[R-390] Carrier Level Meter Issues

Thu Mar 3 17:12:50 EST 2022

Good afternoon,

On the IF deck, I had previously replaced C553 and have now replaced C548
and C551.  With RF Gain full on a strong local AM station, the meter shows
zero in slow, pins on medium for a second then settles in at about 15 and
stays there when I move to fast.  Going back to medium, no change, then
going to slow and it is at about 2 or 3dB.

Thanks again to everyone as I continue to troubleshoot.  I will send later a
list of the resistances measured on each connector as compared to the
resistances stated in TM11-5820-358-15 pages 98 and 99.

73 Gary

From: David Wise <David_Wise at Phoenix.com> 
Sent: March 2, 2022 12:47 PM
To: Jacques Fortin <jacques.f at videotron.ca>; gary.biasini at shaw.ca;
hamfish at comcast.net; R-390 at mailman.qth.net
Subject: RE: [R-390] Carrier Level Meter Issues

Barring the miraculous outlier, every R-390 and R-390A that has not had C551
replaced, needs it.  They go leaky which strongly affects AGC behavior.  You
can put the new one in the IF deck, either in the old one’s can or
underneath, or you can mount it behind the front panel as part of my mod,
“Ending the Moment of Silence”.

It’s also a good idea to either replace C553, or insert a current limiter
which is easily made from a cheap abundant LND150 depletion-mode FET.

Dave Wise

SWL in Hillsboro Oregon (inactive)

From: r-390-bounces at mailman.qth.net <mailto:r-390-bounces at mailman.qth.net>
<r-390-bounces at mailman.qth.net <mailto:r-390-bounces at mailman.qth.net> > On
Behalf Of Jacques Fortin
Sent: Wednesday, March 02, 2022 11:16 AM
To: gary.biasini at shaw.ca <mailto:gary.biasini at shaw.ca> ; hamfish at comcast.net
<mailto:hamfish at comcast.net> ; R-390 at mailman.qth.net
<mailto:R-390 at mailman.qth.net> 
Subject: Re: [R-390] Carrier Level Meter Issues
Importance: High

Gary, does it make a difference when you try the AGC in Slow / Medium / Fast
??
When listening to a very strong local BCB station, what did you measure as
the AGC line voltage (TB102 3+4) ???

73, Jacques, VE2JFE in Montreal

-----Message d'origine-----
De : r-390-bounces at mailman.qth.net <mailto:r-390-bounces at mailman.qth.net>
<r-390-bounces at mailman.qth.net <mailto:r-390-bounces at mailman.qth.net> > De
la
part de gary.biasini at shaw.ca <mailto:gary.biasini at shaw.ca> 
Envoyé : 2 mars 2022 13:18
À : hamfish at comcast.net <mailto:hamfish at comcast.net> ; R-390 at mailman.qth.net
<mailto:R-390 at mailman.qth.net> 
Objet : Re: [R-390] Carrier Level Meter Issues

Craig,

I missed your message until just now. It is in the AGC position.

Thanks for your message.

-----Original Message-----
From: hamfish at comcast.net <mailto:hamfish at comcast.net>  <hamfish at comcast.net
<mailto:hamfish at comcast.net> >
Sent: February 27, 2022 10:16 AM
To: gary.biasini at shaw.ca <mailto:gary.biasini at shaw.ca> ;
R-390 at mailman.qth.net <mailto:R-390 at mailman.qth.net> 
Subject: RE: [R-390] Carrier Level Meter Issues

Hello Gary,

Is the function switch in MGC or AGC??

Regards,
Craig

-----Original Message-----
From: r-390-bounces at mailman.qth.net <mailto:r-390-bounces at mailman.qth.net>
<r-390-bounces at mailman.qth.net <mailto:r-390-bounces at mailman.qth.net> > On
Behalf Of gary.biasini at shaw.ca <mailto:gary.biasini at shaw.ca> 
Sent: Sunday, February 27, 2022 9:00 AM
To: R-390 at mailman.qth.net <mailto:R-390 at mailman.qth.net> 
Subject: [R-390] Carrier Level Meter Issues

On my 1967 EAC S/N 4996, I have zeroed the meter as follows:

I tuned the radio to a dead space, unhooked the antenna and turned the RF
gain fully counter-clockwise. I then adjusted R523 to zero the meter.

However, when I tune to 2 different local (strong) AM stations on the BCB,
even though I start to hear the audio when the RF gain is at 4.5 and it is
heard very loudly at 7, the carrier level meter only starts to register when
the RF gain is at 7.5 and at full clockwise, only registers 40 db.

I would like to troubleshoot this but don't know where to start. If anyone
could guide me as to what to check, I would be most grateful.

Thank you. 

Gary

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