[Elecraft] K2, PSK31 & microphone

[Jim Price]

Conventional wisdom seems to be always use an isolation transformer in the
PSK-31 output to your mike input.  I think most also agree it best to use
one in your PSK-31 input from your rigs audio out.  Several of the
commercial kits/units do not do the latter.  I have tried it with and
without and not seen a 60-Hz line (or harmonic thereof) in my audio.  YMMV.

73, Jim - N4ST