[rabbit73]

I have noise margins that range from -10, to -15 for the signals that I want the most.

Special effort is required to receive weak signals with a negative Noise Margin.

Without a preamp, signals below NM -2 dB with an antenna gain of 12 dB can not be received because of the tuner NF that is added to the thermal noise floor and the minimum required SNR of 15 dB.

With a preamp, the antenna gain must bring the signal SNR up to at least the minimum required SNR plus the preamp NF BEFORE the preamp input, because the preamp NF makes the NM more negative.





Fortunately, the tvfool report has poor accuracy with 1 and 2Edge signals, and signals can often diffract over terrain interference and the curvature of the earth to arrive at your antenna.

You need a way to measure your progress, to tell you if more effort and expense are justified. A SiliconDust HDHR can give you SNR, which they call signal quality. My Sony TV gives SNR as low as 13 dB on the Diagnostics Screen, but only if it has picked up the channel. You could get your system noise figure down to about 1 dB if you use a halfwave coaxial balun and a preamp with a NF of 0.4 dB.

C) What do I expect to see in gain from both of them vs one? I’ve heard that you add 3 dB, to what you’d get with a single XG91. Is this correct?

The theory says 3 dB, but there are combining losses. When you use a splitter in reverse as a combiner, it has an internal loss of 0.5 dB, so the most I have been able to get is 2.5 dB gain.

I currently have an HDB8X antenna at 15 feet up and no rotor, and it’s barely cutting it for me.

Any chance of getting it higher? Does your tvfool report look any better higher?

Are there any trees or other buidings in the signal path?