[R-390] Varying gain [WAS: Filters]

[quartz55]

Yes, the audio tracks the gain changes, as does the diode load voltage.  My thinking is when it's at it's most sensitive, it's about equivalent in module gain as the module with the bad(?) filters.  But it always settles down to some lower gain value.  I'm doing this all in MGC, so the AGC shouldn't be affecting it.

I've got all replacement caps coming for C551 as well as all the bypass and coupling caps.  The Orange Drops I put in the other module were so large, I opted to buy smaller radial Panasonic ones for this module.  The ODs make it nearly impossible to work on.

I'm going to pull the 2 bad (?) filters out of the 2nd module and see if that makes the AGC work on that one, which it is not at all now.  Maybe I'll find a bad cap or something in the filters.  Otherwise the gain on the 2nd one seems good, however it will go into oscillation if I crank up R519 too much.  I don't know if that's 'typical'?

I've found Z503 on the module with bad AGC is open.  I've tried tracing the fine wires back to where it goes in the glue, but nada. That will kill the AGC for sure. Fair Radio has a used one for $16.  Anyone else have any?

N3DT