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Old 4-Mar-2018, 11:37 PM   #9
Retired A/V Tech
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,716
I did lose 2 stations without amp on. They are WSIU Carbondale IL and WTUV Vincennes IN. WSIU is not on my plot map. Virtual 16 and actual 19 I think.
WSIU is on your TVFool report, but it is not on your report because it is more than 100 miles away. As before, NBC is not on your TVFool report, but it is on your report. There is no WTUV; it doesn't exist.

Adjusting the voltage will not do what you want.

If you want to continue to use that antenna with its built in preamp and try to find results between amp IN and amp OUT, you would need to insert an attenuator between the antenna and its internal preamp. It would be a custom modification, not easily done.
I would like to try it on a titan 2 or something in that type of amp just for grins..
Your report indicates that a preamp should not be used. If you must use a preamp, it should be a medium gain preamp that is resistant to overload like the Antennas Direct Juice. Even then, you would overload your tuner and need to add an attenuator before the tuner.

What weak signals are important to you? When you have very strong local signals and you also want some weak signals, there will be a great difference between the two. Your system is only able to receive a limited dynamic range. You must tailor your signals to that limited range.

When your strong local signals begin to cause overload, it will produce IMD (Intermodulation Distortion) that will create spurious signals in the preamp and in the tuner. These spurious signals (spurs) raise the noise floor and wipe out your weakest signals because their SNR is reduced below the minimum required 15 dB.

The goal is to have just enough antenna gain and just enough preamp gain so that you can receive the weakest desired signals without causing overload from the strong local signals.

WTVW has a Noise Margin of 88.7 dB even before adding any antenna or preamp gain; clearly overload territory:

Interpreting Noise Margin in the TV Fool Report

If are not happy with your present antenna with its preamp OFF and you want a system that gets weak signals at your location, you will need an antenna system like this:

antenna > custom CH 28 bandstop filter > attenuator if needed > overload resistant preamp > coax > grounding block > power inserter > TV

Grounding the coax with a grounding block connected to the house electrical system ground helps to reject interference.

You might also need an FM filter; you have some strong local FM signals that might cause interference to TV reception:
Attached Images
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If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 5-Mar-2018 at 12:19 AM.
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