[Elecraft] K4 Features and current K3+

[Andy Durbin]

"I need to be able to switch from digital (M110A) to voice on a moments notice so can not use the digital modes.  The mike is hot while transmitting digital.  Most mikes leave the mike element hot.  The PTT is a SPST switch.  This means that you have to be careful not to have any noise in the shack while transmitting digital.  If there is a way on the K3, service was not able to point it out."

It would be very surprising to me if K3 and K4 had such a limitation.  This situation is handled perfectly in the Kenwood TS-590 by using 2 distinct keying commands.   Front panel PTT is equivalent to CAT TX0; and takes modulation from the front panel mic jack.  TX1;  and the equivalent ACC hardware PTT, take modulation from the USB Audio CODEC or ACC analog audio input leaving the mic muted.   

Switching between front mic and digital is simply accomplished by asserting the appropriate PTT line or CAT command.  The digital mode application asserts TX1;  Keying mode cannot be changed while transmitting so first keying command wins until TX stops.

73,
Andy, k3wyc