[Elecraft] K3S Sub - No Signals

[Byron Peebles]

I have found myself again in this mode where pressing the SUB button 
reveals white noise but no signals.
When I flick the A/B or hold the BSET buttons, they are really LOUD.  
But noting on SUB.

I have checked that the antenna is correct (same as MAIN (ANT1), the RF 
GAIN and AF GAIN are up, and there are no words or icons in the display 
to suggest I have something else set.

When this happened to me and the radio was new, it was the wrong ANT, 
not not this time.

Any suggestions?  It's a pain tracking the TX3X guys without SUB giving 
me signals.

73, Byron