[Collins] R-388/51j4 crystal filter

[Grant Youngman]

I have my 51J4 aligned and working well, with a good (on the third try -- thanks, Fern!) 3.1 KHz mechanical filter, Lankford SSB mods, and my Sherwood SE-3 modified to be switchable between 455 and 500 KHz IFs.

Except for one thing ... sometimes, not all the time, when I turn on the crystal filter to any position the radio sounds like the "divine wind" has started to blow.  A significant noise level appears in the output, somewhat affected in character by the phasing control.  Before I tear into the radio  again, I wonder if anyone has encountered something like this and has a clue where to point the finger?  There isn't anything added to the signal path except for the crystal itself and a parallel 10 pf cap in position 1.  Any thoughts?  A grounding issue maybe?

Thanks .. Grant NQ5T

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