[R-390] Carrier Level Meter Issues

[Jacques Fortin]

Hello Gary,

Please also replace C547 with a reliable film capacitor (Mylar or
polypropylene dielectric) if that is not already done.
What type of replacement capacitor did you used for C551 ??
Please check the value of R549: should be within ± 10% of 82K.

Is your Carrier Level meter a replacement or an original one ??
Does this receiver behaved correctly for you before, or it is a new
acquisition ??
Was all the tubes tested good on a reliable tube tester (not the emission
only tester variety) ??

ONE TEST STEP FURTHER: DIVIDE TO CONQUER.
The intent of the following test procedure is to break the AGC distribution
in two parts.
This way, it could be known if the problem comes from the generation of the
AGC voltage, or it's distribution in the IF and RF modules.

1_ With the receiver OFF, remove the jumper between TB102 contacts 3 and 4.
2_ Connect the contact 4 to GND, using a flying lead or whatever you can
use: this will lock the AGC line distribution to zero volts.
3_ Connect a voltmeter to the contact 3 to measure the voltage there (to
test differences between Fast, Medium, Slow modes).
4_ With the RF gain control at zero, power the set in AGC mode.
5_ Once heated up, bring the RF gain "up" when tuned to a strong local BCB
station until the Carrier Level meter start to move.
6_ You should be able to peg the meter to max on a strong signal, check the
voltage(s) on pin 3 with the meter at half-scale.

If the developed AGC on pin 3 is enough to deflect the meter to the max,
your set problem is within the distribution to the IF or RF module (all the
AGC line destinations connected to pin 4).
If so, my prime suspect will become leakage in one (or many) of the
secondaries of the mechanical filters...

You can also measure the resistance of the AGC line from pin 4 to GND.
It should be around 1.77 Meg ohms, due to the AGC voltage divider between
R201 and R234 on the RF deck (AGC to the V201 grid). 
Lower than that... well, please report your findings.

73, Jacques, VE2JFE in Montreal