[Elecraft] FSK Issue

[Dave Reed]

I seem to have this recurring problem with FSK on my K3.  Up until now, the
problem was intermittent, often solved by rebooting my computer and/or
reloading MMTTY.  Well, without changing anything, the problem has now
become consistent, persistent and predictable:

 

At 0 - 22W on 80m, or any power level on 6m - 40m, MMTTY (using my
interface) will key the K3 and send normal RTTY tones using the FSK-D data
mode.

 

At 23W and above, on 80m, MMTTY will key the K3, but I only get the high
tone.

 

Of course, if I put the radio into test mode, I get normal RTTY tones.

 

Am I overlooking something obvious?  Going crazy?  SWR presented to the K3
is 1:1 (SteppIR BigIR vertical).

 

AFSK works fine using the AFSK-A data mode, but I don't want to use AFSK.
:-)

 

73,

Dave, NX7F