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Old 25-Apr-2014, 1:19 AM   #8
mulliganman
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Join Date: Jul 2012
Posts: 147
Quote:
Originally Posted by GroundUrMast View Post
Yes. The goal is to prove the antenna, by itself, is receiving a reliable signal. By using a short section (50' or less) of known good coax and a known good receiver, the antenna is the only variable left. Once the antenna has been proven to produce reliable reception of the desired signals, you can turn your attention to troubleshooting other parts of the system.

Here is a source for attenuators: http://www.3starinc.com/drop_in-line_attenuator.html The exact value is not critical in most cases. You don't want to add too much loss though. The goal is to isolate the imperfect input impedance of the filter from the imperfect impedance of the cable and connector from the antenna. The resistor network in the attenuator is likely closer to 75Ω than either. Try one 3 dB attenuator and if needed, experiment with two 3dB attenuators stacked end to end. The attenuator should be installed on the AC7 with no cable in between.

Be open to the idea that AC7 can be located near the antennas... Or not. If it's more convenient to run each antenna lead into a protected location and the combine, that's fine. I'm thinking of situations with a preamp at the antenna and power inserter inside the house. In these cases, I'm prone to place the combiner downstream of the preamp power insertion block. This also keeps the combiner protected from the weather while also making future service access much easier.

An FM trap needs to be between the antenna and preamp. The TVPRAMP1R has an FM trap built in... Simply verify the switch is set correctly.
Thanks for the link on attenuators. Regarding installation, do you install it on the "output" of the AC7? How will I know if I need two 3ds while testing?

The only tuner I have that has both a signal quality and signal strength indicators is the DVR+. So, I may try it there (it is where I am seeing the signal quality fluctuations). If you advise against it, please share. I will say if I bypass the CM3414 when running this test, I don't think my signal strength will be high enough to get a reliable picture (past tests have shown this to be the case).

I didn't know that about the AC7 combiner. Based on the diagram, I thought it had to be located at the antennas to get the best results: http://www.tinlee.com/PDF/AC7-custom...kup%20Info.pdf

I thought it had to be there too as to make a better, cleaner combined signal. But, you are saying I could install the RCA preamp on the 91XG antenna and connect both leads from each antenna inside the attic though. Correct? I also assume by power inserter you are referring to the CM3414?

I did pickup the Radio Shack FM trap. I realize the RCA preamp has a trap also, but just in case I don't use the trap on that or need that preamp, where/how does the FM trap get installed? I know you said between the antenna and the preamp but I'm a little confused as to proper installation.

I'm wondering if the C2V may need to be moved a little and if that isn't causing some interference the DVR+ is picking up on when I see the signal quality fluctuations. Right now, the two antennas are probably a couple of feet or so apart.

If all the troubleshooting doesn't fix the issue and I find I need to replace the C2V do you have a recommendation? I am presuming if there is an issue it would be with that antenna since it is the one that should be receiving the ABC signals.
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