[R-390] R-390A IF gain setting and S/N measurement

[Bill Kulze]

One method I have used which gives me a visual aid in setting optimal gain is that I connect the IF output to an SDR. I turn off the AGC in the SDR so I'm getting the straight IF signal. As you adjust you can see a point where the noise floor jumps right up where you don't want it. You can set it so that you can maximize the difference between the noise floor and the signal peak. You can even get a rough idea of how many db that is.

I've also used that setup doing all of the RF sections also.

Bill W2NVD

-----Original Message-----
From: R-390 [mailto:r-390-bounces at mailman.qth.net] On Behalf Of Larry H
Sent: Wednesday, June 22, 2016 6:19 AM
To: r-390 at mailman.qth.net
Subject: Re: [R-390] R-390A IF gain setting and S/N measurement

Thank you Charles - very good information.


  tradeoff in overload performance), you can also accomplish much more 
  easily simply by tweaking the IF gain control.  
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The question had to do with measuring the S/N.