Low noise amp

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Dave_sn25
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Joined: Sun Feb 17, 2019 9:52 am

Low noise amp

Post by Dave_sn25 » Tue Jul 23, 2019 2:02 pm

I have recently installed a 20db gain LNA in my attic connected to either a discone or a dipole for NOAA Satellites.
The SDR I am using is sdrplay rsp1a. I have noticed a marked improvement in the signals received however I am a bit puzzled by the gain settings on the sdr software. In both Sdruno and SdRconsole, changing the gain level has little effect on Smeter reading. Initially I set the gain low too prevent any overloading but really it had little effect. I have noticed on SdRconsole that as I change the gain, the signal strength shoots up then suddenly then backs off. I have tried adjusting the agc but it has little effect. This seems to happen in both AM and FM. Is the rsp1a merely controlling the signal level to prevent overloading?
Last edited by Dave_sn25 on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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g1hbe
Posts: 493
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire, UK

Re: Low noise amp

Post by g1hbe » Tue Jul 23, 2019 2:50 pm

AFAIK, the RSP's alter the s-meter calibration as the gain is changed, so the reported signal strength is always shown no matter how you fiddle with the gain. Now if you could alter the gain of your pre-amp, you would see the signal strength change as the RSP is not aware of external amplification or attenuation.
Last edited by g1hbe on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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Andy

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mikeladd
Posts: 186
Joined: Wed Jul 08, 2015 3:18 am

Re: Low noise amp

Post by mikeladd » Tue Jul 23, 2019 5:13 pm

SDR-Console, for whatever reason does not apply the RF and IF gains properly.

This guide will help with understanding the IF and RF gain settings in SDRuno
https://www.sdrplay.com/wp-content/uplo ... SDRuno.pdf

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