[Elecraft] K3 Transmit Issue on 80M SSB

[Dave Fugleberg]

I seldom operate 80M phone, so don't know if this is a new issue or not. K3
S/N 8334 with latest firmware. When I key the transmitter and speak or
whistle into the mic, I get no RF output. I can hear myself in the monitor.
If I enable VOX, speaking engages the transmitter, but no RF output.
Engaging the TUNE function does produce RF output as expected.
If I switch the mode to CW and tap the straight key, the radio transmits
with expected output. If I THEN switch mode back to LSB, radio functions
normally with expected output.
Note that all of the above is with radio connected to a dummy load, so my
antenna is out of the picture.

Once I switch to CW, key the radio, and switch back to LSB as described
above, transmit works fine until I power cycle the radio, or adjust the RF
Power control (even if I just dial it down a couple watts and then right
back to where it was). Either of those two events appears to disable SSB
transmit until I 'kick' it by transmitting with CW.

As far as I can tell, this behavior is ONLY on 80M. The rig is NOT in 'Test
mode', and Xmit Inhibit is turned off in the menu.  All other radio
functions and bands seem to work FB.

Any ideas ?