[Collins] Need KWM2 help

[John Page]

I have aKWM2 that is giving me fits. It hasnt beat me yet but its winning so 
far. So read the following and if anyone can suggest anything, I sure would 
appreciate it.

Turned it on the other day and everything seemed normal. Transmit and 
receive worked fine. Then I turned up the gain and "wow" feedback like mad. 
Loud squeal. Starts at about 1/3 gain. Here is what I have done so far.

* Swapped out V15 and V16 with known good tubes. no help
* Opened the audio line at the gain control. problem gone
* So I fed an audio signal in at the gain control and audio section worked 
normal.
* Reconnect gain and problem back.
* Opened line from T5 to V15 (avc rec). Problem still there.
* So I now think the problem is in the avc rect and prod det circuit.
* Remove the coupling cap from V15A to V15B and problem still there.
* Ok so maybe its in the prod det.
* All voltages and res. measurements ok.
* Replaced all caps in the prod det circuit and checked all res. problem 
still there

So if anyone can shed some light maybe I can still whip this guy. Thanks in 
advance. John



John Page K4KWM
Hollow State since 1953
(ex W8PKU,N8BLB,NA8O)

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