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Old 4-Jun-2017, 8:25 PM   #14
Retired A/V Tech
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,286
Originally Posted by urhstry View Post
Here is my link...

I have a CM5018 and a CM-7777 Amp. I can NOT get channel 64 which is 8 channels (64-1 to 64-8) that I really wish I had. Thanks for the manual tuning help.... I'm going to try that now.
Thanks for the tvfool link. Very close to my estimate.

Which 7777 do you have; the old one with two antenna inputs, or the new one with only one antenna input? Where is the antenna located on your property? Where is the 7777 located? How long is the coax from the preamp to your power inserter and TV?

WQPX is your weakest possible signal. It is difficult to receive any signals with a NM of less than -10 dB. If you do receive a signal that has a NM of less than -10 dB, you have an excellent antenna system, your tvfool report is wrong, or they have been enhanced by Tropospheric Propagation.

This is the way it works: You must have enough antenna gain to give at least the minimum required SNR of 15 dB plus enough gain to offset the NF of the preamp. Once there is enough signal for the preamp, it will amplify the signal and the noise to overcome distribution losses and bury the noise figure of the tuner in the amplified thermal noise floor.
If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 11-Sep-2017 at 11:58 PM.
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