SB300 Troubleshooting

[Bill Evans]

Hello all
I've got a SB-300 which is a second receiver for me, and it does fairly
well except for one problem.  As I tune past strong signals I notice
that after the signal passes out of the xtal filter passband, the
signal has a definite peak just outside of the passband.  I have
measured the following (very approximately since I'm using the Heath
dial to get the frequencies!)
On a strong signal, (any band) there is a peak in signal strength:

USB:  3000 - 4000 Hz higher in freq than zero beat (in opposite
sideband area)
LSB:  5500 - 6500 Hz higher in freq than zero beat (higher in freq than
the xtal filter is supposed to allow through)

I am using the heath SSB xtal filter Part number N-404 (2.4 kHz?)
the USB xtal is about 40 Hz low from specs
the LSB is about 80 Hz low (unless, of course my freq counter is not
calibrated!)

I at first thought it was a shielding problem, and have taken the
boards out and cleaned along where they contact the chassis, I have
checked all shielded cables and all sources of grounds.  I have tried
bypassing some signal lines-- I have checked voltages on tubes... and I
am stumped.  Any one have any ideas?

Thanks for reading.
Bill
wb4css

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