[R-390] Newbie needs help

[Bill Kulze]

I stumbled on something interesting regarding the IF gain adjust while tinkering with feeding the IF out in to an sdr (winradio G303) tuned to 455kHz. It's best to have the sdr agc off. As I increased the IF gain on the 390a I hit a point where the noise floor jumped right up, with the SN ratio going right to crap. I set it to just under that point and it seems to have the largest delta between signal peaks and noise floor.

Bill W2NVD

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net] On Behalf Of Mike Bracey
Sent: Sunday, October 06, 2013 4:23 PM
To: R-390 mailman
Subject: Re: [R-390] Newbie needs help

Thanks again for every ones help. I bought my beautiful condition 390a from a local ham. He sold it to me for $200 because it was blowing the B+ fuse and he was tired of "messing" with it. I finally traced  the problem to a bad cap in the IF module. My radio is a Collins unit that at some period had a depot rebuild so it is a mix of modules. The meters had also been replaced with white faced meters. The previous owner had replaced the deadly caps, replaced the filter caps and solid stated the power supply. 
 
Since my cap repair it has worked great except for the BC band distortion. I have set the IF gain per Chuck's method and it seems to be working fine.
After using it for a while I'm going to take it to a friend who is a retired Air Force radio tech. He has agreed to do a full alignment for me.
 
Finding this forum has been a blessing for me. When I first bought this receiver I asked a couple of questions on the 'zed. I was answered so rudely that I erased them from my browser and have never gone back. There does seem to be a lot of  asshats in our hobby who lurk on the forums.
 
73,
Mike, KE5YTV
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