[Elecraft] [K2]K2 filters continue to "drift" out of alignment

[K1FFX]

Don Wilhelm-4 wrote
> The bottom line is that the BFO frequency is 'drifting'.
> The most probable cause is a defective solder connection in the BFO area.
> Carefully lift L33 and reflow the soldering of the BFO crystals. Reflow 
> the soldering of C173 and C174, RP6. D37, D38, C169 and Q24.
> Make certain when you replace L33 that the leads of the resistor are 
> well soldered and the leads of L33 are soldered to the resistor leads.

Thanks for the specific and detailed hints, Don (and thanks also to Matt and
Bob for helpful e-mails).  I decided to defer handling L33 and the two BFO
crystals.  I went ahead and reflowed the soldering for the other components. 
This has fixed the immediate problem: the center frequencies moved "up" and
was I able to easily align all the filters.  Hopefully, this will be a
permanent fix and there will be no further significant BFO drift.  If I
continue to see drift, then I'll go ahead deal with L33 (whose solder joints
all looked fine to me yesterday) and reflow the BFO crystals' soldered
leads.

Thanks again!

- Bruce K1FFX




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Bruce Rosen
K1FFX
K2/100 6982 KSB2 KAT100-1

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