Cumming, GA: Can't pull in ABC OTA - AVS Forum
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post #1 of 9 Old 12-16-2012, 06:56 PM - Thread Starter
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OK folks, here's one that's stumping me.

First off, my TV fool: http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3dcc4916e961a383. I've recently put an Antennacraft HBU-33 in my attic, and without amplification, I can pull in all the stations down to the weak WSB-TV 2.1 @ 7.3NMdB, which is our local ABC affiliate. If I amp it, I can get more, including that PBS at -0.6NMdB on channel 30 while pointed @ about 200 degrees.

So, my neighbor was interested in what I had done, so I ordered him the same antenna. We stuck the antenna in his attic, pointed it in the same direction, and immediately started seeing all the usual channels come in, including even the VHF WXIA station. However, we could not pull in WSB-TV at ALL. Tried on three different TVs, different brands even. No signal at all on that channel (2-1). Hooked a 10G202 Antennacraft 30dB amp up to his line, and still no WSB-TV 2-1 channel. Tried turning the antenna a little to the right, a little to the left... no go. It's as though the channel just doesn't exist on the spectrum.

When I check the signal strength for the ABC 2-1 channel at my house, its around 60% unamped. That's stronger than some of the other channels that both he and I are receiving. With the amp, he even receives the ABC tower at 142 degrees, but with some pixelation because the antenna is pointed towards 200(ish) degrees.

My question is, where the heck is the ABC signal coming from 204 degrees? WSB-TV, real channel 39, virtual 2-1. All of the other channels that I get, he gets just fine. I would expect at least a weak signal coming from that tower, but the TVs pick up nothing, zero, nada on that frequency. Any ideas what could be interfering with his ability to pull in that one single channel? I'd understand if all the channels were spotty or weak, but everything else comes in solidly.

Thanks
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post #2 of 9 Old 12-16-2012, 07:18 PM
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Did you try moving the antenna to a different area of the attic? It may be sitting in a dead spot for that particular channel. This is quite common, especially in an attic environment where signal reflections are more liklely than with an outdoor installation.
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post #3 of 9 Old 12-16-2012, 07:41 PM
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All bets are off when using an attic antenna. I've seen these results before in similiar set-ups. If you can, try to test the antenna on the roof and see if you get 2.1.

Or if you do not want to go through the trouble, try this as a test. Turn the antenna in the attic to 124 deg to get the stronger WSB-TV on Ch 46, or 142 deg for Ch 31. If you can get it, then get a smaller UHF antenna, could even be an indoor loop/rabbit ear. Install in the attic pointing to WSB Put the HBU-33 back to 200 deg. Join the 2 antennas together into a 2-way splitter in reverse.
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post #4 of 9 Old 12-17-2012, 04:38 AM
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It's as though the channel just doesn't exist on the spectrum.

The antenna is in a dead spot for that channel. Move the antenna.


Quote:
Join the 2 antennas together into a 2-way splitter in reverse.

Good luck with that one.
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post #5 of 9 Old 12-17-2012, 11:07 AM - Thread Starter
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Thanks all. I didn't realize there could be a dead spot for just one channel. I thought dead spots affected all the channels.
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post #6 of 9 Old 12-17-2012, 11:31 AM
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Yes, check ALL channels each time you move the antenna. Once you find a good spot for 2.1, one or more other channels may worsen. It may take some experimentation to find a sweet spot for ALL channels to be acceptable.
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post #7 of 9 Old 12-17-2012, 11:56 AM
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^^^^ that's where rotors come in real handy.
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post #8 of 9 Old 12-17-2012, 12:31 PM - Thread Starter
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Originally Posted by Otto Pylot View Post

^^^^ that's where rotors come in real handy.

I don't think a rotor would help in my situation because all of the channels I'm trying to receive are coming from towers located at 201 to 204 degrees from me. The direction shouldn't need to change as much as actual vertical/horizontal placement.
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post #9 of 9 Old 12-17-2012, 03:37 PM
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Because of reflected signals, the optimum direction for aiming the antenna for a particular channel may be different from the actual direction to the transmitter. I have two stations (WLOS, an ABC station broadcasting on RF channel 13, and WUNF, a UNC-TV (PBS) station on 25) whose transmitters are on the same tower about 80 miles away (Mt. Pisgah near Asheville NC). My rooftop antenna setup has optimum orientations 20 degrees apart for those two stations, probably because of reflected signals from my rooftop or a large tree in my front yard. Inside an attic, you're likely to have strong reflections from more different directions.

I usually get pretty good reception from both stations despite the distance, because of their elevation, but I have to use my rotor when I switch from one to the other.
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