[R-390] Carrier Level Meter full deflection

[Larry H]

Hi Gary,  Good progress.  That low resistance on term 3 is still a big
problem - it must read about 500k ohms in order for the agc to work
correctly.  You might have a problem with the wiring.  Keep at it.

Regards, Larry

On Wed, Sep 20, 2023 at 8:43 PM <gary.biasini at shaw.ca> wrote:

> Larry,
>
>
>
> I have replaced C551 and resistance at terminal 3 was 457 ohms and on
> terminal 4 was 1.57M ohms.  Voltage with a VOM is -3.41 so much better.
> However, on a very strong BCB station, the carrier level meter does not
> deflect any further.
>
>
>
> I’ll try tube replacement again, next.
>
>
>
> Thanks for your patience.
>
>
>
>
>
> *From:* gary.biasini at shaw.ca <gary.biasini at shaw.ca>
> *Sent:* Wednesday, September 20, 2023 9:08 PM
> *To:* 'Larry H' <larry41gm at gmail.com>
> *Cc:* 'R-390 at mailman.qth.net' <R-390 at mailman.qth.net>
> *Subject:* RE: [R-390] Carrier Level Meter full deflection
>
>
>
> Thanks Larry.  I have now been able to replace C548 with no difference.
>
>
>
> I will replace C551 and see what happens.
>
>
>
> Thanks again.
>
>
>
>
>
> *From:* Larry H <larry41gm at gmail.com>
> *Sent:* Wednesday, September 20, 2023 7:54 AM
> *To:* gary.biasini at shaw.ca
> *Cc:* R-390 at mailman.qth.net
> *Subject:* Re: [R-390] Carrier Level Meter full deflection
>
>
>
> Hi Gary,  Good deal on the recapping.  Since the resistance on term 3 is
> so low it points directly to C548 or C551.
>
>
>
> Regards, Larry
>
>
>
> On Tue, Sep 19, 2023 at 11:00 AM <gary.biasini at shaw.ca> wrote:
>
> Larry,
>
>
>
> Thanks for pointing me to the 2 tutorials.  They were very helpful.
>
>
>
> Unfortunately, my VTVM is 2,000 miles away and all I have is a VOM made by
> Klein Tools.  Initial reading was -3.5V at 3 and 4.  After removing the
> shorting bar, resistance at 3 was 350 ohms and on 4 was 1.65M ohms.  I then
> set out to recap the IF module and was able to get to all the caps except
> for C545 and C548 which I couldn’t confidentially reach as the areas were
> quite crowded with other wires or components.  I will try again later.
>
>
>
> After changing most of the caps, the voltage now reads -0.17 (so worse)
> and the resistance is 456 ohms at 3 (better) and 1.56M ohms on 4 (worse).
> The meter now only deflects to 1 on the strong signal and up to 3 if I turn
> the RF gain totally CW – however severe distortion of the sound results.
>
>
>
> Another nagging issue has raised its ugly head again.  With the Line Meter
> switch turned off and the line gain turned greater than 5, the line meter
> deflects up to 40 with line gain at full CW and the amount of deflection
> tracks the sound amplitude.
>
>
>
> I love a mystery but this one is getting daunting.  I continue on.
>
>
>
> Regards,
>
>
>
>
>
> *From:* Larry H <larry41gm at gmail.com>
> *Sent:* Friday, September 15, 2023 9:46 PM
> *To:* gary.biasini at shaw.ca
> *Cc:* R-390 at mailman.qth.net
> *Subject:* Re: [R-390] Carrier Level Meter full deflection
>
>
>
> Hi Gary,  Insufficient c/l meter deflection is usually caused by low gain
> in the agc amp circuits or bad caps on the agc line.  Try replacing V508
> and V509.  The caps that usually cause this are C547, C548 and C551, but
> there are many other problems that can cause it.  See Charles Steinmetz
> agc diagnosys document on our website and my agc diagnosys part 2, both in
> the 'repair tutorials' section.
>
>
>
> Regards, Larry
>
>
>
> On Fri, Sep 15, 2023 at 9:24 AM <gary.biasini at shaw.ca> wrote:
>
> Larry,
>
>
>
> Thanks.  Manfred Antar advised me privately to adjust the pot for the
> carrier level meter.  While that brought the meter to zero, it barely
> deflects 30% even on the strongest local BCB stations.  As well, on MGC,
> the needle now goes negative.
>
>
>
> I will replace V506A and check the value of the plate resistor.
>
>
>
> Thanks for your input.
>
>
>
>
>
> *From:* Larry H <larry41gm at gmail.com>
> *Sent:* Friday, September 15, 2023 12:17 AM
> *To:* gary.biasini at shaw.ca
> *Cc:* R-390 at mailman.qth.net
> *Subject:* Re: [R-390] Carrier Level Meter full deflection
>
>
>
> Hi Gary,  One possibility is that V506A is very weak or dead or its plate
> resistor R549 is open or a very high value.
>
>
>
> Regards, Larry.
>
>
>
> On Thu, Sep 14, 2023 at 5:59 PM <gary.biasini at shaw.ca> wrote:
>
> Good evening,
>
>
>
> I am hoping for some help on this.  On EAC S/N 3122, upon turning on the
> radio, even without an antenna attached and not tuned to any signal, the
> carrier level meter deflects fully in both AGC and MGC mode.  The AGC
> appears to be working because, on strong signals, the sound at the output
> is
> not as strong as on MGC.
>
>
>
> Any thoughts as to what may be causing this issue?
>
>
>
> Thanks in advance.
>
>
>
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