[R-390] Carrier Level Meter Issues

Wed Mar 2 15:07:04 EST 2022

Hi Gary,

I believe that you have AGC line problems

Needle pinning when switching between medium and slow is normal for a
“stock” IF deck.

There is a simple way to solve that, but too long to explain here.

However, it puzzle me that you did not have a meter reading in Fast mode,
but
 is C548 in the IF desk still in place and good ??

Is the C551 on the IF deck still the original one ??

The meter reading directly depends on the AGC line level, and with the meter
at 100dB (100mV input) the AGC line should be around -12V.

Another AGC line problem could came from a leakage inside one of the
mechanical filters (see how the AGC is applied to V502).

I have a solution for that without rebuilding the filters, but if C551 is
still the original one, it have to be replaced first IMHO.

Could be that your whole IF deck is due for a rebuild

73, Jacques, VE2JFE in Montreal

De : gary.biasini at shaw.ca <gary.biasini at shaw.ca> 
Envoyé : 2 mars 2022 14:39
À : Jacques Fortin <jacques.f at videotron.ca>; hamfish at comcast.net;
R-390 at mailman.qth.net
Objet : Re: [R-390] Carrier Level Meter Issues

Jacques, 

Thanks for weighing in. AGC voltage is -5VDC with Bandwidth 16kc, RF gain
fully clockwise, Limiter off.

DB meter starts at 45 in Slow AGC, pins the needle to the right for a second
or so in medium then settles on 58 and does not move in fast AGC. Going back
to medium, no change, back to slow pins the meter for a second and then it
settles at 45.

Regards,

Gary I. Biasini

  _____  

From: Jacques Fortin <jacques.f at videotron.ca <mailto:jacques.f at videotron.ca>
>
Sent: Wednesday, March 2, 2022 12:16:07 PM
To: gary.biasini at shaw.ca <mailto:gary.biasini at shaw.ca>
<gary.biasini at shaw.ca <mailto:gary.biasini at shaw.ca> >; hamfish at comcast.net
<mailto:hamfish at comcast.net>  <hamfish at comcast.net
<mailto:hamfish at comcast.net> >; R-390 at mailman.qth.net
<mailto:R-390 at mailman.qth.net>  <R-390 at mailman.qth.net
<mailto:R-390 at mailman.qth.net> >
Subject: RE: [R-390] Carrier Level Meter Issues 

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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