MR-1 distortion on strong SSB signals - HELP!

[Sandy Gerli]

Hi,

Going through my MR-1 which seemed to work all right, I noticed that
some feller had removed the 8uF/475V cap at the B+ input and also
had disconnected the 750 ohm 10W dropping resistor. Hmmm...I
restored the configuration to normal. Now, I notice that, on strong
SSB signals, there's considerable audio distortion which goes away
if I crank the RF Gain way back. Perhaps Joe Ham had low B+ and was
trying to jack it up a bit. Anyway, I'm using an HP-20 with the
correct voltages.

All other alignment parameters seem just fine; I went through the
whole procedure. What's left is this distortion and a weak S-meter.
That takes a 1000mV signal from my HP sig gen to get an S-9 signal.
Supposed to be 100uV for S-9. All tubes check out well.

I suspect something in the AVC line, but I'm not sure where to
start. That 6T8 triode/triple diode is an odd duck on the schematic.
It's hard to tell from the envelope diagram WHICH section is the AVC
rectifier, although I suspect it's off Pin 2, going to the AVC buss
through several high-value (2.2 meg and 1 meg) resistors.

Anyone have any suggestions?

73,

--
Sandy Gerli, AC1Y
500 Country Club Road
Avon, CT  06001-2406
(860) 675-5566
E-Mail: angerli at home.com

Life Member: ARRL, QCWA
Collins Collectors Association
Hallicrafters Collectors Association
Intrepid Heathkit Aficionado

Boatanchors are Ham Radio's living heritage!
Restore something! Smell that hot solder!
Better 'n booze...
And, you can get up afterwards if you stay away from the B+!!
Keep your finals dipped, now...

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