am sure grateful for this forum and all those TV engineers, hobbyists, and EE"s that explain the why's and why not's as well as the do's and don't.

Thanks to all those that know their stuff!!:)

I purchased the wire that has 1/4" squares at my local Menard's. (20AWG). I could not see ANY improvement in my reception, except it is like a sail in the air. And by the way, you need a lot of this stuff for the 7' parabolic. (Holy Cow) :D

P.S. The antenna was down for 2 hours, so perhaps the conditions changed.

Any feedback on my tvfool post would be helpful... (See below)

I wouldn't expect the improvement to be night and day but fairly subtle and would be most noticeable with analog reception looking at distant signals that were problematic from co-channel interference. You might also notice improved multipath performance (less ghosting on analog). Improvement in digital performance would then be inferred from what you are seeing on the analogs and might take some time and experimentation to become more certain.

Adding the mesh to a 7' parabolic would increase the wind load by a ton. I'd probably compromise by screening just the area immediately behind the driven element i.e. the center part of the reflector at maybe only a 12 inch of radius on a hemisphere.

As far as any further recommendations go, for better performance on uhf you'd need to stack 2 or 4 yagi corner reflectors horizontally. Whether this would get you your desired stations would still be uncertain, but you could dependably improve your performance.

Using the latest HDTV tuners also helps. The 5th gen LG and the 5th Gen from Samsung are excellent with the 5th Gen LG being slightly better for long distance reception in my experience.

Using a GaSFet low-noise preamp would be another option.
I'm not sure if I caught what model preamp you are using currently.

Finally, going higher in the air can help but may or may not be feasible depending on your installation.

My situation got delayed because of some snags with orders, but when trying to decide about what connectors to use to put everything together, I found a couple of things that I wanted to ask about.

There is a choice of whether to use screw on, compression or crimp connectors...does it make a difference in terms of the quality of signal conveyed? There are gold plated connectors available for a few dollars more...should I get these?

There are sealants and tape available for weatherproofing connections, which is better? Are these necessary when using a gold connector?

If I understand correctly, an AGC reading of over 100 is terrible and one would not be able to lock on to a signal. All of my readings are over 100, and I am able to receive a number of channels. All channels, two with signal strength readings of close to 100, SNR 32, have this big AGC number. Weaker channels, 85 signal strength, 23 SNR, have the same big AGC numbers, 110 or so. I just wonder if there is some clue to improving my reception stability, reliability, in these numbers? These readings are from the Sony's diagnostic screen
Walter

Where did you get the info that an AGC reading over 100 is bad? Signal strength and AGC are numbers from an arbitrary scale made up by the manufacture so if you make a change you can see if you went in the correct direction, but the numbers can not be compared to anyone else's. AGC is a measurable quantity and a stable value of a little below 20 should produce artifact free pictures. Equipment to accurately measure it costs more than your tv but your TV may have circuitry to estimate it based on some parameter such as average bit error rate. If there is a short drop in signal strength it may not show up on the average but will cause picture artifacts.
John

John, are you saying that my AGC numbers are on a arbitrary scale set by the manufacturer and can't be used except as a base to make comparisons to my own changes? By the way, I went back to a CM 4228 this weekend. I have it up a little higher, and found an old balun that seem to give me a little more gain. The CM spartan 3 does a better job on physical 13 than the 7777, about the same on all the other UHF channels. I don't know if it is the good weather or what, but I think I might have gained 5% or so. Will have to see. Walter

Yes, after reading your post again, that is what you are saying. Are the SNR numbers real, and or comparable to others?

Blackduck,
John's right that the diagnostic displays show arbitrary values as a guide to optimizing your reception, but meaningless for comparisons across products. You and I may be seeing similar displays. I have a Sony 34XBR970 HD-CRT and it shows a nice signal strength display (bar graph with numeric values) at the top then channel/frequency data, then locks, errors and finally S/N ratio and AGC.

When I tested a range of home-built antennas, I recorded S/N and AGC values with signal readings to see if they fit any sort of pattern. The only one that correlated with reception quality was the signal reading. The other two may be useful in fine tuning, but I haven't tried it. They seemed kind of noisy, but then I was working indoors in a highly diffracted signal field. You may find them very useful with a tall roof mount and a high gain antenna.

Frank

I see alot of you guys discussing the size of the reflector screens and from the antenna modeling and building I've done 2" x 2" wire spacing is as small as is needed for UHF channel 60 or lower. Of course smaller doesn't hurt but the wind loading goes up quite a bit for no real gain in reception. I've had real good success with 2" x 4" fencing as a reflector screen just be sure to use it so that the 2" spacing is vertical and 4" is horizontal and make sure that it is the type that has all the wires are welded together. (NO chainlink fence type)
I've also found that using a 36" x 36" screen behind a 4 bay antenna like a CM 4221 or w4400 greatly improves VHF high reception and slightly improves UHF reception.
I've built both a cm4221 and w4400 style 4 bay antennas. They were scaled to a lower frequency centered around channel 30 using the 36" x 36" reflector and both receive signals as well as and sometimes better than a cm4228 especially on VHF high.

> There are gold plated connectors available

Gold is highly conductive, and doesn't corrode.

> There are sealants and tape available for weatherproofing connections,
> which is better? Are these necessary when using a gold connector?

Yes, you still need to waterproof things. I haven't looked into
details, since I have my antennas in the attic.

I believe some connectors have o-rings, which seems like a good idea.

The RG6QS cables sold at Lowes claim to be weatherproof, and claim to
have gold plated connectors.

> I've built both a cm4221 and w4400 style 4 bay antennas. They were
> scaled to a lower frequency centered around channel 30 using the
> 36" x 36" reflector and both receive signals as well as and sometimes
> better than a cm4228 especially on VHF high.

The obvious next step is to add a 6 foot square reflector to a 4228
and test the VHF-LO. :-)

I'm in process of building a 8 bay bowtie (cm4228) version with a 54" reflector and the 2 4 bays spaced 26" apart. The modeling program doesn't show any usable gain any VHF low frequencies. :-( The elements are just too short for VHF low, but VHF high and UHF look good I hope to finish and test in the next week.

MAXHD / Holl_ands

Is it worth $100 more to have a Rohn 20 over the American tower? That is, for a 50 tower.

This is the cost to make the change.

Your comments..

Well, I played around with 20' of pipe in the air and just made the plunge of ordering a NEW American 50' tower.

Holy cow, did these go up in price.

My dealer quoted me:

$550 - 5 Sections of tower (1 pc S-7 & 4 pcs S-5) ($650 if I want Rohn 20)
$120 - Concrete
$160 - Labor
$ 20 - House bracket
======
$850 ($950) Rohn 20
My old system is in the attachment.

Any feedback?

Please post some pictures of these home-brew antennas, if possible.

They're on the antenna-making thread.
http://www.avsforum.com/avs-vb/showthread.php?t=798265

I'm in process of building a 8 bay bowtie (cm4228) version with a 54" reflector and the 2 4 bays spaced 26" apart. The modeling program doesn't show any usable gain any VHF low frequencies. :-( The elements are just too short for VHF low, but VHF high and UHF look good I hope to finish and test in the next week.

One rule of thumb in antenna making is that antennas will have gain peaks at their design wavelength and at 3x design wavelength. Look at the VHF band:
- VHF-low is 57-85 MHz
- 3x VHF-low is 171-255 MHz
- VHF-high is 177-213 MHz

This was not some happy accident. VHF was designed to take advantage of antenna reception characteristics, and big, multi-bay arrays attempt to do the same thing for UHF and VHF-high.
- 3x VHF-high is 531-639 MHz
- UHF now is 473-~800 MHz, will be 473-695 MHz.

I'll be interested in the results, as will the antenna-making thread.

Frank

Okay, me again. Now I am trying to figure out signal strength fluctuation. Sometimes the signals are very steady, others, like last night, the are up and down, from really strong to weak, causing dropouts. I am currently using a CM 4228, but have had the problem with other antennas. I understand multipath could be the cause, however, I don't recall any ghosting problems when I was using analog. As always thanks for everyone's time and help.

Walter

Rick, I have a Winegard 9095 in my collection, is it that much different than an 91 xg? I haven't tried it in this new location because I wasn't impressed with it's performance this winter, but maybe I didn't give it a chance. At the time, I wasn't aware of how much reception can change day to day. I only left it up for an hour or so. Does everybody feel that multipath is the only possible cause of my signal quality, fluctuation? One other thing, channel 13, my only vhf, was quite stable.

Walter

Walter,

I tested the Wingard 9032, (which I feel is a step upward from the 9095), againist the XG91, and was surprised.

The XG was able to capture signals that the 9032 could not even see. So, I have a brand new 9032 in the garage, with the 91XG in the air.

Better results will be accomplished with the 91XG. ($58.47 online) :D
Google = Your Best Friend

Rick, I have a Winegard 9095 in my collection, is it that much different than an 91 xg? I haven't tried it in this new location because I wasn't impressed with it's performance this winter, but maybe I didn't give it a chance. At the time, I wasn't aware of how much reception can change day to day. I only left it up for an hour or so.

Walter

There are sealants and tape available for weatherproofing connections, which is better? Are these necessary when using a gold connector?

I've always used coax-seal. Yes, you should waterproof even with gold-plated "outdoor" type connectors.


http://www.amazon.com/Parts-Express-COAX-SEAL-60/dp/B0002ZPINC

Okay, me again. Now I am trying to figure out signal strength fluctuation. Sometimes the signals are very steady, others, like last night, the are up and down, from really strong to weak, causing dropouts. I am currently using a CM 4228, but have had the problem with other antennas. I understand multipath could be the cause, however, I don't recall any ghosting problems when I was using analog. As always thanks for everyone's time and help.

Walter

I've got hills, 4228, 91XG, with preamps,rotors and samsung dtb h260f with fluctuating signal strength and the best description of what I experience is fading. Too close to the hill. Sat locals seem to be in the cards.

I've also found that using a 36" x 36" screen behind a 4 bay antenna like a CM 4221 or w4400 greatly improves VHF high reception and slightly improves UHF reception.Do you try to space the screen so that it will act as a reflector at a target frequency, or do you just place the screen close to the elements primarily to shield signals from the back of the antenna?

Do you try to space the screen so that it will act as a reflector at a target frequency, or do you just place the screen close to the elements primarily to shield signals from the back of the antenna?

The screen is used as a reflector and is spaced at the same distance as the original smaller reflector. My semi educated guess is that the larger reflector actually works as a reflector on VHF HI as opposed to the smaller stock size. I use a 5" spacing on my antennas but they are tuned for best gain and SWR match from ch 14 - 50. I imagine that 4 1/2" spacing would be fine on a stock cm4221 or winegard 4400

Okay, me again. Now I am trying to figure out signal strength fluctuation. Sometimes the signals are very steady, others, like last night, the are up and down, from really strong to weak, causing dropouts. I am currently using a CM 4228, but have had the problem with other antennas. I understand multipath could be the cause, however, I don't recall any ghosting problems when I was using analog. As always thanks for everyone's time and help.

Walter

Just a shot in the dark but you could be getting noise generated from any one of a number of sources causing your problems. Since the digital signal indicators built into most receivers are signal to noise ratio indicators not absolute signal strength a high noise level due to static generated by power lines, neon signs, electric fences, motorized houseold items can raise havoc with DTV. I had powerline problems, almost every time it rained my DTV signals would drop out but the analog signals looked fine except for some small static bars on the vhf channels. I used an AM radio to confirm the noise issue and the electric company came out and fixed the problem (tree limbs lying on the lines).

My testing also revealed it did slightly better than the 4228. ;)

The 91 xg will out perform the hd9095 and pr 9032. you will need a rotor. You can also tilt the 91xg easily 10-15 degrees. you might get lucky.


go higher

Anyone ever put some 1/4" screening on the reflectors of their 91XG?

MAXHD,

Just ordered the American 50'. Decided to pass on the Rohn 20, and save the $100. Could not pass-up the $850 deal for the install with my antennas.

Will be talking to you about that highbander (real soon). Do you have a data sheet for it?

One easy option when stations are 180* apart is to use a multi-bay antenna like the DB4 or CM4221 without it's reflector.

Would removing the V-shaped reflectors on a yagi style UHF antenna achieve the same result?

The same result? No. Removing the corner reflector from a Yagi will greatly reduce it's forward gain. Especially in the lower UHF frequencies. While allowing a little better reception from the back, it will have 0db gain over a dipole from the rear, and not much better from the front. The multiple bow-tie style works much better for a figure-8 pattern with gain in both forward and rearward directions.

I agree with Neil L., faberryman.

A bowtie is a simple dipole, and there's one in every Yagi, too, but only one and it's not alone. Yagi's use the elements in front (directors) as much as the ones behind (reflectors) to focus EM energy onto the single dipole element. The directionalilty is built into the directors as much or more than the reflector, and the reflector has, as noted, a strong effect on lower channel gain.

Here's some Yagi modeling results, with and without the reflector, about 2/3 of the way down.
http://www.hdtvprimer.com/ANTENNAS/types.html

Bowtie arrays use interactions among the elements to focus gain in a preferred axis, and a reflector just makes that bi-directional gain pattern a one-sided pattern.

Frank

Hey guys,

I'm a newbie to the OTA stuff. I just ordered Dish Network (install set for next Friday) and I want to get my locals in HD (not offered in Montgomery, AL). I've been doing some research on these antennas and have decided that I better go ahead and get one. I'm looking at either the DB4 or the DB8 multidirectional because our NBC affiliate here in montgomery is at 182 degrees while everything else is between 250 and 280. Would this be a good idea? I could use all the help I can get right now...

TIA

Keith

I have a couple of questions:

1) If a bow-tie antenna closely resembles a simple dipole, why does it need to be twice as wide? Each "whisker" of a 422x bow-tie is about 8", which would be the length of both sides of a simple dipole, right?

2) After reviewing the 4248 results on the HDTV Primer site w/o the corner reflector, would there be any benefit to using one for upper VHF or is the band narrow enough to alleviate this need. The effect on UHF was an eye opener.

Thanks,

I'm looking at either the DB4 or the DB8 multidirectional because our NBC affiliate here in montgomery is at 182 degrees while everything else is between 250 and 280. Would this be a good idea? I could use all the help I can get right now...


The TVFool.com plot for your ZIP code shows strong signals of -36 to -67dBm. You may want to run one for your exact coordinates to be sure, however.

WSFA/NBC will be returning to VHF 12 next year, so you may want to consider adding a VHF antenna if the DB4, etc. doesn't work out. However, WCOV/FOX is slated to be in the same direction as NBC next year, but it will be on UHF. (if both were VHF in that direction it would simplify things) Wouldn't co-location be nice?

For now, you may get lucky and find that there is an angle which will allow you to pick up all the needed stations. A Channel Master 4221 is another 4-bay to consider and it isn't too bad at VHF 12 for a UHF antenna.

Keith: The DB-4 and DB-8 are over priced garbage. Consider a quality, American made product of Channel Master such as CM-4221 (4-bay) UHF antenna

http://www.channelmasterintl.com/4221.html

or, even better, a CM-4228 (8-bay) UHF antenna instead.

http://www.channelmasterintl.com/4228.html

Would I need to get a rotator for these antennas, or are they multi-directional?

Would I need to get a rotator for these antennas, or are they multi-directional?

The 4221 has a wider angle than the 4228. The higher the gain, the more directional the antenna is. Looking at the ZIP code plot, the 4221 should do the job, but I would suggest running your exact plot to be sure.

However, you may need a rotator regardless of which antenna(s) you choose. It can be tricky to get stations over 45 degrees apart, even with a 4221.

A gain plot for the 4221 may help illustrate this point:

http://www.hdtvprimer.com/ANTENNAS/cm4221.html

I assume you have the same thoughts for the 91XG?

Keith: The DB-4 and DB-8 are over priced garbage. Consider a quality, American made product of Channel Master such as CM-4221 (4-bay) UHF antenna

http://www.channelmasterintl.com/4221.html

or, even better, a CM-4228 (8-bay) UHF antenna instead.

http://www.channelmasterintl.com/4228.html

The DB4/DB8 are comparable in uhf performance to the 4221/4228 but cost twice as much or more. Additionally, as the DB8 has non-continuous back-screening, it is a much poorer performer for high vhf vs. the 4228.

After weeks of playing around with different antennas and amps, I am beginning to think it might be not in the cards. Up until 2 weeks ago, I thought I might win. I had good reception for about two months, February and March with a RS VU-190. In trying to make things better, I've tried a number of antennas, which I've mentioned in earlier post, none giving any real improvement. I have yet to try the 91XG. I will most likely give it a try, because I can return it, unlike some of the others in my collection. I wish I could say I was at all hopeful of it working, buy I'm not. Stations that have been giving me good signals are lately not even a blip, than an hour later are at full strength. At this point, antennas seem to be as rational as the stock market. I am posting my TVfool results again, in case anyone is interested. I might be back, if not, thanks so much for all the help that has been offered by many of you on this great site. Walter

I'd sure try the 91-XG with a pre-amp at your distance from the stations, the CM-7777 with the 91-XG should work pretty well, will sure need a rotor though, the 91-XG is extremely directional. I need a rotor with mine hopefully this next week I'll get one. Plus you can tilt the 91-XG up 12-15 degrees if you have a tee problem or some other obstruction. I can get Orlando stations analog and digital from here even in daytime with the 91-XG at distances of 70-85 or so miles. There is some fade on analogs during mid-day but having no rotor yet i can't make a true judgement because can't pinpoint.

bozy45, Blackduck is probably not going to see a significant improvement by changing antennas. He is 5 miles closer to the stations than I am but tvfool indicates his signals are about 6 dB weaker than what I get. We are both receiving signals that are blocked by at least two sets of hills. This is not Florida- it is likely there is a hill 500 feet high 5 miles away from the us blocking the signal and another one 10 -20 miles away at 1000 feet high. Also the transmitters are located about 300 meters above average terrain. What is the Orlando transmitter antenna height? Tilting antenna up in almost all cases will make the signal weaker. The solution for blockage is to raise the antenna.
John

After weeks of playing around with different antennas and amps, I am beginning to think it might be not in the cards. Up until 2 weeks ago, I thought I might win. I had good reception for about two months, February and March with a RS VU-190. In trying to make things better, I've tried a number of antennas, which I've mentioned in earlier post, none giving any real improvement. I have yet to try the 91XG. I will most likely give it a try, because I can return it, unlike some of the others in my collection. I wish I could say I was at all hopeful of it working, buy I'm not. Stations that have been giving me good signals are lately not even a blip, than an hour later are at full strength. At this point, antennas seem to be as rational as the stock market. I am posting my TVfool results again, in case anyone is interested. I might be back, if not, thanks so much for all the help that has been offered by many of you on this great site. Walter

Looking at your TV Fool plot results as compared to my parent's house in Mystic, it does not look good. Did the trees start filling in early this year?

With all the trees we have in the area and the hills, I have problems with stations above -110dBm, especially pointed towards Providence. I can only receive WPRI on VHF 13 in that direction. The Hartford (New Britain) results were better, but one of the two local ION stations (WHPX) make reception difficult. The other ION station, WPXQ, is a problem when pointing to Providence.

Another poster had similar problems in Westerly, though he seemed to be in a better spot. Have you tried posting to the local reception forum (Providence)?

If we can ever get any SFN's, SE CT and SW RI could really benefit. I'm still baffled that WNAC is pointing most of its energy away from this area and, from their post-transition application, still plans to do so.

I wonder if WPRI will share WNAC's antenna post transition antenna and we lose both CBS and FOX from RI.
John

John

Was the reception bad this weekend, strong signals fading to very weak, then back to strong in short time periods? Is this to be expected until next fall or winter? I didn't mind the fluctuations with analog, because most networks were almost always quite viewable, but the digital dropouts will drive one insane. I hate to give in to dish people, but my sanity is more important. Thanks Walter - No Falcon, no leaves yet. You mean it can get worse?

I am moving out of my condo into a house so I can finally have Satellite and OTA! But I am new to OTA stuff so I'm nervous about making a mistake. I'm thinking I want to get a CM 4220 and mount it on my roof. I have a friend that bought the RS 15-1634 and has had good success with it, but as I've not seen much mention of it in these forums, I'm leaning towards brands that you guys have had success with.

Do you think a roof-mounted CM 4220 would be sufficient for the attached radar info? My NBC affiliate is pretty far away, but we're supposed to be getting a local one in a few months, so i'm not as worried about that one specifically.

Do I need to plan for any pre-amps or amps?

Any advice would be appreciated!

Do you think a roof-mounted CM 4220 would be sufficient for the attached radar info? Any advice would be appreciated!

No. The 4220 is a UHF antenna. There are two VHF stations that you should be able to receive.

Yet if would be happy with CBS, CW, FOX, and ABC and could live without PBS and NBC, the 4220 would get those 4 stations.

To get all networks, try the Winegard HD7696P with a rotator. I wouldn't buy a preamp unless you have excessive dropouts.

No. The 4220 is a UHF antenna. There are two VHF stations that you should be able to receive.

Yet if would be happy with CBS, CW, FOX, and ABC and could live without PBS and NBC, the 4220 would get those 4 stations.

To get all networks, try the Winegard HD7696P with a rotator. I wouldn't buy a preamp unless you have excessive dropouts.

I'm not too worried about the VHF stations as I have a UHF ABC available and could care less about PBS. I'd like to get NBC, but as it should fall into the range of other local stations in just a month or two, I don't think it would be prudent to make a decision based on getting the one that is long range to me right now.

I was slightly concerned about the fact that the 4220 doesn't say "omnidirectional" but I assume it is, is that a correct assumption? I'm mainly thinking the 4220 b/c of cost and footprint, I don't want a massive antenna if I can help it.

John

Was the reception bad this weekend, strong signals fading to very weak, then back to strong in short time periods? Is this to be expected until next fall or winter? I didn't mind the fluctuations with analog, because most networks were almost always quite viewable, but the digital dropouts will drive one insane. I hate to give in to dish people, but my sanity is more important. Thanks Walter - No Falcon, no leaves yet. You mean it can get worse?

See my post in the local forum, Providence thread. The leaves have a small affect but what we see is caused mostly by changes in temperature layering in the troposphere resulting in signal bending.- sometimes towards and sometimes away from your location. This can result in reception from hundreds of miles which is bad for the local stations where we see the interference on analog stations and a loss of signal on digital stations. This is most common in the summer often a few nights a week. Back around 2000, the locals were not on digital yet and several evenings I was able to watch whole shows on WCBS-DT from NY at 115 miles. I have also received digital station from VA a Few times. Things should get a little better after analog shutdown.
John

I was slightly concerned about the fact that the 4220 doesn't say "omnidirectional" but I assume it is, is that a correct assumption? I'm mainly thinking the 4220 b/c of cost and footprint, I don't want a massive antenna if I can help it.

The CM4220 is not omnidirectional. It is unidirectional as are most TV antennas and any TV antenna with much gain.
John

The CM4220 is not omnidirectional. It is unidirectional as are most TV antennas and any TV antenna with much gain.
John

Thank you, I guess that was a dumb assumption. I think it would probably still work for me as most everything comes from the NE, but at least I can factor that into my decision accurately now.

> I thought the 91xg was a big piece of junk when I first saw the
> box and the ridiculous packages of pieces and parts in it . The
> 91xg works but overall build is questionable.

Does someone make a yagi with similar performance to the 91xg but
with higher build quality?

Thank you, I guess that was a dumb assumption. I think it would probably still work for me as most everything comes from the NE, but at least I can factor that into my decision accurately now.

One nice thing about multi-bay arrays (like the 4220/4221/4228) is that their directional characteristics are due to the reflector. Remove it and you have a bi-directional antenna, which may be a better choice given your signal pattern. It's gain in any one direction is lower, but it's equal front and back, zero to the sides. You can get some of that gain back by moving from a 2-bay 4220 to a 4-bay 4221 while retaining the bi-directional gain pattern.

The best part (to me) is that if you want, you can make one to see if it works!
http://www.avsforum.com/avs-vb/showthread.php?t=798265

Frank

Hey Blackduck, are you sure you aren't getting overloaded by that 3/4 of a million watts of energy 11 miles distant? That could explain a lot of your grief.

The CM4220 are popular antennas, but I use a wideband Delhi CYD1470 yagi and it works perfectly fine. I don't want a big flyswatter on my tower thanks.

The 4248 appear to have been discontinued. That is too bad since it appears to be the about the best yagi out there. It tested better than the 91xg here.
http://www.avsforum.com/avs-vb/showthread.php?p=6245872

donnyyaguar
No, I'm not sure, I just haven't figured out how to get rid of it without having a filter made for 17 and 69. I think they are always broadcasting. I thought of asking them to shut down for an hour or so, but I don't think they'd go for it. Seriously, I tried running without any amplification, still a lot of signal fluctuation, just at lesser levels. On paper, the station should be in a null of most of the antennas I've tried, but it is always there, strong, no matter what direction the antenna faces. If you or anyone have any suggestions on how to isolate it, even temporally, please let me know. I would just hate to spend more money on another wild goose chase.

Filtering out 69 probably isn't worth your time at this point, but getting a filter for 17 is easy enough, if you don't need any UHF channels under 20. This cable TV filter eliminated it, but as I wasn't able to get Providence UHF channels anyway, I sent it back:

http://www.solidsignal.com/prod_display.asp?prod=CPNF-469

Custom filters are expensive, but I will be trying one on my next trip.

falcon_77
Seems you would have to get rid of 69 as well as 17 to test. By the way, I have a hunch ctdish would have tried this already, but maybe not.

I've read some but not all of this thread.

Are there any INDOOR preferably amplified type antennas that would be like a rectangular window screen grid or something that would go behind a painting, etc. for aesthetics purposes? I'm looking for something that's less of an eyesore than rabbit ears, but less work involved than running an attic antenna.

Allargon,
See the link in post 1729 above; spokybob has some nice shots. Bowtie arrays vary in size but their most basic form is flat, so there are a number of things that can be done. This is my favorite:
http://www.digitalhome.ca/forum/showpost.php?p=676791&postcount=260

Placement will depend somewhat on the orientation of the room relative to the stations and which way the antenna needs to point. A basic 2-bay bowtie (CM4220, DB-2, etc.) without the reflector will fit behind an 18x20" wall hanging, and can be made less than 1" thick.

If no one's asked yet, please post a TVFool.com analysis for your house so we have some idea what kind of signal field you've got. There's a signal analysis FAQ that explains the values.

Frank

> I thought the 91xg was a big piece of junk when I first saw the
> box and the ridiculous packages of pieces and parts in it . The
> 91xg works but overall build is questionable.

Does someone make a yagi with similar performance to the 91xg but
with higher build quality?

Televes DAT 75, Funke 4591, Triax Unix 100 wide band uhf version

Seems you would have to get rid of 69 as well as 17 to test. By the way, I have a hunch ctdish would have tried this already, but maybe not.

WPXQ 69 is surprisingly weak in Mystic. I don't know if it is just the trees or if they are broadcasting at reduced power, but WPXQ 17 is very strong by comparison. I had a custom 17/26 filter made a while back, but haven't had a chance to test it yet.

Of course, until WHPX turns off their DTV 34 transmitter, it may not help much.

I did some more digging and found some info on an old antenna:

http://www.rocketroberts.com/cm4251/cm4251.htm

Wouldn't this be fun to try... :D

Of course, I probably will never see one, but the author of the article appears to be local to Mystic. Have you seen one of these, John?

I was slightly concerned about the fact that the 4220 doesn't say "omnidirectional" but I assume it is, is that a correct assumption?

The 4220 does not say multidirectional because is is somewhat unidirectional. A multidirectional antenna is often a bad thing. Multidirectional antennas pick up less signal and are prone to multipath.

It's bigger brother, the CM-4228, should do the trick.
http://www.channelmasterintl.com/4228.html


With stations raging from 59 degrees to 85 degrees, the narrow beam of the 4228 would be a mistake.

Speaking of defunct antennas, what happened to the CM Quantum series?

I installed one of those in the mid to late 90's, but moved away from that house soon after. As I recall, it did not have a UHF corner reflector and had "parasitic fly elements." I don't remember it performing much better than the old VHF/UHF combo we had though. Once in a great while I will see one, but I'm assuming it was never very popular?

Great sites for the parabolics! Anyone else notice that the active element is a 2-bay bowtie with reflector, aimed back into the parabola?

Allargon,
See the link in post 1729 above; spokybob has some nice shots. Bowtie arrays vary in size but their most basic form is flat, so there are a number of things that can be done. This is my favorite:
http://www.digitalhome.ca/forum/showpost.php?p=676791&postcount=260

Placement will depend somewhat on the orientation of the room relative to the stations and which way the antenna needs to point. A basic 2-bay bowtie (CM4220, DB-2, etc.) without the reflector will fit behind an 18x20" wall hanging, and can be made less than 1" thick.

If no one's asked yet, please post a TVFool.com analysis for your house so we have some idea what kind of signal field you've got. There's a signal analysis FAQ that explains the values.

Frank

Thanks, Frank.

Here's my TV fool info: (I didn't embed to keep the page load small for this thread.)

http://i101.photobucket.com/albums/m55/allargon/home_theater/TVFool_Radar-All.png


Here's my antenna web info


DTV Antenna
Type Call Sign Channel Network City, State Live
Date Compass
Heading Miles
From Frequency
Assignment
yellow
uhf KLRU 18 PBS AUSTIN, TX 192° 12.2 18
* yellow
uhf KNVA-DT 54.1 CW AUSTIN, TX 191° 11.9 49
yellow
uhf KNVA 54 CW AUSTIN, TX 191° 11.9 54
* yellow
uhf KLRU-DT 18.1 PBS AUSTIN, TX 188° 12.0 22
* yellow
vhf KTBC-DT 7.1 FOX AUSTIN, TX Feb 17, 2009 (post-transition) 188° 12.9 7
* yellow
uhf KEYE-DT 42.1 CBS AUSTIN, TX 192° 12.3 43
yellow
uhf KEYE 42 CBS AUSTIN, TX 192° 12.3 42
yellow
vhf KTBC 7 FOX AUSTIN, TX 188° 12.9 7
yellow
uhf KVUE 24 ABC AUSTIN, TX 192° 12.2 24
* yellow
uhf KXAN-DT 3.1 NBC AUSTIN, TX 191° 11.9 21
yellow
uhf KXAN 36 NBC AUSTIN, TX 191° 11.9 36
* yellow
uhf KVUE-DT 24.1 ABC AUSTIN, TX 192° 12.3 33
green
uhf KHPZ-CA 15 TFA AUSTIN, TX 28° 9.0 15
green
uhf KBVO-CA 51 TFA AUSTIN, TX 191° 11.9 51
lt green
uhf KHPX-CA 28 TFA AUSTIN, TX 33° 8.1 28
* red
vhf KAKW-DT 62.1 UNI KILLEEN, TX 313° 21.8 13
red
uhf KAKW 62 UNI KILLEEN, TX 313° 21.8 62
* red
uhf KTBC-DT 7.1 FOX AUSTIN, TX 188° 12.9 56
* blue
vhf KWTX-DT 10.1 CBS WACO, TX Feb 17, 2009 (post-transition) 19° 62.7 10
blue
uhf KWKT 44 FOX WACO, TX 18° 61.9 44
blue
uhf KDAS-CA 31 UNI AUSTIN, TX 192° 12.1 31
blue
vhf KWTX 10 CBS WACO, TX 19° 62.7 10
blue
uhf KXXV 25 ABC WACO, TX 19° 63.8 25
blue
uhf KNCT 46 PBS BELTON, TX 6° 34.8 46
blue
vhf KCEN 6 NBC TEMPLE, TX 25° 62.2 6
* violet
uhf KNCT-DT 46 PBS BELTON, TX Feb 17, 2009 (post-transition) 6° 34.8 46
* violet
uhf KNCT-DT 46.1 PBS BELTON, TX 6° 34.8 38
* violet
vhf KCWX-DT 2.1 CW FREDERICKSBURG, TX 01-09 240° 57.2 5
violet
vhf KCWX 2 CW FREDERICKSBURG, TX 240° 57.2 2
violet
vhf K09VR 9 IND AUSTIN, TX 174° 14.2 9

I have a couple of questions:

1) If a bow-tie antenna closely resembles a simple dipole, why does it need to be twice as wide? Each "whisker" of a 422x bow-tie is about 8", which would be the length of both sides of a simple dipole, right?

2) After reviewing the 4248 results on the HDTV Primer site w/o the corner reflector, would there be any benefit to using one for upper VHF or is the band narrow enough to alleviate this need. The effect on UHF was an eye opener.

Thanks,

1) You're exactly right. I think it has something to do with the bowtie shape, since that spread is supposed to affect frequency spread of the gain curve. I've tried my antenna once with the wiskers parallel, and it didn't work as well, but it wasn't a serious test.

2) Sure; I think that's what the Wade single channel VHF antennas look like. I'd be more interested in the corner reflector, given its broad flat gain curve, but it gets big, fast at lower frequencies.

Frank

Thanks, Frank.

Here's my TV fool info: ...

You'll get lots of stations with just about anything resembling an antenna!

I'd love to have this kind of signal field ... Unless you're in a steel building, one of the home-built 4-bays will probably give you lots of stations. I would avoid amplification unless you have a long coax run; you don't need it to get these stations.

It's also possible ... Yes, there's a bunch more stations at weaker signal levels that don't fit when analog stations are shown. You're in serious DX-ing territory if you have an uncontrollable urge to spend money on OTA equipment.

Frank

I would disagree. My testing, has revealed that this big beast will not always capture the HD feeds as well as the yagi type antennas. I have a 12 of these 4251's. Even did the chicken wire thing, and decided to remove it. :cool:

The best UHF antenna ever made for consumer use.

http://www.geocities.com/n4yqt/fimages/cmparascope42504251.jpg

It's also possible ... Yes, there's a bunch more stations at weaker signal levels that don't fit when analog stations are shown. You're in serious DX-ing territory if you have an uncontrollable urge to spend money on OTA equipment.

DX'ing can be difficult in areas like this. There are few channels not blanketed by locals, but it should improve post-transition.

So much for White Spaces, huh? :rolleyes:

What White Space? There's precious little around Austin! Maybe WSD's won't work in the plains ...

You'll get lots of stations with just about anything resembling an antenna!

I'd love to have this kind of signal field ... Unless you're in a steel building, one of the home-built 4-bays will probably give you lots of stations. I would avoid amplification unless you have a long coax run; you don't need it to get these stations.

It's also possible ... Yes, there's a bunch more stations at weaker signal levels that don't fit when analog stations are shown. You're in serious DX-ing territory if you have an uncontrollable urge to spend money on OTA equipment.

Frank

The subchannels and PBS are iffy. The same goes for the digital Univision station at 13 (62.1) I'm currently using the Philips +50dB gain split to my Mitsubishi 57732 and my Dish Network vip622. http://www.consumer.philips.com/consumer/en/us/consumer/cc/_productid_SDV2510_27_US_CONSUMER/TV-antenna+SDV2510-27 All of my high powered analog stations come in crystal clear. I will drop by Fry's and look at their bowties as well as check out some of the Terk's (HDTVa, HDTVlp, TV5) to see if that will help. Thanks again for looking.

I wouldn't call it uncontrollable. I just don't like unstable signals when the weather is cloudy, etc. Pixelation is no fun. Therefore, I want the best signal I can get without getting a large outdoor or attic or clip-on to my satellite dish antenna.

Hi All:

I'm currently using a cheapie Radio Shack 300 to 75-ohm balun connector on my CM4228, and it works fine (or so I think). Wondering if there's any better quality balun out there that I should consider putting on there that might eek out a little more signal by providing a better coax line match.

Thanks in advance...

I've read some but not all of this thread.

Are there any INDOOR preferably amplified type antennas that would be like a rectangular window screen grid or something that would go behind a painting, etc. for aesthetics purposes? I'm looking for something that's less of an eyesore than rabbit ears, but less work involved than running an attic antenna.
FYI: Antennas Direct makes a Picture Frame UHF antenna:
http://www.antennasdirect.com/PF7_antenna.html
http://www.antennasdirect.com/images/hires/pf7.jpg
http://www.antennasdirect.com/pdf/IndoorAntennas.pdf
The Lacrosse Micron (above) was just announced and looks
like an oversized napkin (or mail?) holder....

There are also several vertical mount Planar UHF Antennas:
http://newcaststore.com/digital-flat-antenna-an2.html
http://artectv.com/ehtm/products/an2.htm
http://www.bhphotovideo.com/c/product/550801-REG/Kingbox_AN2_DIGITAL_FLAT_ANTENNA.html
also:
http://www.itenna.com/
http://www.jr.com/JRProductPage.process?Product=4211173
and:
http://www.kowatec.com/prod/cis/products.php?i=cs102
http://www.youtube.com/watch?v=EcfidQbMA2w

This one is fatter:
http://www.amazon.com/dp/B000VL1QF6?smid=ATVPDKIKX0DER&tag=cnet-ce-20&linkCode=asn
http://www.buy.com/prod/philips-mant940-indoor-outdoor-hdtv-antenna/q/loc/111/205604033.html

You could also try a simple UHF loop:
http://www.cnaweb.com/index.asp?PageAction=VIEWPROD&ProdID=1843

Planar antennas need to mounted so they are NOT on a wall in SAME line as stations.

Minimal VHF performance may or may not be adequate for now and Post-Feb2009....
At which point you may also need an indoor VHF antenna, such as a DIY Folded Dipole:
http://www.wfu.edu/~matthews/misc/dipole.html

Hi All:

I'm currently using a cheapie Radio Shack 300 to 75-ohm balun connector on my CM4228, and it works fine (or so I think). Wondering if there's any better quality balun out there that I should consider putting on there that might eek out a little more signal by providing a better coax line match.

Thanks in advance...

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

About half way down is a short comparison of a couple RS baluns with a Channel Master, with clear winners and losers, as on the pre-amp compaison below it, but without the latter's big effect on reception. 0.5dB isn't much.

I thought CM included a balun with their antennas?

The subchannels and PBS are iffy. The same goes for the digital Univision station at 13 (62.1) I'm currently using the Philips +50dB gain split to my Mitsubishi 57732 and my Dish Network vip622. ... All of my high powered analog stations come in crystal clear. ...

I would have called PBS and Uni "strong" stations! Uni is VHF 13 so you're adjusting the rabbit ears, right? When you say PBS you mean KLRU? If so, how does KXAN do, 1 channel over? If you mean KNCT, you'll need more antenna for that one.

Looking at the TVFool plot, I don't see a need for an amp, especially one with 50 dB of gain! You only have 1 splitter (-4dB) and RG-6 is ~-6dB/100 ft. so there's not enough loss to worry about. The gain's adjustable; what happens when you turn it down/off? With so many strong signals, multipath can be expected and overload would not be a surprise with 50dB of gain.

I've never seen subchannels drop out when the main channel was locked; their quality is degraded by the limited bandwidth. Are you seeing more than bandwidth limits?

Analog and digital signals are fundamentally different in composition and in weaknesses; analog needs "strong as possible," digital only "strong enough." Analog sees multipath as a ghost image, digital drops out. If low signal strength is not your problem, perhaps high signal is?

Turn down the amp and let us know what you get.
Frank

I would have called PBS and Uni "strong" stations! Uni is VHF 13 so you're adjusting the rabbit ears, right? When you say PBS you mean KLRU? If so, how does KXAN do, 1 channel over? If you mean KNCT, you'll need more antenna for that one.

Looking at the TVFool plot, I don't see a need for an amp, especially one with 50 dB of gain! You only have 1 splitter (-4dB) and RG-6 is ~-6dB/100 ft. so there's not enough loss to worry about. The gain's adjustable; what happens when you turn it down/off? With so many strong signals, multipath can be expected and overload would not be a surprise with 50dB of gain.

I've never seen subchannels drop out when the main channel was locked; their quality is degraded by the limited bandwidth. Are you seeing more than bandwidth limits?

Analog and digital signals are fundamentally different in composition and in weaknesses; analog needs "strong as possible," digital only "strong enough." Analog sees multipath as a ghost image, digital drops out. If low signal strength is not your problem, perhaps high signal is?

Turn down the amp and let us know what you get.
Frank

The compression artifacts are likely due to the subchannels. However, I believe the pixelation, freezes and breakups are due to reception issues. I'll turn it down. I had some issues I used to have my antenna on top of my tower to the right of my display. I have since set it down on the hearth of my fireplace. (This is Central TX. It's really just for show.) I'll crank the gain down. I never had it up to max. Max caused more problems. I never tried the lower settings. I definitely need an amplified antenna for our CW channel (54.1/49). I'm going to try it at half power. (My local Fry's didn't have any of the good Terks--only the generic rabbit ears.)


=====post edit=====

Lost Univision (analog AND digital) doing it that way. For some strange reason, I am still having difficulty getting subchannel 24.2 (weather) on my TV's tuner, but not on my Dish receiver. I'll continue playing with it. Oh... I definitely meant KLRU for PBS. KXAN is fine for an NBC station. The macroblocking w/ KXAN with football games is due to NBC being NBC.

Thank you, Frank, Holl_ands and others for assisting me with this.

I totally agree about the 91XG.

The facts:

Best price on-line: $59.49 + shipping

In my opinion, it is the best bang for the buck.

End of story...

http://www.antonline.com/p_Terrestrial-Digital--91XG--Terrestrial-Digital-Long-Range-Directional-HDTV-Antenna---XG91-_423299.htm

Originally Posted by Falcon_77
I have a couple of questions:

1) If a bow-tie antenna closely resembles a simple dipole, why does it need to be twice as wide? Each "whisker" of a 422x bow-tie is about 8", which would be the length of both sides of a simple dipole, right?


Yes, its still a dipole, think of the bow tie flat still a dipole.. Just increases
the bandwidth or frequency range for the same bow tie/dipole if it were flat..
ARRL Antenna Book is great for discussions on Antennas BTW.

Oh one more thing ever notice the active dipole or doriven element on some of the yagis notice the tubes curled around this does that same thing, making it effectively wider..

In my opinion, it is the best bang for the buck.


Over channel 50 at least. The 91XG is still a top performer under 50, however.

I am curious to see if they will put out a new design for 51, but perhaps not. I'm guessing that that "14-83" range is kept to allow for the international market to use it. I have seen the 91XG design in Europe and Australia, so it isn't clear to me which country can claim it as a native design.

Okay, I'm new to this thread, but I need help so I'll just dive right in. Even when I lived in a house I got spotty reception, but now that I'm in an apartment my reception is poor-to-non-existent.

I'm on the ground floor, and out the east windows, which faces closer to where the stations are, there are no obstructing buildings nearby. Out the west windows, there are some trees and the other apartment buildings. I get crap reception out of either, and I'm using rabbit ears with that little circular rotating thing in the middle, connected by shielded coax to my decoder.

I can put them high, up by a window, aim them all around, I get crap. I'm thinking I need an outdoor one, but I'm a little scared by the process. Are they permanent installations? Cuz I doubt they'd like me drilling holes. Plus I would like to *not* have a big long cable running through two rooms in my apartment if that can be avoided (which is what would be necessary were the antenna to be placed by the eastern windows). And it has to be cheap, too, since I only watch one station on weekdays (I work second shift so it's PBS HD for me).

They sell u bolts designed to go around 2x4's, 4x4's, all different sizes.
So it doesn't have to be permanent.

It's hard to tell what you need with out a TVFOOL.com read out, go there.
As for cheap, depends what you consider cheap, maybe under $100.
Write back.
:)

Hiram,
The Hound asks for a TVFool.com plot so we have some idea what channels are broadcast in your area, in what directions and what effective signal strength they have at your location. There are a number of alternatives, the cheapest of which starts here:
http://www.avsforum.com/avs-vb/showthread.php?t=798265

Even a basic outdoor antenna, used indoors, will have lots more gain than a UHF loop and rabbit ears. The question is how much you need, and TVFool will help answer that.

Frank

Here ya go.

http://img227.imageshack.us/img227/580/radardigitalzs5.th.jpg (http://img227.imageshack.us/my.php?image=radardigitalzs5.jpg)

I'm on the ground floor, and out the east windows, which faces closer to where the stations are, there are no obstructing buildings nearby. Out the west windows, there are some trees and the other apartment buildings. I get crap reception out of either, and I'm using rabbit ears with that little circular rotating thing in the middle, connected by shielded coax to my decoder.

What do your analog results look like? Do you see a lot of ghosting? Which DTV stations can you receive? What tuner/TV are you using? Are you using an amplified antenna?

With signals in the -35dBm to -55dBm range, reception should not be difficult. However, amplified rabbit ears in such a setting can be a multi-path nightmare, especially for older tuners.

Here ya go. ...

I'm using a home-built 4-bay bowtie array like those on the link I gave you yesterday, mounted in the attic with great success and my strongest station is -70 dBm. You should do at least as well in the living space because I don't see a big benefit moving to the attic. If nothing else, it's a cheap option to try and if you don't like it, hide it in a closet or behind the couch.

I started with a simple UHF clip-on like yours and was surprised I got a picture occassionally. It gave me the incentive to make a Yagi, now the 4-bay, which is rock steady at 90+ signal strength on all stations on my TV (but 60-80 signal strength using a DigitalStream DTX9900 CECB).

Frank

What do your analog results look like?

Mostly crap.

Do you see a lot of ghosting?

I don't think so, just lots of static.

Which DTV stations can you receive?

I receive 4.1 and 28.1 most reliably. The rest are spotty-to-non-existent.

What tuner/TV are you using? Are you using an amplified antenna?


Rabbit ears, and it's amplified but the amplification wasn't making a huge difference, plus it was shocking me whenever I adjusted the antenna so I left it unplugged.

Rabbit ears, and it's amplified but the amplification wasn't making a huge difference, plus it was shocking me whenever I adjusted the antenna so I left it unplugged.

An antenna with an unplugged preamp is much worse than an antenna with no preamp.

If you are being shocked whenever you touch the amplified rabbit ears,
something is seriously WRONG....

THROW IT AWAY---BEFORE IT KILLS SOMEONE!!!!!!!

If you are being shocked whenever you touch the amplified rabbit ears,
something is seriously WRONG....

THROW IT AWAY---BEFORE IT KILLS SOMEONE!!!!!!!

It could be more serious than the rabbit ears. Check your 120V outlets to see if they're wired properly.
The small flat blade should be Hot, the bigger flat blade should be Neutral, and the middle U shaped hole is ground. If you don't know how to confirm which is which, get a pro to look it over.

If your apt is old, it's VERY possible that there's been a wiring mistake made over the years. It's common for it to happen if a "grounded" outlet is used to replace an old 2-prong outlet in a home that has no ground system. (Of course it's also possible if the home/apt is not old.)

The house I grew up in had an outlet wired wrong in the garage. It's ground terminal was wired to the 120V hot. When we'd plug a car's engine heater into the outlet, the body of the car was at 120V potential !!! It existed that way for years until I discovered it and corrected it while in high school. No law or physical barrior prevents an idiot from wiring an outlet. So you gotta wonder....who wired yours ?

I once serviced a C-band satellite installation in the old British Embassy in which the hot and neutral connections to the outlet had been swapped, and someone had then disconnected the outlet's ground wire, probably to stop it from tripping the breaker. The satellite receiver had a three-prong plug and apparently, there was a short from the isolation winding to the case, so the case was electrically hot, but because the receiver was set back on a wooden shelf and the owner used his remote control, this shock hazard persisted for years.

When I was on the roof, checking the dish alignment, I felt a heavy "thud" when I touched the mast, even though I was wearing sneakers, but I had no idea it was a solid line voltage source, so I came back with a ground wire to ground the mast, and I crawled into the ceiling crawlspace where I was going to connect the ground wire to a cold water pipe, but the groundwire was bare and it sparked as it grazed another metal object before I got to the point where I had the hot ground wire in one hand and the water pipe in the other.

I connected it to ground, and when I got back into the apartment, the resident said that something I did had tripped the 20 amp breaker and now he couldn't make it stay on. If he had reset it before I had completed the connection, I might be dead.

The antenna shocked me even when I lived in a new house.

The antenna shocked me even when I lived in a new house.

Get rid of it!

Safety issues aside, whatever is causing that is probably also affecting reception.

Try a $10 un-amplified rabbit ear/loop combo and see what happens then. A Silver Sensor may be worth a look, but it's designed for UHF.

I'll try making fbov's suggestion, when I can. I have a screwdriver but no drill, so I'll have to scare one up for a few minutes' use.

I have a couple of questions:

1) If a bow-tie antenna closely resembles a simple dipole, why does it need to be twice as wide? Each "whisker" of a 422x bow-tie is about 8", which would be the length of both sides of a simple dipole, right?

2) After reviewing the 4248 results on the HDTV Primer site w/o the corner reflector, would there be any benefit to using one for upper VHF or is the band narrow enough to alleviate this need. The effect on UHF was an eye opener.

1) You are thinking of a half-wavelength dipole. UHF bowtie antennas usually use a full-wavelength dipole, with a fat element diameter for wide bandwidth. This configuration, which is sometimes called a collinear pair or 2-element collinear or two half-waves in phase, has a number of advantages. First, you get 1.6 dB more gain. Second, by selecting the proper shape and thickness of the elements you can achieve good bandwidth and a good match to the half-wavelength phasing lines that connect the dipoles together in the 4-bay array, at maximum possible gain.
For example: A 1-wavelength dipole with a total length of 16 inches (8" each side) and 1-1/2 inch diameter elements (L/D=approx 10) will have a BW of 130% and a feed point impedance of 330 ohms. (The feedpoint impedance with a thin diameter would be much higher.) A 2-bay using whiskers or triangles for CH 13, would have elements and phasing lines about 26 inches long.

References:
1. TV Antennas and Signal Distribution Systems by M. J. Salvati, Howard W. Sams #21584, 1979, ISBN 0-672-21584-5, pp 23 & 24. Fig 1-9 gives the bandwidth and impedance of 8 different dipoles (some for VHF). Chapter 3 bowtie and Hoverman info. Chapter 8 stacking info. This is a must-have book if you are interested TV antennas. I see 7 listings on isbn.nu for used copies, 5 on abebooks.com, 19 on bookfinder.com, and 20 on used.addall.com. You could also borrow interlibrary thru your library.
2. The ARRL Antenna Book (not The ARRL Handbook), chapter on VHF and UHF Antenna Systems, section on Large Collinear Arrays, pp 18-8 to 18-9 and fig 9 (showing the classic 4-bay) in the 18th Ed, ISBN 0-87259-613-3. Mentions why element should be supported at center instead of end to reduce losses. Basic theory is in Multielement Arrays chapter, section on Collinear Arrays, pp 8-32 to 8-33.
3. VHF/UHF Manual by G.R. Jessop, G6JP, 4th Ed, RSGB, Antennas section, pp 8.14 to 8.18 on stacked dipole arrays. Table 7 gives resonant lengths of full-wave dipoles of various diameter ratios; fat elements are shorter.
4. The Channel Master bowtie should more properly be called a fullwave fan dipole, which is a simplification of the fullwave bi-conical dipole. See Radio Communication Handbook, 5th Ed, RSGB, p 12.35.
5. Antenna Engineering Handbook, Johnson & Jasik, 2nd Ed, McGraw-Hill, 1984, ISBN 0-07-032291-0, Chapter 29 TV Receiving Antennas, Section 29-5 Triangular-Dipole Antennas, pp 29-12 to 29-13. Mentions why triangle is better than whiskers. (Update 8-28-10: but I'm not convinced.)
Fig 29-5 is an interesting gain vs freq chart of a bowtie with 7.5" 70 degree triangles, which I used to optimize an antenna for CH 15 using a formula derived from the first gain peak (about 570 MHz) of the top gain curve: L"=4300/F in MHz, giving me 2dB more gain than a CM3021 which is like the CM4221.
I used 9" sheet aluminum triangles (supported at the center of each triangle), 9" phasing lines between the dipoles, and a reflector of galvanized metal hardware cloth with 1/4-inch squares. This was mounted in an attic.

If I had to do it again I would use 5500/F (from the 2nd peak-733MHz) giving 9.5 to 10" elements with 10" bay spacing for CH 31, my weakest important channel. I'm using a new formula because we have lost the upper channels and because of the excellent computer modeling of UHF 4-bays with reflector done by mclapp.

I also tried phasing two 3021s using a 75ohm splitter/combiner, which gave me 2.5dB more than one as measured with my Sadelco 719-E Signal Level Meter (It has an analog rather than digital meter so I can see level changes as they happen.). I thought that my Sadelco wouldn't be of much use for DTV and I would have to resort to watching the drop-out on the TV when I inserted various levels of attenuation. But the Sadelco gives me a useful comparison of signal strength for digital signals (but not absolute value) as it does for analog. Using the speaker feature, the analog video carrier is a buzzing sound; the digital carrier sounds like white noise. It doesn't tell me about multipath problems like the TV or a spectrum analyzer would.

Yes, I'm an antenna nut! But, I still have a lot to learn.

The house I grew up in had an outlet wired wrong in the garage. It's ground terminal was wired to the 120V hot. When we'd plug a car's engine heater into the outlet, the body of the car was at 120V potential !!! It existed that way for years until I discovered it and corrected it while in high school. No law or physical barrior prevents an idiot from wiring an outlet. So you gotta wonder....who wired yours ?

Fortunately, testing outlet wiring is both easy and safe: Hardware stores and the big-box home centers sell inexpensive, three-prong, plug-in testers that verify the wiring of any outlet. A standard tester costs about $4, while one that can check a GFI outlet costs about $8.

I found the same wiring problem Tobias had, also in the garage, while testing a power strip that has indicator lights for proper grounding and surge protection. The strip indicated "no ground" on the garage outlet, but showed normal function once plugged in at its intended location. Bought the GFI tester since the garage outlet is protected by a GFI located elsewhere, and plugged it in at the garage outlet. Voila! It indicated swapped hot and neutral wires, and the GFI test function showed the wiring error was interfering with GFI protection at all four covered outlets -- all without removing the wall plate. It had apparently been that way since the place was built 25 years ago. Cut the power, switched white and black wires to the correct terminals, put everything back and re-tested all four outlets in less than 10 minutes.

Standard house current is HIGH VOLTAGE that is not to be messed with. Consumers can safely use these testers to detect possible problems, but if you doubt your ability to correct any house wiring problem you find safely, call in an electrician. It will be money well spent. Best of all, most sparkies charge less for house calls than plumbers do!

And, no, I'm not an electrician. Or a plumber, for that matter. :D

What is the Best indoor antenna for the Zenith DTT-900? I've been looking at the Terk HDTVA, but that rascal costs $70.00. I'm not buying till i hear more.

I just got 2 dtv converter boxes. "Digital Stream DX9900"
I posted about my antenna troubles about 4 months ago in the local Peoria IL area, and have made modifications since then.
I have a yagi, radioshack-VU90 in the attic, and have twin lead 300 ohm run to a receptacle on the first floor.
I run a 6 foot twin lead 300 ohm to my DX9900.
I was told to change my wiring to coax and use a different antenna, such as a CM4221 four bay.
I haven't changed the wiring, but decided to build an antenna using the U-tube video here:
http://www.youtube.com/watch?v=EWQhlmJTMzw "clothes hanger antenna"
I hooked it up in the attic, and it made very little difference.
It seems to work OK on the ground floor, but is not an improvement over the yagi in the attic.
I'm having trouble with 2 channels that are only about 10-15 miles away.
I live in a river valley.
One channel doesn't come in at all, (ch. 19/40 ABC) the other one only gets 25% (ch 25/57 NBC) on my meter.

I have another TV and DX9900 in another room, and I have a double bowtie antenna. (one that sits on top of the TV).
I can pull in the "unavailable" (ch. 19/40 ABC) at 25-30%, but is at the threshold of almost unwatchable.
I have included my tv-fool plot "Radar-Digital.png" and pics of the bowtie and homemade antenna.
These channels are locals and come in very well on analog. What can I do to improve reception for the digital cutoff date?
I haven't gotten to the store to buy a "proper" antenna because I don't have a way to transport it home, I'll use a taxi later when I get this figured out.

Fortunately, testing outlet wiring is both easy and safe: Hardware stores and the big-box home centers sell inexpensive, three-prong, plug-in testers that verify the wiring of any outlet. A standard tester costs about $4, while one that can check a GFI outlet costs about $8.



I've got a tester like you're refering to, but I'm not convinced that it would have indictated a problem in my or your badly wired outlets.

Since my outlet had a jumper between the ground terminal and the neutral terminal inside the handy-box, they would have been at the same potential. And like your outlet, the hot and neutral had been swapped enroute from the house to the garage. So from the tester's point of view, it would have seen 120V between the outlet's hot terminal and neutral terminal; 120V between the hot terminal and the ground terminal; and 0V between the neutral terminal and ground terminal. All three of these are normal/good conditions.

For the device to have indicated the problem, it would have needed a way to reference true ground, without relying on the connections made by the three prongs.

I made my determination by sticking one lead of my volt meter in the snow and the other on the handy box.

Hi All:

I've been following with some interest several online pages and the accompanying forum thread, where a number of antenna hobbyists are attempting to improve an older UHF antenna design (Gray-Hoverman) for current-day UHF reception:

http://www.digitalhome.ca/ota/superantenna
http://www.digitalhome.ca/ota/superantenna/performance.htm
http://www.digitalhome.ca/ota/superantenna/design.htm
http://www.digitalhome.ca/forum/showthread.php?t=81982

Some are reporting superior results to the CM4228 with a double (8-bay) version of this antenna (with 30" x 75" reflector screen), although I've seen comments in this forum doubting such results, apparently based on the performance of a previously-commercialized 8-bay version, the Antennacraft Super G-1483.

I was wondering whether the currently-modified version of this antenna is the same as, or is an improvement on, that Antennacraft Super G-1483. Reason I ask is that a modified version of this antenna (by element size, spacing, etc.) for peak reception at the lower end of the UHF band might be helpful for my needs.

Thanks...

I've been pondering the advantages of modifying the Gray-Hoverman design in such a way that the screen is spaced behind the elements at such a distance as to produce an in-phase reflection at a target frequency. I think that way you could get a gain peak where you need it instead of at the upper end of the spectrum. I'm sure some would benefit more from a high UHF gain peak, but all the stations I'm concerned with receiving are on channels 25, 28, 29, 30 and 39, and all are between 70 and 80 miles away. I'm thinking a design with a gain peak around channel 30 would be ideal for my situation.

I have another question that has most likely been beat to death.

I live between two markets. After the digital transition, both markets will have both UHF and VHF channels. I had planned on using a pair of YA-1713 VHF antennas joined by a jointenna. One market will have channels 7 and 9 while the other market will have channel 11. I figured a jointenna for channel 11 would do the trick.

I had planned on a pair of XG91 UHF antennas. One would receive all of the locals in one market while the other would receive channel 50 in the other market. I would use a channel 50 jointenna for this.

I am wondering about the XG91 directivity. I have seen models where this antenna receives virtually nothing from the sides or rear. The markets are 225 degrees apart. One market is about 20 db stronger than the other market, but both require long range antennas (-75db vs -95 db).

If I could get by without needing a jointenna for UHF, I could attempt to get a lower power station that broadcasts from the same tower as channel 50, but directs its beam away from me. This station will have a very weak signal (about -120 db), but I strongly suspect I may be able to pull it in. With the jointenna, this channel (46) will be blocked by the jointenna.

Given the antenna selection and the difference in signal direction (225 degrees), is it likely that I can combine these two antennas without the use of a jointenna, or will they simply interfere with each other?

Thanks,

Bill

I've been pondering the advantages of modifying the Gray-Hoverman design in such a way that the screen is spaced behind the elements at such a distance as to produce an in-phase reflection at a target frequency. I think that way you could get a gain peak where you need it instead of at the upper end of the spectrum. I'm sure some would benefit more from a high UHF gain peak, but all the stations I'm concerned with receiving are on channels 25, 28, 29, 30 and 39, and all are between 70 and 80 miles away. I'm thinking a design with a gain peak around channel 30 would be ideal for my situation.

I've built a Gray-Hoverman and several different versions of 4 and 8 bay antennas. The one I like the best is a 4 bay with a larger reflector the elements are 10" long and spaced 9 5/8" apart with a reflector spaced 5 inches behind the elements. The reflector screen measures 36" h x 40" w and I bend the outer 8" of the reflector on each side forward about 2 1/2". I also bend the driven elements forward 2".

I modeled the Gray-Hoverman with different reflector spacings but didn't find much that could be improved upon, some spacings gave slightly better raw gain but at the cost of an impedence mis-match which would have lowered net gain.

I have a large 8 bay built based on the 4 bay design above but with a 40 x 56" reflector. I hope to try it this weekend weather permitting.

Bill:

I have a 91XG in my attic that I'm currently testing on analog signals while I await my soon-to-arrive HDTV. It's pointed roughly northwest to receive UHF channel 25 at 55 miles, which it pulls in at about an 8 out of 10 (in analog). A UHF channel 24 in the south-southwest direction (at 65 miles) comes in around a 1-2 out of 10 (again in analog), with significant multipath present in that weak signal. Channel 24 would be around a 6 out of 10 if the 91XG were pointed toward it.

Of course, there may be some signal bouncing in the attic, but I get very little multipath distortion in signals when this antenna is pointed toward the station. People are saying that digital signals (especially with the newest generation of tuner chipset) are good at resisting multipath, such that combining two 91XG's may be possible if the stations are far enough away. For my local stations, the 91XG pulls off-axis stations in strongly, albeit with lots of multipath.

Another option you might consider for your channel 46 and 50 situation (instead of a jointenna) is to use a low-pass filter like this one - http://www.solidsignal.com/prod_display.asp?PROD=CPLPF-600. If you put this in the line for your one 91XG, it would allow everything above UHF channel 40 to come in through the other 91XG, if I understand these correctly. $34.99 might be reasonable if that did the trick for you. My stations are too scattered by channel number to do this, unfortunately.

Hope this is helpful...

Bill:

One more thing I forgot to add - if at least one of the channels you want to receive from your first 91XG is above channel 40, you could try inserting a tunable trap from Winegard that can knock out two channels simultaneously (channels 46 and 50) from that first 91XG, so that you can then combine the other 91XG with a simple backwards splitter. That trap is shown here:

http://www.summitsource.com/winegard-variable-uhf-trap-part-ut2700-ut2700-p-5344.html

http://www.vancebaldwin.com/products/?UT-2700 (cheaper here...)

Given the antenna selection and the difference in signal direction (225 degrees), is it likely that I can combine these two antennas without the use of a jointenna, or will they simply interfere with each other?




In addition to various filters you might be evaluating, keep in mind that sometimes it's better to aim an antenna in the direction that nulls out the undesirable signals, rather than aiming it to strengthen the desired signals. For example, if desired signals were at precisely 0°, you might find it better to point the antenna at 352°. This might cost you one or two dB in signal strength of the desired channels, but if it drops the undesired channels down by 10 dB, it could be worth it.

Several months ago I ordered the Jointenna since I have a digital channel 23 available from New Mexico about 60 miles away plus all of the digital channels are currently on UHF in El Paso about 30 miles away. I had the jointenna set to channel 23.
Upon arrival I did some tests by first hooking up the "El Paso" antenna to the all channel input of the Jointenna. It did successfully block channel 23 and somewhat attenuate channels 20 through 25 as would be expected. However, when I connected the "New Mexico" antenna to the channel 23 input of the Jointenna it continued to receive channels 14 through 30 from El Paso with no attenuation at all. Of course, it also receives 14-30 from the "El Paso" antenna when both are connected and causes severe multipath as can be seen on the analog stations, some of which I am still interested in.
My conclusion was that the Jointenna does not insert just one channel but a large block of channels which may actually be to an advantage in some situations but not for here. I went back to a RF switch.

What happened to Delhi (Jerrold) log antennas? They measured better than any other types I've ever tried for all channel antennas and by a good margin. I see them listed now as owned by Wade, but don't find dealers selling them.

I have acquired what might be the last of the new Wade/Delhi/Jerrold VIP-307sr models still in circulation. Ah, the beast is mine ...

FYI, the (very helpful) people at Wade say they will restart production for bulk orders, 30+.

Give 'em a call:
http://www.wade-antenna.com/TACO/Contact.htm

Several months ago I ordered the Jointenna since I have a digital channel 23 available from New Mexico about 60 miles away plus all of the digital channels are currently on UHF in El Paso about 30 miles away. I had the jointenna set to channel 23.
Upon arrival I did some tests by first hooking up the "El Paso" antenna to the all channel input of the Jointenna. It did successfully block channel 23 and somewhat attenuate channels 20 through 25 as would be expected. However, when I connected the "New Mexico" antenna to the channel 23 input of the Jointenna it continued to receive channels 14 through 30 from El Paso with no attenuation at all. Of course, it also receives 14-30 from the "El Paso" antenna when both are connected and causes severe multipath as can be seen on the analog stations, some of which I am still interested in.
My conclusion was that the Jointenna does not insert just one channel but a large block of channels which may actually be to an advantage in some situations but not for here. I went back to a RF switch.


It might be worth your while to contact Channelmaster and send it in to be recalibrated. I had one last year that originally arrived mistuned. I returned it to them, they retuned it, and it came back performing much better.

I just got 2 dtv converter boxes. "Digital Stream DX9900"
I posted about my antenna troubles about 4 months ago in the local Peoria IL area, and have made modifications since then.
I have a yagi, radioshack-VU90 in the attic, and have twin lead 300 ohm run to a receptacle on the first floor.
I run a 6 foot twin lead 300 ohm to my DX9900.
I was told to change my wiring to coax and use a different antenna, such as a CM4221 four bay.
I haven't changed the wiring, but decided to build an antenna using the U-tube video here:
http://www.youtube.com/watch?v=EWQhlmJTMzw "clothes hanger antenna"
I hooked it up in the attic, and it made very little difference.
It seems to work OK on the ground floor, but is not an improvement over the yagi in the attic.
I'm having trouble with 2 channels that are only about 10-15 miles away.
I live in a river valley.
One channel doesn't come in at all, (ch. 19/40 ABC) the other one only gets 25% (ch 25/57 NBC) on my meter.

I have another TV and DX9900 in another room, and I have a double bowtie antenna. (one that sits on top of the TV).
I can pull in the "unavailable" (ch. 19/40 ABC) at 25-30%, but is at the threshold of almost unwatchable.
I have included my tv-fool plot "Radar-Digital.png" and pics of the bowtie and homemade antenna.
These channels are locals and come in very well on analog. What can I do to improve reception for the digital cutoff date?
I haven't gotten to the store to buy a "proper" antenna because I don't have a way to transport it home, I'll use a taxi later when I get this figured out.
Jon: I am surprised that the YouTube does not work for you even down in Pekin. I am going to install a Youtube antenna over in Morton in May. She is having trouble with the amplified indoor antenna they sold her at Circuit City. I am surpised that you are receiving FOX (43.1) ok. Let us know when you come up with something good.

Regarding the UHF Jointenna, it is what it is and isn't what it isn't. It is basically a cheap combination bandpass filter, band reject filter, and low loss combiner. It typically passes the desired channel with negligible loss, passes the adjacent channels with an edge-to-edge rolloff of a few dB, and slopes through the next channel or two until a rejection depth of about 20dB is attained.

The band reject curve is close to an inverted version of the bandpass curve, with the caveat that its shape is rather irregular through its tapers.

There is one internal band-pass filter center frequency adjustment and one internal band-reject center frequency adjustment, and there is some other primitive, folded metal strip inductor that can probably be "touched up" by someone who knows what its purpose is, but when I connected a few UHF Jointennas to a white noise generator and spectrum analyzer, I couldn't figure out what effect flexing that inductor might have.

Without a signal measuring device, like a spectrum analyzer or an FSM, it is not possible for an experimenter to even estimate its attenuation at different frequencies. If you have a strong signal in the presence of a weak one, even if a Jointenna attenuates the strong signal by 20dB, it might produce the same "% signal strength" value on your tuner's signal strength display.

Thanks for the info on the Delhi's. So looks like it is just our local starkelectronic that is dropping them.

That antenna is pretty good (VIP- 307), as I have mine at 52' in the air. However, it is pure overkill, as I only need a high bander 7- 13 with the digital domain. So, I will be taking mine down. (Less winload)

What price did they quote you?

That antenna is pretty good (VIP- 307), as I have mine at 52' in the air. However, it is pure overkill, as I only need a high bander 7- 13 with the digital domain. So, I will be taking mine down. (Less winload)

What price did they quote you?

I want to stabilize my reception of a Channel 4 from 90 miles out, as well as take a shot at a 5 and a 10. I also have a 7 and a 12, so it's going to get a workout here.

The people at Wade referred me to Lafayette Electronics. He had the one vip-307 left, and sold it to me for $255 shipped. He says he will continue to stock the vip-306 for the forseeable future.

Jon: I am surprised that the YouTube does not work for you even down in Pekin. I am going to install a Youtube antenna over in Morton in May. She is having trouble with the amplified indoor antenna they sold her at Circuit City. I am surpised that you are receiving FOX (43.1) ok. Let us know when you come up with something good.

I cannot get FOX (43.1). It shows only about 20-25% on the meter.
I'm not worried about FOX, my main concern is recieving ABC. I watch "Lost"
I finally got the U-tube antenna working with marginal picture quality for ch. 19 WHOI, (25-30%) and slightly better with ch. 25 WEEK, (25-35%).
I just placed the antenna at an upward angle, facing the sky, about 60 degrees, pointing toward the creve cour tower. It seems like my antenna works better at a sky facing angle, than at true vertical.
I do have a very large tree behind my house that is about 30-35 feet tall. It is off to the west of my north-east facing antenna.
ch 46 PBS is always at 90% or better, and ch 31 WMBD is usually at 90%. I also get ch. 39 WAOE at 70-75%

Jon,
I have a DTX9900 running off a 4-bay (with reflector) home-built antenna in the attic. My signal field is weaker than yours (-70 to -78dBm) and my DTX is getting 80-90 on these stations. (I only wish it were stable at 80-90 ...)

One big difference is downlead; mine is short and RG-6 coax. Yours is long and twin-lead, and I think it may be acting like a second antenna, causing you multipath issues. Let me suggest two tests:
- try disconnecting the antenna from the downlead and running on twin-lead only.
- connect the 4-bay with a balun and a short piece of coax next to the TV.

Anything you get without the antenna attached to the twin-lead is multipath and can be eliminated by using coax. It's possible you don't need an antenna; twist the leads together when you disconnect it so you don't get an open circuit.

Using a short, shielded lead off the 4-bay will also eliminate any downlead pick-up. You report that the 4-bay worked OK on the ground floor; does that mean you pick-up the stations you don't get above? Were you using twin-lead downstairs?

By the way, a 4-bay gets its gain by narrowing its vertical spread. Compare the dipole pattern near the top with the 6-bay array below it to get the idea. (Note both are bi-directional due to the absence of a reflector.)
http://www.hdtvprimer.com/ANTENNAS/types.html

With a 4-bay aimed up at 60*, you're using one of the low-gain lobes, the lumps at top and bottom, not the main lobe. Usually, in strong fields, if an antenna only works aimed away from ALL terrestrial sources, it's either a multipath issue or your a radio astronomer.

Have fun,
Frank

Jon,
I have a DTX9900 running off a 4-bay (with reflector) home-built antenna in the attic. My signal field is weaker than yours (-70 to -78dBm) and my DTX is getting 80-90 on these stations. (I only wish it were stable at 80-90 ...)

One big difference is downlead; mine is short and RG-6 coax. Yours is long and twin-lead, and I think it may be acting like a second antenna, causing you multipath issues. Let me suggest two tests:
- try disconnecting the antenna from the downlead and running on twin-lead only.
- connect the 4-bay with a balun and a short piece of coax next to the TV.

Anything you get without the antenna attached to the twin-lead is multipath and can be eliminated by using coax. It's possible you don't need an antenna; twist the leads together when you disconnect it so you don't get an open circuit.

Using a short, shielded lead off the 4-bay will also eliminate any downlead pick-up. You report that the 4-bay worked OK on the ground floor; does that mean you pick-up the stations you don't get above? Were you using twin-lead downstairs?

By the way, a 4-bay gets its gain by narrowing its vertical spread. Compare the dipole pattern near the top with the 6-bay array below it to get the idea. (Note both are bi-directional due to the absence of a reflector.)
http://www.hdtvprimer.com/ANTENNAS/types.html

With a 4-bay aimed up at 60*, you're using one of the low-gain lobes, the lumps at top and bottom, not the main lobe. Usually, in strong fields, if an antenna only works aimed away from ALL terrestrial sources, it's either a multipath issue or your a radio astronomer.

Have fun,
Frank

Thank you for your thorough reply. :)
I definitely have a multipath problem. I disconnected my twin lead and twisted the ends together.
I still receive all previously mentioned stations with about 5-10% decrease in signal strength according to the DX9900 meter.
(ch. 19 WHOI) is gone now, signal meter is at 5-7%
I measured the length of the twin lead run, it is 35 feet from the baseboard receptacle in my living room to the top of the attic. I just realized there is some of the twin lead coiled up in the unfinished part of my attic.
I just bought some new RG6 cable, connectors and crimping and stripping tools. I'm going to wait till it cools down tomorrow and run the RG6 to the receptacle, and use RG6 to my DX9900. I'll try to keep the length as short as possible.
Once I've done this, I'll go from there.
I previously connected the youtube antenna to a blaun and coax next to my TV.
This was my first test when I first put it together, 2 days ago. Recpetion was similar to my attic mounted yagi.
Would placing a screen on the back of my youtube antenna help? Does it need to be exactly four inches behind the 8 elements/whiskers?

That is a "fair" price. Enjoy your new antenna.:D

I want to stabilize my reception of a Channel 4 from 90 miles out, as well as take a shot at a 5 and a 10. I also have a 7 and a 12, so it's going to get a workout here.

The people at Wade referred me to Lafayette Electronics. He had the one vip-307 left, and sold it to me for $255 shipped. He says he will continue to stock the vip-306 for the forseeable future.

I have Directv and just ordered an AM21 OTA reciever. I have RG6 prewired in the attic so I wanted to put the antenna somewhere in the attic. I am in 48335 area code and need a recommendation. Will the attic location be sufficient or do I need to go outside with it?

Any help is appreciated.

Thanks
MIKE

...
I just bought some new RG6 cable, connectors and crimping and stripping tools. I'm going to wait till it cools down tomorrow and run the RG6 to the receptacle, and use RG6 to my DX9900. I'll try to keep the length as short as possible.
...
Would placing a screen on the back of my youtube antenna help? Does it need to be exactly four inches behind the 8 elements/whiskers?

You have a good antenna in a fairly strong signal field and coax losses are only -6dB/100 ft. at the high end of the UHF band so a few feet won't matter. Leave yourself plenty of slack, avoid sharp bends in favor of looping turns, it's just best practices.

A reflector increases gain at the expense of bi-directionality. You don't need back-side gain if I recall your signal field correctly, and for an 8" bowtie size, a 4" spacing is just right. Let us know how you do.
frank

Mike,
Looking at TVFool.com, you have a very rich signal field; almost any antenna will give you 1-2 dozen stations without a rotor, and with one you can make it 3 dozen. Neat thing about Detroit; lots of Canadian stations, most south of your local towers. Most are UHF now, but Fox, WJBK, is going back to VHF7, albeit with a very good signal.

Any of the short-distance UHF/VHF combos will work, as may a mid-range UHF array, given your single VHF station is in rabbit-ear territory.

Frank

Will the attic location be sufficient or do I need to go outside with it?You have a bunch of station available at your location from a number of different directions. Looks like an attic install would get some of them. Outside with a rotor might get all of them. Which stations do you want to receive?

Oooops! fbov posted a good reply while I was typing.

Frank...
Thanks for the reply.
Would you have a brand/model recommendation?
I know there are Audiovox's, RCA, Terks, etc out there.
I just want to get one at a decent price that functions well.
Thanks
MIKE
p.s. the main stations I want to get are the ABC, NBC, CBS, PBS, and Canadian CBC channels.

fbov,
WOW!! Thank you, thank you. :)
Replacing the twin lead with rg6 coax resulted in a dramatic improvement in reception. I replaced it all, even the short pigtail near the TV. My results are:
(Ch. 19 WHOI) went from a paltry 6% to 80%-85% on the DX9900's meter. (This is good enough to record my fav show now!) :)
(Ch. 25 WEEK) is around 57%-85%
My other channels showed slight improvement, not much, but these channels were already in the high 80's to 90's anyway. (Ch31 WMBD) and (Ch 39 My59) and of coarse, (Ch. 46 PBS)
I decided to try (43 FOX Bloomington). It gets a steady 45%. I really don't care much for this channel anyway.
I still have the option to re-position my antenna.
I am still using the youtube antenna without a screen.
It is located in the peak of my attic, which is a pyramid shape.
I just have one question.
My other large TV is on the opposite end of the house. If I just stack a second balun on top of the existing balun (on my antenna), will that setup act as a splitter? I would like to run a second coax to that room from the peak of the attic.

BTW, I did leave some slack at both ends, and there are no sharp bends.
Again, thank you very much. :)
Jon

I have almost the exact same question as Mike.

I have the DirecTV HR-20 and I'm in zip code 78413. I did an exact address search on TV fool. I think I know what the results mean, but I don't know if the numbers are "good" or "bad"

ABC - 151kW - 11.9 miles - 266 true
NBC - 30kW - 12.9 miles - 293 true
CBS - 6.3kW - 14 miles - 281 true
PBS - 90kW - 9.7 miles - 264 true

For now, top priority is NBC for the NHL Western Conference Finals. (Go Stars!)

I'm hoping that something inexpensive ($30-$50) will work for now and I'd really like to put it in the attic rather than on my house.

Recommendations please?

I'm hoping that something inexpensive ($30-$50) will work for now and I'd really like to put it in the attic rather than on my house.

Recommendations please?

Try a $10 rabbit ear/loop combo. With signals above -65dBm for 78413, this may be all you need. If not, these signals should be easy to receive from the attic. This assumes that the antennas aren't looking through a metal or stucco wall, however.

Are your exact results also above -65dBm?

Try a $10 rabbit ear/loop combo. With signals above -65dBm for 78413, this may be all you need. If not, these signals should be easy to receive from the attic. This assumes that the antennas aren't looking through a metal or stucco wall, however.
Any particular brand/model of rabbit ear/loop to look for? I'm headed to Home Depot on the way home from work. Would be nice to grab one there considering their return policy.

No metal or stucco. I have a 1 story wood/brick single family home.

Other questions:
According to antennaweb, my NBC, ABC and CBS affiliates are VHF on frequency assignments 13, 10, and 8 respectively. This means that I need a VHF antenna, correct?

Can I put the rabbit ear/loop in the attic? I'd like it to be out of sight and I'm going to be running some wire up there anyway.

Are your exact results also above -65dBm?
Are you referring to the Rx(dBm) column? Here's the table of my exact address with that column added..
ABC - 151kW | -41.5 dBm | 11.9 miles | 266 true
NBC - 30kW | -52.3 dBm - 12.9 miles | 293 true
CBS - 6.3kW | -63.4 dBm - 14 miles | 281 true
PBS - 90kW | -49.0 dBm - 9.7 miles | 264 true

Look ok?

(Thanks for the help!)

fbov,
WOW!! Thank you, thank you. :)
Replacing the twin lead with rg6 coax resulted in a dramatic improvement in reception.
...
If I just stack a second balun on top of the existing balun (on my antenna), will that setup act as a splitter? I would like to run a second coax to that room from the peak of the attic.
...

Jon,
Love to hear about happy endings, especially when I guessed right! Multipath is a new and nefarious enemy for most of us.

A splitter costs you >4 dB and it's predictable. A second balun on the antenna changes feedline impedence and that's hard to predict. I'd split; in my testing, I don't see the splitter at all - same signal readings with or without.

Frank

wjd03,
That little Rx number is the most important thing TVFool brings to the discussion - an actual estimate of signal available at your site. It's what says "rabbit ears" instead of "pre-amp, rotor and big antenna on the roof." The actual rabbit ears are a VHF antenna while the "loop" in the middle is the UHF antenna. Returnability is a wonderful thing!

The only attic issue is that you want to run RG-6 coax, but a lot of rabbit ears have twin-lead output. Getting one with an F-connector would be a good thing, or use a balun to connect the twin-lead to the coax. Amplification is not likely to help, but may if you've got a long run.

Good luck,
Frank

wjd03,
That little Rx number is the most important thing TVFool brings to the discussion - an actual estimate of signal available at your site. It's what says "rabbit ears" instead of "pre-amp, rotor and big antenna on the roof." The actual rabbit ears are a VHF antenna while the "loop" in the middle is the UHF antenna. Returnability is a wonderful thing!

The only attic issue is that you want to run RG-6 coax, but a lot of rabbit ears have twin-lead output. Getting one with an F-connector would be a good thing, or use a balun to connect the twin-lead to the coax. Amplification is not likely to help, but may if you've got a long run.

Good luck,
Frank
Thanks so much. I've been a cableco subscriber for such a long time that I never really paid attention to this stuff. I love all the HD's on DirecTV but they don't have my locals in HD yet, so I need to get this done..

I'll see what they have at HD this afternoon and I'll definitely try to get one with a F connector or at least some sort of adapter.

My run is short. The highest point in my attic is pretty much directly above my TV. Maybe a 25' run.

Any particular brand/model of rabbit ear/loop to look for? I'm headed to Home Depot on the way home from work. Would be nice to grab one there considering their return policy.

Just don't get one that has a built-in amp. The $10 one at Target (RCA ANT 115) has worked well enough for me, though I haven't been able to find it on their website. Here is a link from another site:

http://www.buy.com/prod/rca-ant115-indoor-antenna/q/loc/111/90111991.html

I use it as a test antenna.

I am helping a freind with a tv/antenna setup using a walmart durabrand tv with built in dgital tuner (made by funai) and a homemade coathanger db2 type antenna without a screen. I want to put the antenna in the attic of a one story ranch type house but am wondering about signal loss through the roof material/shingles. I will use a 25 foot coax cable. The area code is 45230.

I am helping a freind with a tv/antenna setup using a walmart durabrand tv with built in dgital tuner (made by funai) and a homemade coathanger db2 type antenna without a screen. I want to put the antenna in the attic of a one story ranch type house but am wondering about signal loss through the roof material/shingles. I will use a 25 foot coax cable. The area code is 45230.

Shingles or wood wont cause any significant loss, go for it.

Shingles or wood wont cause any significant loss, go for it.

Say what ?

I am helping a freind with a tv/antenna setup using a walmart durabrand tv with built in dgital tuner (made by funai) and a homemade coathanger db2 type antenna without a screen. I want to put the antenna in the attic of a one story ranch type house but am wondering about signal loss through the roof material/shingles. I will use a 25 foot coax cable. The area code is 45230.

45230... You're in Cincinnati? You may be OK with putting that in the attic. You may also have problems getting WCPO (digital channel 10) and WKRC when they switch to broadcasting their digital signal on channel 12 after analog shutoff. If you have problems, you can stop by the Cincinnati HDTV Thread (http://www.avsforum.com/avs-vb/showthread.php?t=306883) for more help.

I am helping a freind with a tv/antenna setup using a walmart durabrand tv with built in dgital tuner (made by funai) and a homemade coathanger db2 type antenna without a screen. I want to put the antenna in the attic of a one story ranch type house but am wondering about signal loss through the roof material/shingles. I will use a 25 foot coax cable. The area code is 45230.

Contrary to some opinions, conventional roofing will cost you 10-15dB in signal, and the 4-bay (CM4221) tested in the attached lost more like 25dB. Coax loss is more like 6dB/100ft, and that only at upper UHF frequencies that TV abandons, post transition.

Thankfully, it looks like you have a strong signal field, but local terrain variations can cost you another 25dB - be sure to check your friend's exact address. That said, I use a 4-bay home-built with reflector in my attic and get -78dBm stations at ~90% on a Sony 34XBR970 TV and more like 80 on a DTX9900 CECB. A 2-bay (DB-2) will not do nearly as well as a 4-bay, but it's a start.

Looking at the signal field, now and post transition, you do have VHF stations to consider. WCPO-DT will be a good test as it's at it's permanent frequency (VHF 10) and near long-term power. If this antenna gives a good signal for 9.1 today, your friend should get WKRC just fine when it moves back to VHF 12. If not, try an oversized reflector. I see no need for back-side reception in this signal field, and an opportunity to improve front-side if needed. Additional thought are to expand to a full 4-bay and to increase the scale of the antenna to more-closely match the desired channels.

That said, thoraX695's suggestion to check the local HDTV thread will only help.

Frank

I probably didnt need th DB8...maybe I could have gone with the DB4 but Im growing tired of trying Antennas that arent good enough. I wanted the strongest UHF gain that isnt directional. The DB8 attracted me because it covers an area of 90 degrees from where the Ant is pointed. Maybe I could pick up everything that is coming from NYC without having to adjust it for the best sig. Either way its a clear upgrade from the Stealth.

vinnyv07:

I looked up Staten Island on antennapoint.com. You have over 45 broadcast towers that should be available to your DB-8, which was a good choice with its power and beam width. 22 stations are northeast of you, 12 of which are within 10 miles. Another 16 are within the range of the DB-8 to the southwest. To get them all, you will need a second DB-8, one pointed NE (36°), the other SW (240°), connected to an infra red A/B switch (for convenience), unless you want to get up and switch the A/B switch each time you need the second antenna for exercise.

Getting them all is a good investment in entertainment. Your DB-8 will receive all your local stations, including multi-cast programming adding several additional local off-air programs. With 2 DB-8s, you will be able to receive out-of-town channels from both directions, carrying blacked out sports programs or network broadcasts not available to you locally.

I added 2 additional sections onto my existing 91XG to increase the directivity. These are the last sections that you need to add, or you will mess up the director spacing.

Here are some photos.

More to follow... (Stay tuned)

I added 2 additional sections onto my existing 91XG to increase the directivity. These are the last sections that you need to add, or you will mess up the director spacing.

Here are some photos.

More to follow... (Stay tuned)
Cool!! Any comparison data to a plain, vanilla 91XG??

I added 2 additional sections onto my existing 91XG to increase the directivity. These are the last sections that you need to add, or you will mess up the director spacing.



Perhaps it's a photographic illusion, but there appears to be some droop/sag occuring. Does that affect the performance much?

I added 2 additional sections onto my existing 91XG to increase the directivity.The addition of those extra director elements probably adds very little to the gain, but it sure increases the mechanical problems of mounting and securing that very long boom.
Cool!! Any comparison data to a plain, vanilla 91XG??My guess would be less than 1dB added gain. Where maximum gain is required, it is customary to use a pair of identical antenna suitably connected, rather than one long array, thus reducing the mechanical problems, and yielding more gain.

The addition of those extra director elements probably adds very little to the gain, but it sure increases the mechanical problems of mounting and securing that very long boom.
My guess would be less than 1dB added gain. Where maximum gain is required, it is customary to use a pair of identical antenna suitably connected, rather than one long array, thus reducing the mechanical problems, and yielding more gain.
The rule of thumb for Yagis is that to get 3 dB more gain, you have to double the boom length.

That's essentially what PCTools has done. However, the big gap between directors 22 and 23 (which I assume is the junction of the regular antenna and the extension) does not look optimum.

Ron

What are some of the advantages and disadvantages of a horizontal vs a vertical stack?

I know it is so much easier to do the vertical stack. Trying to get hardware in a small town is difficult. I have to drive an hour to get to a Home Depot. :mad:

Vertical stacking narrows the gain pattern in the vertical plane, leaving the horizontal gain pattern basically unchanged. Horizontal stacking does the opposite, and seems to be more effective. The gain should be the same either way, but horizontal stacking seems to be more effective against multi-path interference, which improve reception to a greater degree than extra gain in most cases.

The professional installations in my area (I'm talking cable TV systems here), use quad stacked LPAs. In fact, the cable system in my town used eight low VHF LPAs in a double quad stack, and a single quad stack for high-VHF and another for UHF.

I'll build on Neil L's comments a bit by referencing Ken Nist's 16-/32-bay work on HDTVprimer.com.

He found that a vertical stack of two 4228's worked better than a 2x2 array of four 4228's. His reasoning was based on diffracted signal field characteristics - the entire vertical stack fit within a positive interference node while the wider 32-bay spanned positive and negative nodes. I believe he ended up with a switch-selectable pair of 16-bay vertical stacks, each in a different transmitter location's diffraction sweet spot.

A vertical stack is also preferred if you want the wide directional gain, and can deal with increased sensitivity to tilt. In general, however, it's easier to aim a roughly circular aperture than a thin slit. Think in terms of a spotlight vs. car fog lights.

With Yagi's, there is an advantage to stacking in that you have no crossbars to deal with. Proper side-by-side Yagi mounts have a separate mount for reach antenna that keeps the cross member out of the antenna aperture, since all horizontal conductors within that aperture participate in signal reception. You want this:
http://www.atechfabrication.com/products/dual_antenna_boom.htm
not this:
http://www.atechfabrication.com/products/x300-db_integrated_stacking_boom.htm

With Yagi's, there is an advantage to stacking in that you have no crossbars to deal with. Proper side-by-side Yagi mounts have a separate mount for reach antenna that keeps the cross member out of the antenna aperture, since all horizontal conductors within that aperture participate in signal reception. You want this:
http://www.atechfabrication.com/products/dual_antenna_boom.htm
not this:
http://www.atechfabrication.com/products/x300-db_integrated_stacking_boom.htm

Or, just use fiberglass for any horizontal components. Either will work.

Horizontal is the way to go in my experience.
You'll also get better results with stripline combiners vs. ferrite splitters, probably as a result of superior phasing characteristics of the stripline combiner.

Antennas need to be identical (including baluns) and coax feeds should be of equal length to the combiner.

Thanks for the feedback, however, this site is dufunked. They never return my calls! So buyer beware. Any other places?

You want this:
http://www.atechfabrication.com/products/dual_antenna_boom.htm
not this:
http://www.atechfabrication.com/products/x300-db_integrated_stacking_boom.htm[/QUOTE]

Thanks for the feedback, however, this site is dufunked. They never return my calls! So buyer beware. Any other places?



You'll need to make it yourself most likely. In case you didn't see it, here's my earlier reply to you on the subject (edited to include link for CM attic mounts):

http://www.avsforum.com/avs-vb/showthread.php?p=13625302#post13625302

Fbov,
I may have jumped the gun when I first posted my meter readings and vast improvements in reception, in my last post.
The improvements in reception are available only if I have my youtube sitting on top of my yagi.
I set it up this way when I first built it. The first attached photo shows this.

Later that day and the next day, I tried just using the youtube antenna mounted to the pole by itself. (I took down the yagi) I had lost 10-20% reception on four stations.
I tried placing it in different locations and higher up. I still never got the great reception that I got on the first day, when I just propped it on top of my then disconnected yagi. Also, spreading the front elements on the disconnected yagi effected my reception, (since the top yagi element is in direct line with the bottom four elements on the youtube antenna).

So this is where I'm going to leave it, for now.
I think I still have a multipath problem, and decided to build a second youtube antenna, with a screen.
Since all the stations I view are within a semi-narrow path, I think a screen would help.
There are 2 shots of my new youtube antenna.
I built it to exact dimensions as the author of the video. 7 inch whiskers, spaced on the wood at 5 3/4 inches apart.
I didn't have a 2x4, so I designed a mount which places the screen, 3 1/2 inches from the elements.
I noticed the youtube author used light weight clothes hangers. I only have the "pants" type hangers and they are somewhat thicker.
When erecting the antenna with the hanger wires under the screws, the whiskers angle inward as seen in the side view pic.
Should I bend them back so they are on a flat plane?
I haven't tried this new antenna yet, but will as soon as I get some time to hook it up.

I need advice on selecting an antenna for my new Samsung TV, The factors are: The stations are 40 to 50 miles from my house, per antennaweb.org. I have a one story house with very little obstruction, a few large trees but no buildings. I am not on a hill but in an elevated area. I prefer an outdoor antenna because everything I've read states that outdoor antennas are far superior. The broad cast stations I want to pick up are located N.E, East and S.E. from my house, What strengths do I need? Will rooftop be enough or do I install on pole? I currently have a satellite dish, the dish 500 I understand I can actually hook into the satellites coax. Is that true? What special tools or splitter would I need? How about an additional ground?If I decide to do a pole mount can anyone point me to a good source on how to install an antenna on a 20' pole. Yeeks, I've got so many questions on this. Unfortunately my budget is limited and after calling a few installers I got prices on the basics for 400 up to 800 dollars,.... out of my range, so I would attempt to do it myself or at the very least purchase all my materials and just pay for installation. Any feedback is appreciated

Greg,

Looks like I will be making up the stuff this weekend. Just finished the concrete pour on the tower. 3/4 yard for the Rohn 20 - 50' tower. Put the house bracket at 16'.

Thanks for the pictures. :D

I stacked two of the 91XG's (Vertical) and working Channel 32 out of Chicago. 242 miles! :rolleyes:

You'll need to make it yourself most likely. In case you didn't see it, here's my earlier reply to you on the subject (edited to include link for CM attic mounts):

http://www.avsforum.com/avs-vb/showthread.php?p=13625302#post13625302

Looks like I will be making up the stuff this weekend. Just finished the concrete pour on the tower. 3/4 yard for the Rohn 20 - 50' tower. Put the house bracket at 16'.

Thanks for the pictures. :D

I stacked two of the 91XG's (Vertical) and working Channel 32 out of Chicago. 242 miles! :rolleyes:

I'd like to see a pic of the tower when you get a chance.

VERTICAL STACKING

Stacking two identical antennas on a common vertical mast significantly narrows the vertical beam-width angle. That is, vertically stacked antennas more effectively reject those interfering signals arriving from above or below their horizontal plane than does a single antenna. It’s as though they were looking through a horizontal venetian blind. Because there’s nothing mounted to the side of either antenna, their side-to-side vision is virtually uneffected. In the process, gain increases about 2.5 dB over that of a single antenna.

Vertical stacking improves both gain and vertical directivity. This helps reduce airplane flutter and attendant picture roll, and certain types of ground noise and ground reflections.

The basic principle of stacked antennas involves the difference in the time of arrival, and therefore the phase, of signals intercepted by the antenna combination. If a pair of identical Yagi antennas are mounted one above the other, a wavelength apart, on a common vertical mast and are oriented identically (pointed) toward the signal source, any TV signals traveling horizontally and arriving from any direction will be intercepted simultaneously by both antennas.

Because the antennas are identical, the generated signal voltages arriving at the output terminals shared by the antennas will be in phase, causing them to add directly. Theoretically, there should be a 3 dB increase (double) in signal power over that of a single antenna, but, because of losses in the coupler and cable, the actual gain increase will be somewhat less than 3 dB.

An important point to remember is that, regardless of the azimuth angle between the antenna orientation and the signal source, the arriving signal will strike any given identical points on the two antennas simultaneously. However, if the signal is arriving from a source above or below the horizontal plane of the antenna, the previous statement is no longer true. For example, if the wavefront is from a source below the plane of the antenna, the signal will arrive first at the lower antenna and the signal voltage from the top antenna will lag the signal from the lower antenna. The signal voltages at the antenna output terminals will no longer be in phase, and partial cancellation will take place. The opposite is true if the signal arrives.

The angle of arrival and the resultant difference in arrival time causes a phase difference which reduces the magnitude of the combined voltages. You should begin to see now why two vertically stacked, identical antennas have a more restricted "vision" to signals arriving from a point above or below the horizontal plane than does a single antenna.

HORIZONTAL STACKING

Stacking two identical antennas side by side in a horizontal plane significantly narrows the horizontal beam-width angle. That is, the antenna combination, like a horse wearing blinders, "sees" fewer interfering signals arriving from the sides while its vision up and down (in a vertical plane) is virtually unaffected. In the process, gain increases approximately 1.2 dB over that of a single antenna.

If two identical antennas are arranged side by side in a horizontal plane and the signal wavefront arrives directly from the front, each antenna "sees" the same wave or field at the same time. If the wavefront arrives from a source above or below, the same is still true, except that the individual antennas are not operating as efficiently. However, if the wavefront arrives from one side or the other (Fig. 5A and C), the antenna on the side from which the signal is arriving will "feel" the signal first, causing the voltages induced in each antenna to be out of phase. This, in turn, causes partial cancellation of the antenna voltages when they are combined.

The up and down (vertical) "vision" of a horizontal stack is comparable to that of a single antenna, but its side-to-side "vision" is more restricted.

QUAD_STACKS

Stacking four identical antennas, two vertically and two horizontally in a rectangular or diamond pattern, restricts the vision of this combination in all directions off the axis. Called a quad stack, it "sees" as though it were looking through a tube pointed in the direction of the transmitting antenna.
Gain is increased approximately 4 to 5 dB over that of a single antenna.

GENERAL TECHNIQUES

Before you start putting up an array, you should be aware of the following basic considerations which apply to dual and quad stacking of antennas:

1) Stack only identical antennas
2) Maintain approximately one wavelength spacing (at lowest channel frequency) between antennas
3) Cut phasing lines or connecting cables to equal lengths
4) Length and phase oftwinlead interconnecting harnesses is critical
5) Horizontal supports should be nonmetallic
6) Avoid running interconnecting cables horizontally.

Vertical stacking is easier than horizontal stacking simply because in vertical stacks theantennas mount on a common vertical mast and spacing is easily adjusted.

However, with the excellent gain and high directivity of most Yagis today, vertical stacking is seldom necessary. If additional gain is needed, two vertically stacked identical antennas spaced more than ‘/2 wavelength apart will increase signal power by 3dB compared to that of one antenna. However, part of the increased gain will be lost in the connecting cables and the coupler.

Horizontally stacked antennas also must be spaced so that their booms are separated by a distance equal to more than ‘/2 wavelength of the lowest channel frequency. This spacing is needed to prevent the tips of the longest reflector elements from touching. Also, the horizontal supports must be nonmetallic; redwood or cedar 2’ x 4’ s are commonly used.

The severe ghosts caused by high-rise buildings, water towers and mountains can be reduced or eliminated by horizontallystacking two Yagis. However, the wavelength of a channel 2 signal exceeds 17 feet, making such an array for channel 2 unwieldly, heavy and subject to damage from ice and/or high wind. Fortunately, ghosting is more of a problem at high-band channels, and highband antenna dimensions are significantly smaller. For these reasons, usually only high-band Yagis are stacked horizontally.

These stations are VHF and UHF, I prefer to have an antenna that has both VHF and UHF capabilities, although after Feb 2009 I am not sure whether this will be a factor

These stations are VHF and UHF, I prefer to have an antenna that has both VHF and UHF capabilities, although after Feb 2009 I am not sure whether this will be a factor

Go to the signal finder tool at TV Fool (http://www.tvfool.com/index.php?option=com_frontpage&Itemid=1). It provides an excellent estimation of the stations you can pull in from your location. The site will show current and post transition stations, direction, distance, channels - in short all the information needed to offer informed advice on antenna selection.

One of my channels (ch. 19 RF 40) was getting worse on some days and I was getting dropouts during a storm the next day. I studied this page about attic antennas http://www.hdtvprimer.com/ANTENNAS/glossaryA.html#attic
In bold RED printing it says:
"There should be no horizontal or diagonal wires or pipes in front of the antenna. "
I realized I had a 110 volt horizontal romex wire running straight across my antennas' path at 10 feet above the finished floor.(see attachment)
The next day I completely removed these light fixtures and wiring. I installed the light fixtures at a lower height (7 feet), and ran the romex along the side and below my antennas.
Now (ch. 19 RF 40) comes in with a 10-20% signal strength increase on my CECB (Digital Stream DTX9900).
(ch. 25 RF 57) also showed much improvement, about 20-25% increase in signal strength.
I didn't move or touch either one of my antennas. I just relocated the 110 volt wiring.
During the 2 days that I have studied this and worked on my wiring, there has been some windy/stormy weather. This may throw off my findings on my meter readings.
Also included is my TV-Fool plot. "Radar-Digital.png"

I do not know why the bottom antenna is a little longer.

More to follow...

Here are a couple of pics... :)

Don't forget to put the rocks in the bottom!

I'd like to see a pic of the tower when you get a chance.

The trusty VIP-307 mounted on my first Rohn 50' tower. :D

Will be stacking the 91XG's on the NEW tower. (listed above)

Rick,

I agree, however, if you would accidently install the wrong piece the overall length of the antenna would not change. (Just the spacing would be impacted). These antennas have different lengths.

Both antennas are on the ground and I am in the process of a "horizontal stack." I will post my findings.

Thanks!

The 91 xg antenna has 3 sections.

looks like the top has the front 2 and the bottom has the middle 2 or someting in that effect. the spacing is farther apart on the back of the second section.

you would need to take the antennas down and arrange the parts appropriately. Otherwise the antennas are not perfectly matched as they should be when staking for maximun effectiveness

PCtools,
This is very useful summary of stacking describing the result beamwidth with horizontal and vertical stacking. A couple of points probably need a clarification. In either case the gain from combining two independent antennas will be 3 dB minus the loss in the combining circuit so the gain in not generally lower in horizontal stacking. The need for the antennas to not be coupled and therefore independent gives rise to the required minimum spacing. In general the higher the antenna gain the larger the required spacing requirement. For very narrowband, high gain yagis, amateur radio operators use a rule of thumb of half the boom length. Broadband TV antennas have less gain for a given boom length so they can be spaced somewhat closer. Horizontal and vertical stacking distance for yagis will be larger than half a wavelength and the plane with the narrowest beamwidth will need the largest spacing. For either plane it will come out less than half the boom length for TV antennas.
John

VERTICAL STACKING

Stacking two identical antennas on a common vertical mast significantly narrows the vertical beam-width angle. That is, vertically stacked antennas more effectively reject those interfering signals arriving from above or below their horizontal plane than does a single antenna. It’s as though they were looking through a horizontal venetian blind. Because there’s nothing mounted to the side of either antenna, their side-to-side vision is virtually uneffected. In the process, gain increases about 2.5 dB over that of a single antenna.

Vertical stacking improves both gain and vertical directivity. This helps reduce airplane flutter and attendant picture roll, and certain types of ground noise and ground reflections.

The basic principle of stacked antennas involves the difference in the time of arrival, and therefore the phase, of signals intercepted by the antenna combination. If a pair of identical Yagi antennas are mounted one above the other, a wavelength apart, on a common vertical mast and are oriented identically (pointed) toward the signal source, any TV signals traveling horizontally and arriving from any direction will be intercepted simultaneously by both antennas.

Because the antennas are identical, the generated signal voltages arriving at the output terminals shared by the antennas will be in phase, causing them to add directly. Theoretically, there should be a 3 dB increase (double) in signal power over that of a single antenna, but, because of losses in the coupler and cable, the actual gain increase will be somewhat less than 3 dB.

An important point to remember is that, regardless of the azimuth angle between the antenna orientation and the signal source, the arriving signal will strike any given identical points on the two antennas simultaneously. However, if the signal is arriving from a source above or below the horizontal plane of the antenna, the previous statement is no longer true. For example, if the wavefront is from a source below the plane of the antenna, the signal will arrive first at the lower antenna and the signal voltage from the top antenna will lag the signal from the lower antenna. The signal voltages at the antenna output terminals will no longer be in phase, and partial cancellation will take place. The opposite is true if the signal arrives.

The angle of arrival and the resultant difference in arrival time causes a phase difference which reduces the magnitude of the combined voltages. You should begin to see now why two vertically stacked, identical antennas have a more restricted "vision" to signals arriving from a point above or below the horizontal plane than does a single antenna.

HORIZONTAL STACKING

Stacking two identical antennas side by side in a horizontal plane significantly narrows the horizontal beam-width angle. That is, the antenna combination, like a horse wearing blinders, "sees" fewer interfering signals arriving from the sides while its vision up and down (in a vertical plane) is virtually unaffected. In the process, gain increases approximately 1.2 dB over that of a single antenna.

If two identical antennas are arranged side by side in a horizontal plane and the signal wavefront arrives directly from the front, each antenna "sees" the same wave or field at the same time. If the wavefront arrives from a source above or below, the same is still true, except that the individual antennas are not operating as efficiently. However, if the wavefront arrives from one side or the other (Fig. 5A and C), the antenna on the side from which the signal is arriving will "feel" the signal first, causing the voltages induced in each antenna to be out of phase. This, in turn, causes partial cancellation of the antenna voltages when they are combined.

The up and down (vertical) "vision" of a horizontal stack is comparable to that of a single antenna, but its side-to-side "vision" is more restricted.

QUAD_STACKS

Stacking four identical antennas, two vertically and two horizontally in a rectangular or diamond pattern, restricts the vision of this combination in all directions off the axis. Called a quad stack, it "sees" as though it were looking through a tube pointed in the direction of the transmitting antenna.
Gain is increased approximately 4 to 5 dB over that of a single antenna.

GENERAL TECHNIQUES

Before you start putting up an array, you should be aware of the following basic considerations which apply to dual and quad stacking of antennas:

1) Stack only identical antennas
2) Maintain approximately one wavelength spacing (at lowest channel frequency) between antennas
3) Cut phasing lines or connecting cables to equal lengths
4) Length and phase oftwinlead interconnecting harnesses is critical
5) Horizontal supports should be nonmetallic
6) Avoid running interconnecting cables horizontally.

Vertical stacking is easier than horizontal stacking simply because in vertical stacks theantennas mount on a common vertical mast and spacing is easily adjusted.

However, with the excellent gain and high directivity of most Yagis today, vertical stacking is seldom necessary. If additional gain is needed, two vertically stacked identical antennas spaced more than ‘/2 wavelength apart will increase signal power by 3dB compared to that of one antenna. However, part of the increased gain will be lost in the connecting cables and the coupler.

Horizontally stacked antennas also must be spaced so that their booms are separated by a distance equal to more than ‘/2 wavelength of the lowest channel frequency. This spacing is needed to prevent the tips of the longest reflector elements from touching. Also, the horizontal supports must be nonmetallic; redwood or cedar 2’ x 4’ s are commonly used.

The severe ghosts caused by high-rise buildings, water towers and mountains can be reduced or eliminated by horizontallystacking two Yagis. However, the wavelength of a channel 2 signal exceeds 17 feet, making such an array for channel 2 unwieldly, heavy and subject to damage from ice and/or high wind. Fortunately, ghosting is more of a problem at high-band channels, and highband antenna dimensions are significantly smaller. For these reasons, usually only high-band Yagis are stacked horizontally.

I'm in the 15210 zip code. Looking at the info from tvfool my transmitters are located from North to Southeast.What I am trying to do is find the best antenna solution which does not use a rotor.This would be mounted on the chimney of a two story house. I know that this will involve stacking two antenna on the same mast that are pointing in different directions. One a little East of North and one to the Southeast. If you look at the plot from tvfool, the stations the I would like to receive would be:48,38,25,26,42,43,51,and49. Any thing else would be a bonus.

I would like to ask the members of the forum for any suggestions you may have.As to why I do not want a rotor,my wife is a channel clicker. She has to change the station when a commercial comes on.I don't think the rotor could handel it.

What I am trying to do is find the best antenna solution which does not use a rotor.

Aim a Channel Master 4220 at 352 degrees for 25, 42, 43, and 48. Get another 4220 aimed at 133 degrees for 51. Use a channel 51 (or perhaps a channel 52) Jointenna to add them together. Aim a Winegard HD7694P at 44 degrees and use an A/B switch to watch PBS. (No commercials to zap)

I don't see channels 26 or 49 listed.

Channels 26 and 49 would be great. Like I said, Anything else would be a bonus.

Re mis-assembled 91XG's:

I agree, however, if you would accidently install the wrong piece the overall length of the antenna would not change. (Just the spacing would be impacted).

No, the front section is shorter than the other two. See the attached picture of the 91XG that I assembled a few days ago, and which will hopefully go up tomorrow. Front is at the top in this picture. Also note that the spacing between the elements should decrease steadily from front to back, except for the frontmost one.

I'm in the 15210 zip code. Looking at the info from tvfool my transmitters are located from North to Southeast.What I am trying to do is find the best antenna solution which does not use a rotor....I would like to receive would be:48,38,25,26,42,43,51,and49. ...As to why I do not want a rotor,my wife is a channel clicker. She has to change the station when a commercial comes on.I don't think the rotor could handel it.

Your stations are at a range of angles but not all that weak. A number of us on the antenna making thread have been experimenting with simple 4-bay bowtie arrays, in my case to get stations at -77 dBm indoors. High on a mast, you'll get far weaker stations, maybe -20dBm, which should get you Ch 51. This leads to an interesting suggestion.

You could use two reflectorless 4-bays stacked vertically, but aimed in perpendicular directions to get an omnidirectional antenna. Here's a link to an image of a similar set-up, but aimed in the same directions.
http://www.digitalhome.ca/forum/showpost.php?p=425467&postcount=163

The basic bowtie antenna is a dipole, and a 4-bay array is a strongly bi-directional gain pattern. Commercial antenna usually come with a reflector that increases gain by making it highly directional. Remove the reflectors, aim them at 90 degrees and mount them vertically >16" apart and you should get omni-directional reception.

The only downside is -4dB loss in the combining, but mounting on a mast helps a lot compared with my family room and attic. Multipath issues could be maximized by the wide reception area, but the solution to that is the directionality that comes from a reflector, at the price of stations at 180 degree separations.

Anyone see any other caveats?

Let us know what you do,
Frank

Well, the best performance is with the horizontal stack.

The brackets on these 91 XG's are terrible. I noticed that the antennas spin up and down (when windy). Goind to replace the thumbscrews with bolts.

Look at picture #1, and let me know your comments on how I attached the five foot pipe to the vertical mask. I just drilled 2 holes and inserted a U-Bolt. I wonder if this is going to be good enough.

Thanks!

I'm in the 15210 zip code. Looking at the info from tvfool my transmitters are located from North to Southeast.What I am trying to do is find the best antenna solution which does not use a rotor.This would be mounted on the chimney of a two story house. I know that this will involve stacking two antenna on the same mast that are pointing in different directions. One a little East of North and one to the Southeast. If you look at the plot from tvfool, the stations the I would like to receive would be:48,38,25,26,42,43,51,and49. Any thing else would be a bonus.

I would like to ask the members of the forum for any suggestions you may have.As to why I do not want a rotor,my wife is a channel clicker. She has to change the station when a commercial comes on.I don't think the rotor could handle it.

Keep in mind, ch 49 (the CW - and not on the air digitally) will move to ch 11 as soon as WPXI ends analog, and WQED will be moving back to ch 13 from 38 next spring.

Anyone see any other caveats?

In a shadowed situation close to the towers the multipath will be higher than normal. This suggests that omnidirectional antennas could be more troublesome.

What is the best way to run the coax from the balun to the antenna mast on a single 91XG? Is it straight out the back from the balun, then down the back of the screen, continuing that angle over to the mast with the coax in the open until reaching the mast? Walter

In a shadowed situation close to the towers the multipath will be higher than normal. This suggests that omnidirectional antennas could be more troublesome.

That's exactly my concern, but I only know two ways to get stations across a 155* direction span ... the alternative is to use semi-directional antennas, like commercial 4-bays, and hope the gain pattern is wide enough to span 350 to 44 degrees and 99 to 133 degrees.

Frank

the front element is missing on both antennas.

Also, loop the coax out through the back screen and straight back through the screen into the balun. you have the coax jammed in front of the screen in front of the balun.

for stability use a small/narrow plastic tie to attach the coax onto the screen and on the antenna prior to the balun...after the coax fitting is tightened.

Rick, I must be missing something here in this cable running. I don't see where there is any coax jammed in front of his screens/baluns, could you provide us with a photo or diagram of your suggested coax path?

Well, the best performance is with the horizontal stack.

The brackets on these 91 XG's are terrible. I noticed that the antennas spin up and down (when windy). Goind to replace the thumbscrews with bolts.

Look at picture #1, and let me know your comments on how I attached the five foot pipe to the vertical mask. I just drilled 2 holes and inserted a U-Bolt. I wonder if this is going to be good enough.

Thanks!

I doubt it will hold up. #1 the antennas will spin around the fiberglass with just the single attachment. You need add another horizontal piece of fiberglass (similar to what I showed you). This will require another u-bolt attachment to the secondary boom on the antenna. You'll then have better stability in the tilt plane.

#2 the u-bolt drilled directly through the fiberlass is likely to crack it over time. This is the point at which the installation sees the most stress. You need a 90 degree metal bracket of some sort. Again, you might consider something similar to what I've shown in my pics previously.

Around 57 inches horizontal spacing works best for me.

Using this formula: http://www.astronwireless.com/topic-archives-stacking-yagi-antennas.asp

It will calculate to around 57 inches if you use channel 14 in your calculation.

Right around 57 inches is also the recommendation from Televes for the DAT 75.

That's exactly my concern, but I only know two ways to get stations across a 155* direction span ... the alternative is to use semi-directional antennas, like commercial 4-bays, and hope the gain pattern is wide enough to span 350 to 44 degrees and 99 to 133 degrees.


I have had exchanged some e-mails with Denny Duplessis @dennysantennaservice.com.. His original advice for my situation was to install his UP-7 antenna, which from what I can find only he sells,pointing a little East of North.Install a Winegard HD9032 pointing Southeast. Couple them together with the CC7870 antenna couple and a Winegard AP 8700 preamplifier. He figured that I would have some signal loss from the weaker stations like 49 and 50 and I would not receive others.

Is this a viable solution? Would the HD9032 receive channel 51, would it receive anything else? As you say above I need two antenna with a wide enough gain pattern to receive the signals from the two areas. Since I can find no other info on the UP-7 antenna I don't know if I could mount two of them on the same mast at 90* angles?

It would be nice if I could just buy the antennas and not have to worry about building them. My feeling from what I have been reading is the antennas must point directly at the transmitter for the best reception. Any help would be most welcome.

the front element is missing on both antennas.

Also, loop the coax out through the back screen and straight back through the screen into the balun. you have the coax jammed in front of the screen in front of the balun.

for stability use a small/narrow plastic tie to attach the coax onto the screen and on the antenna prior to the balun...after the coax fitting is tightened.
Also, the directors on the middle section of 1 antenna are facing the wrong direction, according to the assembly instructions.

Well, I did get that 91XG that I showed a picture of yesterday, up on my roof today, along with a Winegard YA-1713 for VHF. This combination replaced a Radio Shack VU-190XR VHF/UHF combo. (pictures attached)

If I had seen Rick0275's postings in time, I would have had the installers loop the coax through a reflector screen on the 91XG like he describes, but now I'll just wait until I need to get something fixed up there.

It's probably too early to come to conclusions about differences in reception because atmospheric conditions might be unusually favorable tonight, and I haven't seen how this setup behaves when the wind kicks up, but...

Several out-of-market stations at about 70 miles that have been marginal around 6 pm the last few weeks, gave me solid reception at that time: RF channels 22 and 23 out of Charlotte NC, and 32 and 48 out of Columbia SC. Around 8 pm, RF channels 27 and 34 (85 miles) out of Charlotte showed up, and have been solid all evening; these are stations that I could get only semi-regularly in the evening before, with 34 coming in much less often than 27.

Among my in-market stations (Greenville SC / Asheville NC), I've previously had some problems with three of them: RF 57 which has some interference from analog 57 in Columbia, now comes in steadily; RF 14 which has been strong but erratic because of (I think) multipath from trees etc., now comes in steadily; RF 25 from Asheville which has interference from analog 25 in Columbia, is still erratic, but may be a bit better now (and the interference will go away next February in any event).

On the other hand, RF 45 out of Asheville, 47 out of Charlotte, and 41 out of Columbia aren't quite as good as before, although still good enough for stable reception.

I can't come to any conclusions about VHF yet, because I have only two digital VHF channels: 8 out of Columbia which is OK, and 9 out of Greenville which is erratic because of interference from analog 9 out of Charlotte; no change from my previous setup.

Overall, I'm pleased with the results so far, but I'll need to watch for a while over a variety of weather conditions to be sure.

Well, to do things "right" I made the plunge and purchased the Blonder Tongue BTY-MC stacking bracket. Holy Cow, these things are NOT worth their price. $100 for a bracket. I could have bought a ten foot section of tower for that.

http://www.solidsignal.com/prod_display.asp?prod=SS4879

Spec's http://www.tonercable.com/Files/ProductFiles/552/PDFFile/BT-BTY%20BROAD.pdf

Picture http://www.tonercable.com/Files/ProductFiles/552/Images/ProductImage1_Large.jpg

Jtbell,

Congrats on your new purchase. Would it be possible to capture a picture on how you looped the coax out the back of your 91XG?

Well, I did get that 91XG that I showed a picture of yesterday, up on my roof today, along with a Winegard YA-1713 for VHF. This combination replaced a Radio Shack VU-190XR VHF/UHF combo.

Well, to do things "right" I made the plunge and purchased the Blonder Tongue BTY-MC stacking bracket. Holy Cow, these things are NOT worth their price. $100 for a bracket. I could have bought a ten foot section of tower for that.

http://www.solidsignal.com/prod_display.asp?prod=SS4879

Spec's http://www.tonercable.com/Files/ProductFiles/552/PDFFile/BT-BTY%20BROAD.pdf

Picture http://www.tonercable.com/Files/ProductFiles/552/Images/ProductImage1_Large.jpg

They're stainless steel and very heavy duty.

I really hope I'm not posting on the wrong thread. I just got my DTV converter box and the quality of the channels I do get is gorgeous! However, I lost a bunch of the ones I used to get with just by rabbit ears (grainy, but at least I had PBS then). I'm assuming I need a better antenna to recover the lost signal of the rest of the channels (and this MUST happen before tomorrow night so I can watch Lost! ). According to antennaweb.org I need an outdoor small multi-directional antenna. I can't really see myself installing something like that in my rental -- do I really need this? Plus, I'm on the top floor of a 4-story walk-up in a very residential part of Bklyn (not many tall buildings here, although "close" to JKF airport), so I think that something like an outdoor/rooftop thing would be overkill. Is there such a thing as a great indoor antenna I can just get instead and would fix the issue?

Thanks!

Is PVC sufficiently RF transparent that I might mount something like a couple of Winegard PR-9022s on a 2" PVC horizontal boom with the dipole elements being behind the boom? I figure I would just drill a couple of 1/4" holes in the boom at the antennas balance points and have the U-bolts penetrate the boom from the underside. That would make it real esay to experiment with horizontal spacing by just sliding one of the antennas nearer to and further from the other one.

Is PVC sufficiently RF transparent that I might mount something like a couple of Winegard PR-9022s on a 2" PVC horizontal boom with the dipole elements being behind the boom? I figure I would just drill a couple of 1/4" holes in the boom at the antennas balance points and have the U-bolts penetrate the boom from the underside. That would make it real esay to experiment with horizontal spacing by just sliding one of the antennas nearer to and further from the other one.

I don't think there will be any problems with interference. The problem you may run into is it just isn't stiff enough and it will sag.

Here's a pic of a stack of pr-9032's I did. The performance wasn't as good as I'd hoped.

JWould it be possible to capture a picture on how you looped the coax out the back of your 91XG?

Here's a telephoto shot in which you can make out the balun and the coax. There's a pretty sharp bend coming out of the balun. Whenever it fails, I'll get it re-done properly.

I really hope I'm not posting on the wrong thread. I just got my DTV converter box and the quality of the channels I do get is gorgeous! However, I lost a bunch of the ones I used to get with just by rabbit ears (grainy, but at least I had PBS then). I'm assuming I need a better antenna to recover the lost signal of the rest of the channels (and this MUST happen before tomorrow night so I can watch Lost! ). According to antennaweb.org I need an outdoor small multi-directional antenna. I can't really see myself installing something like that in my rental -- do I really need this? Plus, I'm on the top floor of a 4-story walk-up in a very residential part of Bklyn (not many tall buildings here, although "close" to JKF airport), so I think that something like an outdoor/rooftop thing would be overkill. Is there such a thing as a great indoor antenna I can just get instead and would fix the issue?

Thanks!

You need an antenna that can pick up the UHF band fairly well. Your old rabbit ears probably just can't do the entire job.

Have you tried building a DB2 clone? Usually that would work fine in Brooklyn. What type of line of sight do you have to the Empire State Building?

I'm willing to bet you could build an excellent antenna for yourself that would pick up almost all of the stations.

I live on Staten Island and my DB4 clone is very good. It picks up stations from as far away as Poughkeepsie. I can get CBS from Philadelphia if I turn the antenna a bit.

JTBell,

Thanks for the photo. I was unable to loop RG6-Quad shield in front of the balun. (Like your photo). It was to large of a radius in this turn, and too much stress on the balun for me.


Here's a telephoto shot in which you can make out the balun and the coax. There's a pretty sharp bend coming out of the balun. Whenever it fails, I'll get it re-done properly.

Mr. Cpcat,

Per the Astron wireless page, here are some calculations I made for a pair of 91XG’s.

Distance (S) = 51/Beamwidth (BW)

S = 51 / 20 (Beamwidth of 91XG)
S = 2.55

Now, tuning for the desired frequency is your choice. However, channels 52 – 69 are in the process of being cleared once conversion to digital TV is accomplished. Channel 37 is reserved for radio astronomy in the US, Canada, Bermuda, and Bahamas.

So, I picked Channel 30.

Wavelength in inches = 11803/F (Frequency)

Wavelength = 11803/570

Wavelength = 20.70”

Using this formula, a wavelength at 570Mhz is:

20.70” X 2.55 (wavelengths) = 52.78”

Space the stack 53” apart…

Any other comments?

TV in NY,

Thanks! I've looked into this whole UHF thing, and I was about to go looking for an indoor antenna that would help with that. However, I like the idea of making my own antenna! Would it still have to go on my roof, though?

Also, I'm pretty sure I can see the Empiere State Bldg from my rooftop. I've only been there once, since I'm afraid of heights, which would explain my apprehension about installing a rooftop antenna. :)

Mr. Cpcat,

Per the Astron wireless page, here are some calculations I made for a pair of 91XG’s.

Distance (S) = 51/Beamwidth (BW)

S = 51 / 20 (Beamwidth of 91XG)
S = 2.55

Now, tuning for the desired frequency is your choice. However, channels 52 – 69 are in the process of being cleared once conversion to digital TV is accomplished. Channel 37 is reserved for radio astronomy in the US, Canada, Bermuda, and Bahamas.

So, I picked Channel 30.

Wavelength in inches = 11803/F (Frequency)

Wavelength = 11803/570

Wavelength = 20.70”

Using this formula, a wavelength at 570Mhz is:

20.70” X 2.55 (wavelengths) = 52.78”

Space the stack 53” apart…

Any other comments?

That's right. I personally use channel 14 in the calculation simply because that's the lowest channel I receive. The wider spacing doesn't seem to negatively effect the upper channels while improving the lower ones. I've tested extensively and right around 57 inches has always worked best for me with both the Televes DAT75 and the Triax Unix 100A. I'd leave extra length (at least 60 inches) incorporated into the length of the fiberglass rods you use so there's room for adjustment and experimentation.

TV in NY,

Thanks! I've looked into this whole UHF thing, and I was about to go looking for an indoor antenna that would help with that. However, I like the idea of making my own antenna! Would it still have to go on my roof, though?

Also, I'm pretty sure I can see the Empiere State Bldg from my rooftop. I've only been there once, since I'm afraid of heights, which would explain my apprehension about installing a rooftop antenna. :)

Lola,
Since no one mentioned it, go to TVFool.com, tell it your address and you'll get a chart showing what stations you cna get and how weak their signal might be. I threw in Jamaica NY's long and lat to get some idea what you've got, and it should be an easy situation. Almost everything comes from the Empire State Building, and with enough signal for indoor antennas.

TVFool also tells you channels, now and post transition. After Feb 07, you'll again have VHF stations, so save those rabbit ears.

In the mean time, you don't need much. If you want to kill a coat hanger, something like the attached may suffice, or just get the little bowtie that comes with a lot of TV's (Radio Shack p/n 15-234). You're close enough that one of these little guys facing the ESB should get you plenty of signal through the walls, and if not(steel construction?), certainly through a window.

Let us know,
Frank

The 53" inch spacing is probably reasonable. My quad of 4248 are at 48".
Are you using horizontal or vertical spacing? If horizontal the beamwidth will be fairly narrow. On channel 17 the -3dB response would be about 7 Deg from beam center with a deep notch at 14 Deg. On channel 58 the same responses would be 4 Deg and 9 deg.
John

Mr. Cpcat,

Per the Astron wireless page, here are some calculations I made for a pair of 91XG’s.

Distance (S) = 51/Beamwidth (BW)


Space the stack 53” apart…

Any other comments?

To my knowledge the spacing in-between the antennas (stack) will be same for horizontal or vertical stacking. To answer your question, it will be horizontal stacking.

I will go with a 60" spacing between the 91XG's.

The narrow beamwith is a slight concern, as with the CM 9521 rotator may not be capable of indexing such a small movement, thus always overshooting your transmitter. I decided to hold-off on the Quad stack until I purchase a Yaesu rotor in the future. Yaesu = $400. :D

I'll post some pictures as I am installing this on Friday.

The 53" inch spacing is probably reasonable. My quad of 4248 are at 48".
Are you using horizontal or vertical spacing? If horizontal the beamwidth will be fairly narrow. On channel 17 the -3dB response would be about 7 Deg from beam center with a deep notch at 14 Deg. On channel 58 the same responses would be 4 Deg and 9 deg.
John

To my knowledge the spacing in-between the antennas (stack) will be same for horizontal or vertical stacking. To answer your question, it will be horizontal stacking.

I will go with a 60" spacing between the 91XG's.

The narrow beamwith is a slight concern, as with the CM 9521 rotator may not be capable of indexing such a small movement, thus always overshooting your transmitter. I decided to hold-off on the Quad stack until I purchase a Yaesu rotor in the future. Yaesu = $400. :D

I'll post some pictures as I am installing this on Friday.

The 9521 has worked well for me. It's the only rotator I know of with remote control.:)

You might find 60 inches a little too much. I think the calculcations are nice, but in the end there's no substitute for real world testing. I bet you'll end up somwhere b/w 52 and 58 inches. Test it on the smaller mast if you need to before installing it on the tower (if it won't be easily accessible after it's on the tower).

I posted a bit back on page 241.. I'm connecting an Antenna to a DirecTV HR-20. I'd like something inexpensive that will work in my attic.

Here are the tvfool numbers for my location.

ABC - 151kW | -41.5 dBm | 11.9 miles | 266 true
NBC - 30kW | -52.3 dBm - 12.9 miles | 293 true
CBS - 6.3kW | -63.4 dBm - 14 miles | 281 true
PBS - 90kW | -49.0 dBm - 9.7 miles | 264 true

Per the advice I got on my prior posts, I bought an inexpensive Phillips VHF/UHF antenna and tried it indoors on top of my entertainment center last night. Link: http://www.consumer.philips.com/consumer/en/us/consumer/cc/_productid_SDV2270_27_US_CONSUMER/TV-antenna+SDV2270-27

My entertainment center is about 20 feet from an exterior wall (with windows) that's in the general direction of the towers.

My best station was PBS, the signal strength hovered around 60-70. Next best was ABC, I'd get 40-50 with an occasional dropout. No signal on the other two. Obviously, these signals arent acceptable. I really need to get a strong signal on NBC by Saturday afternoon.

Questions..
1) Would I see a substantial improvement in signal by moving this same antenna into the attic?

2) Should I try another antenna (perhaps the unamplified RCA suggested to me previously?

3) Inexpensive antennas are typically indoor, is the attic considered "indoor" or are these antennas susceptible to heat?

1) Some improvement, but probably not substantial.
2) Yes, the amplifier is probably wrecking you signal. If you can't switch the amplifier off, certainly worth trying a non-amplified model.
3) Outdoor antennas are no more costly than indoor, and will work great in the attic. In fact, a good antenna will likely cost less than a amplified indoor antenna.

1) Some improvement, but probably not substantial.
2) Yes, the amplifier is probably wrecking you signal. If you can't switch the amplifier off, certainly worth trying a non-amplified model.
3) Outdoor antennas are no more costly than indoor, and will work great in the attic. In fact, a good antenna will likely cost less than a amplified indoor antenna.
You know, I saw the knobs on that thing and thought to myself "I think I'm supposed to NOT get an amplified model, and I bet the knobs mean that it's amplified.." but I bought it anyway.. Oh well, easy to take back..

So I'm thinking I'll stop by Radio Shack and/or Best Buy. If they have a relatively inexpensive ($30-ish) unamplified outdoor I'll grab that and try it in the attic as you suggest. Worst case, I can mount it on my DirecTV pole. I might also pick up some cheap-o rabbit ears and give those a whirl. My "local HDTV" thread here on AVS has several people that are a few miles farther from the towers getting 90+ signal strength on everything with just rabbit ears in the attic.

Also - My stations go from 8 in the "VHF High" band up to 24 in UHF. Do I need a UHF/VHF antenna or will just UHF work? Will just rabbit ears work?

Is this another new Winegard offering, the HD-1080:

http://www.solidsignal.com/prod_display.asp?PROD=HD-1080

I only see a 2-bay version at the moment. I might be inclined to try it, but it's a bit pricey for a 2-bay.

Yeah, the HD1080 seems a bit high priced to me as well. I've been planning to make my own antenna something like it though, to receive to two stations that are local here. Channels 19 and 8.

Horizontal Stack of the 91XG's at 56' in the Air.

2 - Antenna's Direct 91XG's
1 - Winguard High Bander

Rohn 20 Tower - 50 Ft
- 3/4 Yrd of Concrete
- House bracket (16ft of ground)
Channel Master 9521 Rotator
Channel Master 7777 Pre-Amp
RG11U - Coax

One fat installer. (Not me)

Special thanks to Greg & Bob!

PCTools,

That is one nice set-up. Thanks for including pictures of the installation. I've never seen a tower installed (except when I and a couple of buddies put mine up). What kind of a winch/lift mechanism was the installer using to raise the tower sections and antenna assembly?

Horizontal Stack of the 91XG's at 56' in the Air.
2 - Antenna's Direct 91XG's
1 - Winguard High Bander
Rohn 20 Tower - 50 Ft
- 3/4 Yrd of Concrete
- House bracket (16ft of ground)
Channel Master 9521 Rotator
Channel Master 7777 Pre-Amp
RG11U - Coax
One fat installer. (Not me)
Special thanks to Greg & Bob!

Wow! that's an impressive rig. The tower climbing guy: a pro, or a buddy with more cojones than brains? :)

What kind of a winch/lift mechanism was the installer using to raise the tower sections and antenna assembly?
It's in the pictures. It's called a "gin pole". Usually powered by "elbow grease" at ground level.

Ron

Rick,

I went with 54" spacing. Also, thanks for the info on how to place the coax. :)

Make sure you throw away those thumb screws and use some nuts. The thumbscrews do not have enough torque to hold them in place. I also placed silcon on the backs of the reflectors to help prevent them from moving in the wind.

Very nice setup.

What was your final decision on spacing on the two 91 xg's

PC Tools,

"A thing of beauty and a joy forever!"

Thanks for the multiple shots of each of those phases of completion.

Horizontal Stack of the 91XG's at 56' in the Air.

2 - Antenna's Direct 91XG's
1 - Winguard High Bander

Rohn 20 Tower - 50 Ft
- 3/4 Yrd of Concrete
- House bracket (16ft of ground)
Channel Master 9521 Rotator
Channel Master 7777 Pre-Amp
RG11U - Coax

One fat installer. (Not me)

Special thanks to Greg & Bob!

Very nice indeed. Another Dxer in the making. :)

Can't say I don't envy the extra height you have as I'm pretty much limited to around 30 feet max. Someday maybe.

Great pics. Thanks, PCTools.

It must be nice to be able to place an antenna on one's roof. Living in a condo, this doesn't seem to be possible, but I'm doing ok with the attic right now. Still, a nice tower like this would be sure to turn some heads.

How is it working out so far?

Yes. This antenna has been mentioned in the past on another thread.

How about the new CM offering?

http://www.channelmasterintl.com/2016.html

This looks very basic. I have to wonder how effective sweeping the VHF elements forward is in this case.

I continue to question the value of putting out new designs for UHF 69. Sacrificing performance under 37 doesn't seem like a good idea in the long run.

Horizontal Stack of the 91XG's at 56' in the Air.

2 - Antenna's Direct 91XG's
1 - Winguard High Bander

Rohn 20 Tower - 50 Ft
- 3/4 Yrd of Concrete
- House bracket (16ft of ground)
Channel Master 9521 Rotator
Channel Master 7777 Pre-Amp
RG11U - Coax

One fat installer. (Not me)

Special thanks to Greg & Bob!

Nice pics chad.Looks good and hats off to the fatman with the big noogets.Let me know when you want to put up a Big highbander...:-)

Greg b

Gents,

Thanks for the feedback on the new system.

If you have any questions, let me know.

Chad

Have you looked at something like these for a rotor?
Ebay 310051918223 and 290231488754

John

1) Replace the Wingard 1731 and go with a MAXHD High Bander.


Is the MAXHD available domestically? At 13', however, I probably wouldn't be able to put it anywhere.

Are the specs in dBd or dBi? It has 3 different reflectors or are those the various options it has?

As a side-note, bow-tie antennas don't seem to be very popular in Europe. Does anyone know why?

Here's a couple of pics. It's better by a fair margin than the Y10 7-13 but needs more spacing to stack.

Is the MAXHD available domestically?

Are the specs in dBd or dBi? It has 3 different reflectors or are those the various options it has?

As a side-note, bow-tie antennas don't seem to be very popular in Europe. Does anyone know why?What Falcon said (err, or asked). I'd like to read the answers to those questions as well.

Come next year, I'll be in the less than desirable position of needing high gain on channels 5, 13, 24, 28, 29, 30. Now all my DTV channels are UHF, and I'm getting by fine with a CM 4228. That high bander MAXHD is talking about, look really cool, but I doubt I really need that much for one channel. And that still leaves me looking for a channel 5 solution. Oh well, I'll get looking, reading and planning for a little while longer.

Come next year, I'll be in the less than desirable position of needing high gain on channels 5, 13, 24, 28, 29, 30. Now all my DTV channels are UHF, and I'm getting by fine with a CM 4228. That high bander MAXHD is talking about, look really cool, but I doubt I really need that much for one channel. And that still leaves me looking for a channel 5 solution. Oh well, I'll get looking, reading and planning for a little while longer.

Well, the Triax Unix 100a (uhf 14-38) would do a fine job for your uhf channels. You could then go with a wideband vhf below it or even a high band + cut channel 5.

Funke uses dBi, so subtract 2.15 dB.

Nice setup. But tell us how it works!

Well, I did get that 91XG that I showed a picture of yesterday, up on my roof today, along with a Winegard YA-1713 for VHF. This combination replaced a Radio Shack VU-190XR VHF/UHF combo. (pictures attached)

If I had seen Rick0275's postings in time, I would have had the installers loop the coax through a reflector screen on the 91XG like he describes, but now I'll just wait until I need to get something fixed up there.

It's probably too early to come to conclusions about differences in reception because atmospheric conditions might be unusually favorable tonight, and I haven't seen how this setup behaves when the wind kicks up, but...

Several out-of-market stations at about 70 miles that have been marginal around 6 pm the last few weeks, gave me solid reception at that time: RF channels 22 and 23 out of Charlotte NC, and 32 and 48 out of Columbia SC. Around 8 pm, RF channels 27 and 34 (85 miles) out of Charlotte showed up, and have been solid all evening; these are stations that I could get only semi-regularly in the evening before, with 34 coming in much less often than 27.

Among my in-market stations (Greenville SC / Asheville NC), I've previously had some problems with three of them: RF 57 which has some interference from analog 57 in Columbia, now comes in steadily; RF 14 which has been strong but erratic because of (I think) multipath from trees etc., now comes in steadily; RF 25 from Asheville which has interference from analog 25 in Columbia, is still erratic, but may be a bit better now (and the interference will go away next February in any event).

On the other hand, RF 45 out of Asheville, 47 out of Charlotte, and 41 out of Columbia aren't quite as good as before, although still good enough for stable reception.

I can't come to any conclusions about VHF yet, because I have only two digital VHF channels: 8 out of Columbia which is OK, and 9 out of Greenville which is erratic because of interference from analog 9 out of Charlotte; no change from my previous setup.

Overall, I'm pleased with the results so far, but I'll need to watch for a while over a variety of weather conditions to be sure.



After a week or so, how do you feel about your new system in comparison to your old VU-190? Walter

I am mounting a homebuilt hoverman with screen in the attic and want to add a set oif rabbit ears on top to pick up a vhf channel better. Should I use an antenna combiner or could I just attach the rabbit ear twinleads onto the same screws as the 300/75 transformer on the hoverman?

I am mounting a homebuilt hoverman with screen in the attic and want to add a set oif rabbit ears on top to pick up a vhf channel better. Should I use an antenna combiner or could I just attach the rabbit ear twinleads onto the same screws as the 300/75 transformer on the hoverman?

I have built a DBGH and have been experimenting with it for VHF frequencies today. The Gray Hoverman unmodded is bad at VHF, worse than rabbit ears. (look at the vhf graph Autofils posted, I found it to be pretty correct) I attached two 3/8 inch tubing pieces to it parallel to the last top vees (45degree angle), connected to the top vee vertex, about 45 inches long each (which I had lying around and didnt want to cut). Low and behold, I got analog channels 2, 3 and 6 as good as or even maybe a bit better than rabbit ears. Analog channel 10 was about as good as rabbit ears, but analog channels 11, 12, 13 a little worse than rabbit ears. What was interesting, in almost all cases, and in almost all positions, adding those two elements did nothing to effect the analog uhf reception, good or bad. So if you have low vhf local channels, that may be an option for you.

In my case after 2/17/09, Ill have digital channels 6 and 12 moving back to their original spots. I think with the above mod, and if the FCC isnt lying, I should be OK with channel 6 DTV reception. But with channel 12, Ill still have to play around with.
Yes, I already cut elements for channel 12s wavelength, and the reception got worse with the correct element length. Some parts of the Gray Hoverman are just counter-intuitive.

I actually thought the system would perform better. Then again, you know how us engineer's are.... Think we can work miracles with this stuff.

Debating about doing a Quad Box stack.

The real thing, is that it will take a boat load of money to make any (if any) improvement of what I have.

Nice setup. But tell us how it works!

In my quad stack I found that going to a stripline combiner and Research Communications preamp gave moderate but noticable improvements. The little splitter/combiners have about as much loss as the stacking gain of two antennas.
John

I am mounting a homebuilt hoverman with screen in the attic and want to add a set oif rabbit ears on top to pick up a vhf channel better. Should I use an antenna combiner or could I just attach the rabbit ear twinleads onto the same screws as the 300/75 transformer on the hoverman?

Use a combiner.

How about the new CM offering?

http://www.channelmasterintl.com/2016.html


It has been said that this antenna has already been discussed here. I can't find other references to it in a search. Can someone point me in the right direction? Thanks.

I am mounting a homebuilt hoverman with screen in the attic and want to add a set oif rabbit ears on top to pick up a vhf channel better. Should I use an antenna combiner or could I just attach the rabbit ear twinleads onto the same screws as the 300/75 transformer on the hoverman?
A VHF/UHF Splitter/Combiner will have less than 0.5 dB loss,
while all-band Splitter/Combiners, as well as standard (cable)
RF Splitter/Combiners have about 3.5-4.0+ dB loss.

You need the low-loss VHF/UHF Combiner that has twin screws for both VHF and UHF:
http://www.summitsource.com/antenna-signal-combiner-uhf-vhf-philips-ph61006-offair-aerial-lead-connection-splitter-gold-75300-ohm-adapter-part-ph61006-p-5303.html
http://www.amazon.com/Philips-PH61006-Vhf-Splitter-combiner/dp/B00099ZG3I******sr_1_1?ie=UTF8&s=electronics&qid=1211573821&sr=8-1
This one has coax output, which is preferred for downlead.

You'll need a 75-ohm to 300-ohm transformer balun to adapt to twin-lead output.

They used to make devices with twin-lead output, but I haven't found any.

In my quad stack I found that going to a stripline combiner and Research Communications preamp gave moderate but noticable improvements. The little splitter/combiners have about as much loss as the stacking gain of two antennas.
John
Which stripline coupler are you using and how much did it cost?
The Lindsay couplers seem to have disappeared in the last corporate reorg...

I am using the Lindsay four port UHF combiner. I think it was around $100. After I got mine I saw a post from another AVSer that said that they were discontinued but Lindsay found one left in inventory for him. Unfortunately I have not found anything similar available.
John

Which stripline coupler are you using and how much did it cost?
The Lindsay couplers seem to have disappeared in the last corporate reorg...

MAXHD has a source that will custom make them for a reasonable price. I saw a pic of one and it looks very similar to the Lindsays.

Combiner pic:

How about the new CM offering?

http://www.channelmasterintl.com/2016.html

This looks very basic. I have to wonder how effective sweeping the VHF elements forward is in this case.

I continue to question the value of putting out new designs for UHF 69. Sacrificing performance under 37 doesn't seem like a good idea in the long run.
Does that pick up FM radio as well?

Thanks

The FM radio band is between TV channels 6 and 7, so while the CM is not designed for FM, it doesn't take much antenna to pick up strong signals. For weak and distant FM, you would do better with a dedicated FM antenna, or a VHF/FM antenna.

MAXHD has a source that will custom make them for a reasonable price. I saw a pic of one and it looks very similar to the Lindsays.

Thanks for posting the pic I sent you.Ole Dave says he can make a dual or quad combiner in any frequency range you want.If I get this new tower in the air the next couple of days,I'll try it out and see how it works.

http://www.hamtv.com/oal.html

Gregb@etczone.com

A VHF/UHF Splitter/Combiner will have less than 0.5 dB loss,
while all-band Splitter/Combiners, as well as standard (cable)
RF Splitter/Combiners have about 3.5-4.0+ dB loss.

You need the low-loss VHF/UHF Combiner that has twin screws for both VHF and UHF:
http://www.summitsource.com/antenna-signal-combiner-uhf-vhf-philips-ph61006-offair-aerial-lead-connection-splitter-gold-75300-ohm-adapter-part-ph61006-p-5303.html
http://www.amazon.com/Philips-PH61006-Vhf-Splitter-combiner/dp/B00099ZG3I******sr_1_1?ie=UTF8&s=electronics&qid=1211573821&sr=8-1
This one has coax output, which is preferred for downlead.

You'll need a 75-ohm to 300-ohm transformer balun to adapt to twin-lead output.

They used to make devices with twin-lead output, but I haven't found any.

Hello, these type of UVSJ also; http://www.summitsource.com/uhfvhf-band-separator-combiner-coupler-antenna-signal-tv-video-multi-source-component-distribution-device-splitter-rfi-shielded-51000-mhz-part-jvi-25uvsj-p-6976.html?osCsid=5555950dcfcf08be701fdbd68e4a3d67
and, http://www.solidsignal.com/prod_display.asp?PROD=HLSJ#MORE
Baluns are no problem, Menards has them for $1.98 ea.:o

Can some one tell me how to contact midwest dxer (max hd) i want to purchase the psp 1922 antenna.After reading many posts i am going with this set up.
uhf 91xg,vhf psp1922,winegard 269 preamp,and pico usjv combiner.
I live in laporte,in. 53 mi. ota to chicago sears tower.Hope to pick up after 2/11/09 all or most chicago dtv channels. am i on the right track with my selections?
Thanks-1edmon

Can some one tell me how to contact midwest dxer (max hd) i want to purchase the psp 1922 antenna.After reading many posts i am going with this set up.
uhf 91xg,vhf psp1922,winegard 269 preamp,and pico usjv combiner.
I live in laporte,in. 53 mi. ota to chicago sears tower.Hope to pick up after 2/11/09 all or most chicago dtv channels. am i on the right track with my selections?
Thanks-1edmon

Scroll up a few posts and drop him a PM.:)

Consider pre-filtering the psp1922 by using the hi port of a hlsj in addition to using the uvsj to combine the uhf/vhf sections. That way, low band and FM are more completely filtered before amplification.
http://www.picomacom.com/specs/pico/C/C24.pdf

For some reason, I thought I remembered Chicago had a low band digital?

Thanks cpcat,post 2/11 wbbm will be vhf 7,so i'll be o.k. I kown this sounds stupid but i don't know what pm means.Do you know if max hd has a website?

I tried the email link but the email was unsucessful.

Sorry cpcat the light blub just lit up ,i sen max hd a pm(private message)
thanks again

Thanks cpcat,post 2/11 wbbm will be vhf 7,so i'll be o.k. I kown this sounds stupid but i don't know what pm means.Do you know if max hd has a website?

Actually, WBBM-DT 3 is moving to channel 12 and WLS-DT 52 is moving to its analog channel 7.

Steve

You are correct steve,that's why i'm hoping to get the psp 1922 for vhf 7-12.I have a PM for max hd and am waiting to here from him.I have a question for you ,as per tv fool the recommened height for wbbm is 45' all other dtv channels are from 20 to 30 ', i plan to go 30' do you think i would be out of luck for wbbm (2.1)?I'm going to use the winegard hdp 269 preamp.My set up will be 91xg uhf,psp1922 vhf,pico uvsj combiner.
Thanks-Ed

I think you'll pro'ly be fine but you just never really know 'til you try. :)

"More than half of over-the-air (OTA) TV viewers nationwide
live in areas where reception of DTV signals will be
challenging, according to new research from Centris."

http://broadcastengineering.com/hdtv/study_foresees_dtv_recpetion_0411/?cid=top5

http://www.centris.com/pages/ViewNews.aspx?newsID=34&SiteID=9

The Centris study was debunked back in February, which it first came out:
http://www.avsforum.com/avs-vb/showthread.php?p=13133695

Results are bogus, since Centris used antennaweb.org to predict reception, which
many posters on this thread have found seriously UNDERPREDICTS reception.

andy.s.lee conducted a much more believable study:
http://www.tvfool.com/index.php?option=com_content&task=view&id=50

We talked about the Centris study a bunch when it came out. There are systematic issues with it's sampling methodology that make its predictions questionable. You can't use it for any positive purpose here.
Frank

I have an old antenna on my roof which has 2 pairs of 300 ohm attachments. Which I believe is VHF and UHF. My TV of course take only a single 75 ohm source. How should I combine the 300 ohms signals?

See post #7322.

Thanks. Is it suitable for out door use? What is inside the box?

My twin-lead wires are kind of old and I am concerned about interference. I want to replace them with a coax. Does it make sense for me to combine the twin-leads together and connect them into this?

http://www.summitsource.com/outdoor-matching-transformer-300-to-75-ohm-balun-coax-cable-with-weather-proof-boot-magnavox-m61009-offair-tv-antenna-signal-twin-lead-balum-converter-connection-gold-part-m61009-p-4847.html

Sure you could scrap the twin lead.
Get 2 baluns run the coax inside use a combiner or combine outside and run one coax to the set.

I have an old antenna on my roof which has 2 pairs of 300 ohm attachments. Which I believe is VHF and UHF. My TV of course take only a single 75 ohm source. How should I combine the 300 ohms signals?
Use a pair of 300-ohm to 75-ohm Balun Transformers...one for VHF and one for UHF.
A pair of coax runs connect to UVSJ low-loss VHF/UHF Combiner and then coax downlead:
http://www.solidsignal.com/prod_display.asp?PROD=UVSJ
http://www.summitsource.com/uhfvhf-band-separator-combiner-coupler-antenna-signal-tv-video-multi-source-component-distribution-device-splitter-rfi-shielded-51000-mhz-part-jvi-25uvsj-p-6976.html

Be sure to use waterproof sealer on all connections.

Alternatively, if you don't have any "nearby" towers, use a Preamp with separate
UHF and VHF inputs instead. Choice of preamp depends on distance to towers...

====================================
PS: Solution for jcs444 (post #7322) was for ATTIC use, presuming coax or twin-lead output.

I don't want to sound like a jerk. Can it be made simpler?

What I am trying to minimize is the number of connections and cables. If I go with the above plan, I would need 2 Balun Transformers, 3 segments of coax cables and a water proof VHF/UHF combiner.

The transformer and (twin-lead) combiner cost just $0.69 and $0.49 respectively. Whats inside them?

The Centris study was debunked back in February, which it first came out:
http://www.avsforum.com/avs-vb/showthread.php?p=13133695

Results are bogus, since Centris used antennaweb.org to predict reception, which
many posters on this thread have found seriously UNDERPREDICTS reception.

andy.s.lee conducted a much more believable study:
http://www.tvfool.com/index.php?option=com_content&task=view&id=50

And even the TVFool data seems to be too conservative in my particular case. I recently aimed a 91XG with no amplification and about 125' of RG-6 into a tower farm in Austin, 60 miles away. The TVFool info reports the digital signals from these six stations as ranging from -102 to -111 dBm at an antenna elevation of 13' AGL. Five of these six stations come in with a very strong, clear signal -- better than the compressed signal I get from D* -- and the last station (the one at -111) occasionally stutters and pixelates a little but is also usually a better picture than the D* feed.

Based on the TVFool info, I was being told not to get my hopes up much, but what I'm getting blows my mind.

The TVFool info reports the digital signals from these six stations as ranging from -102 to -111 dBm at an antenna elevation of 13' AGL. Five of these six stations come in with a very strong, clear signal -- better than the compressed signal I get from D* -- and the last station (the one at -111) occasionally stutters and pixelates a little but is also usually a better picture than the D* feed.


Yep, just about the same thing for me. I also have stations in an antenna farm 60.8 miles away, ranging from -81.1dBm to -115dBm. All better than -106.0dBm come in strong and consistant. The lone -115dBm station only rarely locks on. (It will be -100.2dBm after 2/19/09 so no problem). This is with my non-amp DBGH with 300ohm downlead and balun on the end.