Different Radio RF Gain on VHF and UHF

SatNOGS
1

Hi all,

This is my third week with SatNOGS, my station is still in testing mode. I have VHF/UHF fan dipole and LNA powered by RTL-SDR bias-tee. On UHF it seems the LNA + 22.9 dB Radio RF Gain is a good option, but on VHF it is too much.

Is there any easy way to have different Radio RF Gain settings for VHF/UHF?
The option to disable bias-tee on VHF would work also, but having different gain settings would be more convenient in my case.

Thanks!
Andriy
W9KM

2

Got an idea how to disable bias-tee, inspired by this comment: Pre/post script format
I can make a custom pre/script which will check the passed {{FREQ}} parameter. If I correctly understand what {{FREQ}} means…
Would it work?

A.

3

The Pre/Post script works, I can turn bias-tee on or off depends of the passed frequency. Unfortunately the LNA I use is fixed-gain, and its too much on one band an not enough on another. I would really like to have a way to set a separate RF Gain for VHF/UHF in the SatNOGS client settings. Until then (or until I’ll get another SDR) I’ll keep my station UHF only.

4

Hi @w9km and welcome to SatNOGS!

Unfortunately you can not set different gains depending on the frequency/band.

Please open an issue at satnogs-client repo, to suggest this feature.

5

Reduced supply voltage as gain limiter for the LNA?

6

Have you tried it? I have RTL-SDR, not sure if bias voltage is configurable there. Also, the LNA linearity will be affected with reduced voltage, I guess?

7

Yes. Don’t do this.

Dropping voltage will reduce gain, but it will also degrade the linearity of the device at the same time, which is usually not a good idea. Operate the device at the manufacturers stated supply voltage…