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K2 filter alignment problem

Posted by Elecraft mailing list on Apr 11, 2019; 1:28am
URL: http://elecraft.85.s1.nabble.com/K2-filter-alignment-problem-tp7650809.html

I have aligned my K2 crystal filters with Spectogram many times, but
this time I've run into a problem that I can't figure out.

Using Don's [and the manual's] instructions, I can align F1,F2,F3 in
decreasing bandwidths. All works as per expectations. On F4, the
alignment goes "ok," [as per Spectogram] but when I use it with
on-the-air signals, the signal "disappears" and shows up about 900 cps
lower and in "reverse" orientation [BFO on opposite side]. When the
signal disappears, I can change filters [F1/F2/F3] and it's right there
where it should be with the bandwidth getting narrower as expected. But,
switching to F4, it's gone. I have tried changing the BFO frequency
throughout its whole range when in F4, thinking that I've aligned it on
the "wrong" side. No luck. I'm stumped. Any and all suggestions welcomed.

...robert
--
Robert G Strickland, PhD ABPH - KE2WY
[hidden email]
Syracuse, New York, USA
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