[Elecraft] KPA500 code oscillator

[W1GO (Joe)]

Hi all,

Finished assembly of KPA500 and a little surprised at the magnitude of hum / buzz during CW (no real issue on SSB); I've read about it but was surprised at just how pronounced it is.   I could use the KPA500 as a code oscillator for practice; no need to keep monitor turned on.  I've read most of the historical dialogue regarding methods to minimize "the buzz": use yellow wire tap, keep wires from touching chassis, make sure everything (including transformer) is good and tight, etc.  all those things are done with little positive impact.  I'm running off well regulated 240 VAC.

I just wonder if anyone has any other "secrets" they might share.  My code proficiency is not great, at this point, and having the KPA500 groan in response to my keying is somewhat distracting; even with headphones when monitor is turned up higher than usual.

Best regards,

Joe
W1GO