The Official AVS Antenna Topic! [Text View] - Page 13

Oldfart

10-17-05, 12:19 PM

Demisod:

The OTA tuner in the HR10-250 sucks. Below is my experience:

My HD TiVo (HR10-250) is replacing a Sony HD 200 and a Series 2 TiVo. A number of OTA channels that I received perfectly on the HD 200 were not received at all on the HD TiVo. I got the message "Searching for signal on: Antenna In". The only thing that the installer did was to disconnect the antenna line from the Series 2 TiVo setup (and lay it aside) and disconnect the antenna line from the HD 200 and connect it to the HD TiVo.

Looking into the problem further, I determined that there are 11 channels transmitting from the Miami/Fort Lauderdale antenna farm that is 36 miles from me. I used to receive 8; channels transmitting on 8,9,18,19,20,22,31 and 52. After “trading” the Sony HD 200 for the HD TiVo, I received only the VHS channels, 8 and 9. Since UHF requires more power to produce the same reception as VHF, and my antenna setup did not change, I concluded that the tuner in the HD TiVo was not as sensitive as that in the Sony HD 200, and that my solution was to replace my Terk TV 35 with a CM 4228, which has much higher gain.

I installed the CM4228 in my attic, directly in front of the disconnected Terk TV 35, merely removing the lead from the Terk and attaching it to the 4228. Instant success! I now receive all the channels that I did on the Sony HD 200 except for the one transmitting on channel 8. That might have been expected, since the 4228 is a UHF antenna, although it does have considerable gain in the high band VHS frequencies.

Bottom line: The OTA tuner in the HD TiVo is considerably less sensitive than that in the Sony HD 200, and if you are considering trading the latter for the former, be aware that you may have to upgrade your antenna in order to get the reception that you previously did.

hardballpete

10-17-05, 03:11 PM

I'm down in Davie, & since getting the HDTIVO, I've had all kinds of OTA reception problems. Plainly speaking, it's tuner stinks out loud!

Weak, and a lot of stuttering & pixellation even though signal reads strong!

Found a spot outside finally, after 4 weeks of trying 4 different indoor antennas with lousy results.

If this thing didn't record in HDTV, I'd crush it's digital skull with my louisville slugger!

Very annoying tuner and molasses slow guide too!

TotallyPreWired

10-17-05, 04:30 PM

In doing testing in the mountains from 2 different locations(0.6 mile apart), we are having some success at receiving stations from 50+ miles. All of the stations that we are trying to receive have signal peaks in the 80's or 90's. However, in the ones that we can't lock, every few seconds the signal drops to zero. I assume that this is multipath. Correct?

Now, if this is multipath, is there a general theory, guess, speculation that one might make on how much the signal needs to be boosted in order to 'lock' the station? 2db, 3db, 4db, just forget it kid?

Thanks,
....jc

sregener

10-17-05, 05:03 PM

However, in the ones that we can't lock, every few seconds the signal drops to zero. I assume that this is multipath. Correct?

Now, if this is multipath, is there a general theory, guess, speculation that one might make on how much the signal needs to be boosted in order to 'lock' the station? 2db, 3db, 4db, just forget it kid?

If the signals are weak enough, most meters drop to zero when they can't figure out what the stream is anymore. After all, what good is an error ratio if you can't tell what the signal ought to be? I wouldn't assume multipath - check analogs for snow or ghosting. It's probably snow (weak signals.)

And you're backwards on your solution. You can't solve multipath with signal boosting. You can only solve multipathing by nulling the reflected signal, attenuating it below the noise floor (while leaving the primary signal above) or using a special tuner designed to add multiple signals together.

TotallyPreWired

10-17-05, 05:34 PM

I wouldn't assume multipath - check analogs for snow or ghosting. It's probably snow (weak signals.)
Thanks for the info!

I don't think that the signals are weak. Like I indicated the signal strength's are in the 80's or 90's before they drop to zero. Say, 2 seconds at 85%, then 1/2 second at zero, then back to 85%. They are acting like something is interrupting them. And, this phenomenon is pretty standard among all of the stations that will not lock. Of course, this could just be this particular receiver. Now, if the signal stayed steady, at say 20%, and the receiver needed 30% to lock, I could see where signal strength would be an obvious issue.
....jc

bobchase

10-17-05, 07:52 PM

Thanks for the info!

I don't think that the signals are weak. Like I indicated the signal strength's are in the 80's or 90's before they drop to zero. Say, 2 seconds at 85%, then 1/2 second at zero, then back to 85%. They are acting like something is interrupting them. And, this phenomenon is pretty standard among all of the stations that will not lock. Of course, this could just be this particular receiver. Now, if the signal stayed steady, at say 20%, and the receiver needed 30% to lock, I could see where signal strength would be an obvious issue.
....jc
What you are looking at is a 'signal quality' meter, even if it is labeled a 'signal strength' meter. Most set top boxes use a combination of signal strength measurement and Signal to Noise Ratio (S/N) to generate a 5 to 10 step readout for the consumer. So when the S/N ratio drops down low, the box looses lock on the digital signal and gives you a 0 readout until it reaquires lock. Not all boxes use the same values, so some boxes loose lock at a high number, some at a much lower number. I have only seen two STB's that actually gave a signal level readout and only one that had a S/N ratio readout.

sregener gave you some good advice, check the analogs. Once you describe what they look like (snowy, ghosty, moving ghosts, etc.) we will be able to give you some advice on what to try next.

Bob Chase

TotallyPreWired

10-17-05, 08:19 PM

What you are looking at is a 'signal quality' meter, even if it is labeled a 'signal strength' meter.
Thanks for that info Bob.

sregener gave you some good advice, check the analogs. Once you describe what they look like (snowy, ghosty, moving ghosts, etc.) we will be able to give you some advice on what to try next.
I will check the 2 that are available(and those are the worst ones!). I am trying to get signals from the now infamous Denver area. When I say that only 2 are available, it's the fact that the analog transmitters and the digital transmitters are not in the same locations(not even close), so analog/digital comparisons are meaningless. And, all of the stations are at low power. Want a challenge, try this place!

I would like to make a decision this week on the next step to take. So, I should have that info this week.

Thank you both for the input!
....jc

sregener

10-18-05, 07:27 AM

I would like to make a decision this week on the next step to take. So, I should have that info this week.

You don't say what antenna you're currently using, but multipath is usually cured with a higher gain antenna, a different design style, or a horizontal stack (assuming, of course that the multipath is ground-based. If it's from the air, a vertical stack works better.)

Since you can't do the standard analog test, getting hold of a spectrum analyzer would be a big help. It will actually let you "see" the wave and what's happening with it. Your signal meter basically forces you to guess what the problem is. Of course, spectrum analyzers aren't cheap, and unless you can borrow one, probably not worth the cost. But there is no better tool for your needs.

Marksnewa10

10-18-05, 07:51 AM

I just ordered installation of my HD DVR from Directtv. I am going to have them also bring out the OTA antennae that they offer as well. Has anyone had experience with this antennae for local HD shows? Just looking for some quick feedback. Here is the URL to the page on the directtv page. Itwont let me add the URL since I am a newbie and have not submitted 5 posts.

Thanks.
Mark

JPat

10-18-05, 11:51 AM

I have a Mitsubishi WS-65813 RPTV and according to my manual it is fully integrated HDTV. What is the best indoor antenna can I use for this tv to pick up HD and digital channels?

TotallyPreWired

10-18-05, 04:01 PM

...sregener gave you some good advice, check the analogs. Once you describe what they look like (snowy, ghosty, moving ghosts, etc.) we will be able to give you some advice on what to try next.
This may not help, but here goes:

The best info I can give you is from the 'main' antenna. Now it doesn't receive 2 stations that I need, but it does receive several others. This antenna is pointed toward downtown Denver, not toward the other signal that I need(31). This antenna is mounted on a mast on top of a 25' tower.
Wingard 8200
Winegard AP 8780

Using this to tune analog 31, the picture is decent, with single large ghost to the right of the picture. The digital 'signal strength'(or whatever), peaks around 70%, and drops to zero. Back & forth.

I plan on using either a CM 4228 or a 91XG(with a CM 7775) mounted below the 'main' antenna(directly on a tower leg) for this station(31). Testing with these antennas was done on a tripod located near the tower, but only about 8' high.

With the 4228 pointed in the correct direction, the picture is a bit fuzzier, with the same large ghost to the right side of the picture. There is no digital signal for this station(height obviously makes a big difference here). Turn this antenna toward Denver(about 15 degrees), this antenna is able to pick up a few of the stations(digital).

The best scenario for testing, obviously, would to have the 4228 mounted on the tower. However, my tower climbing friend was not available to help move it. Previously we did test the 4228 on the tower leg(using the 'main' antenna's preamp), and the station(31) locked right on. However, once the preamp was removed, the signal was lost(we had to restore the 'main' antenna). So, we don't know if atmosphere was an issue or not(the transmistters are about 53 miles away).

I'm sure that you may still need more info, just ask. But I would like to use the 4228 for channel 31. If need be, I can get another one and vertically stack them(horizontal stacking would be a bit more difficult)

I welcome any suggestions.

Thanks,
....jc

sregener

10-18-05, 05:13 PM

I'm sure that you may still need more info, just ask. But I would like to use the 4228 for channel 31. If need be, I can get another one and vertically stack them(horizontal stacking would be a bit more difficult)

Stacking a 4228 is counter-productive. It's already a stack.

It sounds like you got good results with the 4228 and a preamplifier. That's the route I would go. If you only need channel 31 with the 4228, and everything else comes in on the Winegard, a Channel Master Jointenna tuned to channel 31 should work for you. If you need more stations than that from the 4228, you should probably run a second run of coax to an A/B switch (and a second preamplifier), as filtering gets expensive.

Given what I've heard about Denver stations and power levels, you're getting very good results already.

plumeria

10-19-05, 12:05 AM

<snip> I've seen suggestions of the CM 7777 amp but I seem only to find CM 7775 to buy online.
Do a simple Google search and you'll find lots of places to buy it online

peter

cpcat

10-19-05, 06:55 AM

Do a simple Google search and you'll find lots of places to buy it online

peter

SolidSignal would be my choice as they are (?were) a forum sponsor. Others include Warren, Starkelectronics.

MAX HD

10-19-05, 11:53 AM

cpcat

10-19-05, 01:07 PM

Charles,

Thanks for the compliment on that other thread.I'm flattered!

Sounds like this prewired guy in Denver could use some of our Band A's neither of us are using right now.IMO there is nothing better for the lower UHF channels.Been debating whether to keep the ones I have.Still got yours?

Greg B

Mine are back up so they're not available. :) The DAT75's just didn't give me the stable reception I need for my primary Knoxville channels (digital 34 and 30). I did pick up a few more upper uhf's but even they weren't completely stable. In addition, the PBS 41 from Sneedville is now full power and is stable even with the Band A's.

I'd agree it's (the Band A) a great choice for ch. 31. Two stacked would be even better.

TotallyPreWired

10-19-05, 07:24 PM

Stacking a 4228 is counter-productive. It's already a stack.
Ok, but since the antenna area would double, might that not make a difference?

...If you only need channel 31 with the 4228, and everything else comes in on the Winegard, a Channel Master Jointenna tuned to channel 31 should work for you.
That brings up the infamous Join-Tenna question I asked a week or so ago. Please read and give me your opinion.

When the weather clears(they forecasted up to 8" of snow for today), we'll be reinstalling the 4228 on the tower with it's own 7775(I'll worry about possibly combing the antennas later). Hopefully by Friday. If it picks up 31, I'm set, if not the saga continues.

Thanks,
....jc

sregener

10-20-05, 07:21 AM

Ok, but since the antenna area would double, might that not make a difference?

That brings up the infamous Join-Tenna question I asked a week or so ago. Please read and give me your opinion.

It's been tried: http://www.hdtvprimer.com/ANTENNAS/16bay.html

See also: http://www.hdtvprimer.com/ANTENNAS/32bay.html

Honestly, I'm already worried about your tower and wind loads, as the 4228 nears the maximum load for my tower. Maybe yours is a more sturdy model. But 2 4228s is a serious amount of weight, and if the wind hits that thing just right....

I think the most likely possibility with the jointenna relates to overload, but it's just a guess. Unless somebody goes out with a spectrum analyzer and does some investigating, it's impossible to know for sure.

TotallyPreWired

10-20-05, 08:41 AM

It's been tried: http://www.hdtvprimer.com/ANTENNAS/16bay.html

See also: http://www.hdtvprimer.com/ANTENNAS/32bay.html
Yes, this is exactly what I was talking about, and I've read these articles.

Honestly, I'm already worried about your tower and wind loads, as the 4228 nears the maximum load for my tower. Maybe yours is a more sturdy model. But 2 4228s is a serious amount of weight, and if the wind hits that thing just right....
Yes, wind was the #1 consideration in locating the tower. Due to high downslope winds from the West, the tower is located next to the East side of the house. In fact just last week, I clocked an all time high gust of 65mph.

And, yup, I have a lot-o-crap on this tower. The biggest weight/wind load is the Direcway dish, and it'll be coming down, as the cable company finally added internet. The 'sidearm' antenna is also no longer needed.

In this pic, the 4228 was mounted in the best location for it(near the top of the tower). A friend has an old 7' parabolic dish, but due to the winds here, there is no way that I was going to attempt to put it on the tower.

http://panelcrafters.net/tower_1.jpg

I think the most likely possibility with the jointenna relates to overload, but it's just a guess. Unless somebody goes out with a spectrum analyzer and does some investigating, it's impossible to know for sure.
Just for grins, we'll reconnect it and see if it somehow restores the signals that I once had. The JT combines the 'main' and the 'sidearm' antennas.

bbig119

10-20-05, 09:50 AM

I recently installed a fusion 5 lite in my htpc to tune OTA HD, and its been little more than dead weight. I can lock in all stations, but it seems I get much more frequent signal dropouts on on the htpc using the fusion than I do with my tv's OTA tuner.

I'm 7-7.5 miles from the antenna farm in philadelphia which are all broadcasting UHF . They're all coming from about the same direction too. I've got an old antenna on the roof currently hooked up, and I've bought a radioshack(15-2160) one to put up there when I get the chance thinking it might improve signal(considering the old one is rusted on solid and I can't move it an inch). I get decent reception using the TV's tuner with both the antenna on the roof and the new one, currently on the living room floor. I get frequent drop outs on the htpc with both of these antennas.

I want to be able to tune OTA HD without the frequent dropouts, mainly for recording purposes. From everything I've read, I shouldn't have any problems tuning the local channels. I do have several large trees that are well above the antenna on the roof which may be causing the problem. I also realize that I might be fighting with multipath problems and not low signal, but I don't know how to distinguish between multipath and low signal.

I've also toyed with the idea of getting a channelmaster antenna, but they're more difficult to return than the ones from radioshack down the street. In theory, I shouldn't have a problem tuning these channels with a dinky little indoor antenna(which I've also tried- a POS terk, and 15-624 from ratshack- the outdoor antenna are better).

holl_ands

10-20-05, 01:51 PM

bobchase gave some useful pointers on how to determine whether you have TOO much signal or not enough by watching analog NTSC channels:
http://www.avsforum.com/avs-vb/showthread.php?p=6298960#post6298960

videobruce

10-20-05, 02:20 PM

with the SquareShooter separated by several dB below the group.
It also was a terrible VHF antenna, contrary to W-G published claims.
So why would anyone buy one, other than it "matches" their SAT dish???Matches their Lexus and Sony..................

August West

10-20-05, 03:04 PM

SolidSignal would be my choice as they are (?were) a forum sponsor. Others include Warren, Starkelectronics.

To the poster looking for a CM 7777, I just bought a CM 7777 a few days ago from Solid Signal and it has shipped. I have previously bought from them with no problems.

holl_ands

10-20-05, 03:15 PM

cpcat

10-20-05, 07:03 PM

Yes, this is exactly what I was talking about, and I've read these articles.

Yes, wind was the #1 consideration in locating the tower. Due to high downslope winds from the West, the tower is located next to the East side of the house. In fact just last week, I clocked an all time high gust of 65mph.

And, yup, I have a lot-o-crap on this tower. The biggest weight/wind load is the Direcway dish, and it'll be coming down, as the cable company finally added internet. The 'sidearm' antenna is also no longer needed.

In this pic, the 4228 was mounted in the best location for it(near the top of the tower). A friend has an old 7' parabolic dish, but due to the winds here, there is no way that I was going to attempt to put it on the tower.

http://panelcrafters.net/tower_1.jpg

Just for grins, we'll reconnect it and see if it somehow restores the signals that I once had. The JT combines the 'main' and the 'sidearm' antennas.

If you're willing to give up uhf channels 40 and above, the best single uhf antenna I know of is the Triax Unix 100 Band A. You could diplex it with that combo through a CM 7777 and keep your vhf if you want as well. It's big, but still less wind load than a single 4228. MaxHD has two he might be willing to part with. If that won't do it, there's no single antenna that will and you'd have to do a stack of them.

videobruce

10-21-05, 08:49 AM

More like a Scion xB in Flat Dark Green with bird dropping highlights.Love it; ROTFLMAS...............
Is that the camouflaged version? :eek:

TotallyPreWired; Your pic ruined my day. ;)

DR_LaRRY_PEpPeR

10-22-05, 07:40 AM

So, do you guys think it's OK to place the antenna right across the roof peak, wired on each side/end to keep it in place? I'll go hold it up there as a test soon to decide if it'll be "mounted"...

A question about coax: can most all of it be used outside?? I haven't really seen designations for outdoor or not. I have some white Radio Shack RG-6 around here that I'd use if it's OK... I see their current cable DOES say indoor/outdoor, but I didn't know if there was a special rating, etc. for it. It's regular RG-6 BTW -- quad-shield wouldn't make much difference, would it? I don't know that there's any interference where it'll run outside compared to in the house. :confused:

Also, after taking the antenna out of the attic, I noticed that there's a crack/cut in the twin-lead's insulation coming off the terminals -- don't know how that happened. :( Should that be fixed if it was outside? It doesn't seem like it would be an issue as far as shorting is concerned, since the terminals are exposed a couple inches away. :p But the copper wire might corrode in the weather, right?

Finally, I can just use a weatherproof F-connector (with silicone & O-ring) at the antenna without needing a boot too, can't I?

Thanks for any answers. :)

sregener

10-22-05, 08:38 AM

1) So, do you guys think it's OK to place the antenna right across the roof peak, wired on each side/end to keep it in place?

2) A question about coax: can most all of it be used outside??

3) It's regular RG-6 BTW -- quad-shield wouldn't make much difference, would it?

4) I noticed that there's a crack/cut in the twin-lead's insulation coming off the terminals -- don't know how that happened. :( Should that be fixed if it was outside?

5) Finally, I can just use a weatherproof F-connector (with silicone & O-ring) at the antenna without needing a boot too, can't I?

1) Okay? Yes? Ideal? No. You want at least 6' of open "space" around an antenna to be ideal. But sitting on the peak of your roof outside beats being under the roof anywhere.

2) Yes, it can be used outside. Only the exposed ends would have issues.

3) Quad-shield can help with interference. But it probably doesn't make much difference in real-world conditions for 99.9% of the public.

4) Yes, fix any exposed wiring. It will corrode, quickly, and then your signal will degrade.

5) That's what my professional installers do, so I assume it would be good enough.

toenail

10-22-05, 05:15 PM

Thought I'd throw my observations of the CM 4228 into this thread since it seems appropriate. I have a Tosh 52HM94 w/ built in tuner. Had previously connected it to nasty rooftop antenna from previous tenant (25 yrs old?) and was able to get 5 local HD towers in the Providence RI area from within 10 miles ABC, CBS, NBC, FOX, and PBS. Recently tho local FOX tower went down right in the middle of the MLB playoffs and I couldn't watch, so started researching reasonable antenna options. At $50 the 4228 seemed like a good choice. I mounted it to the same mast the nasty old one had been on and aimed it at the Boston market, 30* off axis from the Providence towers and located 40 miles away. Bingo! I get tons of digital and HD from the Boston market, including FOX and can now watch MLB WS without worry. Nice to have back-up channels in HD for all major networks. As a bonus, despite being 30* off optimal axis, I still get all the Providence market stations as before, without need to use the old antenna or a rotor. This thing's got pretty good gain and pretty good off-axis reception and suits me well.

Set

10-22-05, 05:44 PM

Hey folks,

I have a CM4228 and CM7777 that I'm planning on mounting in the attic, and have yet to find a sweet spot. I'm about 50-60 miles from the antennas I'm aiming for, all of which are within about 4 degrees of each other, so it's a pretty straight shot. I'm using about 100 feet of RG6 coax at the moment, but could trim it down to about 50 I imagine. I'm not sure about the roof, I know it uses the asphalt-based shingles, but am unsure if there's any metal under it. The siding is cement-based hardiplank, some of which I'd aim through in the attic in one of the possible mounting locations.

I've yet to get a decent signal at all in the attic, but when I bring the antenna downstairs near the tv, it gets a little better, though I still don't have a stable signal. There are some trees in the way, so I may be hitting some multipath issues. Tomorrow I'm going to try bringing the antenna outside to test it out, but wanted to see if anybody else had any ideas? Too much RG6? Roof and siding not letting the signal through? SOL? :)

Thanks!

cpcat

10-22-05, 10:05 PM

AntAltMike

10-22-05, 11:58 PM

...with the SquareShooter separated by several dB below the group. It also was a terrible VHF antenna, contrary to W-G published claims.
So why would anyone buy one...???

No one has denigrated the Square Shooter on this website more than I have, but it has the best overall rear rejection characteristics of any easy-to-install, gizmo antenna, combined with a horizontal beamwidth that allows it to serve as a rotorless, single antenna solution in a lot of metropolitan and suburban situations. I still think, however, that Winegard has a lot of nerve furnishing just a single, "Average UHF Gain" figure.

holl_ands

10-23-05, 02:42 AM

CM4221/4225 4-Bay Bowtie F/B specs are higher than SquareShooter above CH27 and slightly lower below.
W-G PR-9014 Corner Yagi F/B specs are higher than SquareShooter above CH35 and about the same below.

SquareShooter's primary "advantage" would be the slightly higher beamwidth than either of these antennas,
along with a significant disadvantage wrt antenna gain.

Of couse if you don't absolutely NEED the extra beamwidth, the wider beamwidth will also let in more multipath and other undesired interference.

AntAltMike

10-23-05, 04:27 AM

holl_ands

10-23-05, 10:05 PM

The CM4221/42225 and PR-9014 are not "easy to install, gizmo antennas". You have to install a mast to use those antennas. A lot of people would be in over their heads if they had to find a way to install a support tripod on a sloped roof, for example.

If you have to install on a sloped roof, how easy would a SquareShooter mount be?

The relatively heavy (10.5 lb) SquareShooter installs with 4 bolts....presuming you have a strong enough ledger board
or whatever to attach it to...that may or may not survive strong winds.

Any small mast mounted antenna can be similiarly attached using either a stand-alone "J-Pole" mount or a simple pair of brackets,
as shown here for various 4-Bay and 8-Bay antennas (which have higher gain, are a lot lighter with much lower wind resistance):
http://hdtv.forsandiego.com/messages/1/357.html#POST3009
http://hdtv.forsandiego.com/messages/4/16.html#POST20677
http://hdtv.forsandiego.com/messages/4/16.html#POST20671

You can also readily attach them to an existing Dish mount:
http://hdtv.forsandiego.com/messages/5/3552.html#POST18965
http://hdtv.forsandiego.com/messages/1/3272.html#POST18916
Note that the above uses a dual CM4221 and CM4228 antenna system with a very low loss 2-port Lindsay Combiner.

And if you want, you can stick them high in the air to obtain additional height gain and lower multipath,
thereby greatly exceeding the performance of the low gain SquareShooter.

===================================================
If station directions are widely separated, maybe what you need is a multiple antenna system,
such as the dual CM4221 and CM4228 system shown above,
or the fol. triple Yagi system using the very low loss 4-port Lindsay combiner:
http://hdtv.forsandiego.com/messages/1/2780.html#POST16670

A dual GEMDTV-1 or CM4221 system with a 2-port Lindsay combiner would cost about as much as a SquareShooter.

AntAltMike

10-23-05, 11:53 PM

I see the "forsandiego" thread participants are having a love-in with the Lindsay low loss combiner. In order for someone to uniquely benefit from such a monstrosity, they would have to be receiving signals from two different directions that developed only around -40dBmV each to need to eliminate the typical loss incurred in a $.35 hybrid splitter before preamplification. How often does that occur in the real world?

And even if it does, what about the countervailing, adverse effects of avoiding 3dB of reduction of the strengths of the stronger signals present? Some of the intermod products will go up by 6dB and some will go up by 9dB. Even though low-loss combining improves the post-combiner S/N of those anemic signals by 3dB, it increases the relative strength of the intermod products six or nine dB, so is the net result better or worse quality signals?

Channel Master says that if the output of a preamp with a two channel load is 54dBmV, then the intermod products that concern them are down by 46dB. O.K, then those undesired byproducts are at 8dBmV where they occur. Now suppose that, in the same system, there is a desired signal so weak that someone might be concerned that it will drop below, say, 20 dB S/N before preamplification. Then it must be at about -38dBmV and, even with 26dB of preamplification, it would be boosted to only -12dBmV. So how much is it corrupted by any in-band (meaning in-channel) intermod product developed by the strong signals with which it is preamplified? It is already getting creamed by it. Concurrently, if inadvertently, sustaining the signal strength of the strong signals will make the bad situation worse.

I'd say that, 99 times out of a hundred, a person considering using a Lindsay low loss combiner to couple antennas pointed in different directions would be better off preamplifying just one of his antenna inputs, or, for that matter, if he had an FSM and understood what he was doing, he could do an unbalanced coupling of the antennas using a directional coupler backwards, and incur a "pre" preamplifier loss of maybe 1.5dB or less on the weakest antenna downlead using a $1 part (like a -8 dB directional coupler).

As far as wind loading is concerned, Channel Master 2-bay and 4-bay bowties have twice and four times the cross section, respectively, of a Square Shooter, and typically, the tops of those antennas will be five feet above the fulcrum/attachment point, whereas the lever created by of the Square Shooter will be half that long. Admittedly, the Square Shooter is solid, but a funny thing about screens is that the faster the wind blows, the more a screen acts like a solid. I have installed some Channel Master 4421s on ten story buildings and the screens have been deformed enough by the wind that I have had to replace those antennas.

cpcat

10-24-05, 07:44 AM

Set

10-24-05, 08:36 AM

Go outside, and as high as is practical. The length of cable won't matter with the preamp so I wouldn't worry about that as much.
Actually ran it just outside, let it sit on the ground, and ended up picking up everything cept NBC, so I may play around with it a bit more. I'm probably going to try and keep it on the ground since I'm getting decent signal there (and it'll be much easier for the wife to stomach there rather than on the roof :)). It just amazed me though...I knew I'd be able to get better signal out there, but didn't expect just about everything to come in!

greywolf

10-24-05, 09:28 AM

Why are people so afraid of rotators?Surfing becomes a pain and dual tuner recorders an impossibility.

cpcat

10-24-05, 10:29 AM

Surfing becomes a pain and dual tuner recorders an impossibility.

I guess a "pain" is a relative term. It's not very painful for me to rotate my antenna via remote from my easy chair. It does take seconds to one minute to reposition the antenna. It wasn't that long ago that you actually had to get off your *ss and change channels. :)

Dual tuner recorders still work, just not from two stations simultaneously from two different bearings. Most people will still have multiple stations from a single bearing.

AntAltMike

10-24-05, 10:39 AM

Does anyone make a rotor that accepts discrete, infrared pointing commands, i.e., "127 deg"?

cpcat

10-24-05, 10:52 AM

Does anyone make a rotor that accepts discrete, infrared pointing commands, i.e., "127 deg"?

Yes. The CM 9521 which is available at Lowe's and most other CM dealers. It has a digital display (000-360) and IR remote. 3-conductor wire is all that's required. Bearings are selectable in one degree increments. It will also work with the more familiar "up, down" keys. In addition, it has a memory feature to remember specific locations for you. I'm fairly sure there's also one by Zenith as well.

dc_pilgrim

10-24-05, 03:57 PM

Believe it or not, I did search, and came up with some ideas already, just want to refine my thoughts a bit.

I had previously bought that radio shack HD tuner box, plus a SS, plus a $30 philips amplified indoor antenna from WM.

With the SS - the RS tuner got zero channels, and seemed to get about a 17% signal strength. With the amplified philips - the RS tuner got no channels, but around a 40% - 50% signal. I returned the RS tuner, and the philips antenna. The SS was bought online, so I hadn't gotten to doing anything with that.

Flash forward. I bought a Sony 30XS955 HDTV w/ATSC tuner. The Sony + SS got 2-3 DTV channels. I live about 13 miles from the Providence, RI towers, and 28 miles from Boston's. Based on the prior test, I am thinking the SS is not the best indoor antenna for me.

Should I - 1. get the recommended radio shack antenna Model 15-1880 (http://www.radioshack.com/product/index.jsp?productId=2103917&cp=2032057.2032187.2032189.2032204&pg=1&numProdsPerPage=20&parentPage=family) ?
2. go get that Philips that I got from WM?
3. get an amplifier for the SS (if so, which one)?
4. something else (other than get an outdoor antenna)

We may go the outdoor antenna eventually if we decide to drop cable, but for now it would just be a backup item.

Thanks,

holl_ands

10-24-05, 05:16 PM

In my experience, the Lindsay UHF combiner provides a small but reproducible improvement over using a splitter in reverse with horizontal stacking. I've seen a similar small difference with their VHF combiner as well.

The combiners are designed for stacking. I don't see the application for pointing antennas in different directions. You're better off amplifying one or both of the antennas separately through a power-passing splitter. All of this assumes the array even works to begin with. The only way it can work without filtering is if the second antenna happens to be positioned in a relative null for the other. Otherwise, multipath will potentially kill the signal.

Why are people so afraid of rotators?
When you point antennas in different directions, the standard hybrid combiner has about
a 4 dB loss for each antenna. The Lindsay is always 0.2 dB.

When you point matching antennas in the same direction, there is about 0.5 dB of loss in the
standard hybrid combiner, plus whatever antenna gain and phase mismatch loss that gets dumped in the
hybrid's internal imbalance resistor. The Lindsay is always 0.2 dB.

cpcat

10-24-05, 05:36 PM

When you point antennas in different directions, the standard hybrid combiner has about
a 4 dB loss for each antenna. The Lindsay is always 0.2 dB.

This is incorrect.
Anytime you try to combine antennas that aren't phased properly, loss
occurs which is independent of whatever combiner you use. It is impossible to properly phase two dissimilar antennas which are pointed in different directions. It makes no sense to spend that kind of money on a combiner for that application when the majority of the loss will come from the array itself. Additionally, standard wide-band splitters have thru-loss of around .5-1db, not 4db when used in reverse. The 4db figure is calculated by the split (3db) plus thru loss.

If you amplify them (or just the one with weak signals) before combining, the loss will be still be there but you're more likely to end up with usable signal. If signals are strong on both, you may still end up with usable signal without amplification. This assumes that signal-killing multipath is not produced.

The best way would be to diplex them first (which is possible with minimal loss) followed by amplification if needed.

TotallyPreWired

10-24-05, 06:43 PM

The best way would be to diplex them first (which is possible with minimal loss) followed by amplification if needed.
Other than the aforementioned Lindsay combiner, what combiner would you suggest(stacking application)?
....jc

PamP

10-24-05, 07:26 PM

For all you antenna and reception experts...I have an antenna on my roof that is probably 18 years old. It was installed by Davis Antenna in MD and we have never been really thrilled with the reception. Luckily, DirecTV offered local Wash, DC channels and we have been using that for the last couple of years. Then we got a HDTV plasma. Now we have very spotty reception on the digital channels. The weather doesn't seem to play a factor because tonight it is pouring down rain and I am getting an 85% signal strengh on the local channels but yesterday, they were terrible. Can someone tell me why it is not consistent before I call out Fairfax antenna to install a new antenna?

thanks, Pam

cpcat

10-24-05, 07:29 PM

Other than the aforementioned Lindsay combiner, what combiner would you suggest(stacking application)?
....jc

Any wideband splitter with specs that indicate -3.5db on each leg will thus provide through loss of .5db when used as a combiner (assuming the specs are correct). This means that if the antennas are perfectly phased 2db of gain would be theoretically possible or a factor of 1.67x signal improvement over a single antenna. This requires identical antennas properly spaced with identical lengths of coax before the combiner and *aimed in the same direction*. In addition, beamwidth will be narrowed in the plane of the stack which can often be even more important, particularly if they're horizontal. Pico makes good splitters/diplexers: http://www.picomacom.com/specs/pico/C/C5-C6.pdf
RS makes a decent one I'm sure and you can probably find one with similar specs at Lowe's. They need to be wideband (at least 1 Mhz)

I'd still recc. that you consider the Band A antenna I mentioned previously (singly first) assuming you can give up uhf channels 40 and up. I didn't see much I'd watch out there over 40. :)

lovebohn

10-24-05, 08:39 PM

Has anyone ever used the Channel Master telescopic tower? I bought one but wanted to get a few tips before i spend a day messing around with the install. Thanks.

Dave

AntAltMike

10-24-05, 08:42 PM

AntAltMike

10-24-05, 08:50 PM

DR_LaRRY_PEpPeR

10-24-05, 09:19 PM

Stupid quick question again: does there need to be a good F-connector to SHIELD connection on coax to carry the signal correctly? i.e. does it need to make a complete circuit? (I'm thinking yes...) Would it not work if only the center conductor was connected?

I was testing earlier using old cable with twist-on connectors, which didn't work very well, but's all I could use, and I don't think they have much connection to the shield...

G.B.

10-24-05, 09:39 PM

If your trying to get digial you can not have a bad connection. So I use only the crimp end F connectors

cpcat

10-24-05, 09:41 PM

Not that I personally ever have to give a hoot about fractions of a dB - since I do all my work in metropolitan markets - but as I do the arithmetic, if a hybrid splitter does indeed lose just one-half a dB when used as a combiner (I've never experimentaly confirmed that), then if two, stacked antennas each input 10dBmV of the desired signal into the combiner, and if 9.5 dBmV of each signal passes through, then 9.5dBmV plus 9.5dBmV equals 12.5dBmV, so the gain is theoretically 2.5dB.

Logarithms ar funny things. When I was younger and had more neurons, I understood them better. Or I thought I did...

Teach me how you are adding the dBmV values. Assuming .2db loss per leg (in the Lindsay) how would it come out?

Also, aren't dB expressed as proportional values whereas dBmV is actually quantitative? I guess I don't understand logarithms that well either.

I do understand that +3db is 2x and -3db is .5x and so on but from there, well...

AntAltMike

10-24-05, 10:06 PM

I didn't really add them. I just know that when something is doubled, it goes up by just over 3dB. You can't literally add dB. If you go back far enough, you may remember being told that you can't add with a slide rule either, for the same reason. There is no linear scale on a slide rule.

To combine quantities that are measured in dBmV, you have to convert from dBmV to some linear form of wattage, add those values, and then convert back to dBmV.

Consumer-grade RF equipment is commonly engineered to have 75 ohm system impedance, and so the dBmV used to evaluate those circuits is properly written dBmV(75ohm). It is the voltage necessary to develop one milliwatt when impressed upon the industry standard, reference impedance. Commercial-grade RF equipment is more commonly engineered to have a 50 ohm system impedance.

In commercial audio, dBmV typically means dBmV(600 ohm). The difference between dBmv(unreferenced) and dBmV (600 ohms) is 2.21. The difference between dBmv and dBmV(75 ohms) is 8.75, which is why the various conversion factors for dBmV and for microvolts to dBm end in 8.75.

I haven't had to calculate any of this professionally for over a decade and probably never will, because RF circuitry is so robust that no one working in the field gives a rats patooie about fractions of a dB. I've memorized the fractional values of about half a dozen common logarithmics, and I can manipulate them in my head well enough that I always come out to within a dB of the exact, calculated value of whatever I am trying to estimate, so I never need to calculate it any more precisely than that.

AntAltMike

10-24-05, 10:33 PM

So doing this the simple way, if each identical, in-phase signals drops from 10dBmV to 9.8dBmV through the Lindsay combiner, then they would combine to develop a signal power of 12.8dBmV. This primitive method works most readily when the two quantities being combined are equal.

I use slightly more complicated seat-of-the-pants methods to add unequal amounts. A 1dB increase is just over 25% more and 5dB is 200% more. Such knowledge can be used in seat-of-the-pants ciphering to readily estimate sums of logarithmically notated quantities that are accurate within a tenth of a dB or so of the exact, calculated values.

newsposter

10-25-05, 08:36 AM

Is a pre amp the same as an amp? :) Obviously they are 2 different names but here's why I ask. I went to home depot and got an amp for 35 bucks that supposedly adds 25db. It has an FM trap and a knob to crank up the gain, though I see no difference no matter where the knob is. The antenna is in my attic and the way I have it now, there's a 6ft wire from the DB8 to the amp, then 50 ft of wire to the hd tivo. I see from the one web site that a pre amp has a connection on the antenna then one regulator inside the house to make the thing work.

so is the pre amp made that way(2 pieces) because you can't run AC up outside on an antenna? And is the amp I now i have inside my attic ok or will a pre amp help me even more in my situation? Oh and yes, there is a definite difference with/without the amp I have plugged in so I definitely need something for my cable run.

sregener

10-25-05, 09:19 AM

I was testing earlier using old cable with twist-on connectors, which didn't work very well, but's all I could use, and I don't think they have much connection to the shield...

Twist-on connectors can work very well. However, the quality of your cable will determine how well the twist-on (or any) connector works. If you have a lot of wire shielding, then a good contact is easy to make. If you have very little wire shielding, it gets harder.

Basically, you have to bend back the shielding wire so that it contacts the screw-in part of the connector. Do this, and you're good. Don't do this, and the whole thing works poorly.

sregener

10-25-05, 09:25 AM

Is a pre amp the same as an amp?

Yes and no. Ideally, you want the amplifier as close to the antenna as possible. With preamplifiers, you get a DC unit that is weather sealed, and an AC unit that converts the power to DC and fires it up the coax. With amplifiers, you get an indoor-only AC unit.

However, electronically, amplifiers and preamplifiers are designed differently, with different goals. An amplifier typically has more gain, but also injects a lot more noise into the signal. A preamplifier has less gain, but is much less noisy. Fundamentally, once you've exceeded line loss and tuner resistance by a few dB, it doesn't matter how much gain your preamplifier has. Amplifiers are less prone to overloading than preamplifiers.

For digital reception, a preamplifier, especially a low noise (2.0db or less) one, is superior to a noisy amplifier (which can have noise above 4db.) The reason is because you don't need a strong signal to get good reception, but you do need a clean one. The noise added by an amplifier is likely to confuse the tuner by increasing the error rate. Never buy a preamplifier that doesn't list its noise factor.

dr1394

10-25-05, 09:48 AM

For those interested in correct information on dBmV, see:

http://www.maxim-ic.com/appnotes.cfm/appnote_number/808/ln/en

Ron

AntAltMike

10-25-05, 11:22 AM

For those interested in correct information on dBmV, see:

http://www.maxim-ic.com/appnotes.cfm/appnote_number/808/ln/en

Ron

The information that cpcat needs to add dBmV can be found in "Table 2. Conversions of Power 75 Ohms".

Find each dBmV value that you want to add in the left column, then go to the far right mW 75 column, which is a linear measure of power, then add up those power values and go down to that sum in the mW 75 column, then go across to the far left, dBmV column and that will be the sum, expressed in dBmV.

The only tricky part, for those who don't recognize the notation, is that the mW 75 ohm values corresponding to 8dBmV through 28dBmV are in exponential form, so one would have to convert them by moving the decimal point the requisite number of places to the left

Table 2. Conversions of Power 75 Ohms

dBmV dBµV dBm 75 mVrms mW 75
8 68 -40.75 2.51 8.4E-05
9 69 -39.75 2.82 1.1E-04
10 70 -38.75 3.16 1.3E-04
11 71 -37.75 3.55 1.7E-04
12 72 -36.75 3.98 2.1E-04
13 73 -35.75 4.47 2.7E-04
14 74 -34.75 5.01 3.3E-04
15 75 -33.75 5.62 4.2E-04
16 76 -32.75 6.31 5.3E-04
17 77 -31.75 7.08 6.7E-04
18 78 -30.75 7.94 8.4E-04
19 79 -29.75 8.91 1.1E-03
20 80 -28.75 10.00 1.3E-03
21 81 -27.75 11.22 1.7E-03
22 82 -26.75 12.59 2.1E-03
23 83 -25.75 14.13 2.7E-03
24 84 -24.75 15.85 3.3E-03
25 85 -23.75 17.78 4.2E-03
26 86 -22.75 19.95 5.3E-03
27 87 -21.75 22.39 6.7E-03
28 88 -20.75 25.12 8.4E-03
29 89 -19.75 28.18 0.011
30 90 -18.75 31.62 0.013
31 91 -17.75 35.48 0.017
32 92 -16.75 39.81 0.021
33 93 -15.75 44.67 0.027
34 94 -14.75 50.12 0.033
35 95 -13.75 56.23 0.042
36 96 -12.75 63.10 0.053
37 97 -11.75 70.79 0.067
38 98 -10.75 79.43 0.084
39 99 -9.75 89.13 0.106
40 100 -8.75 100.00 0.133
41 101 -7.75 112.20 0.168
42 102 -6.75 125.89 0.211
43 103 -5.75 141.25 0.266
44 104 -4.75 158.49 0.335
45 105 -3.75 177.83 0.422
46 106 -2.75 199.53 0.531
47 107 -1.75 223.87 0.668
48 108 -0.75 251.19 0.841
49 109 0.25 281.84 1.059
50 110 1.25 316.23 1.333
51 111 2.25 354.81 1.679
52 112 3.25 398.11 2.113
53 113 4.25 446.68 2.660
54 114 5.25 501.19 3.349
55 115 6.25 562.34 4.216
56 116 7.25 630.96 5.308
57 117 8.25 707.95 6.683
58 118 9.25 794.33 8.413
59 119 10.25 891.25 10.591
60 120 11.25 1000.00 13.333

newsposter

10-25-05, 12:28 PM

Yes and no. Ideally, you want the amplifier as close to the antenna as possible. With preamplifiers, you get a DC unit that is weather sealed, and an AC unit that converts the power to DC and fires it up the coax. With amplifiers, you get an indoor-only AC unit.

However, electronically, amplifiers and preamplifiers are designed differently, with different goals. An amplifier typically has more gain, but also injects a lot more noise into the signal. A preamplifier has less gain, but is much less noisy. Fundamentally, once you've exceeded line loss and tuner resistance by a few dB, it doesn't matter how much gain your preamplifier has. Amplifiers are less prone to overloading than preamplifiers.

For digital reception, a preamplifier, especially a low noise (2.0db or less) one, is superior to a noisy amplifier (which can have noise above 4db.) The reason is because you don't need a strong signal to get good reception, but you do need a clean one. The noise added by an amplifier is likely to confuse the tuner by increasing the error rate. Never buy a preamplifier that doesn't list its noise factor.

Very interesting. Sounds like the amp I have may actually be causing problems with noise. Maybe I'll get a pre amp after all. And try the rat shack one since it's local and can be easily returned.

http://www.radioshack.com/product/index.jsp?productId=2103094&cp=&pg=10&y=7&s=D-StorePrice-RSK&x=15&kw=antenna&parentPage=search

Model: 15-2507

TotallyPreWired

10-25-05, 12:38 PM

Very interesting. Sounds like the amp I have may actually be causing problems with noise. Maybe I'll get a pre amp after all. And try the rat shack one since it's local and can be easily returned.

http://www.radioshack.com/product/index.jsp?productId=2103094&cp=&pg=10&y=7&s=D-StorePrice-RSK&x=15&kw=antenna&parentPage=search

Model: 15-2507
newsposter,
U didn't read sregener's post close enough:
For digital reception, a preamplifier, especially a low noise (2.0db or less) one, is superior to a noisy amplifier (which can have noise above 4db.)
There is no way that a Rat Shack preamp has that low of a noise figure!
....jc

AntAltMike

10-25-05, 12:49 PM

newsposter

10-25-05, 12:56 PM

AntAltMike

10-25-05, 01:02 PM

Have newposter's needs been evaluated previously to determine what, if anything, he needs for preamplification?

TotallyPreWired

10-25-05, 01:11 PM

I assume you'd prefer I wait the week to get a

http://www.solidsignal.com/prod_display.asp?main_cat=03&CAT=&PROD=ANC7777

But other than that, I guess what you are saying is use the home depot amp or nothing ...vs trying the rat shack one?
Who knows what I am saying? I guess that sregener's advice is solid. And for about the same $$$ you can get a preamp with lower noise. That's all.
....jc

newsposter

10-25-05, 01:37 PM

deconvolver

10-25-05, 01:58 PM

I think I should wait until I get home tonight and give you all some numbers. I wrote down signal strengths for each channel and that may help you determine where I'm going wrong. Getting these signals in is the sole deciding factor on buying a new tv. If I can't get locals OTA HD, I'm going to have to wait for Q4 2006 for them to upgrade my HD tivo to mpeg4. I was hoping to get at least 1 yr out of this db8 and maybe buy a new tv. But DTV doesn't have enough for me to buy a tv right now
You need to go to antennaweb.org and see what analog and digital stations are near you. We need to know how strong both the channels that you want are and how strong any nearby sources that could overload the amp are. You can't tell signal strength from your tuners display, it really shows signal quality not strength.

holl_ands

10-25-05, 03:17 PM

The Radio Shack amp identified above is actually two amplifiers: one which looks like a 300 ohm to 75 ohm balun and is mastmounted, and one in the base unit, which also powers the mastmounted unit. The noise figure of the mast mounted component is much more important than the figure for the base unit, which is functioning as a distribution amplifier. I doubt that either unit has an exceptionally low noise figure, but have no practical means to check it.
The manual for the R-S 15-2507 claims Noise Figure of 4.5 dB for VHF/UHF, but does not have any overload specs.

C-M claims a UHF Noise Figure of 2.2 dB for the CM7777, which is consistent with the 2.0 dB NF measured at CH30, as reported in IEEE Transactions on Broadcasting Jun04 article. C-M claims max output of 111 dBuV (i.e. 85 dBuV input) for two strong signals and 5 dB less for 4 strong signals.

However if you are less than about 15-20 miles from a nearby transmitter (give or take additional attenuation from intervening terrain or attic locations), then you need to worry about not only overloading the input of the preamp, but also overloading the input of the HDTV due to the high gain of the Preamp.

The Winegard lower gain, higher overload Preamps (e.g. AP-4700, AP-8700 and newer HDP-269) are better suited for operation in suburban environments.
W-G claims a UHF NF of 2.9 dB for the AP-2880 and AP-4700, which is consistent with 2.6 dB NF measured at CH30 as reported in the IEEE article.
W-G claims max output of 118 dBuV (i.e. 99 dBuV input) for 5 strong signals.
That is nearly 20 dB higher overload capability than the C-M Titan (CM7777) and Spartan series.

W-G's new HDP-269 (VHF/UHF spec NF = 3.0 dB) has a slightly lower gain, resulting in pushing the overload capability to 123 dBuV (i.e. 108 dBuV input), which is another 9 dB increase in overload capability.

PamP

10-25-05, 03:33 PM

What's your zip code? Do you have a preamp? A rotor?

You could call Davis again. The only people who are working for them now who were also working for them eighteen years ago are likely to be Buddy and John themselves.

Our zip is 22728 but we are closer to 22739. We called Davis about 8 years ago and a guy came out and said he couldn't do any better. But we have neighbors who get much better reception than we do. It's probably just time to replace everything.

sregener

10-25-05, 05:18 PM

It's probably just time to replace everything.

18 years is getting close to double the average service time for an outdoor antenna. I think you could do better with a new antenna, and preamplifiers today are much better than they were several years ago. You're about 40 miles from DC, so there's no reason (other than low tower location or low output power) to struggle with reception with a good antenna.

Oldandslow

10-25-05, 07:18 PM

newsposter

10-25-05, 07:47 PM

You need to go to antennaweb.org and see what analog and digital stations are near you. We need to know how strong both the channels that you want are and how strong any nearby sources that could overload the amp are. You can't tell signal strength from your tuners display, it really shows signal quality not strength.

Im 40 miles away from the Philly locals. Everything is at 130 except fox at 128. I have a DB8, which I thought would be pretty good for me as someone 1 mile from me has one and gets everything perfectly. Of course theirs is outside but I don't think that's my problem. I played outside extensively and because of trees etc, my current best position is in the attic. I've moved the antenna to every part of the attic so I'm confident I have the best pic up there.

If I dare a roof climb, I could get about 6 more feet in height. Unless you or I have a crystal ball, i'm not sure 6 ft will help. I know it wont hurt. But it's a big deal to get up there so I'm asking for input regarding multipath etc based on my readings. Gut says it will help though so hope for a dry weekend to get on the roof.

Here are my readings from my HR10 250 strength meter as the antenna hangs in my attic. Also I have a 25db amp hooked up 6 ft from the antenna to help with the 50+ foot run. Disconnecting the amp weakens the signal so it must be doing something

uhf station signal power height
26 (cbs3) 90-92 770/375
31 (pax61) 90-91
32 (upn 57) 80-85 250/400
34 (wbye35) 80-85 358/377
42 (fox 29) 25-45 305/161
54 (wb 17) 70-71 500/354
64 (abc 6) 75-85 500/390
66 (65) 65-75 not digital
67 (nbc10) 65-83 560/377

viewing observations: uhf channel 34 and lower are great/steady/reliable enough to Tivo unattended/42 doesn't even come in/54 and higher aren't reliable enough to tivo and risk missing a recording and they go up and down too much. Thing is, 64 and 67 are 2x the power of 32 yet 32 is sooo much more stable

amazing that 64 and 67 are 2x the power as 32 but that's so much more reliable :(

Also there is some sort of police/ambulance tower 1 mile from me but it's not between me and the 130 direction. Not sure if that matters or not

newsposter

10-25-05, 08:09 PM

I received some good information here about what was available in regards to antennas and amplifiers. As "pay back", I posted a webpage dealing with my experiences with the Channel Master 7777 amp, Winegard YA-1713 VHF antenna, Channel Master 4228, Antennas Direct SAG91 antenna, Channel Master 9521A antenna rotator, and the 30' telescoping mast from Lowes. Perhaps, this will help someone else make a choice about what to buy. I hope so.

My HDTV Antenna Experience (http://home.indy.rr.com/challengerul/antenna.html)

I'll edit and add to this web page as time and need warrant.

Thank you for all that posted here,

Larry

thanks for the nice write up.

How do you stablize it up so high? I need to put a DB8 at least as high as my chimney. The antenna in my attic now just isn't high enough to get over trees. I really dont want to climb up the roof so would be happy to put 3 10 foot poles together or whatever I need to get up high.

I may have an advantage as I can use the part of the chimney that sticks out of my house to guide the 30 ft up . So the part not leaning up against the chimney support would only be a few feet. I guess I'd just attach the pole to the 90 degree inside angle and that would be pretty good against any wind movement.

I have what is called 'shaped concrete' or perhaps permastone. But of course concrete block is under there. What do you recommend to attach to such a surface?

Do you have to worry about an antenna being so close to a chimney operating 365 days a year? (will the db8 die from carbon monoxide or anything lol)

edit: after thinking about this, I guess I'd need some kind of support up higher anyway right? If that's the case, I may as well risk climbing up on the roof if i'd have to secure any longer poles i've made from the ground anyway.

MAX HD

10-25-05, 08:38 PM

cding

10-26-05, 12:56 AM

I am in San Diego North County and purchased a PR4400 antenna, I can received most of the LA OTA channels except ABC and KCAL. So I upgraded my antenna to 8-bay PR8800. But I don't see any improvement which I expect at least extra 10dB gain.

So my question to those have a PR8800 antenna, is there any tricks when assemble the PR8800, especially couple two 4-bay. Any difference between PR8800 and PR4400 on installation and assembly.

thanks
Chris

sregener

10-26-05, 09:44 AM

But I don't see any improvement which I expect at least extra 10dB gain.

10dB of gain more? Um... no. Maybe 3dB in a perfect world. No more. (After all 3dB is a doubling of gain, and there's twice the antenna there.)

Maybe your problem isn't signal strength? How do analogs from the same towers look? Snowy? Ghosty? Both?

keepsmyling

10-26-05, 09:57 AM

Hi,

I have been trying to figure out which antenna would be best for me but am not quite sure. Can I have some suggestions? I went to the antennaweb website, and these are the channels I would like to receive. As you can see, the towers are within a 25 mile radius. I live in a housing subdivision with 2-3 story houses. I am open to roof installation as well as on a pole. Which antenna would you recommend? I want to get clear HD reception for the mentioned channels.

Thanks.

yellow - uhf WTVD-DT 11.1 ABC DURHAM NC 153° 20.9 52
* yellow - uhf WRAZ-DT 50.1 FOX RALEIGH NC 151° 20.7 49
* yellow - uhf WRAL-DT 5.1 CBS RALEIGH NC 151° 20.7 53
* yellow - uhf WNCN-DT 17.1 NBC GOLDSBORO 151° 20.7 55
* green - uhf WRDC-DT 28.1 UPN DURHAM NC 151° 20.7 27
* red - uhf WUNC-DT 4.1 PBS CHAPEL HILL 270° 23.5 59
* red - uhf WLFL-DT 22.1 WB RALEIGH NC 151° 20.7 57

newsposter

10-26-05, 10:17 AM

the more I think about this, the more I dont want to go on the roof. But I definitely need that height.

Anyone ever taken say 2 or 3 - 10 ft poles, and shimmy the antenna up from the ground by just adding them one at a time. If you got the highest wall mount up first, and got the antenna installed above that, to clear the mount itself, it seems it 'should' work. Then you'd just aim from the ground by spinning the pole.

Assuming the peak is 20-25 ft, i have no idea actually and would have to measure, I'd think the wall mounts at about the 14 ft and 7 ft marks from the ground could be ok. My 8ft ladder with me on it should get me to 14 ft easily. Then the mast would be rested right up against the roofline, providing some degree of 'support.'

comments?

I also have a porch roof that I could stand on to get some height for the mounts. Almost forgot about that.

AntAltMike

10-26-05, 10:33 AM

Anyone ever taken say 2 or 3 - 10 ft poles, and shimmy the antenna up from the ground by just adding them one at a time. If you got the highest wall mount up first, and got the antenna installed above that, to clear the mount itself, it seems it 'should' work. Then you'd just aim from the ground by spinning the pole.
.

I've done it many times, but I've always guy wired the mast. A tall mast is a long lever, placing a lot of stress on the mounts. In addition to guy wiring, you must make sure the wall brackets are secure. I often use threaded rods through the wall with a backing plate on the backside, when I am installing a tall, wallmount mast.

After installing the first two ten foot lengths, it may be easier to use five foot lengths if your lowest bracket is only 7 feet above the ground.

newsposter

10-26-05, 11:58 AM

I've done it many times, but I've always guy wired the mast. A tall mast is a long lever, placing a lot of stress on the mounts. In addition to guy wiring, you must make sure the wall brackets are secure. I often use threaded rods through the wall with a backing plate on the backside, when I am installing a tall, wallmount mast.

After installing the first two ten foot lengths, it may be easier to use five foot lengths if your lowest bracket is only 7 feet above the ground.

I'm ready to give up....JK....the more I think about it, I think of new things. I understand wall brackets must be very secure. But drilling through my 'permastone' freaks me out. I'd be worried at what point I'd hit a concrete block. If it was open space, I'd probably use toggle bolts. But if not, I guess just plain ole screws.

If a pole is up against a house, how do you guy it? to the house? I have a 6ft concrete walk all along the back of my house and would need to extended this into the yard and that's really not an option because of logistics I wont bore you with. But if i'm going to already drill into the house, I'd have no problems guying a few in that way.

Chimney and height is suddenly looking better. The scales are tipped, that's for sure. Reason: as long as directv locals in HD come in clear for me next year, this antenna is coming down. So it's not worth me investing this time/money to put up a big mast come to think of it.

UnderDaHill

10-26-05, 12:00 PM

I've been reading through this thread along with several other AVS threads related to HDTV, Antennas, and Windows Media Center. I've come to the conclusion that although I can figure out most of what I am trying to do, I do not feel that I have enough experience with the antenna/signal aspect of what I'm trying to do to make an accurate decision.

Here is what I'll be doing.

I'm dropping my local COX cable tv service along with my COX telephone service. I'm switch to vonage or packet8 for phone and will be using an antenna to pull in local HDTV and standard TV channels. That is all we watch now anyways so I'm not losing much by dropping COX other than an easy antenna mechanism.

Now here is where I'm having troubles. I don't know what do do for OTA reception. I'll be routing it all to my HTPC which will feed my xbox and xbox 360 over a wired network. The HTPC will have a standard tuner and an HDTV tuner. So I plan to run two wires from the attic (one from an HDTV/UHF andtenna and the other a VHF antenna). The idea is that I can have two (or possibly more) antennas in my attick pulling in as much OTA content as possible. The problem is that the VHF and UHF are both coming for two reasonbly disperse directions. I've attached my antennaweb results.

To further complicate the situation my neighbor has a line of wind break trees (the tall skinny ones) planted just south of my house and they have grown to be well over the height of my house. So I'll be trying to pick up signals through these trees no matter where I install my antennas.

Does anyone have an attic antenna setup suggestion for me. If all else fails I could mount an antenna outside on a boom. But I REALLY do not want to do that.

I also have a fairly small opening going up into my attic. I'm sure a CM 4221 will go up but the CM 4228 will not unless it can be disassembled (looked like it was riveted together in the one picture I saw).

Oh... The Sony KD-30XS955 is awesome. Can't wait to start getting some good XBOX 360 and HTPC content piping to it. Anyone know if WMVHD DVD's will play on the xbox 360?

Thanks,
bob

Oldandslow

10-26-05, 12:10 PM

I'll help you with an edit.Nice catch on WSIL DT.It's on channel 34 from Harrisburg,IL.Probably a little further than Louisville,Ky :-)

Greg B
Greensburg,In

Greg,

Thanks. I've changed it. I was receiving several Louisville stations, at the time, and thought that was just one more from there.

Larry

sregener

10-26-05, 01:16 PM

Chimney and height is suddenly looking better. The scales are tipped, that's for sure. Reason: as long as directv locals in HD come in clear for me next year, this antenna is coming down. So it's not worth me investing this time/money to put up a big mast come to think of it.

I used a chimney mount (basically, wire straps that "hug" the chimney) for my antenna for quite some time, and I've seen others hold up for years. They're cheap, effective, and work great as long as you don't go too high above the chimney. They also are non-penetrating, so they come down just as easily.

I can think of at least three reasons why local reception via an antenna is better than local reception via satellite. First, you won't get rain fade from terrestrial sources. If you're in an area that needs severe weather updates, it won't do you any good if the rain blocks your satellite signal. Second, DirecTV has done a lot of "data shaping" in the past, where they have compressed and overcompressed signals in order to get more stations to "fit" in their available bandwidth. "In theory" they shouldn't have to do this with HD LiL, as they have a lot of space up there, but as the saying goes, "In theory, theory and practice are the same. In practice, they're not." Finally, you won't be paying extra for the antenna, but you will be paying extra for Locals from DirecTV.

jmccrossan

10-26-05, 02:41 PM

Hi All,

Thanks for all of the great info.

I am planning to do my first install. I live within the LA DMA (about 41 miles from Mount Wilson) and wish to receive all of the ATSC broadcasts coming from Mount Wilson.

After reading through a number of posts, I have decided to get the CM4228 antenna as it seems to be a good choice to receive both UHF and VHF-hi broadcasts.

I currently have an antenna mast which I plan to wall mount. This mast has a 1.785 inch outside diameter. Unfortunately, I believe that the mounting arrangement on the CM4228 is designed to accept up to a 1.6 inch diameter mast.

Does anyone have any experience with adapting the CM4228 to a mast with a larger diameter?

Thanks for any help,
joemcc

cpcat

10-26-05, 02:55 PM

If a pole is up against a house, how do you guy it? to the house? I have a 6ft concrete walk all along the back of my house and would need to extended this into the yard and that's really not an option because of logistics I wont bore you with. But if i'm going to already drill into the house, I'd have no problems guying a few in that way.

.

Do a ground mount strapped to the house on the way up with wall mounts every 6-8 ft or so. This is a very sturdy installation and doesn't need guying as long as you don't go more than say 10 ft above roof line for most installations. If you have a particularly heavy antenna or higher wind load, I'd stay under 8 ft above the roof. Channelmaster sells a 30 ft. telescoping mast which works very well for this application. I installed mine upside down so the largest diameter section is on top. This also allows me to raise and lower the antenna easily by loosening the top section. I mounted to brick veneer with masonry anchors. The wall mounts are available from CM and your size will depend on your eave overhang.
The top attachment at the peak is an eave mount which I modified--the bottom bracket I had to cut the "ledge" off of to allow the mast to pass on down to the ground.

keepsmyling

10-26-05, 02:59 PM

I think I.ve pretty much homed into a medium uni directional antenna. What are some of he most popular models out there that people like? (42XG, CM4228...?)

Thanks.

TotallyPreWired

10-26-05, 03:00 PM

I currently have an antenna mast which I plan to wall mount. This mast has a 1.785 inch outside diameter. Unfortunately, I believe that the mounting arrangement on the CM4228 is designed to accept up to a 1.6 inch diameter mast.

Does anyone have any experience with adapting the CM4228 to a mast with a larger diameter?
Mine is down, so I just checked it. It looks like you might be able to get it to work with 1.75" mast. Might. If it won't work you'll need to drill(or widen) one of the holes(top & bottom), and get a larger 'U' bolt. You'll also need a larger clamp for the pole('U' bolt goes thru it).
....jc

cpcat

10-26-05, 03:27 PM

I think I.ve pretty much homed into a medium uni directional antenna. What are some of he most popular models out there that people like? (42XG, CM4228...?)

Thanks.

Good medium range uhf choices include the CM 4221, Antennasdirect DB4, Antennasdirect 42xg. If you truly are at medium range( 20-35 mi) you can't go wrong with the CM 4221. It's decent for high band vhf as well as being around half the price of the DB4.

I'd consider the CM 4228 long range.

holl_ands

10-26-05, 03:40 PM

Does anyone have an attic antenna setup suggestion for me. If all else fails I could mount an antenna outside on a boom. But I REALLY do not want to do that.

I also have a fairly small opening going up into my attic. I'm sure a CM 4221 will go up but the CM 4228 will not unless it can be disassembled (looked like it was riveted together in the one picture I saw).

bob

First question: do you really NEED a VHF antenna, and if so, how big?
ALL of the VHF stations listed in antennaweb results are Analog, and their DTV equivalents are ALL in the UHF band.....for now.

In the future, when analog stations shut down (April 2007 is current proposal in Congress), nearly all of those VHF stations will go away, leaving the current UHF DTV station.
Exceptions to this trend are distant CH 8, 9 and 10 who have elected to operate DTV stations on their old analog frequencies.
Not very favorable: they are quite distant, you would need a rotator for CH9, you are too close to local transmitter to use a Preamp and hence would require significant UHF antenna gain (maybe more than the CM4228), and even then they may not be received reliably.....
Just doesn't seem to be worth the trouble when they are DUPLICATES of local networks...

As I see it, currently you don't really NEED a special VHF antenna to receive DTV, and pretty much any chunk of wire (incl. CM4221) will work for nearby Analog CH 3, 6 and 7 as backup for whenever the DTV equivalent is off-line.

Of course, unless you have room to install a rotator in the attic, you're going to have to point it in one direction...such as about 220 to 230 degrees to optimize reception at 20+ miles for WB and FOX.
You might get TBN network, but you probably won't get the other "purples", which are duplicates anyway, except maybe with a big antenna on an outdoor rotator.

The CM4221 might be adequate, then since antennaweb shows three DTV stations in the "blue" and you can't use a Preamp, you're probably better off with the higher gain CM4228.
You'll have to make these decisions based on reports from other people in the area.

====================================================
The CM4228 would provide significant gain for VHF and UHF channels and about as much as rabbit ears for nearby CH3.

To dissemble, the two side-by-side rear screens comes off real easy by twisting some tabs.
You would need to drill out eight rivets in the two cross bars connecting the two 4-Bay stacks.
The center feed would come apart by loosening two screws.

To reassemble in the attic, if you didn't want to bother with rivets, you could use screws/bolts in place of the rivets.

It all looks pretty easy to me.....and soon I'll see if I actually need the above procedure, when we upgrade my son's CM4221.

cpcat

10-26-05, 03:51 PM

The CM4228 would provide significant gain for VHF channels and about as much as oversize rabbit ears for CH3.

.

The CM 4228 does pretty well for high vhf (7-13).

It's very poor for low band vhf (2-6).

Fully extended rabbit ears will do much better for channel 3 and depending on their extended length will approach that of a channel 3 dipole (about 2dbi).

http://www.kyes.com/antenna/rabbitear.html

holl_ands

10-26-05, 04:56 PM

The CM 4228 does pretty well for high vhf (7-13).

It's very poor for low band vhf (2-6).

Fully extended rabbit ears will do much better for channel 3 and depending on their extended length will approach that of a channel 3 dipole (about 2dbi).

http://www.kyes.com/antenna/rabbitear.html

See fol. posts for info on actual measurements performed by Kerry Cozad (Dielectric):
http://hdtv.forsandiego.com/messages/1/3476.html#POST19916
and see DTV ANTENNAS REVD for latest spec/NEC/measurement comparison spread sheet:
http://hdtv.forsandiego.com/messages/1/2846.html#POST20074

Although you might be able to make a more effective oversize Rabbit Ear antenna (see above, where 2.15 dBi = 0 dBd),
these tests show that the CM4228 (2 dBd = 4 dBi) clearly outperformed commercially available Rabbit Ear/Loop antennas:

cpcat

10-26-05, 05:13 PM

See fol. posts for info on actual measurements performed by Kerry Cozad (Dielectric):
http://hdtv.forsandiego.com/messages/1/3476.html#POST19916
and see DTV ANTENNAS REVD for latest spec/NEC/measurement comparison spread sheet:
http://hdtv.forsandiego.com/messages/1/2846.html#POST20074

Although you might be able to make a more effective oversize Rabbit Ear antenna (see above, where 2.15 dBi = 0 dBd),
these tests show that the CM4228 (2 dBd = 4 dBi) clearly outperformed commercially available Rabbit Ear/Loop antennas:

Those figures pretty much fly in the face of conventional wisdom and I'd say they're suspect. There's nothing in a 4228 that even gets close to .5 wavelength for low band vhf and I just can't see how it could be so.

The uhf gain he measured for the 4228 is on average 3dbd higher than Channelmaster's own figures. See http://www.starkelectronic.com/cmg5.htm
15dBd at channel 32 would be awesome performance. In fact, that's about equivalent to my 100 element Band A antenna. Don't believe it though, sorry.

Neil L

10-26-05, 07:10 PM

holl_ands

10-26-05, 07:52 PM

Those figures pretty much fly in the face of conventional wisdom and I'd say they're suspect. There's nothing in a 4228 that even gets close to .5 wavelength for low band vhf and I just can't see how it could be so.

The uhf gain he measured for the 4228 is on average 3dbd higher than Channelmaster's own figures. See http://www.starkelectronic.com/cmg5.htm
15dBd at channel 32 would be awesome performance. In fact, that's about equivalent to my 100 element Band A antenna. Don't believe it though, sorry.
Manufacturer's specs are typically for some fictious Gain called "Free Space Gain",
which is either calculated via NEC simulations or measured in an anechoic chamber.

When you actually place an antenna at some distance (e.g. 20-30 feet) above the ground,
then the measured gain increases somewhat due to receiving both the direct path,
the reflected path bounced off the ground and reflections from other nearby objects.
[Yup, these are major sources of multipath in the real world.]

Just one more reason an outdoor antenna placed well above the roof line is better than one buried
inside an attic and hence doesn't "see" the ground bounce reflections.

Therefore it is more important to compare one antenna to another under the same test conditions,
rather than to Free Space Spec values.

cpcat

10-26-05, 07:58 PM

I have never done gain measurements, and don't really have the ability to do so. But, I have on the very rare occasion picked up an analog station that is 70 miles distant on channel 3, with my 4228. I can verify that the low vhf gain (if any) is nowhere near that of high vhf. I get channel 13 from the same area as that channel 3 anytime I look for it, day or night. All analog, the digitals are from channel 25 up to 52.

If it was providing even 2dBi of gain on channel 3 (equivalent to a simple dipole) and assuming that's a full power analog, you'd likely be able to get at least a snowy picture almost anytime. It would probably be even a watchable picture much of the time. Low band vhf really gets out.

keepsmyling

10-26-05, 10:26 PM

Good medium range uhf choices include the CM 4221, Antennasdirect DB4, Antennasdirect 42xg. If you truly are at medium range( 20-35 mi) you can't go wrong with the CM 4221. It's decent for high band vhf as well as being around half the price of the DB4.

Thanks cpcat. My signal situation is such that I can get most channels already with a little radioshack rabbit ears that was lying around. The signal strength stays around 30-60% on most channels. And here are my channel requirements (all within 25 miles):

yellow - uhf WTVD-DT 11.1 ABC DURHAM NC 153° 20.9 52
* yellow - uhf WRAZ-DT 50.1 FOX RALEIGH NC 151° 20.7 49
* yellow - uhf WRAL-DT 5.1 CBS RALEIGH NC 151° 20.7 53
* yellow - uhf WNCN-DT 17.1 NBC GOLDSBORO NC 151° 20.7 55
* green - uhf WRDC-DT 28.1 UPN DURHAM NC 151° 20.7 27
* red - uhf WUNC-DT 4.1 PBS CHAPEL HILL NC 270° 23.5 59
* red - uhf WLFL-DT 22.1 WB RALEIGH NC 151° 20.7 57

I dont think I can install anything on the roof/chimney due to restricted covenants. Will a good indoor antenna be enough for me? It not, I will just go with the 4221 as you suggested since I do not know any better anyway, unless you have some other suggestion considering this additional information. I do not mind paying more coz its a one time cost but I am looking for the antenna thats the best option for me. Once again, thanks a lot for sharing your knowledge and helping newbies like me.

cpcat

10-26-05, 10:47 PM

Thanks cpcat. My signal situation is such that I can get most channels already with a little radioshack rabbit ears that was lying around. The signal strength stays around 30-60% on most channels. And here are my channel requirements (all within 25 miles):

yellow - uhf WTVD-DT 11.1 ABC DURHAM NC 153° 20.9 52
* yellow - uhf WRAZ-DT 50.1 FOX RALEIGH NC 151° 20.7 49
* yellow - uhf WRAL-DT 5.1 CBS RALEIGH NC 151° 20.7 53
* yellow - uhf WNCN-DT 17.1 NBC GOLDSBORO NC 151° 20.7 55
* green - uhf WRDC-DT 28.1 UPN DURHAM NC 151° 20.7 27
* red - uhf WUNC-DT 4.1 PBS CHAPEL HILL NC 270° 23.5 59
* red - uhf WLFL-DT 22.1 WB RALEIGH NC 151° 20.7 57

I dont think I can install anything on the roof/chimney due to restricted covenants. Will a good indoor antenna be enough for me? It not, I will just go with the 4221 as you suggested since I do not know any better anyway, unless you have some other suggestion considering this additional information. I do not mind paying more coz its a one time cost but I am looking for the antenna thats the best option for me. Once again, thanks a lot for sharing your knowledge and helping newbies like me.

There's so much trial and error in this it's not even funny. That said, the Zenith Silver Sensor would be worth a try, especially if you could get it somewhere with a return policy. You've got the one station due west of you with the rest being at around 150 deg. (SSE) so you'll have to take that into account.

If that doesn't work a CM 4221 in the attic probably would. You might get lucky and get the one off-bearing station through the back.

I'm sure you know that you are permitted an outdoor antenna regardless of HOA covenants by law.

DR_LaRRY_PEpPeR

10-27-05, 07:14 AM

deconvolver

10-27-05, 07:31 AM

Manufacturer's specs are typically for some fictious Gain called "Free Space Gain",
which is either calculated via NEC simulations or measured in an anechoic chamber.

When you actually place an antenna at some distance (e.g. 20-30 feet) above the ground,
then the measured gain increases somewhat due to receiving both the direct path,
the reflected path bounced off the ground and reflections from other nearby objects.
[Yup, these are major sources of multipath in the real world.]

Just one more reason an outdoor antenna placed well above the roof line is better than one buried
inside an attic and hence doesn't "see" the ground bounce reflections.

Therefore it is more important to compare one antenna to another under the same test conditions,
rather than to Free Space Spec values.
Don't we wish that manufacturers all published free space gain, that is the most honest figure they could list. Real world reflections from the ground or nearby structures arrive at the antenna with typically random phase. Sometimes the reflections improve the antenna gain but they can just as easily degrade it. When the antenna height is correct to improve one channel's frequency it would not likely be correct to improve another channel. If you have only one problem channel, and if you have a reflecting ground (no UHF absorbing shrubs), and you take the time and have the mast height to fine tune the antenna location to maximize the problem channel's signal, then maybe the figure including the improvement with a lucky ground effect would be appropriate; but otherwise the free space gain is best. Real world measurements that include ground effect without carefully accounting for the change in gain that causes are notoriously unreliable. For that reason the ARRL now refuses to accept antenna advertisements with measured gain figures and instead requires the more typically accurate and honest free space value calculated with a program such as NEC.

By the way, one method to get reliable performance for many channels is with a vertical stack. This vertical diversity ensures that when one portion of the antenna is in a null (node) another portion is in a region with good signal (antinode). The 4-bay high bow-tie antennas like the CM4221 and CM4228 are examples of this principle. Another interpretation of vertical diversity is that the antenna has enough vertical aperture to at least partially attenuate the ground reflection (for instance if it includes an equal number of nodes and antinodes then there is a vertical beam null on the reflected path).

P.S. One reason that attic antennas often perform poorly is the presence of reflections from indoor structures- pipes, wiring etc.

greywolf

10-27-05, 08:55 AM

Do grounding blocks differ in quality, or do they degrade the signal at all? Is a $2 Radio Shack one OK? And can the grounding block be put inside the house right after the cable enters? (Properly wired, of course. ;)) I think I saw a post from greywolf that said it's fine.

I mentioned a few days ago that the twin-lead coming off the antenna has a small crack in the insulation... I'm not sure what the best way to repair it is. Some kind of sealant/glue, weatherproof tape... No idea. :confused: It goes together when not bent, so I think I could almost carefully melt it back together with something...

Radio Shack has a transformer for $4 that comes with a boot, so maybe I should just get that and not need to buy the weatherproof connectors... :confused:I've seen grounding blocks rated for frequency ranges. I've seen warnings to make sure to get 3GHz grounding blocks in satellite applications. I just don't get it. I've never seen any post about having to replace a grounding block with a better performing grounding block. I wouldn't be concerned. There is some loss whenever the is a connection. Again, I wouldn't be concerned about it.

The NEC says the grounding block is to be placed near the entrance of the coax to the building. Inside or outside is okay. I like inside because connections are not exposed to the weather. Also, with the block inside, only one drip loop in the coax at entry is needed instead of 3 since I don't like water running down the cable trying to wash the silicone dielectric grease out of the block connections.

What I would be concerned about is the matching transformer. I would definitely replace rather than try to repair a damaged one. I have an R/S unit right now since I have an R/S antenna. Knowing what I know now though, I'd opt for something else such as Channel Master et. al..

cpcat

10-27-05, 09:11 AM

By the way, one method to get reliable performance for many channels is with a vertical stack. This vertical diversity ensures that when one portion of the antenna is in a null (node) another portion is in a region with good signal (antinode). The 4-bay high bow-tie antennas like the CM4221 and CM4228 are examples of this principle. Another interpretation of vertical diversity is that the antenna has enough vertical aperture to at least partially attenuate the ground reflection (for instance if it includes an equal number of nodes and antinodes then there is a vertical beam null on the reflected path).
.

I don't doubt the validity of this statement as it makes perfect sense, but I've tried vertical stacking more times than I care to admit, and have always returned to horizontal because it performs better (for me). Vertical certainly was better than a single antenna, though.

The other disadvantage to vertical (if you use a rotator) is you end up with such a long lever arm above the rotor. A guyed alignment bearing is usually necessary.

sregener

10-27-05, 12:11 PM

I don't doubt the validity of this statement as it makes perfect sense, but I've tried vertical stacking more times than I care to admit, and have always returned to horizontal because it performs better (for me).

Vertical does nothing to tighten the beamwidth (directionality) of the stack. Horizontal does. You also would lose ground bounce with a vertical stack, assuming it is beneficial.

deconvolver

10-27-05, 03:38 PM

Vertical does nothing to tighten the beamwidth (directionality) of the stack. Horizontal does. You also would lose ground bounce with a vertical stack, assuming it is beneficial.
Obviously vertical stacking tightens the vertical not horizontal directionality. The benefit is in losing the ground bounce. Unless an antenna is carefully located so that multipath like groundbounce is beneficial then it is more likely to degrade performance which is a reason for stacking. One would generally benefit the most by stacking in the dimension that multipath is a problem. The narrow beamwidth that results from stacking can require a rotor or tilter to allow fine steering of the beam's response.

Remember that adding random elements to an antenna will almost always degrade performance. Gound bounce is like adding an image of the antenna vertically. Unfortunately depending on the terrain the image is like stacking with a deformed copy of your antenna with a random length feed wire joining it to the real antenna. Moving the antenna vertically can usually only align the phase of the reflected wave for one channel. With multiple weak channels it may not be possible to find a location where the gain of a channel with ground effect is not significantly worse than the free field value. In that case the vertical 2 antenna stack can lead to an improvement of more than 3dB for the worst case channel versus a single antenna. Of course if horizontal multipath is the problem then a horizontal stack would be appropriate. Horizontal multipath also often has much greater time delay than ground bounce does. If the horizontal multipath delay is beyond the tuner's ability to compensate then the horizontal beampattern will need to correct the situation.

dc_pilgrim

10-27-05, 09:00 PM

cpcat

10-28-05, 06:21 AM

Vertical does nothing to tighten the beamwidth (directionality) of the stack. Horizontal does. You also would lose ground bounce with a vertical stack, assuming it is beneficial.

The beamwidth is narrowed in the plane of the stack.

All this talk about "beneficial multipath" is making me queazy. Catching a reflected signal by non-intuitive aiming is one thing, but for me I'd just as soon not see a ghost and I prefer my signals arrive on time thank you. :)

DR_LaRRY_PEpPeR

10-28-05, 06:56 AM

Thanks for your reply greywolf. :)

I got some Coax-Seal (www.radioshack.com/product/index.jsp?productId=2062667) from the Shack yesterday and it looks like that might work pretty well on the transformer's little insulation crack (I guess I'll use it around the F-connector too).

Now I have a couple more grounding questions. :) I can put a grounding strap on the boom to take care of that, right? About the only other thing I have to figure out is the grounding wire to use... I'll have to see if there's #10 stranded copper with white insulation available (OK, I assume? for flexibility/looks), or get new white RG-6 with attached ground, if available...

Also, we now have the satellite dish and its grounding block on a rod on the opposite end of the house from where the electric service ground rod is (which is the one the antenna ground will be closest to, if the 2 are bonded). It's been that way for years :(, but since reading on here that separate rods must be bonded, I might as well take care of that too. I will take about 55' to go across the basement, if that matters. Am I right to think that I don't have to actually run the bond wire to the service rod itself, but simply attach it to the wire that runs out there from a breaker panel? If so, what's the best way to do that since I'm not that familiar with methods -- split bolt...? BTW, there's 2 service panels with ground wires running to 2 rods ~6" apart. Should they have used the same rod?

Finally, for curiosity, what's the difference between using #6 to bond the 2 versus NOT using the satellite's separate rod and just running a #10 across the basement to the "main" rod (too far?); or, for that matter, using #10 for bonding?

Sorry for all the questions (I think I'm about done asking! :)), but I appreciate everyone's help. :cool:

greywolf

10-28-05, 10:14 AM

holl_ands

10-28-05, 02:17 PM

The beamwidth is narrowed in the plane of the stack.

All this talk about "beneficial multipath" is making me queazy. Catching a reflected signal by non-intuitive aiming is one thing, but for me I'd just as soon not see a ghost and I prefer my signals arrive on time thank you. :)
Then you'll want to special order a "FREE SPACE ONLY" antenna and mount it in....well....Free Space.

Recommend you start Astronaut training....you'll be moving to the Space Station.
PS: I hear that it isn't very "free"....but there will be LOTS of DTV stations...too many actually.... :cool:

The rest of us on terra firma will have to live with reality:
http://www.hdtvprimer.com/ANTENNAS/siting.html

cpcat

10-28-05, 02:25 PM

Recommend you start Astronaut training....you'll be moving to the Space Station.
PS: I hear that it isn't very "free"....but there will be LOTS of DTV stations...too many actually.... :cool:

The rest of us on terra firma will have to live with reality:

]

You can say whatever you want, I'll bet mine is still bigger than yours. :p

The "reality" is that random multipath degrades the signal and using the reflections to somehow pad the gain figure doesn't make sense. I guess you could just reset the zero point up 3db for everyone but I don't see what good that would do. Maybe a new gain convention could be invented and called dBc (dB Cozad):)

Newer digital receivers may be able to take advantage of these reflections at some point, but for now that's still vaporware.

deconvolver

10-28-05, 05:05 PM

You can say whatever you want, I'll bet mine is still bigger than yours. :p

The "reality" is that random multipath degrades the signal and using the reflections to somehow pad the gain figure doesn't make sense. I guess you could just reset the zero point up 3db for everyone but I don't see what good that would do. Maybe a new gain convention could be invented and called dBc (dB Cozad):)

Newer digital receivers may be able to take advantage of these reflections at some point, but for now that's still vaporware.
You are right that the gain results in one multipath environment are less applicabe to another multipath environment than the free field results would be. Both multipath cases differ from the free field case but possibly in the opposite direction. When a manufacturer like Winegard carefully adjusts the measurement set-up to increase the gain numbers they are making the results less reliable.

With a single antenna input it is mostly BS to say that you get an improvement by combining the multipath signals a-la the casper chip set. The reason for that is that when multipath causes a dip in the signal spectra below the noise floor at a frequency there is no way to recover that portion of the spectra. That fact and the case where the multipath lag is outside of the filter's adaptive range are the main reasons that multipath compensation fails in a receiver. So don't expect magical results from future receiver chips; the best that will happen is that the range of multipath lags (and rate of change of lags) that can be compensated may be extended.

DR_LaRRY_PEpPeR

10-29-05, 05:28 AM

I think you'll find the panels are bonded with heavy guage wire on each going to a metallic water pipe or being connected by metallic conduit or something like that. That takes care of bonding the rods. Giving the antenna its own ground rod provides a shorter distance to ground while bonding it keeps the rods at the same potential. Lightning arrestor systems use a number of bonded ground rods around a building for maximum protection. 6ga bonds are earth to earth while grounding wires are air to earth. Earth conducts high energy electricity better than air and you want to keep as much of that energy in your grounding system as possible.

I like the pipe clamp style of connection for masts better than strap connectors because they bite through the mast's anti corrosion coating and provide an air tight area of contact due to the pressure involved. When attaching a strap to a steel mast, getting metal to metal contact can be more difficult and bimetal galvanic corrosion can occur more easily.

A split bolt would be the way to connect two ground or bond wires. Again, check your local codes. The NEC says the following are permitted grounding points. (a)The building or structure electrode system as covered in 250-50. (b)The grounded interior metal water piping system as covered in 250-104 (a). (c)The power service accessible means external to enclosures as covered in Section 250-92 (b). (d)The metallic power service raceway. (e)The service equipment enclosure, or (f)The grounding electrode conductor or the grounding electrode conductor metal enclosures. The panel ground wire indoors with a split bolt attachment to a grounding wire or bonding wire is a fine connection but if you want to meet code requirements, I'm not sure if (c) covers it.

Again, thanks Pat. :) The 2 service panels are touching, and there are 2 other ground wires going in or out of each, but I didn't look to see where they go, but nevermind about that, since it looks like they probably do bond somehow. :) The wire out to the rods looks to be 7 strands of 16ga -- so would that be 8ga?? I guess connecting to that wouldn't be good enough for bonding (it's not more than 6' to the rods)?

Anyway, I checked at Lowes and 6ga solid was $0.40/ft. :eek: I thought it might be half that, but that was an uneducated guess. :p And it appears very stiff to work with.

It's the sat. dish with its own rod now, the antenna will go to the service ground. Since the sat's has been unbonded for over 8 years (yes! :o), and we will be moving sometime, is there anything cheaper I can do instead of buying 55' of 6ga? I mean, anything would be better than unbonded, right? There's some 12/2 with ground here (not sure how long), and using those 3 wires together would be like an 8ga, correct?

Stranded 10ga (white) was $0.27, and I need almost 40' to go from the antenna to grounding block (I'll go "through" it to ground, one of your posts said it's OK); I'll use bare or whatever for the 20' or so to service ground. Then I saw the Shack has 40' aluminum wire (www.radioshack.com/product/index.jsp?productId=2049611) for less and it appears white-ish in the photo, but I'm thinking that's wrong and it's actually bare... Besides, you shouldn't put aluminum with copper, at either the block or panel connection, right? (Though I saw some of the split bolts DO have a separator.) The sat. ground wire is aluminum connected to the copper rod -- would that explain why the wire just "broke off" the rod a few months ago (galvanic corrosion)? (Or the aluminum was/is too close to the earth.)

I'm not going to use a mast, but just tie the antenna across the roof peak (seems OK, no one said not to, and I'll have a few small sheets of aluminum on the peak for it to rest on), so I was asking about the strap since I can't use a clamp as far as I know. Then I realized they must be copper for use on water pipes, and that shouldn't be on the aluminum boom? Are there aluminum straps, or what should I do? If so, I assume they can handle a copper wire. :) Ahhh, I don't know how it's all going to fit together when I don't know the details about parts, etc. :eek:

Oh BTW, I don't think we have any local codes here -- unincorporated, not "officially" in any city. We built the house ourselves (vast majority :)), hands-on, and I don't think there was even an inspection of things (?). :eek: But the one doing the wiring was an electrician-type, so things WERE done according to [national] code, I remember.

Well, thanks for any more advice! :)

sregener

10-29-05, 07:41 AM

Anyway, I checked at Lowes and 6ga solid was $0.40/ft. :eek:

While code calls for really large wires, I've never understood the need for it, myself. After all, we're talking about bleeding off static discharge, here, not carrying 2,000 volts. And if you look at the included "grounding wire" on most RG-6, there's no way it's 6ga. I personally have used single-strand, 16ga covered electrical wire and haven't had a problem with it. When my professional installers came, they grounded the tower, but said not to bond the grounds at opposite ends of the house, saying it would cause more problems than it would solve. No problems with that, either. All of this "to code" talk makes me think that codes are written for "worst case" protection, and few, if any of us, need that kind of protection. But I'm not saying that if you don't do it "to code", that everything will be fine (in order to cover any legal bases.)

DR_LaRRY_PEpPeR

10-29-05, 07:49 AM

Yeah, I get what you mean. :) I'll see...

I think the large wire IS for in the event of a lightning strike, not just for static. Although a lightning hit would still do damage ANYWAY, so... :confused:

And the grounding wire only needs to be 10ga copper (the 6ga is for bonding). What comes on coax is 17ga copper-clad steel or bronze, I believe, which is the same "capacity" as solid 10ga copper, I guess. :)

greywolf

10-29-05, 07:55 AM

You really need to use a mast. Aluminum sheets will become part of the antenna's configuration, and not a good part, plus tying is not secure enough for outdoor wind conditions. I don't like that aluminum wire. It breaks and corrodes too easily. The chart at http://en.wikipedia.org/wiki/American_wire_gauge indicates that the cross sectional area of a 6ga wire would be handled by four 12ga wires. Don't skimp. It's false economy. You may not have had a nearby lightning strike in 8 years but you may have one next week.

It doesn't take much to handle static bleed. 17ga copper coated steel or bronze used in coax messenger wire is fine for grounding the mast. It is not the electrical equivalent of 10ga copper but doesn't need to be. The 10ga copper requirement for a grounding wire is way overkill. The 6ga bond wire requirement is vital though. A nearby lightning strike can cause a large potential difference between two grounding rods and a heavy enough wire to prevent that potential difference from traveling through your equipment is required.

See:
Preventing Damage Due to Ground Potential Difference
http://www.cinergy.com/surge/ttip08.htm

DR_LaRRY_PEpPeR

10-29-05, 08:18 AM

About the mast... it's not just buying a mast, mount, putting holes in the roof, etc. that I want to avoid, but I have none of the hardware that came with the antenna (I could easily get U-bolt, etc.), such as the support boom. Don't know what happened to it. The aluminum sheets are only about 6"x9", just so it wouldn't sit on the shingles at the peak. I didn't know that just touching the boom (not elements) would make it "not a good part," since masts, grounding etc. touch the boom... :confused: And seems to me (but what do I know? :D) that guy wiring near the ends of the antenna to the overhang a few feet away (where the gutter would usually be -- no gutter on this section) should provide as much support as just a mast only in the middle of the antenna.

OK, I understand about the bond wire. :) So, if 10ga copper is way overkill for the ground wire (good to know), which size should be used? 12, 14, smaller? And does that go for both the wire from antenna and the grounding block? Thanks.

greywolf

10-29-05, 09:22 AM

Just about anything can be used for a grounding wire for static bleed purposes. Be aware that using a heavy guage wire with as straight and short a run to ground is often recommended in case of a lightning strike. My feeling is that a grounding wire is about lightning strike prevention though and static bleed is the real benefit. If you get hit you have a problem regardless of wire size so not getting hit is the thing. Static bleed is the best way not to get hit.

Since you say you don't have local codes, check with your insurance company to make sure you won't have a problem with them before using any grounding wire not recommended by the NEC.

Metal in line with and near the antenna becomes part of the antenna system. A mast has a small cross section, is far from the element ends and is at right angles to the antenna plane. Metal sheets in the boom plane and metal guy wiring on the elements may hurt your reception. Try it and see if it work for you if you want. What's important is that it works. Remember that height is usually a good thing too.

bobchase

10-29-05, 09:51 AM

...The 6ga bond wire requirement is vital though. A nearby lightning strike can cause a large potential difference between two grounding rods and a heavy enough wire to prevent that potential difference from traveling through your equipment is required.
Greywolf nailed this one. Lightning strikes don't even have to touch the ground to cause damage to a house. Cloud-to-cloud lightning bolts causes a mirror current to flow in the earth. (A lightning bolt can have a hundred thousand amps flowing in it.) If your grounding rods are not bonded together, then a voltage drop will appear between them from the current flowing in the earth. Some people are lucky and never see the affects caused by this. Others (like me) have had to spend days repairing the equipment that burned up from improper facility grounding. Always bond your ground rods.

Bob Chase
KHWB-TV

AntAltMike

10-29-05, 10:06 AM

Unincorporated communities are often subject to certain state regulations that are passed just for that circumstance, such that they are the controlling regulations in the absence of any local laws. I remember seeing such statutes when I read the Maine state statues about twenty years ago. But as apractical matter, compliance regulation will not likely ever be preemptively enforced by anybody,

The purpose of mandating a minimum size for the mast ground is probably to better assure survivability. Otherwise, even a weak or nearby strike of lightning might melt it, but the owner surely would not realize that it had been broken. The mast ground must be either 8 gauge aluminum, 10 gauge copper or 17 gauge copper clad steel.

In the case of ground wires intended to shunt away high current sources, the minimum size was determined to assure that it had equal or greater current carrying capacity to the circuit it was to shunt the current from, as well as to assure that the resistance was such that no dangerous potential could be sustained between the two grounded items. The ground on the outside of the coax must be solid, insulated copper, approximately equal to the current carrying capacity of the coax's outer conductor but under no circumstance can it be smaller than 14 gauge. Otherwise, if a line voltage source were to come into contact with the outer conductor, as it might in a number of ways, like if an outside electical power line broke during a storm, the ground wire would melt first and then the current would readily flow along the coax and into the residence.

deconvolver

10-29-05, 11:18 AM

The best rule is to follow the NEC unless your local inspector tells you otherwise. The code is based on many years of investigating mishaps like fires and electrocutions and it is not a good idea to think that you are smarter than the code- even if it may seem to have a few rules that are overly strict.

cpcat

10-29-05, 11:42 AM

I just returned from Lowe's and it seems they've scaled back their antenna product section considerably. They no longer carry the CM 3041 preamp, the CM distribution amps or the CM 9251 rotator. I couldn't find any masting either.
Dissappointing.

greywolf

10-29-05, 11:59 AM

That's a good point about the grounding wire being strong enough to handle physical strain. It would explain why 17ga copper clad steel or bronze, 10ga copper, and 8ga aluminum would serve an equivalent purpose.

kflorek

10-30-05, 01:29 AM

I put up 2 antennas with rotors on my roof recently, and here are some comments:

I got a Zenith rotor from Buy-com and a Magnavox rotor from SummitSource-com. They use the identical antenna motor. The paint is a little different shade, and the enamel on the motor wire is a different shade. The packing in the box is also identical. The outer casing is cast aluminum, the bottom access plate is steel.

The controller of the Magnavox's is operated by turning a knob, and the Zenith is electronic. The 3 conductor rotor wire delivers a low voltage AC current (about 18 Volts).

I prefer the knob controller, and it is cheaper. The controller is some sort of motor/transformer that turns to sync with the knob, and while it does, the outside motor turns correspondingly. I don't really know much about the principle of operation, but I believe the two motors, inside and outside, are "phase locked", keeping them in sync except when there may be an extreme load on the outside one, such as from high winds or rotating to the end stops. The controller's motor makes a quite prominent buzz while it is activated.

The Zenith is silent. It can be operated by buttons on the set-top box or with a remote control. There are red LED digits for indicators. Two digits show the angle of rotation divided by 10, that is they go from 0 to 36 as the angle of the antenna goes form 0 to 360. A separate, single LED displays the "program," from alphabetical "a" to "L" (12 programs.) You program it by moving the antenna to a position (by C/CCW buttons), pressing the memory button, then a button from a to L. Pressing a button from a to L by itself makes the rotor go to a programmed position. The programming is retained if the controller is unplugged. There is an "intialize' button so that you can sync the outside with the inside without having to hold down the C/CCW buttons for a minute. If you unplug it, the display goes to 36 regardless of where it was before.

I picked the Zenith over an electronic Channel Master because (1) the Zenith can be operated from the box as well as with a remote, while the Channel Master is by remote only, and (2) the Zenith has an internal power supply, versus one of those PITA external transformer/plugs for the CM. My reading of materials also gave me the impression at the time that the CM did not hold its programming when the power was removed, but I saw later somewhere that it does.

I've always had good luck with Buy-com and the shipped price was vitually the same as, or lower than the many, many other places that carry this Zenith. As is typical from good suppliers, it took 2-3 days for ground shipping from California to here.

SummitSource got the Magnavox (and rotor cables) here fabulously the next day with ground shipping. It seems to be located at the opposite end from me on one one of UPS's standard hops. Unfortunately the rotor motor was defective and it took 26 days to eventually get a working unit, most of that waiting for replies to 2 sets of 3 emails, since it only took 1 day as well to get the return back to them via UPS ground. That was with them sending me back the same unit once, "checked out and working fine," but actually still defective as before. The original unit appeared to be "pre-owned", because the small parts bags were opened before I got it. It was in like-new condition, except for a mysterious glob of tenacious white goo on the cord, which I think is sometimes done to mark refurbs. (Incidently, the date of manufacture on the label was 1998.) The final unit worked just fine, but it had a slight chip out of the casting and minor scratches, like someone had dropped it on a concrete floor and it slid a ways. I was very happy to get it, because by that time I was believing they were giving me the run-around. The price of this Magnavox unit shipped from Buy-com was only about $3 more, as I recall. What actually tipped the deal toward SummitSource was the two 75 foot rotor cables, which were way cheaper, and only a few pennies more for shipping. It would have been a good deal if it had worked right.

The Magnavox did not have a warranty of any kind, on the box or inside it. Nothing. I never encountered anything like that before. The Zenith specifies a lifetime warranty on the box. The warranty is by returning to the seller. Somehow I doubt if a retailer will be accepting warranty returns of, say, ten year old units. Anybody know of a successful return along those lines? Nevertheless, it is better to have some warranty rather than none.

DR_LaRRY_PEpPeR

10-30-05, 06:33 AM

Thanks for the additional posts guys. :)

I went ahead and got 12ga stranded for the ground wire. Home Depot is cheaper than Lowes here -- they have stranded 6ga for the same price as Lowes' solid... I'll get that then after I see exactly how much I need.

I haven't found a grounding strap for the boom yet (forgot to check at Lowes :(). So I picked up a bronze clamp that I thought I might be able to put on there. Now I think I could've gotten a smaller one, which was... zinc (?).

What "device" would you suggest to attach the ground to the square boom? Does the bronze or zinc, in the case of these clamps, act as a proper "separator" between the aluminum and copper? (I don't totally get what's needed to prevent corrosion...; and since our dish's aluminum ground is on the copper rod, I guess THAT IS that why it just broke off after all these years).

Regarding bolting the 6ga bond wire to the service panel grounds: since they appear to be 8ga (7 strands of 16ga), that would defeat the purpose, right? BUT, I thought since there's a wire for each rod/panel, will it work to bolt to BOTH of them? Should be the equivalent cross section of 5ga...

cpcat

10-30-05, 06:47 AM

I put up 2 antennas with rotors on my roof recently, and here are some comments:

I picked the Zenith over an electronic Channel Master because (1) the Zenith can be operated from the box as well as with a remote, while the Channel Master is by remote only, .

Thanks for the info. FYI the CM 9251 rotator *can* be controlled via the controller box (up and down degree function) as well as the remote. Position is also selectable in one degree increments (via remote only).

AntAltMike

10-30-05, 02:31 PM

I haven't found a grounding strap for the boom yet

Regarding bolting the 6ga bond wire to the service panel grounds: since they appear to be 8ga (7 strands of 16ga), that would defeat the purpose, right? BUT, I thought since there's a wire for each rod/panel, will it work to bolt to BOTH of them? Should be the equivalent cross section of 5ga...

The boom doesn't have to be grounded, according to the letter of the code. The mast does. One electrical inspector once wouldn't let me simply ground the bracket supporting the mast because it wasn't the mast.

I don't know if connecting to two 8-gauge wires satisfies the requirement of connecting to one 6 gauge wire, since, during a surge, there is no assurance that the current will be divided equally and theoretically at least, the one carrying the bulk of the current could prove to be insufficient and melt. It certainly would be durable enough for me to be able to sleep soundly if I lived in a house with a system so grounded, however.

How did you determine that the service panel ground strands were 16 gauge? What is the strand composition of 6-gauge stranded wire?

kflorek

10-30-05, 11:42 PM

Thanks for the info. FYI the CM 9251 rotator *can* be controlled via the controller box (up and down degree function) as well as the remote. Position is also selectable in one degree increments (via remote only).
I didn't do justice to the CM, if people are looking for a review of it. The only particulars I mentioned were those that explain why I picked the Zenith. Here are more comments:

I expect that most people would go for the CM, hands down. Not the least reason is that the CM rotor, in it's old electro-mechanical version, has a long term, near-legendary record. For instance, before I moved to this house, I used that particular rotor for 25 years in the former house, and it still worked the same as it did new. (Yes, I went through a couple of antennas, a couple of masts, and a few downleads.) I would think the antenna motor of the electronic version could be as durable.

Since I do not have a CM 9251 rotor, I can't really judge it, but here is some more info. Although both the CM and Zenith are programmable, the user interfaces are totally different. The CM selects programs (preset antenna positions) by numbers. There is a number for every broadcast channel. True, no one is going have that many different antenna positions, but with the overkill you can just use the same number for the program as the channel. For people with a lot of positions, say over 4, it is going to be much frendlier than the Zenith system. The 12 Zenith programs may be more than anyone will have a use for, but that requires you to remember what letter goes with a particular channel (or write them down.)

I wondered why Zenith went with letters when they could have used numbers, considering 7 segment LEDs do not form very good letters. Maybe because it is confusing to remember that a number goes with some other number, rather than with some letter. Maybe because you only need to hit one button, not two.

As mentioned by cpcat, the CM will also take direct entry in degrees, if you like; the Zenith won't. The capability could come in handy finding weak or new stations. Just get the position from antennaweb-org.

The CM displays all three digits needed to specify 0 to 360 degrees. The Zenith oddly cuts corners and just displays the first two. Zenith does seem to keep the exact position in the programs though.

I guess the two buttons on the CM set-top-box does allow it to be operated from the box, in a basic way suitable for a back up. You have to hold the buttons until the antenna gets to its correct position. Even with the electro-mechanical Magnavox, you just turn the knob and leave it. It rotates into the designated position on its own. With the Zenith, programs can be selected at the box, and the antenna motor synced at the box. You don't have to stand there waiting with your finger on a button for 70 seconds. It can also be programmed at the box.

Despite all the remote controls, I usually gravitate to the buttons on the object itself. Therefore I like gadgets to have the controls on them if at all possible.

None of the differences will be a big deal for most people. Then it will come down to price and idiosyncratic likes and dislikes.

In point of fact the rudimentary Magnavox will be MY rotor for MY TV. The Zenith will be for the main TV of the house, mainly used by others. I like gadgets, but I'm so saturated with 'em already, I really don't want another one just to have it. In the end, the possible additional capablilties of an electronic rotor have so little practical value to me that I passed. I was worried that the Magnavox might be "too" chintzy on account of the price, but it turns out to have the identical antenna motor.

The frendliest interface of all would be a remote with a rotating knob like the old CM's or the Magnavox.

cmk

10-31-05, 01:13 AM

I currently have a CM4228 antenna in my attic. I am having multipath issues with it. Just for a test I borrowed my Dad's Silver Sensor. To my amazement the Silver Sensor is outperforming my CM4228. I am baffled. I am going to try to relocate the CM to a higher spot. My struggle is the CM is so big I either need to try to take it apart of cut a bigger hole in the plywood to get the the point in the attic I want to relocate it too. Has anyone ever heard of a SS outperforming CM4228. That little antenna is amazing.

DR_LaRRY_PEpPeR

10-31-05, 06:53 AM

The boom doesn't have to be grounded, according to the letter of the code. The mast does. One electrical inspector once wouldn't let me simply ground the bracket supporting the mast because it wasn't the mast.

Grounding the mast DOES ground the boom since they're obviously connected. Else static would build up in the boom...

I just realized last night that it looks like I can bolt my grounding clamp through the boom's U-bolt holes. I originally thought I was going to put the grounding strap, or whatever, on the lower wing-boom, but I don't know that that's a good idea to have the extra metal "in" the UHF portion, so this seems better.

Is having the stranded ground wire (the stripped end since I wanted white) exposed in the weather going to make it corrode, etc. more than a solid one? I suppose... Anything to do to for protection?

How did you determine that the service panel ground strands were 16 gauge? What is the strand composition of 6-gauge stranded wire?

I can tell the gauge just by looking. :p No, I checked to see which hole in the wire stripper a strand would fit in. :) I think different ones use different numbers/sizes of strands for the desired flexibility, so I don't know about 6ga. The 12ga I got seems to have 18-20 strands. :eek:

sregener

10-31-05, 07:50 AM

I guess the two buttons on the CM set-top-box does allow it to be operated from the box, in a basic way suitable for a back up. You have to hold the buttons until the antenna gets to its correct position. Even with the electro-mechanical Magnavox, you just turn the knob and leave it. It rotates into the designated position on its own. With the Zenith, programs can be selected at the box, and the antenna motor synced at the box. You don't have to stand there waiting with your finger on a button for 70 seconds. It can also be programmed at the box.

Despite all the remote controls, I usually gravitate to the buttons on the object itself. Therefore I like gadgets to have the controls on them if at all possible.

The CM actually has 3 buttons, the third being "sync" which doesn't require 70 seconds of button pushing. :)

I think most of us would prefer not to get up from our lazy chair, walk across the room, and turn a knob in order to change channels. That is so.... 1970s. :rolleyes:

Part of the reason I went with the CM remote was because it was the only motor that was different. All the others come from the same factory in China, and my original rotor lasted less than two years from them. Believe me, it wasn't a happy day when I risked an icy roof to turn the antenna from its locked-up position as a stop-gap until spring when I could replace the rotor safely. Months of staticy, poor reception convinced me I needed a motor that would last.

ssabripo

10-31-05, 09:31 AM

Ok Guys....I need your hand here, as I am now stuck and confused:

as some of you know, hurricane wilma caused some major problems to us here in south florida, and my house suffered some damage...one of the casualties was my HDTV antenna which I had on the roof, which was an RCA ANT711:
http://images.amazon.com/images/P/B00008V6JT.01-A2R0FX412W1BDT._SCLZZZZZZZ_.jpg

Anyways, I spent the whole day installing two antennas from Channel master: the 3018, and the 3020:
http://images.lowes.com/product/020572/020572030182.jpg?wid=158&cvt=jpeg
Niether of these worked as good as my old antenna, because they were not able to get the West Palm beach channels...my guess is that this has to do with the fact that they are directional.

Now, here is a pic of what my location is like...as you can see, I need to get some channels to my south-southeast, and some to my north-northeast......thus, I need an antenna that will be able to pick those up (clik to enlarge):
http://www.ihostphotos.com/imgt/186979.jpg (http://www.ihostphotos.com/show.php?id=186979)

My question is then, what antenna should I get? At worst, I will just get another RCA to replace the one I had, but the problem is that it is made of plastic, and it wasn't very sturdy...it would also be intermitent in strong winds and heavy rain. I know I need a multidirectional antenna, so I don't know what to do, or what to get....

ps- the max distance is 33.5 miles to the north-northeast

UnderDaHill

10-31-05, 03:36 PM

ok... I'm making progress on my setup.

I've got the Windows Media Center software and will be installing that tonight along with a Fusion5 HDTV tuner card and Hauppage(sp) 150mce standard def tuner card. The first gen Xbox now has a media center extender DVD and remote (will be used on 30" widescreen until the xbox 360 is released).

I've got a coax line running up to the attic from the basement (where the computer is located). That line will attach to whatever uhf/vhf antennas I pick. Now here is the question.

I use COX broadband service. That will be the only part of the COX service I'll have after I drop their basic cable service. My question is can I combine my antenna signal line with the COX line coming into the house that has the broadband signal on it and then just route that singal all over house with the existing coax network that COX installed?

I'm wondering if that will cause issues or if I'll have to have some sort of splitter to peel off the broadband signal for the antenna signal before routing that to the cable modem and/or tuner cards OR if the cable modem and tuner cards will ignore the inappropriate parts of the signal. Can I combine them? Will this degrade or compromise the broadband and/or uhf/vhf signals?

Suggestions?

I'm trying to avoid having to run another coax line from the patch area in my laundry room out to the computer for the uhf/vhf signal. I'd like to use the existing cable to carry both signals to the computer if possible.

greywolf

10-31-05, 03:42 PM

CATV and antenna signals cannot run over the same line. They cover pretty much the same frequency range.

UnderDaHill

10-31-05, 03:54 PM

Doh! So much for using one line to get both signals to my PC.

ANyone else have any suggestions? Could I run the signal from the attic to the basement and then have a rebroadsaster or something in the laundry room to pump the signal out so a small antenna at the PC could pick up the internal uhf/vhf signal?

greywolf

10-31-05, 06:41 PM

How about an A/B switch to switch to choose between CATV and OTA?

Jim5506

11-01-05, 09:14 AM

wanger

11-01-05, 12:07 PM

hey guys, I have a really old coxial cable that is probably 10 years or older. I recently bought a hdtv, and I want to be able to watch hd channels with my ota antenna. However, will I need a new set of coxial cables to be able to watch digital and hd channels?? Thanks in advance!

newsposter

11-01-05, 01:35 PM

RG6 is always better than the old rg 59 you probably have. But the only sure test is hook it up, if it stinks, re-wire, if it doesn't....well...no need to rewire in theory but I never heard of new wire degrading a signal, only improving it :) I guess it would depend on how easy it is to rewire. If it's easy, I'd spend the bucks to lay in new wire no matter what.

bernieoc

11-01-05, 04:13 PM

I would like to try a complex situation on you. In Altavista (high point in town)I have Roanoke at 285 deg 47 miles and Lynchburg at 315deg 23 miles a 30 deg spread.
With RS combo VU190xr pointed at about 307 deg I get all with Roanoke 18 and 3 on the edge.Tried pre amp CM7777 with no effect I am looking into edge of a tree on another property (200 yds). Wind can be a problem so I am clearly working with some reflected signals.
Going toward Roanoke at 285 deg puts me into heavy nearby trees and more problems and if far enough a loss of Lynchburg ch34. Otherwise Lynchcburg 20 and 34 are very forgiving. Aiming more toward Lynchburg takes me out of the tree but start losing Roanoke (first 18 & 3)
I would like to enhance my 307deg aim with a better UHF to improve 18 from Roanoke and have all UHF without Rotor and even play around more to improve all without worrying about ch3.
For ch 3 I will use a separate VHF and find its best spot and combine both with CM7777.

How about CM4221 and Wineguard low vhf 1026. Or 4228 or w8800 (good on low uhf)
or XG91 and for vhf Wade single ch 3, or even a better combo ?
I am very close now,you can see why I am confused. More gain -less gain- wide beam - narrow beam.
Thanks for your advise

sregener

11-02-05, 06:33 AM

How about CM4221 and Wineguard low vhf 1026. Or 4228 or w8800 (good on low uhf) or XG91 and for vhf Wade single ch 3, or even a better combo ? I am very close now,you can see why I am confused. More gain -less gain- wide beam - narrow beam.

I'd try the Channel Master 4221. It has the best odds of succeeding at what you're trying to do. However, getting success with both locations is going to be something of a crap shoot - you might get lucky, but then again, you might not.

Based on my experience with the 91XG, I can aim about 30 degrees off-axis and still get strong signals on local digitals (approx 30 miles, no line-of-sight.) But for long-distance reception, it has to be aimed precisely - 1 degree makes a difference.

cpcat

11-02-05, 07:04 AM

I
How about CM4221 and Wineguard low vhf 1026. Or 4228 or w8800 (good on low uhf)
or XG91 and for vhf Wade single ch 3, or even a better combo ?
I am very close now,you can see why I am confused. More gain -less gain- wide beam - narrow beam.
Thanks for your advise

If you have disposable time (and possibly money) you can do a lot of trial and error to try to find something that will work. It's a crapshoot really but you might get lucky.

The CM 7777 will diplex uhf and vhf for you so you can easily separate uhf and vhf for independent aiming. You can further separate it into low vhf + high vhf + uhf by adding a hi/lo separator on the vhf side which will then give you independent aiming of all three assuming you have room for three antennas on the mast.

There's no free lunch. Wider beamwidth=lower gain and performance. No way around it. That's what rotators are for.

newsposter

11-02-05, 07:25 AM

I just realized how lucky I am that all my channels are at the 130 except fox at the 128 and I was able to get it in the 60s and a watchable signal. I couldnt even imagine 3 antennas! I feel for you as getting all this aimed right took forever for me.

Plus with a rotator, you can't even record while you are away unless it's already pointed the right way.

cmk

11-02-05, 12:15 PM

I have been using a CM4228 in my attic for almost a year. It works fairly well but at times I have multipath issues. It is in a pretty tight space in my second floor attic but pretty close to the attic floor because of the roof liine. The CM4228 is too big to get through the access hole to the higher point in the roof. Just out of curiousity I hooked up a Zenith Silver Sensor and to my amazement the SS is outperforming the CM4228. However since the SS is so directional I am having trouble getting a couple stations. My question is can I combine the SS and CM4228 pointed in slightly different directions. The antennas are about 15-20 feet apart in in different areas of the attic? Please advise if this is at all a viable solution and what type of combiner/splitter I would need. These antenna would go into my multiswitch after being combined.

sregener

11-02-05, 05:02 PM

My question is can I combine the SS and CM4228 pointed in slightly different directions. ...Please advise if this is at all a viable solution and what type of combiner/splitter I would need.

Can you? Yes. Should you? No, with one exception: if you only need one channel from one of the antennas. In that case, you could use a Jointenna for that channel (they have two inputs - one for the desired channel and another for "everything else.") Otherwise, your results will be unpredictable - you're creating multipath. Maybe it will be better, but odds are good it will be worse.

PA_MainyYak

11-03-05, 02:52 PM

sregener

11-03-05, 03:57 PM

Greetings all!
I'm new to this forum and to HDTV. Here's my quandry: I have the potential to pick up around 10 DT stations in a 180° arc. I'm planning to use a Channel Master 4228 mounted on the roof with a rotor (and preamp).

...No preamp is needed for the WJAC-DT signal, and will likely cause trouble. The other signals however would appear to require some boosting.

I have had success in the past picking up the Pittsburgh analog VHF stations with a Radio Shack antenna on a rotor.

4228s are murder on consumer-grade rotors. Look into either getting a rotor bearing (http://www.starkelectronic.com/cmmatv.htm#rotor) or a different antenna. For all practical purposes, the AntennasDirect 91XG is at least as good, if not better, and puts much less stress on a rotor. I've posted my review of the 91XG, and at least one other person has posted their results from replacing a 4228 with a 91XG.

A preamplifier is going to kill you. The strong local signal means that the amp will overload, and that will destroy all of your distant signals. All you can do is filter out the local station and hope for the best. However, don't assume you need a preamplifier - not everyone does, and I've gotten good results at 50+ miles without one.

As you may know, VHF and UHF are horses of different colors when it comes to long-range reception, especially when you're physically blocked. You may catch some diffraction from the ridge, or you may not. All you can do is put an antenna up and try.

cpcat

11-03-05, 04:18 PM

Greetings all!
I'm new to this forum and to HDTV. Here's my quandry: I have the potential to pick up around 10 DT stations in a 180° arc. I'm planning to use a Channel Master 4228 mounted on the roof with a rotor (and preamp).
The stations, distance from me (in miles), and bearing:
WJAC-DT 3.5 319°
WWCP-DT 15 227°
WNPA-DT 14 224°
WTAJ-DT 31 58°
WATM-DT 31 58°
WPSU-DT 60 25°
WTAE-DT 46 266°
WPXI-DT 57 279°
WPGH-DT 57 282°
KDKA-DT 61 292°

No preamp is needed for the WJAC-DT signal, and will likely cause trouble. The other signals however would appear to require some boosting.
I'm especially concerned with KDKA since its bearing is rather close to the very strong WJAC signal, and with WTAJ dragging feet on HD, KD appears my only only other OTA option to catch CBS HD programming (Go Steelers!).

My home is 1550 ft above sea level with a reasonably open view to the west (other than the 3100' Laurel Ridge :) ).
I have had success in the past picking up the Pittsburgh analog VHF stations with a Radio Shack antenna on a rotor.

Any thoughts, advice, or dire warnings gladly accepted.

Sregener gave you good advice. The CM 4228 is a large wind load. I load my CM 9251 rotator probably more though and so far it has held up. If you've not already bought the 4228, definitely consider something like the xg91. You'll sleep better at night.

As far as your reception is concerned, I'd agree to be real concerned about the station only 3.5 miles from you for preamp overload. You can get a channel 34 Jointenna from CM and use just one side of it to attenuate 34 (will also attenuate 33 and 35 significantly). I'd *still* worry about the two other stations which are only 14 miles away, though. The only way to know is to try. You might consider a lowish gain preamp like the 20db version from antennasdirect (will not pass vhf) and then an in-line amp indoors such as the CM 3042 at the first split if needed. This should give you higher immunity to input overload vs. using a single high gain preamp.

PGDave

11-03-05, 05:53 PM

cpcat

11-03-05, 06:54 PM

I recently tried stacking two XG91 antennas vertically. Expecting improved reception, I was disappointed to find that signal strength had actually decreased somewhat.

The antennas were placed 40" apart boom-to-boom and oriented in the same direction. I used equal length RG6 from each balun to an ordinary splitter and from there, I used a short length to a CM 7777 preamp and then down to the power supply and receiver.

I think that using the splitter in reverse may have been where I went wrong. I am now looking at either a Winegard CC 7870 or a Channel Master 0538 antenna combiner. Each says that one port passes DC for the preamplifier and the diagrams shown on their web sites suggest that the preamp is used for only one antenna.

Does anyone have an opinion as to which combiner is best and how the preamp should be attached in the array? Out of the combiner into the preamp or one antenna to the preamp and then to the combiner? I would also appreciate any comments as to whether my spacing is correct or any other issues that I should address. Thanks.

I

40 inches spacing is in the ballpark so that's not your problem. Around 36 is what I've used. Be sure the splitter you are using is wideband (at least 1 mhz). The preamp is best inserted as you have it currently and that's really the only way it will work. Be sure the FM trap is "in" on the 7777. Two UHF antennas stacked make an even better FM antenna than one.

Look at the xg91 baluns. There is a question as to whether they are PCB or ferrite core. If they are PCB then the phase *should* be matched for you. If ferrite core, you may have to switch the phase by switching the leads from the antenna to the balun. Alternatively, you could turn one antenna upside-down but you'll have to rotate the u-bolt clamps 180 degrees to keep the mast on the same side of the antenna. If the baluns are out of phase it won't work; the signal will actually cancel. An out-of-phase stack will behave as if it can only see from the sidelobes and the main forward lobe will be nulled.

As I've said before, vertical stacking in my experience isn't as good as horizontal, but it should be better than one antenna. In California, I'd suspect horizontal will definitely be the better of the two.

PGDave

11-03-05, 07:23 PM

Dr_EluSivE

11-03-05, 07:50 PM

Hi, I have a 4 bay UHF antenna mounted in my Attic (looks like a CM 4221, but its probably 25 years old...) and Currently i get all the channels i expected to get OTA so i am pretty happy with it, however i am adding another HDTV in another room and i want to hook that up to this same antenna. I am afraid if i do this though i cut my signal down to much and neither one will work. (some channels are borderline) I was thinking that if i have this problem a Preamp might be a good idea, What kinds are good? I have used cable preamps before and ended up with Worse picture and ghosting so i dont want to get something cheap that will make it worse. I am going to try without first, but i bet i will lose a few. I just plan on spitting the 75 Ohm coax that comes out of the 300Ohm transformer. Does this sound reasonable? How much drop do you think i will have? the current TV is 100' away from the Antenna, and the other will be atleast 30. (long ranch style house)
heres my antennaweb info..
DTV Antenna
Type Call Sign Channel Network City State compass Orientation Miles
From Frequency Assignment
* yellow - uhf WRSP-DT 55.1 FOX SPRINGFIELD IL 58° 16.0 44
green - uhf WICS 20 ABC SPRINGFIELD IL 56° 15.5 20
green - uhf WCFN 49 UPN SPRINGFIELD IL 52° 12.7 49
green - uhf WRSP 55 FOX SPRINGFIELD IL 58° 16.0 55
* lt green - uhf WCFN-DT 49.1 UPN SPRINGFIELD IL 52° 12.7 53
* lt green - uhf WBUI-DT 23.1 WB DECATUR IL 67° 48.0 22
blue - uhf WAND 17 NBC DECATUR IL 68° 49.9 17
* blue - uhf WAND-DT 17.1 NBC DECATUR IL 68° 49.9 18
* blue - uhf WICS-DT 20.1 ABC SPRINGFIELD IL 56° 15.5 42
blue - uhf WBUI 23 WB DECATUR IL 63° 49.5 23
violet - uhf WYZZ 43 FOX BLOOMINGTON IL 23° 72.4 43
violet - vhf WILL 12 PBS URBANA IL 66° 60.1 12
violet - uhf WMBD 31 CBS PEORIA IL 8° 66.8 31
violet - uhf WEEK 25 NBC PEORIA IL 7° 66.4 25
violet - uhf WSEC 14 PBS JACKSONVILLE IL 280° 25.5 14
* violet - uhf WSEC-DT 14.1 PBS JACKSONVILLE IL 255° 19.1 15
violet - uhf WTVP 47 PBS PEORIA IL 6° 66.2 47
violet - uhf W29BG 29 TBN DECATUR IL 76° 38.8 29
violet - vhf W08DP 8 PBS SPRINGFIELD IL 28° 11.9 8
violet - vhf WCIA 3 CBS CHAMPAIGN IL 66° 72.6 3
violet - uhf WHOI 19 ABC PEORIA IL 6° 67.7 19
Note:
The above listing is a conservative prediction of stations received. Depending on the specifics of your installation, you may be able to receive stations that do not appear in this list.

Dr.

cpcat

11-03-05, 10:17 PM

cpcat - Thanks for your suggestions. Both antennas have the same type of baluns--they are round cylinders with two wires that attach to the ends of the loop that is the active element. I opened each case and did not see a printed circuit board. I will switch the leads on the bottom antenna.

Any recommendation on which combiner is best? Thanks!

Sounds like the baluns are ferrite core.

Any wideband splitter in reverse will do it. A small improvement can be had by using a low loss stripline combiner such as the one made by Lindsay: http://www.lindsayelec.com/antenna/commercial.catv/v-u-combiners.html

Triax also makes one as well. The incremental improvement will be small though and they're expensive. You'd likely see much more improvement by going horizontal if vertical doesn't do it with your current setup.

The CM 0538 you mention would likely be equivalent to what you're using now.

sregener

11-04-05, 07:00 AM

I recently tried stacking two XG91 antennas vertically. Expecting improved reception, I was disappointed to find that signal strength had actually decreased somewhat.

If you haven't read this page yet, it's a good start: http://www.hdtvprimer.com/ANTENNAS/siting.html

I used the Radio Shack "gold" splitter/combiner (runs about $10) when I tried a stack. It seemed to work pretty well.

I agree with cpcat that a horizontal stack is more likely to improve your reception than a vertical one.

cpcat

11-04-05, 07:02 AM

sregener

11-04-05, 07:05 AM

Chow7

11-04-05, 09:40 AM

If I get the Winegard sharpshooter indoor antenna, would a preamp increase the rage? I am about 37 miles from the station and This antenna says it can reach 30 miles.

sregener

11-04-05, 12:21 PM

If I get the Winegard sharpshooter indoor antenna, would a preamp increase the rage? I am about 37 miles from the station and This antenna says it can reach 30 miles.

Well, I'd advise against the sharpshooter - it's a terrible antenna. And 37 miles is really pushing things in most areas for an indoor antenna. If you want to try an indoor antenna, the Zenith Silver Sensor has worked very well for many.

But adding a preamp is highly unlikely to help at all. It would probably make things worse.

Jim5506

11-04-05, 02:15 PM

Indoor antennas are not reliable beyond 15 miles, no matter what the manufacturer claims.

For 37 miles you need a mid-range outdoor antenna mounted above your roofline.

Amplifiers are non-discriminating, they multiply noise and signal all together.

PA_MainyYak

11-04-05, 03:36 PM

Sregener gave you good advice. The CM 4228 is a large wind load. I load my CM 9251 rotator probably more though and so far it has held up. If you've not already bought the 4228, definitely consider something like the xg91. You'll sleep better at night.

As far as your reception is concerned, I'd agree to be real concerned about the station only 3.5 miles from you for preamp overload. You can get a channel 34 Jointenna from CM and use just one side of it to attenuate 34 (will also attenuate 33 and 35 significantly). I'd *still* worry about the two other stations which are only 14 miles away, though. The only way to know is to try. You might consider a lowish gain preamp like the 20db version from antennasdirect (will not pass vhf) and then an in-line amp indoors such as the CM 3042 at the first split if needed. This should give you higher immunity to input overload vs. using a single high gain preamp.
Thanks all for the advice.
I've modified my shopping list ... now on to the roof!!

sregener

11-04-05, 04:25 PM

Indoor antennas are not reliable beyond 15 miles, no matter what the manufacturer claims.

That's a pretty general statement, and as most general statements aren't always true, this one isn't either.

People have line-of-sight to the transmitters on Mount Wilson in California at 100 miles. Indoor antennas work just fine for many of them. I've seen indoor antennas, sited on the proper side of the building, next to a window, do a good job at over 30 miles. But that was with good terrain, and involved a fair bit of luck. I wouldn't *count* on an indoor antenna beyond 15 miles, but it rarely hurts to try and results may be surprising.

That said, Winegard is really pushing things by claiming a 30-mile range for this twisted piece of metal from the garbage heap.

DR_LaRRY_PEpPeR

11-05-05, 05:54 AM

I finally got my antenna roughly tied across the roof peak yesterday -- ran out of light to get it secured how I think I want it. It's an improvement over the attic for most channels; especially the one I really wanted (ABC). BUT, now the one (RF channel 56) that was *strongest* in the attic, is just barely NOT coming in! (Just under 50%, attic was in the 60s at least.) :mad: About 10 days ago when I first set it up there to test, it was reading in the 60s also I believe. The other channels were the same as now during testing.

On the roof now, it's maybe 8' to the right and 3' higher than the attic position. I wasn't quite in this exact position when I tested. Maybe the foot or two (sideways) changed things... Since I have holes now, I can't really move left or right, just forward/back and change the vertical angle. Maybe the higher frequency 56 is being affected by the roof more (few inches from the lower wing boom)? *I* don't know... I'll have to see if I can get it when I go up there again. :( Just weird that someplace outside is worse than attic when everything else is better (analogs too! http://www.avsforum.com/avs-vb/images/icons/icon14.gif).

Another thing I was wondering about anyway: to experiment using stuff around here, could I increase the gain by making the Yagi section longer (say 3') with more director elements? For example, using pieces of solid copper wire (12-10ga) cut to the same length as the other directors (8" I think) and spaced the same distance (5-6") on a wood stick (just as a test) or something strapped to the front of the Yagi. Would anything good happen? :p Do the director elements need to be the same "thickness" (RS has like "half oval" bars, maybe 1/2 x 3/4" -- greywolf should have the same type :)), or does that only affect driven elements? Obviously regular wire would be nowhere near the current elements' "diameter"... Oh wait, otherwise I could probably make hollow, "open bottom" ones very similar to what it has by bending strips of my aluminum sheets in half -- if more directors (or longer Yagi section) = more gain, as indicted on HDTV Primer (www.hdtvprimer.com/ANTENNAS/comparing.html) for the CM 3018 and 4242.

sregener

11-05-05, 08:07 AM

Another thing I was wondering about anyway: to experiment using stuff around here, could I increase the gain by making the Yagi section longer (say 3') with more director elements?

Probably add a dB or two, but not much more. You need a lot of directors to make a big difference in gain. And you should look up the length calculations - they're not supposed to be evenly spaced...

Neil L

11-05-05, 08:16 AM

With a true Yagi designed for a single frequency, the directors are not evenly spaced, but most commercial antennas are de-tuned to cover the whole UHF spectrum, and many have evenly spaced directors. At least toward the front end of the antenna.

Adding a few more directors won't make enough difference to be worth the effort. Experimenting with aim and position will make a bigger difference.

cpcat

11-05-05, 08:20 AM

BUT, now the one (RF channel 56) that was *strongest* in the attic, is just barely NOT coming in! (Just under 50%, attic was in the 60s at least.) :mad: About 10 days ago when I first set it up there to test, it was reading in the 60s also I believe. The other channels were the same as now during testing.

.

Antenna beamwidth usually narrows as frequency increases. You might double check your aim. What antenna are you using? Sorry if I missed it.

I hate to be "Mr. Rotator" all the time, but another advantage to a rotatator is it allows fine tuning of aim for marginal channels.

greywolf

11-05-05, 08:20 AM

Putting it on a mast instead of tying it to sheet metal across a roof peak is still my recommendation.

PGDave

11-05-05, 08:27 PM

If they are PCB then the phase *should* be matched for you. If ferrite core, you may have to switch the phase by switching the leads from the antenna to the balun.

cpcat - I switched the leads from the balun to the antenna but it actually made the reception worse. So I switched them back. There didn't seem to be any indication of which lead should attach to which end of the antenna so I'm wondering if it may have been installed incorrectly during manufacture.

I will experiment with moving the antenna on the mast. I might try a horizontal stack later when I have more time. In a horizontal stack, should one antenna be mounted upside down to maintain proper phase?

Thanks for your help.

Dave

cpcat

11-05-05, 09:24 PM

cpcat - I switched the leads from the balun to the antenna but it actually made the reception worse. So I switched them back. There didn't seem to be any indication of which lead should attach to which end of the antenna so I'm wondering if it may have been installed incorrectly during manufacture.

I will experiment with moving the antenna on the mast. I might try a horizontal stack later when I have more time. In a horizontal stack, should one antenna be mounted upside down to maintain proper phase?

Thanks for your help.

Dave

It sounds like you confirmed the phasing. Turning one antenna upside down is just another way of inverting the phase. I was simply giving you this an an alternative to switching leads on the balun as I didn't know how accessible the leads would be. It sounds like you're in phase now, so if you go horizontal you shouldn't have to change anything.

How far are you from your stations?

PGDave

11-05-05, 09:53 PM

It sounds like you confirmed the phasing. Turning one antenna upside down is just another way of inverting the phase. I was simply giving you this an an alternative to switching leads on the balun as I didn't know how accessible the leads would be. It sounds like you're in phase now, so if you go horizontal you shouldn't have to change anything.

How far are you from your stations?

I'm 84 miles southeast of the San Francisco transmitters. With a single XG91, my signal strength would be 69 on most channels but reception was not as consistent as I'd like so I was hoping that by stacking two XG91s, I would have rock-solid reception all the time. But now, with the stack, my signal strength averages about 63 with fluctations down to 35 or less.

cpcat

11-06-05, 07:52 AM

I'm 84 miles southeast of the San Francisco transmitters. With a single XG91, my signal strength would be 69 on most channels but reception was not as consistent as I'd like so I was hoping that by stacking two XG91s, I would have rock-solid reception all the time. But now, with the stack, my signal strength averages about 63 with fluctations down to 35 or less.

I'd leave the vertical stack up and play with it a while. I'm assuming you've tweaked and double checked the aim. Also, try different heights on the mast. Higher is usually better, but not always. Assuming you are using the "combined" input on the 7777, be sure the FM trap is "in". The one predictable thing about reception is that it's unpredictable. You may be back here tomorrow talking about how great your reception has become. I've been burned before by trying to evaluate things with only a short window of time. What are your analogs like now compared to before?

84 miles is a long way for stable reception no matter what. Are you aware that HD DNS is now available through D* for those in so called analog "white" areas? You should qualify for that now. In addition, assuming the San Francisco stations are your locals, you'll be eligible for Local HD through D* in the next year.

TheRatPatrol

11-06-05, 11:17 PM

Forgive me if this has been asked already, but after reading numerous posts about people not being able to get TV signals in their homes, one has to ask, why are we still relying on old rooftop antenna technology that we had 50 years ago?

With todays technology, and the advent of HDTV, one would think they would have come up with a new and better way to deliver TV signals to peoples TV's by now. I mean if I can receive a cell phone signal (and internet on my cell phone) inside of my house on a piece of equipment that can fit in the palm of my hand, why can't we get better TV signals inside of our houses?

Why couldn't the FCC mandate that the cable, telephone and/or electric companys provide free OTA signals to people in their homes that can't receive OTA signals. The FCC is already requiring all stations to go digital anyways.

Most of us out there already have some sort of "cable" (cable tv, telephone or electric) coming into our homes, (we have DSL service over existing phone lines), so why couldn't they add local TV signals over the same cable?

Sorry for the rant.

sregener

11-07-05, 08:47 AM

Forgive me if this has been asked already, but after reading numerous posts about people not being able to get TV signals in their homes, one has to ask, why are we still relying on old rooftop antenna technology that we had 50 years ago?

I've read these types of questions for a couple of years now, and I think there are a few basic answers to this type of query.

First, you have an underlying assumption that "old" technology is inferior to new. This is the "evolution myth" (not to be confused with that other kind of evolution) that states that things are progressing steadily from simple to complex, or from bad to good to better. Not everything old is bad. Not everything new is good. The best antenna design is about 50 years old, developed by a man by the name of Yagi. Nobody has bettered it yet, in spite of Terk's repeated attempts to make a better antenna.

The second thought is that the laws of physics don't change with time. Television signals are sent on a particular band of frequencies. That band hasn't changed much since it was started (UHF was added, and Channel 1 was requisitioned for military use...) The propogation tendencies of those frequencies also hasn't changed. So in order for those signals to suddenly go through materials that they never have, something would have to change about either the nature of those signals, or the nature of the materials in question. Or, alternatively, they could change the frequency band, but since all of them are in use, they'd have to boot something else off a band in order to use it for broadcast television.

You cite cell phones working indoors as an example of a signal that goes through walls and works indoors. Great if you're in a city. Not so great if you're off the major roads out in the country. You're also dealing with a small band of frequencies, which couldn't carry the bandwidth of HD digital television signals, and a high number of towers for distribution. AM radio works well indoors, but from 530kHz to 1700kHz, the entire AM band, is only about 1Mhz and one television station (analog or digital) requires 6Mhz.

Then you ask about all those wires coming into your home and why can't one of them carry those signals? Of course, you state this in a metro area, since rural areas typically don't have DSL, they don't have clean electrical circuits, and cable is probably a dream they just can't see ever happening. In other words, distributing television signals via wires works great if you happen to be in a densely populated area, but the cost per home served becomes impossible in areas that have few homes.

Broadcast television, in the VHF-lo, VHF-hi and UHF bands, provides service to areas approximately 60 miles in radius, to almost everyone in that radius, in most parts of the country. They do so with limited electrical power and limited need for microwave links for distributing the signals. They use single towers instead of hundreds or thousands to cover that area. All that is required is, if you live beyond 15-20 miles of the tower, a simple device attached to the outside of your home that costs under $200, and will give you years of service. I can only dream of the days when cable television costs me less than $200 a decade.

Instead of complaining about how inferior this "old" technology is, ask yourself why all the newer technologies cost more and have so many drawbacks in comparison to broadcast television. Or you can just sit back and enjoy the perfect pictures and sound of digital television from a hunk of metal on your roof and be amazed that anyone thought of doing it at all.

Dominus

11-07-05, 09:05 AM

Bravo! Well said.

TheRatPatrol

11-07-05, 09:33 PM

holl_ands

11-07-05, 10:30 PM

Yes, I agree, very well done. Thanks to your explanations, I have a better idea of how things work now. As they say, you learn something new everyday.

I really wasn't trying to complain about the technology, as I myself have a rooftop antenna (UHF only) and receive free OTA HD signals in the metro area I live in. There's a hill/mountain between me and the towers, so I can't get all of them, but the ones I do get are the ones I want.

I guess what I was trying to ask (or suggest) is if there were other ways for people to get their OTA local channels if they couldn't get them with a rooftop antenna. Those who live too far out of town, live in apartment buildings or have obstacles in their way and can't get a direct line of site view of the towers.

Sorry if I offended anyone.
Most cable systems are providing local HD stations as part of their "Basic Cable" offering via a QAM digital carrier.
All Digital Cable Ready (DCR) HDTV have a QAM tuner capability that can receive local unencrypted channels when a CableCard is not inserted, and have the ability to receive the usual assortment of encrypted digital channels when you pay extra for digital service and insert the cable company provided CableCard.
Some, but not all OTA STB's also have QAM tuner capability.

Unfortunately, the cable companies don't advertise this capability and the customer reps are going to give you a big "huh??" when you ask whether they have unencrypted QAM channels. Your local thread should have information on whether your local cable company has local HD channels via unencrypted QAM.

colofan

11-08-05, 08:56 AM

One little item about above TV analysis is that you could say the same statements about satellite coverage except the distance covered are much larger and terrain for rural areas are typically not an issue. What bites my butt is that 50 year old technology (OTA TV) prevents me from receiving signals from space because of local broadcaster feeling a need to extert thier control over my ability to see distant programming.

Maybe the equipment isn't quite as cheap yet but is isn't very far from that. If congress required the FTA broadcasts were done for network programming my need for OTA would disappear overnight. So yes newer technologies can provide better service.

sregener

11-08-05, 11:05 AM

What bites my butt is that 50 year old technology (OTA TV) prevents me from receiving signals from space because of local broadcaster feeling a need to extert thier control over my ability to see distant programming.

If congress required the FTA broadcasts were done for network programming my need for OTA would disappear overnight. So yes newer technologies can provide better service.

Actually, it's not 50-year-old technology. It's something much older called copyrights.

When it comes to broadcast television, you the viewer are not the customer. You're the target of the service, but the customer is actually the advertisers. They're the ones who pay the money so you can see the programming for free. They do this because they believe that seeing their advertising will influence your buying behavior. They're not doing this out of the goodness of their hearts. The networks, in seeking to make money, create programming that will appeal (they hope) to the target demographics advertisers are willing to spend money for. Then you, the buying public, essentially agree to watch programs that were designed to catch your attention and keep you from switching channels for fear of missing something.

In order for Congress to rule that networks had to distribute their programming FTA, they would have to modify copyright laws to do so, removing the rights of the intellectual property creator to decide how to distribute their IP. I can see no reason why Congress should remove this right, nor do I believe it to be in the best interests of us, the viewers. If local broadcasting went away, the advertising dollars would follow, which means episodes of our favorite shows that cost upwards of $1 million each, would disappear.

There is no law preventing NBC or any other network from creating a "satellite" channel with all their network programming on it. They choose not to do so because they believe they can make more money by not distributing their programming in this manner.

That said, last I checked, the networks were available FTA, but that is always subject to change... (http://www.lyngsat.com/freetv/United-States.html)

richard korsgren

11-08-05, 12:00 PM

Directv is rolling out a new system (MPEG4) to deliver digital (HD) OTA network signals throughout the USA (12 major cities first). Detroit is first and test market for this new delivery system.

RMSko

11-08-05, 01:17 PM

If I have a preamp and amp connected to my outdoor antenna. The preamp is connected to the antenna which is mounted on the roof. I then have about 50' of coax to the amp. The amp is then plugged into the power source and is then connected to my OTA tuner. One of my signals is jumping around a bit and it has been suggested that the preamp/amp may actually be causing this problem. I now want to test this and was wondering whether unplugging the amp from the power source will be enough or will I also need to disconnect both the amp and the preamp and have the coax run directly from the antenna to the OTA tuner. Obviously 'd like to avoid going on my roof, but if I need to I will.

sregener

11-08-05, 01:32 PM

I now want to test this and was wondering whether unplugging the amp from the power source will be enough or will I also need to disconnect both the amp and the preamp and have the coax run directly from the antenna to the OTA tuner.

Most preamp's outdoor unit will not pass a signal if they aren't receiving power. You have to remove it from the line to do your test. Sorry. :(

deconvolver

11-08-05, 01:46 PM

There is no law preventing NBC or any other network from creating a "satellite" channel with all their network programming on it. They choose not to do so because they believe they can make more money by not distributing their programming in this manner.

Isn't this already happening? I think that some of the OTA broadcast network's parent companies also own "cable only" networks like Bravo or ESPN. This lets them choose where to put their premium content like the Olympics or Monday Night Football- exclusively on the broadcast networkp; split between OTA and "cable" or exclusively on cable and satellite. It seems that the recent trend is to move premium content away from the OTA network.

sregener

11-08-05, 02:34 PM

Isn't this already happening? I think that some of the OTA broadcast network's parent companies also own "cable only" networks like Bravo or ESPN. This lets them choose where to put their premium content like the Olympics or Monday Night Football- exclusively on the broadcast networkp; split between OTA and "cable" or exclusively on cable and satellite. It seems that the recent trend is to move premium content away from the OTA network.

What you're describing and what the other poster was railing against are two different things. I don't think he's upset that Bravo is available on cable and satellite systems nationwide. I think he is upset that he can't get, for example, 'Desperate Housewives' from a distant city, presumably because his local station either doesn't offer it in HD, or has an engineering staff with the intelligence of mice that routinely screws up the picture, sound, or both.

And while ABC is moving MNF to ESPN, NBC is going to move Sunday Night football to broadcast from cable-only, which works out to be a wash for trends.

colofan

11-08-05, 02:47 PM

What you're describing and what the other poster was railing against are two different things. I don't think he's upset that Bravo is available on cable and satellite systems nationwide. I think he is upset that he can't get, for example, 'Desperate Housewives' from a distant city, presumably because his local station either doesn't offer it in HD, or has an engineering staff with the intelligence of mice that routinely screws up the picture, sound, or both.

And while ABC is moving MNF to ESPN, NBC is going to move Sunday Night football to broadcast from cable-only, which works out to be a wash for trends.

Well you are correct in that I don't own the copyright material and that I pay by having advertising in the program I disagree about the fact that a local station controls access to material owned by the network. A local station would need to provide compelling programming for me to watch so they can get the dollars they seek from advertisers. Notice that very little local ad's are run during prime time of sporting events because most of the paying customers want national coverage.

As a sticking point as to why government really can require this is it is the "public" that owns the airwaves where most of this programming broadcast through. Yes this includes the backhauls on the satellites so it even impacts channels that are not available OTA.

You are correct in that I live in the Denver DMA and yes we have a disaster when it comes to the OTA DTV since most of the stations have no motivation to carry the signal. But that is another issue all together.

Bottom line is without the government license to use the airwaves these networks would not even exist so what is wrong with requiring that at least network programming be offered in the "clear".

cpcat

11-08-05, 03:01 PM

.

You are correct in that I live in the Denver DMA and yes we have a disaster when it comes to the OTA DTV since most of the stations have no motivation to carry the signal. But that is another issue all together.

.

Have you checked lately to see if you're eligible for HD DNS? I'm in an analog "white area" and was still ineligible until I checked again recently and *wala* I'm now eligible through D*. My HD DNS was turned on about a week ago, no extra charge. I assume the Denver stations aren't O&O or you would have been eligible already.

HD DNS eligibility: http://directvdnseligibility.decisionmark.com/app/AddressEntry.asp

Edit: Looks like you aren't eligible. I feel your pain, though. :(

rdwalt

11-08-05, 03:07 PM

.... or has an engineering staff with the intelligence of mice...
<snicker>

RMSko

11-08-05, 04:20 PM

Most preamp's outdoor unit will not pass a signal if they aren't receiving power. You have to remove it from the line to do your test. Sorry. :(

That's okay, it's what I needed to find out b/c when I did unplug it I didn't get a signal so what you're saying makes sense. BTW - do you think that my preamp/amp could be causing my problems with some of the signals jumping around a bit?

sregener

11-08-05, 04:31 PM

BTW - do you think that my preamp/amp could be causing my problems with some of the signals jumping around a bit?

I think it's very possible, even probable. Your zip code is a poor location for using a preamp, being so close to the NYC stations (both FM and TV.)

RMSko

11-08-05, 07:21 PM

I think it's very possible, even probable. Your zip code is a poor location for using a preamp, being so close to the NYC stations (both FM and TV.)
Thanks. You were correct! I took the amp and preamp off and the signal, while a little bit weaker, seems to have stopped jumping around. For the most part I'm getting readings in the 80's, which I assume should be fine (when I used the amp and preamp, I got readings about 3 "points" higher, but for some channels it jumped and wasn't reliable). The only strange thing is that I'm using the internal tuner of an HD TiVo and for one of the channels (CBS) the signal for one of the tuners is 79 and for the other tuner is 88. This is not the case with any of the other channels. However, if that's the worst result, I guess I can live with it.

jdhlll

11-08-05, 11:21 PM

thedonn

11-08-05, 11:50 PM

madhatter1

11-09-05, 12:00 AM

thedonn...LOL...that antenna has seen it's better days a long time ago. I would relegate it to the aluminum scrap.

holl_ands

11-09-05, 03:53 AM

New to this forum, hope this isn't off target -
I have a single bay HD antenna with pre-amp (not sure on the make of pre-amp) hooked to a HD Tivo.. I'm approx. 35 miles from the towers. No signal without the pre-amp; 90-92 on all channels with pre-amp. I want to hook up another HDTV in parallel since the TVs are on either side of the antenna and about equal distance from the antenna, 100ft. Also, a lot less work for me to install in parallel than series. Question - would will there be any problems operating two pre-amps in parallel from one antenna?
Appreciate any input. Thx.
To match impedances, you would need to feed each Preamp, using an RF Splitter on the signal from the antenna....which reduces sensitivity by about 4 dB.
There is a better way to do this.

The single Preamp should have more than enough oomph to go through an RF Splitter and thence to each HDTV.

Option 1:
If you have to install the Power Insertion Module close to a power outlet (like next to one of the HDTV's),
then you will need to use a "Satellite RF Splitter" which has DC PASS capability.
In addition to the RS 16-2568, the RCA D800 and Zenith ZDS5010 also have DC PASS capability on both ports.
Just to be safe, a DC Block is recommended to prevent DC power from going to the input of the TV on the port that does not have the Power Insertion Module.

Option 2:
If you can locate the Power Insertion Module so that it is directly connected to the Preamp (no RF Splitter in the way) then any ol' RF Splitter connected on the other side of the Power Insertion Module will do the job.

Here are block diagrams:

cpcat

11-09-05, 06:37 AM

thedonn...LOL...that antenna has seen it's better days a long time ago. I would relegate it to the aluminum scrap.

I couldn't find a mast clamp anywhere on the antenna. No wonder it fell down. :)

sregener

11-09-05, 06:56 AM

OK I got pics. How can I take this old dinosaur antenna that fell off the house long ago and use it with my new ATSC card. see pic (http://www.califunknya.com/pc/dino.jpg) Currently it has no connection line goint to it anywhere. Any Ideas?

You probably shouldn't use it, but if you want to try, a $2 balun should do the trick. It has two pieces of wire on one side and a coaxial out on the other. Connect the wires to the gold wires right after the UHF directors. The front of the antenna is the section away from the "mast" section. There look to be 8 directors, followed by the UHF active element. You want the balun to connect to that active element.

TheRatPatrol

11-09-05, 07:44 AM

You probably shouldn't use it.

I wouldn't use it either. But I just did a search for outdoor antenna on radioshack.com and couldn't find any, did they stop selling them?

jdhlll

11-09-05, 08:59 AM

[QUOTE=holl_ands]To match impedances, you would need to feed each Preamp, using an RF Splitter on the signal from the antenna....which reduces sensitivity by about 4 dB.
There is a better way to do this....

Thanks. Would prefer option 2 but don't want to run an A/C circuit to the mast location. Notice you show an optional preamp for each TV. What would be the function of the preamps? Also, thought a signal would not pass through a preamp without the power module?

sregener

11-09-05, 09:12 AM

I wouldn't use it either. But I just did a search for outdoor antenna on radioshack.com and couldn't find any, did they stop selling them?

All they have now are Terk look-alikes, which means you don't want to waste your money on them.

A Channel Master 4221 would be way better than what you've got there, and they're relatively cheap (about $25 +shipping.) Radio Shack antennas don't tend to hold up well in outdoor installations. I'd steer clear of them and look to Channel Master, Winegard, or AntennasDirect.

sammy50

11-09-05, 02:46 PM

rdwalt

11-09-05, 03:01 PM

If your TV only has an NTSC tuner then yes you will need an HDTV receiver - HD is ATSC. You need to try the Channel Master 4221 in the attic and outside. Tree leaves will affect your signal but the good news is Fall is here!

deconvolver

11-09-05, 03:03 PM

Okay another noob here - would appreciate some wisdom... thanks in advance

I have a Zenith LCD HD w/ NTSC Tuner - first off do I still need a separate HDTV receiver?

Assuming I needed one I bought a RadioShack Accurian and hooked it up. Having looked at several posts I bought several VHF/UHF indoor antennas to try - RS-2, Philips-2, etc. the best reception I could get was a 49 (percent?) and after checking what channels I captured - I didnt' get any. I placed the antennas outside and even in the attic. I live in Atlanta within 10 miles of several towers and my house is on a ridge (not down in valley). I do have tall trees on my property.

Can anyone help? Or point me to a list of the basics? If this doesn't work - everything is going back! Thank you
The Accurian will display a 49% reading whenever it is tuned to a strong analog channel (which it can't tune) so that could be your problem. Did you autoscan for the channels? The digital channels are different than the analog ones and you need to scan for the channels or input the real digital channel number to receive the digital broadcast. Once the digital channel has been successfully received (but not before) the box will re-map the station so you can use the old analog number. NTSC is the old analog standard so if the TV only has an NTSC tuner then you do need a box for digital. To find out about the digital stations in your area go to www.antennaweb.org select choose an antenna and then put in your address. In the channel list the last column is the real digital channel number before it gets re-mapped.

sammy50

11-09-05, 03:28 PM

TotallyPreWired

11-09-05, 03:45 PM

Thanks deconvolver for the quick reply - I did check antennaweb and after getting everything together I did the autoscan and didn't get any channels. I guess I'll try to manually select them.
I guess that I'd follow RDwalt's & deconvolver's assertions that if'n you ain't got an ATSC receiver, tuning to anything is not going to get you a digital channel.

An ATSC receiver should be able to program the stations for you.
....jc

deconvolver

11-09-05, 04:01 PM

Thanks deconvolver for the quick reply - I did check antennaweb and after getting everything together I did the autoscan and didn't get any channels. I guess I'll try to manually select them.

So in this example:
WSB-DT 2.1 ABC ATLANTA GA 177° 9.7 39
(where WSB analog is channel 2) I need to input the digital channel "39" - right..

Thanks
Right. Also aim your indoor antenna south (177°) through a window as high up as you can get it. For a DB-2 the front is the bow-ties and the back is the screen. For a silver sensor type you aim it by pointing the arrow in the desired direction. Antennaweb should also tell you what type of antenna is needed- a properly aimed directional one is better than an omni antenna. If there are buildings etc. in the way they could be blocking the signal; you might need an outdoor antenna in that case.

I just checked the fcc website and WSB-DT is broadcasting at 1000KW with a decent antenna height, I would think it should be easy to get only 9.7 miles away. One thing to try is to first connect the antenna directly to the TV's antenna input and tune an analog UHF channel from the same location to point the antenna. So you could tune WPBA channel 30 and adjust the antenna for a good picture. Then move the antenna cable to the Accurian antenna input and switch the TV to view the Accurian's picture before trying to tune WSB-DT.

sammy50

11-09-05, 04:09 PM

Thanks to you all - still no channels - My Accurian is ATSC receiver - right?
I do get 4 to 5 snowy analog channels when I hook the indoor antenna direct to the back of the TV. So I do get analog reception.
Now back to using the antenna thru the HD Receiver - I tried AutoScan and manual input of several numbers via the remote control - no picture.
The Signal Strength always shows in the yellow range (approx "49") and it says "Picture Quality is best when green. On the "meter" the SNR fluctuates between 16 and 17.5 - not sure what that means... Any other thoughts?

TotallyPreWired

11-09-05, 04:19 PM

Thanks to you all - still no channels - My Accurian is ATSC receiver - right?
Sorry, I missed the fact that you also picked up one of those! :(

Many possibilities: Signals are too weak, antenna not connected properly, bad Accurian.

U might try a longer cable and trying to get the antenna outside to see if that helps. Not a solution, but at least you'll be able to eliminate a few things.
....jc

sregener

11-09-05, 04:31 PM

I do get 4 to 5 snowy analog channels when I hook the indoor antenna direct to the back of the TV. So I do get analog reception.

10 miles and you're on a ridge and you've got snow? Sounds to me like your antenna isn't hooked up properly. Try a different balun. Double-check coax connectors.

How does it compare to the analogs on this page: http://www.geocities.com/figbert/8vsb.html

sammy50

11-09-05, 04:57 PM

cpcat

11-09-05, 06:50 PM

How does it compare to the analogs on this page: http://www.geocities.com/figbert/8vsb.html

Just curious, what receiver do you use? I didn't catch it in the review.

sregener

11-09-05, 08:01 PM

Hey sregener - I hooked up a RS powered antenna direct to the back of the TV - (so in ANALOG) - I get Fox strong, ABC very good with some lines (similar to your link), one of the PBS very good, NBC only fair and CBS not at all. It must be the trees. What's a balun??

Ah... You shouldn't be using a powered antenna. They're bad news. I assume your Fox, ABC and PBS are on VHF (channels 2-13.) Most digitals (I know Atlanta has an exception) are on UHF, which means that the comparisons aren't valid. TBS is on channel 17, I believe, which would be a good test.

A balun is a part that has a 300 Ohm connector on one side (two wires) and a coaxial connection on the other (center pin + outer shield.) It's called a balun because it's a balanced/unbalanced connector.

You should return the powered antenna posthaste and replace it with a good indoor antenna. Options include the Radio Shack double-bowtie, the Zenith Silver Sensor, or the AntennasDirect DB2. Any should be a vast improvement for digital reception.

sregener

11-09-05, 08:02 PM

Just curious, what receiver do you use? I didn't catch it in the review.

Zenith C32V37 internal tuner.

I'll admit that results weren't quite as good with a Samsung SIR-T151, though remarkably close for most stations.

sammy50

11-09-05, 08:26 PM

Thanks sregener

Sorry on the reply to cpcat - realized that it was a question to you after I sent it

Ive been reading the ATL thread and the Channel Master 4228 seems to be the ticket for most everyone. The NBC affiliate is the UHF exception - thanks so much for helping a noob! All best

cpcat

11-10-05, 06:17 AM

Zenith C32V37 internal tuner.

.

I suspected it was LG-ish by looking at your pics. Don't know what generation it is, though.

sregener

11-10-05, 08:32 AM

I suspected it was LG-ish by looking at your pics. Don't know what generation it is, though.

Supposedly fourth.

I created the page in response to those who claimed that ATSC 8VSB is a total failure because people can't get reliable reception. My comparison page is intended to show that the standard does work, and surprisingly well. I consider the pictures of WHLA to be conclusive. I'm including the topographic map so you can see just how poor my location is.

The page has proven useful for people who need to compare their analog pictures, though, so I keep referencing it.

cpcat

11-10-05, 03:59 PM

. I'm including the topographic map so you can see just how poor my location is.

.

That's pretty tough. I think tougher than mine. Here's a profile to WVLT-DT in Knoxville from my location followed by one from WCYB-DT in Bristol. WCYB is at 110 miles and is much easier for me even though WVLT is only 66 mi. I think you can see why.

de8212

11-10-05, 05:56 PM

I just received a Zenith Silver Sensor indoor antenna to receive my local OTA HD channels.
I get WRDW-DT fine but WAGT-DT seems to get pixelated a bit too much. I did adjust the antenna and it got a little better but not perfect.
I know very littel about this so I have soem questions.
Both of the above mentioned stations are 121 degrees so the antenna should be pointing the same directions for both, right?
WAGT is .6 miles further, is that probably the reason it's pixelated?

Would an amplifier be something I should try? If so, what brand/model, etc.?
If not, what else could I do?

Also WFXG-DT is 120 degrees and 20.1 miles so would the amplifier help it out much? I can't remember how it looked but I know it was not good.
Thanks for any help.

ken kipnes

11-10-05, 06:28 PM

I live in New Hampshire, surrounded by trees. I have DirecTV; ABC denied my request to get the ABC network feed from DirecTV because there is an ABC station, WMUR, is 10 miles away. The problem is, the WMUR OTA signal is spotty at best. I'd like to try to get the ABC, WB and UPN signals from Boston, 40 miles away.

I entered my data into Antennaweb and got these results:

red - uhf WNEU 60 TEL MERRIMACK NH 336° 10.3 60
red - uhf WNEU-DT 60.1 TEL MERRIMACK NH 336° 10.3 34
red - uhf WPXG-DT 33.1 i CONCORD NH 33° 22.9 33
red - vhf WMUR 9 ABC MANCHESTER NH 336° 10.3 9
red - uhf WMUR-DT 9.1 ABC MANCHESTER NH 336° 10.3 59
red - uhf WPXG 21 i CONCORD NH 33° 22.9 21
red - uhf WZMY 50 IND DERRY NH 175° 9.8 50
red - uhf WUTF 66 TFA MARLBOROUGH MA 198° 33.5 66
red - uhf WUNI 27 UNI WORCESTER MA 215° 39.0 27
blue - vhf WENH 11 PBS DURHAM NH 46° 24.7 11
blue - uhf WENH-DT 57.1 PBS DURHAM NH 46° 24.7 57
blue - uhf WUTF-DT 66.1 TFA MARLBOROUGH MA 198° 33.5 23
blue - uhf WZMY-DT 35.1 IND DERRY NH 175° 9.8 35
violet - uhf WNNE 31 NBC HARTFORD VT 324° 64.0 31
violet - uhf WSBK 38 UPN BOSTON MA 178° 40.9 38
violet - vhf WYCN-LP 13 FMN NASHUA NH 197° 7.3 13
violet - vhf WMTW 8 ABC POLAND SPRING ME 42° 76.1 8
violet - uhf WMFP 62 SAH LAWRENCE MA 165° 40.6 62
violet - uhf WNAC 64 FOX PROVIDENCE RI 188° 69.4 64
violet - uhf WFXT 25 FOX BOSTON MA 178° 40.9 25
violet - vhf WGBH 2 PBS BOSTON MA 179° 40.1 2
violet - uhf WGBX 44 PBS BOSTON MA 179° 40.1 44
violet - vhf WHDH 7 NBC BOSTON MA 177° 40.5 7
violet - vhf WJAR 10 NBC PROVIDENCE RI 188° 69.8 10
violet - vhf WBZ 4 CBS BOSTON MA 179° 40.1 4
violet - vhf WCSH 6 NBC PORTLAND ME 44° 78.0 6
violet - vhf WCVB 5 ABC BOSTON MA 179° 40.1 5
violet - uhf WBPX 68 i BOSTON MA 167° 40.8 68
violet - uhf W33AK 33 FMN NASHUA NH 197° 7.3 33
violet - uhf WUNI-DT 27.1 UNI WORCESTER MA 215° 39.0 29
violet - uhf WLVI 56 WB CAMBRIDGE MA 178° 40.9 56
violet - uhf WYDN 48 DAY WORCESTER MA 225° 44.9 48
violet - uhf WVTA 41 PBS WINDSOR VT 324° 63.6 41
violet - vhf WPRI 12 CBS PROVIDENCE RI 188° 69.1 12

The list doesn't show the digital channels for WCVB, WLVI or WSBK. I've seen other lists where they are mentioned.

My questions:

1) Will there be any chance of receiving these stations from 40+ miles away?
2) Can you suggest the best outdoor antennas for this task?

Thanks!

ken

sregener

11-11-05, 07:59 AM

1) Will there be any chance of receiving these stations from 40+ miles away?
2) Can you suggest the best outdoor antennas for this task?

1) Yes. There is even a good chance. But I'd check this map of WSBK-DT's coverage area for a better idea: http://www.fcc.gov/fcc-bin/FMTV-service-area?x=DT614548.html

(To get coverage maps for other stations, do the following: Go to http://www.fcc.gov/mb/video/tvq.html and enter the call sign of the station you want. Select 'TV Query' from the output list. Submit the form. On the next screen, there will be a list of information. Find the current digital station info and click on the "Service Contour Map" link.)

I've been able to beat the FCC's estimates by about 10 miles, on average, using a high-quality installation. But there are a lot of factors involved, and not everyone should expect to beat the odds.

2) I'd go with the AntennasDirect 91XG. Other good choices include the Channel Master 4228 and the Winegard PR-9032. You may want to try a Channel Master 7777 preamplifier, but be prepared to return it if it gets overloaded with the stations nearby.

Keep in mind that with heavy trees, you will likely have some reception difficulties, especially in windy weather. Still, I'd bet that at 40 miles, you'll get perfect reception all the time if you get your antenna up high enough.

deconvolver

11-11-05, 08:43 AM

1) Yes. There is even a good chance. But I'd check this map of WSBK-DT's coverage area for a better idea: http://www.fcc.gov/fcc-bin/FMTV-service-area?x=DT614548.html

(To get coverage maps for other stations, do the following: Go to http://www.fcc.gov/mb/video/tvq.html and enter the call sign of the station you want. Select 'TV Query' from the output list. Submit the form. On the next screen, there will be a list of information. Find the current digital station info and click on the "Service Contour Map" link.)

I've been able to beat the FCC's estimates by about 10 miles, on average, using a high-quality installation. But there are a lot of factors involved, and not everyone should expect to beat the odds.

2) I'd go with the AntennasDirect 91XG. Other good choices include the Channel Master 4228 and the Winegard PR-9032. You may want to try a Channel Master 7777 preamplifier, but be prepared to return it if it gets overloaded with the stations nearby.

Keep in mind that with heavy trees, you will likely have some reception difficulties, especially in windy weather. Still, I'd bet that at 40 miles, you'll get perfect reception all the time if you get your antenna up high enough.
I think that the fcc service contour maps are just based on the antenna beampatterns and height above average terrain; I don't think that they take local topography into account so they are not much use. Antennaweb does take topography into account but their digital predictions are pessimistic so you may get digital stations that they don't list at all. In that case if there are analog stations in the same antenna farm with similar power, antenna height and frequency then sometimes you can use the antennaweb analog predictions which are optimistic to get an idea on the digital reception.

A Buck

11-11-05, 08:49 AM

sregener

11-11-05, 11:35 AM

I think that the fcc service contour maps are just based on the antenna beampatterns and height above average terrain; I don't think that they take local topography into account so they are not much use. Antennaweb does take topography into account but their digital predictions are pessimistic so you may get digital stations that they don't list at all.

I've found the FCC's projected contours to be pretty good at figuring out how far things "should" reach. I hate Antennaweb's pessimism, and no longer recommend them as more than a starting point.

I typed in a Boston zipcode, and they rated most of the UHF stations as "violet" inside of 15 miles, and still didn't think WSBK-DT would reach. Antennaweb needs to get a clue.

HDTVChallenged

11-11-05, 11:52 AM

LOL ... Well after all, "we" want to sell you the biggest antenna possible to cover the situation. :)

ken kipnes

11-11-05, 01:12 PM

Thanks, everyone, for the feedback. I will look into the antennas mentioned.

ken

sp1dey

11-11-05, 02:29 PM

Quick question for the OTA gurus. I posted this in my regional forum but this is much more active... I'm in Northern CT and get great OTA signal on everything except WB and ABC. When I check the OTA meter, both channels are in the 80's and peak at 90... should be strong enough. But both channels frequently drop out, freeze, or become very pixelated. Since both channels are VHF and operate at low frequencies, 10 and 11... could this be FM interference and would a FM trap help? Also can FM interference become more prominent in bad weather because my signal is now weaker? All my other channels are UHF and get similar meter readings (80's to low 90's) but without any dropoffs.

kflorek

11-11-05, 05:20 PM

Is having the stranded ground wire (the stripped end since I wanted white) exposed in the weather going to make it corrode, etc. more than a solid one? I suppose... Anything to do to for protection?

:eek:
Since I'm rather old (born 1946) and have been through several generations of corrosion fixes, I tend to think some prevention is worth a modest effort. There is nothing that truely stops corrosion; you just delay the inevitable, hopefully a long time.

There is a grease in a 1 ounce tube that will be called something like "no-corrode" or "oxy-gard" in large electrical departments, such as Home Depot. It is readily available for use with service entrance wiring which is normally aluminum, probably in most of the US. But the directions on Ox-gard indicate it is a general purpose product, not only for aluminum, being that it is also for use on automobile battery terminals, which usually are lead. I put it on the enclosed contact parts of the wiring for the grounding block, the coaxial cables and the ground wire. However, in an unsheltered location the weather would probably wash it away in a year or two. For sealing the external metallic parts I used "rope caulk," sometimes found by the weather stripping rather then by the paint or caulk. Inside the box, it looks like children's modeling clay shaped into a 1/4 inch thick rope. I like it because it is not messy and is easy to peal off in case you need to. Caulk in a tube is neither. There is another material sold in a block about a foot long and 1 1/2 inches thick in the electrical department, that I recently noticed, called something like "duct seal." ($1.95) I guess the idea is to seal around holes that electrical wiring has been run through. It is stickier and softer than rope caulk. It looks like the what is wrapped around the conduit at the top of my electrical meter to keep water from running in. This around the connection to the ground rod would protect it very well.

I think you (DR_LaRRY_PEpPeR) also wondered whether corrosion was responsible for the aluminum wiring "just breaking off" of the ground rod. Probably it was for a different reason. I'd think aluminum would hold up to corrosion better than copper.

The problem is that nicking a wire, even a little, disposes it to a phenomenon that concentrates stress at the weakest point. People that work in various materials often use the principle to advantage. They score a materal, like glass, and it magically breaks at just that line with a little pressure or working. Wires that have a little nick in them break off if you bend them a small number of times, even though they may hold up indefinitely otherwise. My experience with aluminum wire is that is more susceptible to this. Just put a sharp kink in it, and it'll break with a couple of bends.

When you attach a wire to a ground rod, the clamp puts a kink in it. So the connection needs to be "immobilized" to hold up. It is not a problem in house wiring, because it normally IS immobilized. Where wire is in the open, people, animals, the wind, or whatever tend to move it around. Using a very thick wire, or alternatively a flexible wire, may help keep the vulnerable point from flexing. Maybe a cable tie. They usually say to bury the ground rod connection, which should immobilze it, but subject it to worse corrosion. Nothing beats the damp, oxygenated dirt that is near the surface for accelerating corrosion (or fungal rot on wood.)

The problems using aluminum in electrical connections are that the corrosion is a far tougher substance than what gets on copper, and less conductive. Aluminum oxide is second to diamond in hardness, and is a fabulous insulator. It is used as an insulator in sub-micron thicknesses in micro chips for instance. The corrosion on copper is displaced by modest pressure or friction. The corrosion products on copper ionize in water, becoming no worse conductors than dirt, so copper ground rods are OK. The soluabilty of aluminum oxide is next to nothing. That's probably why I've never heard of an aluminum ground rod.

As for protecting the wire itself from corrosion, they don't seem to do it. If you see a small half cylinider tube running down an electric pole, it conceals a ground wire. Look under it, and it looks like bare copper, a little corroded. Perhaps the oxide coating on copper is as protective as anything else you might put on it. Oxides on some metals protect it. Gold is said to remain shiney because its oxide is so impenetrable to oxygen. The oxide layer is transparent because it is so thin. Stainless steel is the same. Too bad rust on iron is just the opposite.

sregener

11-11-05, 06:46 PM

When I check the OTA meter, both channels are in the 80's and peak at 90... should be strong enough. But both channels frequently drop out, freeze, or become very pixelated. Since both channels are VHF and operate at low frequencies, 10 and 11... could this be FM interference and would a FM trap help? Also can FM interference become more prominent in bad weather because my signal is now weaker?

Well, you leave out at least one important detail: your tuner brand and model. Signal meters are not the same, and while one may give you solid reception with a "3" another may require "65%." If the signal strength doesn't drop when the channels drop out, then it is probable that you have the dreaded "matrixed" meter, which takes signal strength (in dB) and combines it with signal quality to arrive at some number. It's like seeing a sum of C and trying to guess what the A and B were.

So you're having problems with VHF reception, but your UHF reception is solid. How distant are the channels you're trying to receive? What antenna are you using? Where is the antenna mounted? Are you using an amplifier, and if so what kind?

Could it be FM interference? Of course. Channel 10 is at 192-198Mhz, which happens to be half the wavelength of 96-99Mhz, smack dab in the middle of the FM range. I get terrible FM interference on analog channel 8, and if I turn my antenna just right, I can actually listen to the station that is causing the offending problem. If you have an FM trap, you should give it a shot. Another option is to get a VHF-Hi/VHF-Lo combiner and leave the VHF-Lo side unattached to your antenna (or any antenna, for that matter.) That would cut off the FM frequencies perfectly, while leaving your digital reception okay.

But Hi-VHF is also subject to impulse noise. Impulse noise can come from electrical devices (including those not on your property - some people have all sorts of interference when their neighbors turn on the microwave, for instance.) It can also come from lightning. In fact, one of the strongest arguments against using the VHF frequencies for digital reception is that impulse noise during severe weather could knock out the signal just at the point where public safety information is most important. I suspect this is what you're seeing in "bad weather." There's nothing you can do about lightning, and little you can do about electrical sources of the problem if they're not on your property.

You could try to isolate the problem if its electrical by turning off various circuits at your circuit-breaker box and see if the problem goes away. (If you have an analog VHF-Hi station to use, this will be much easier to see - impulse noise looks like multicolored lines going across the picture and scrolling up the screen. FM noise looks more like a pattern or blockiness.) Disconnect everything not needed to test your system and see if things improve.

Anyway, that's probably a longer explanation than you wanted, and gives you more options and things to try than you wanted. But there are no magic devices we can plug in that just make reception work. If there were, this forum would be a lot quieter. :)

kflorek

11-11-05, 06:47 PM

Actually, it's not 50-year-old technology. It's something much older called copyrights.

....
In order for Congress to rule that networks had to distribute their programming FTA, they would have to modify copyright laws to do so, removing the rights of the intellectual property creator to decide how to distribute their IP. I can see no reason why Congress should remove this right, nor do I believe it to be in the best interests of us, the viewers. If local broadcasting went away, the advertising dollars would follow, which means episodes of our favorite shows that cost upwards of $1 million each, would disappear.

I don't think copyright is much of an obstacle, assuming there is something along these lines in the copyright laws. Congress has countless mandates on actual property and they daily invent new rationales for more. It's endless. It is a fact they are more solicitous to ficticious property than actual property, but I don't think that is what is going on here.

Congressmen always try to preserve what is in their localities. Stations are located in some congressman's district. Beyond that, they want to preserve local content (by which I do NOT mean reruns on the locals), which they justly fear would diminish if local stations didn't have the big revenue stream from network affiliation. Stations get paid for national ads that the networks carry. What would happen if bypassed is that local stations would either get less for carrying network shows, or not get paid and have to pay for content.

I remember, long ago there was a local station that dropped some network shows on one evening when the ratings were so terrible they could do better with their own content (old movies). Their contract with the network only required a certain number of must-carry hours; they could opt out for several hours. Normally the local gets more for carrying the network prime time shows than they could possibly make any other way, so this was very unusual. And annoying, because I used to watched one of the shows they dropped.

I think the networks would love to bypass the locals. Congress is forcing them to operate through locals. The only thing the networks may get out of it is some additional audience from those not hooked to cable or satellite. But mandates are not benificial in total. Any mandate one way or the other subverts a system that would better suit the general population, as they choose it.

quarque

11-11-05, 08:21 PM

I live about 25 miles from Chicago right next to the train tracks. I have a Zenith Silver Sensor that picked up most UHF signals but was highly directional and needed to be tweeked frequently. I just noticed that if I point the OTA atenna north out the window at the railroad tracks (and parking garage) I get 80% + signal on everything. Could the Railroad tracks reflect the signal?
Possibly but not likely. UHF is pretty dead by the time you get below 12" unless you're on a large perfectly smooth surface. So not much signal would even reach the tracks. More likely is the parking garage. Large metal or concrete walls reflect signals pretty well.

kflorek

11-11-05, 10:15 PM

I think most of us would prefer not to get up from our lazy chair, walk across the room, and turn a knob in order to change channels. That is so.... 1970s. :rolleyes:

.

As it happens, I don't qualify as a TV afficianado. I see my OTA HD on a 19" computer monitor two feet away using a $130 ATI HDTV Wonder card. The rotor control is right at hand, so I don't have to get up to twist the knob. I actually like getting up though. My butt un-numbs if I move occasionally. :) The picture quality I get now is astounding. When they broadcast things that were not originally digital, it is too obvious, although still absolutely beautiful. For days, I would watch TV programs (pathetic trash) just to drool over the perfection and look for stuff that you couldn't possibly see on analog. :) I've gotten over that finally.

What even got me started was that the station that is practically the only one I watch (the PBS one) - and I watch very little- got struck by lightning and was out for three months. It was too dangerous for the contractor to work in all the rain and snow, they said (at their web site.) But their digital broadcast, on a different tower, was intact. So I investigated HDTV, which I never gave a crap about before. All too expensive for practically nothing in return, except for possibly a plug in computer card. I didn't buy anything at the time. The rebate went off and bumped the price $20. It only got me thinking about some new gadgetry I could get. I enjoyed the hiatus in TV viewing and substituted listened to the radio in the evening more. The fact that this was a satisfactory substitute shows you my enthusiasm for TV programs.

Part of the reason I went with the CM remote was because it was the only motor that was different. All the others come from the same factory in China, and my original rotor lasted less than two years from them. Believe me, it wasn't a happy day when I risked an icy roof to turn the antenna from its locked-up position as a stop-gap until spring when I could replace the rotor safely. Months of staticy, poor reception convinced me I needed a motor that would last.

Concerning the one that gave up, did something happen to it, or did it just quit? What were the symptoms? Was it flakey before it quit? Did it bust a gear? What brand was it? Did it have a warranty?

Actually, if I remember, you are one of those guys with a monster antenna array load for a home-duty antenna rotor. Yeah, if you are one of those guys, you are fortunate if even a CM rotor holds up. But there are HAM radio operators that use some of the more modest HF antennas with a CM rotor, so it has potential.

What I did to keep the load low, is to keep the top masts short and not get too ambitious with the antenna. The VHF/UHF combo is 6" above the motor. The UHF only yagi/corner reflector has a tiny wind profile and I went with 1'6." Actually I cut both top masts to 2' and clamped the antennas lower. That was in case I hit some adverse signal null on my essential channel.

The wind was reportedly up to 55mph one day. I went out to watch for a while and neither wiggled significantly. So they are OK in normal winds. If the wind gets up to 80mph or more, I would not be upset if something gave. I would consider that normal for home level installation. If it wasn't wrecked, I'd considet that a bonus. The force of the wind goes up as the fourth power of the velocity.

Years ago, in my former home, where I had a CM rotor, there was the worst storm I know of in this area. I don't recall any numbers on the wind, but water was squirting through the cracks around the windows and flowing under the side door. I kept mopping up the stream by the door so it wouldn't flow down the basement stairs. It was raining horizontally, if you can call it rain. It was like a firehose blast. It was quite amazing. That side of the house was plastered with leaves stuck onto the brick when the storm was over. The lower antenna mast bent about 2 feet above the chimney. It was about 8 foot total above the chimney. The antenna was unharmed (a 9' CM). The rotor was fine. The chimney was fine of course. The wind directly on the chimney was probably a bigger load than from the antenna. Once the mast bent, it took off most of that load from the chimney. Yes, bending is a safety feature. You don't want a mast strong enough to hold up to 100mph winds. That could further stress your chimney, or rip open your roof for a roof mount. I just put up a new lower mast and that was it. Not much of an expense, considering.

sp1dey

11-11-05, 10:59 PM

Well, you leave out at least one important detail: your tuner brand and model. Signal meters are not the same, and while one may give you solid reception with a "3" another may require "65%." If the signal strength doesn't drop when the channels drop out, then it is probable that you have the dreaded "matrixed" meter, which takes signal strength (in dB) and combines it with signal quality to arrive at some number. It's like seeing a sum of C and trying to guess what the A and B were.

I'm using a DirecTV HR10-250 (tivo) tuner with a Channel Master 3016 antenna. Not sure how it calculates the signal. But my UHF all come in perfect with no dropout ever. My two VHF channels (at frequency 10 and 11) are 35 and 12 miles away respectively. They clearly fluctuate the most but hover around 80-90 mostly. I'll try the FM trap, but should this give me little positive results, I'll try your other options. Thanks for the input.

sregener

11-12-05, 06:52 AM

I think the networks would love to bypass the locals. Congress is forcing them to operate through locals. The only thing the networks may get out of it is some additional audience from those not hooked to cable or satellite.

Do you have a source that proves that Congress is forcing NBC to distribute programming through broadcast networks?

As far as what the networks get out of it, I think that's obvious. ESPN's Sunday Night Football broadcast of the Eagles vs. Redskins game got a 9 share, but that was only among cable viewers. It was the top-rated cable program of the year.

Here's the top-20 network shows: http://tv.zap2it.com/tveditorial/tve_main/1,1002,272|||weekly,00.html

Here's the top-15 cable shows:
http://tv.zap2it.com/tveditorial/tve_main/1,1002,272|||weekly,00.html

Notice how the top cable show wouldn't even make the top-20 broadcast shows.

No, I don't buy the "Congress forces the networks to use local broadcasters" argument. The networks use the local broadcasters because that is where the money is. NBC could just as easily use Bravo, ABC could use "ABC Family", CBS could use MTV, and they could run worthless programming on their broadcast networks if Congress did force them to have broadcast networks. They don't, and Congress doesn't.

sregener

11-12-05, 07:00 AM

Concerning the one that gave up, did something happen to it, or did it just quit? What were the symptoms? Was it flakey before it quit? Did it bust a gear? What brand was it? Did it have a warranty?

Actually, if I remember, you are one of those guys with a monster antenna array load for a home-duty antenna rotor. Yeah, if you are one of those guys, you are fortunate if even a CM rotor holds up.

Both of my rotor failures (I had a CM that failed as well) exhibited themselves as "freezing up" or refusing to move from one point. The first rotor had a sticking point that would eventually give and start moving if I kept spinning the dial. Finally, during a cold point in the winter, it just plain stuck and wouldn't give, not even after it warmed up. The second one also froze up and stopped turning one day, but as the day warmed up, it began moving again. Not wanting to be stuck in a bad position, I had that one replaced quickly. I don't know the brand of the first one, as a professional installer put it up and didn't give me a box. But it really doesn't matter, as all the rotors from China are from the same factory and are made exactly the same way. I didn't take it apart to find out why it failed. The second one was still under warranty, which covered the rotor, but not the $50 the installer charged me to climb up my tower.

I had a monster antenna array for a day or two with the Channel Master rotor. No more than that. Other than that, the largest "array" I had was a Winegard HD8200P. The biggest thing on the "Made in China" rotor was a Winegard HD7084P. Right now, I'm using just an AntennasDirect 91XG. So I think you're remembering incorrectly.

sregener

11-12-05, 07:04 AM

I'm using a DirecTV HR10-250 (tivo) tuner with a Channel Master 3016 antenna.

The DirecTV HR10-250 is prone to overload. You may want to give a variable attenuator from Radio Shack a try. You can always return it if it doesn't help.

sammy50

11-13-05, 03:54 PM

To: sregener, deconvolver and TotallyPreWired:
Thanks again for your advice a few days ago - I have now joined the 21st Century and am sitting here watching AMAZING "FREE" HD football on FOX and CBS - I also get NBC, ABC, WB, PBS, TBS and a few "extras" - not sure if I should tinker with the antenna to get better signal or just count my blessings. It took a CM 4228 antenna hoisted to the top of the attic rafters and my $79++ Radio Shack Accurian (6000?) tuner. Anyway thanks again.

DR_LaRRY_PEpPeR

11-14-05, 04:59 AM

It's me again. :) I hadn't been back to create any more posts after each trial. ;) I saw the posts by others since my last post that I'm not quoting here (sregener, Neil Laffoon, kflorek; I think that's it). Thanks, didn't want you to think I don't appreciate your posts!

Antenna beamwidth usually narrows as frequency increases. You might double check your aim. What antenna are you using? Sorry if I missed it.

It's a 140" long Radio Shack -- the UHF part (from first director to corner reflector) is only 50". :(

I hate to be "Mr. Rotator" all the time, but another advantage to a rotatator is it allows fine tuning of aim for marginal channels.

Where I was putting it was aimed virtually right at the problem channel that was best in the attic, and changing the aim didn't help...

Putting it on a mast instead of tying it to sheet metal across a roof peak is still my recommendation.

I know! :) But there wasn't/isn't any sheet metal involved yet...

So, here's the story... about 3 weeks ago is when I just set it up there (yes, across the roof peak), just roughly aimed, and in the general area (left or right by a couple feet) of where I planned to put it permanently. I did this 2 times a few days apart to make sure it would work OK. Every channel that I wanted (5 of them) came in no lower than 63-69% I believe on my tuner. Perfectly steady with the first placement, etc. Then I took it back down after verifying, seeing as it worked so easily. Then about a week later (same position), that problem channel was weaker (it WASN'T a problem the first 2 times) -- barely being received. I didn't think much of it, figuring that it was just weaker at that moment. So a few days later when I went to mount it, it was the same way (ALL 4 other channels 69%, and never moved from that level during the 24-hour period I checked).

Then it stormed pretty heavily and everything but 1 channel went away (very weak, no picture). So I decided to replace that old, "damaged" transformer it had. That brought the 4 channels back, though they were barely below 69% then... (Not sure if the trans. got wet or what, it was all sealed as far as I could tell after the storm.)

Since then, trying to get back to the first 2 tests' levels, I have tried adjusting the angle of the corner reflectors (they can move ~3" at the end of the wings?!), using different cable, bypassing the rest of the cable and connecting directly to tuner. I don't know what else. EVERYTHING! That's in addition to trying the antenna in different places on the roof, different heights (holding it above my head, etc.), again EVERYTHING. And yet I can never get all 5 channels as "perfectly" (65%+) as the first couple tests!! :mad:

It seems to be getting worse as the days/weeks go by. Today, only 2 channels were coming in, and just *barely*. :( I give up... I don't know what else to do.

The only thing left that I can think of that changed is the leaves on the trees. When I first tested, most of them were still on (but dry-ish of course), the storm blew a lot of them off, and now I think they're almost all gone in the direction of the stations. I would've thought that no leaves would be better, but maybe they were helping something in my case? Oh, of course the 1/9th power channel 20deg off-axis that I don't care about seems to ALWAYS come in no matter what. :(

Remember I said how clear the analogs were on the roof? Well since then, the VHFs have minor noise/static across the picture now, and the analog UHFs have more snow. The one that came in perfectly clear in the attic, and outside at first, now has visible snow -- that's the off-axis always-received digital one I mentioned above (channels 46/47 a/d).

This really sucks! Man, it was so good at first. Maybe I can go take a picture from the roof soon, just so you guys can see what it looks like in the direction of the towers.

Otherwise, any comments? :rolleyes:

greywolf

11-14-05, 07:20 AM

You may have gotten water in a connection. Connectors need to be an outdoor type with a rubber O-ring seal. Putting silicone dielectric grease in the connector and boot, if any, before assembly is also a good idea. At least some types of RG6 coax have open cell foam dielectric material that can soak up water and wick it into the cable. If that happens, the ends must be trimmed until the watersoaked area is eliminated or the cable must be replaced.

deconvolver

11-14-05, 09:00 AM

...Putting silicone dielectric grease in the connector and boot, if any, before assembly is also a good idea...
Greywolf: What brand of grease do you use and where do you buy it? Thanks.

PamP

11-14-05, 09:05 AM

Please help. We have an old antenna on our roof that I would like to replace. For my birthday, my husband has agreed to this task but wants me to order the material. Our zip is 22739. I have been reading for the last two weeks and can't seem to figure out which antenna would work best for receiving local DC digital stations. We have directv for everything else. Could you please give me some suggestions and also include whether or not I would need to also get an amplifier for the antenna.

Pam

cpcat

11-14-05, 09:05 AM

Greywolf: What brand of grease do you use and where do you buy it? Thanks.

Clear silicone caulk works well.

I use Coax-Seal from RS currently. Honey bees like it in the spring as the pollen tends to coat it. They harvest the pollen and unfortunately some of the seal with it. Maybe silicone might work better for this reason.

sregener

11-14-05, 10:17 AM

I have been reading for the last two weeks and can't seem to figure out which antenna would work best for receiving local DC digital stations.

40-odd miles out. All digitals are on UHF for now, but you probably don't want to have to re-do this in three years when WJLA and WUSA revert to channels 7 and 9.

I'd go with a Winegard HD-7084P and no preamp. It's a solid performer for both VHF and UHF. If you're willing to go UHF-only, a Channel Master 4248, Winegard PR-9032 or AntennasDirec 43XG should all work just fine.

However, DirecTV will be adding HD LiL in a little while, so I don't know if you'd prefer to get your DC stations in HD through them.

greywolf

11-14-05, 10:41 AM

I imagine any of the non-hardening silicone dielectric compounds would work fine. I wouldn't want to use silicone caulk in a connection that I might want to reuse. A search for silicone dielectric and RG6 is what I used to find whatever is in my toolbox right now.

PamP

11-14-05, 11:55 AM

Thanks for the response. I'll check out the first one you listed. I would prefer to pull the channels off the antenna vice directv if I can get decent reception.

de8212

11-14-05, 08:03 PM

Still looking for some help on this. Any ideas?

I just received a Zenith Silver Sensor indoor antenna to receive my local OTA HD channels.
I get WRDW-DT fine but WAGT-DT seems to get pixelated a bit too much. I did adjust the antenna and it got a little better but not perfect.
I know very littel about this so I have soem questions.
Both of the above mentioned stations are 121 degrees so the antenna should be pointing the same directions for both, right?
WAGT is .6 miles further, is that probably the reason it's pixelated?

Would an amplifier be something I should try? If so, what brand/model, etc.?
If not, what else could I do?

Also WFXG-DT is 120 degrees and 20.1 miles so would the amplifier help it out much? I can't remember how it looked but I know it was not good.
Thanks for any help.

storminorm

11-14-05, 08:29 PM

TotallyPreWired

11-14-05, 09:02 PM

Still looking for some help on this. Any ideas?
Antennas are like women....Naw, I can't say that! :p

#1 An indoor antenna may not provide the gain that you need. You may have to get an exterior mounted antenna.

#2 Your location could be the problem. Getting around this could be difficult.

#3 20 miles is nothing. Distance is not your problem.
....jc

TotallyPreWired

11-14-05, 09:07 PM

north Atlanta here, I have a 4228/7777amp but no matter what I do I can't pull in WSB 2.1, all the rest of the digitals come in. I sent an email to antennadirect and they suggested I use a DB8 antenna wit amp.....anyone tried any of the DB antennas? DB4 or DB8 ? I live about 55 miles north of the towers in ATL.
I doubt a DB8 is any better than a 4228. In fact a 4228 is considered by some to be the best. Please read the HDTVprimer and it's here. (http://www.hdtvprimer.com/) It will explain quite a few things that could be the problem.
....jc

DR_LaRRY_PEpPeR

11-15-05, 01:06 AM

You may have gotten water in a connection.

That possibility was eliminated when, after the storm, I replaced the transformer and used a different cable (that's used for satellite otherwise, so it's fine). And that cable has weatherproof connectors (instead of me sealing them) -- not that it matters, as I've taken it in from outside between tests anyway...

That cable is 50' BTW. During the very first tests, it was going to the amp, through the house coax, etc. when it was working fine. Now it doesn't work (well very poorly I mean), whether connected through amp or directly to the tuner. :(

Every part in the chain has been checked and eliminated. There's also 2 separate receivers with the same result, so it's not that either... The only thing different from when it all worked (with ZERO antenna placement effort) is the leaves being off the trees from here to horizon. Could that have a negative impact? You'd think the opposite, but has anyone seen bare trees cause a problem, or is that absolutely not possible?

I didn't get to take a picture from the roof since it's been raining...

AntAltMike

11-15-05, 01:34 AM

Clear silicone caulk works well.

I use Coax-Seal from RS currently. Honey bees like it in the spring as the pollen tends to coat it. They harvest the pollen and unfortunately some of the seal with it. Maybe silicone might work better for this reason.

Silicone caulk, unlike silicone grease, often uses corrosive solvent making it unsuitable for this application.

I like coax seal, and while I have heard that about the bees before, I doubt that they would haul off enough coax seal to allow the water in even one time in a thousand. I have seen what was probably pollen on this compound, but never observed any bare metal.

The newer, self-sealing connectors don't require anything covering them, but if you like, the self-vulcanizing tape like Radio Shack sells (or used to sell) works nice.

cpcat

11-15-05, 07:03 AM

I like coax seal, and while I have heard that about the bees before, I doubt that they would haul off enough coax seal to allow the water in even one time in a thousand.
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You'd be wrong there. I had to redo mine even after a year. I'd say the pollen is worse here, though.

I've not seen any indication of corrosion from silicone caulk, but I assume you have so I won't recommend it any longer. It's not that easy to remove for changing connections, etc, but then Coax-seal isn't either, especially on a hot day.

It's even more difficult with bees flying around your head.:)

qweqaz5

11-15-05, 12:41 PM