Canadian TV, Computing and Home Theatre Forums - View Single Post - Signal Amplifiers (Amps, Preamps, Distro Amps) - See Chart in Post #1
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Old 2005-10-25, 01:49 AM   #38
stampeder
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Quote:
Originally Posted by RASCL
After I repositioned my antenna to the roof, pre-amp (cm 7778) located at the antenna, a single direct run (about 120') of RG-6 cable...
You just hit on the main issue - 120 feet of RG-6 is costing you about 5 or 6db of signal at UHF frequencies. Add the signal cost of the new splitter/cable/lead to the TV, which is as much as 3db. Given that your antenna (a CM3010a as you mentioned in another thread, with a CM7778 preamp) is giving you all its got just to bring in the other Buffalo stations, you start to see why the signal on the weakest station dropped out under that load.
Quote:
Originally Posted by RASCL
1) Is adding a distribution amp the right approach?
1) If the signal is strong enough and clean enough at the end of the 120 foot mark of RG-6 but starts to die off with any downstream splits, you could add about 10db of signal strength at that point with an amplifier to offset the losses shown above. My preference, and if you'd like a bit more insurance of clean signal, would be to put a 10db amp in place at about the 80 to 100 foot mark. Of course you could just test to see where it should be placed to get the cleanest, most powerful feed.

Quote:
Originally Posted by RASCL
2) Should the distribution amp be installed between the pre-amp and amp or after?
2) How many taps do you want running off the antenna? A distribution amp with 4 or more taps would be great if you want to drive several TVs, FM receivers, PVRs, etc. but if its just one TV you may find that a single in/single out amp will do the trick - it depends on your particular layout. No matter which one you choose, that amp will be the final source that all internal house cable strings will branch out from.

The schema is: antenna -> preamp -> outdoor cable downlead -> amp -> indoor branch cable -> TV or FM receiver

If you want to stay with your CM3010a antenna, an inline amplifier is your ticket. OTOH, a move to a higher gain antenna like a CM4228 feeding into your CM7778 would mean probably never having to worry about the load again. Hope this helps!
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