[Elecraft] Obscure RTTY bug?

[Iain MacDonnell - N6ML]

Preparing for the ARRL RTTY Round-Up this weekend, I ran into a strange
problem. Using "AFSK A" mode, feeding transmit audio into the K3's line
in from the computer running MMTTY (also tried with DM780, with the same
result), I would get a crackling noise along with the RTTY tones in the
K3's monitor audio. I don't know if the crackling is transmitted, or
just in the monitor. Levels are set for 5 bars on the ALC meter, and
the problem occurs in "TX TEXT" mode.

After lots of tearing my hair out (well, at least tearing my cables out
and trying other ones), I observed two things that make it go away:

1) Changing to USB ("REV DATA")

2) Turning *off* "TEXT DEC"

I recorded the probleml, from line-out, with text decode on and off:

http://www.dseven.org/k3/


Why the text decode would cause crackle in the monitor audio, and why
not in "REV" mode, I'm not sure... but I would like to be able to have
the decoder turned on...

     ~Iain / N6ML