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Rabbit: Regarding a preamp in my scenario... A little bit of reading, it sounds like the main difference between an amp and a preamp is ultimately the quality and the amount of noise that it introduces? Is that correct?
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Sorry, I have been a little careless with my terminology which has added to your confusion. I have used the terms preamp and amp interchangeably, which isn't very precise.
There are two types of amplifiers in common use for antenna reception.
1. A preamplifier, or preamp, consists of two parts, the amplifier itself which is close to the antenna and designed to be outside, and the power supply or power injector which is inside.
With this setup it is possible to use the same coax for the signal coming down from the antenna AND for the DC power going up to the amplifier without them interfering with each other.
It is desirable for the preamp have a low Noise Figure (NF) so that it adds as little of its own noise that would interfere with the weakest signals, because its noise degrades the SNR of the weak signals. If the SNR falls below 15 dB, the signal drops out as it falls off the "Digital cliff." The NF of the preamp determines the total NF of the system because of its position at the beginning of the signal chain.
2. A distribution amplifier is used inside to feed more than one TV if the signals from the preamp are not strong enough. The NF of the distribution amplifier (DA) should also be low, but it is not as critical as the NF of the preamp. The DA can also be used as a preamp inside as in your case, like the Channel Master 3410.
Update 5/29/2015: Delete 3410 from preamp list on the advice of ADTech. See post 20.
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While I had been using a 100' coax when doing my further afield tests, do you think that I would get much out of a preamp in my normal scenario? Right now, I have a 6' coax from the antenna to the FM trap, and a 3' coax from the trap to the tuner.
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The 100' coax was making your UHF signals about 6 dB weaker. I think you should let you equipment tell you what improves reception because we haven't yet discovered all the factors that affect it.
You already have a good idea of how strong the signal needs to be. You now need to learn how to use the SNR and uncorrected errors to guide you, no matter what the tvfool report says; I can't be there to help you.