The meter comes after the AGC transistor. The AGC circuit consists of a
germanium detector diode with a low-pass filter that feeds a DC amplifier.
The amplified DC voltage controls the gain of the 3 I.F. stages and the RF
amplifier. It is almost impossible to get at the RF amplifier and the mixer.
These devices are embedded in the bandswitch assembly, along with two of the
AGC diodes. Now, if one of those diodes is cracked, that could also cause a
problem.
One of these days, I will dig into the radio. I've got a good T-12B and
T-12C, so at least I have a couple of reference standards.

Pete

"Scott Dorsey" wrote in message
...
Pete KE9OA wrote:

I did receive the manual today. This receiver uses an AGC diode in each of
the I.F. amplifiers, similar to the way that it was done in the Collins
651S-1. No wonder this rig has such a good dynamic range.

And if any one of those stages fails, the system will still work with only
slightly degraded AGC, unless somehow one of those diodes fails into a
short
and pulls down the AGC line. This is something fairly easy to try.

It looks like there is a 2.2uF electrolytic cap that acts as a low-pass
filter after the AGC rectifier.

Where is the meter there? If the cap fails into a short, will the meter
still work? If so, it's not that cap.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."