[Elecraft] K3 - Another push-to-talk question

[Richard Ferch]

Doug, the answer is yes, but the details depend on whether you are using 
MMTTY stand-alone or from inside another application (like N1MM Logger 
or Logger32).

If you are using MMTTY from inside another application, the easiest way 
is to let the parent application handle rig control and PTT. The parent 
application and MMTTY cannot both use the same serial port, and in all 
likelihood you will want the parent to have access to frequency and 
other information from the radio.

If you are using MMTTY stand-alone, then: Open the MMTTY Setup window 
and select the TX tab. At the top right is the PTT & FSK area. For your 
situation (AFSK with no serial port other than the rig control port), 
this should be set to NONE. Below it is a button labelled "Radio 
command". Click on this button to open MMTTY's Radio command window. 
Here you can select the serial port you are using for radio control with 
the K3. Do not do this if you are using MMTTY from inside another 
program that uses the same serial port!

You can use this port not only for PTT control, but also for getting 
frequency information from the radio into the MMTTY log. To do this, you 
set the port speed, etc. (38400, 8, N, 1), do not check any of the flow 
control or DTR/RTS boxes, select "Kenwood, Elecraft" as the Group at the 
bottom of the window, set Model to "Kenwood, Elecraft", and set the 
Frequency offset to OFF. You will see commands in the Rx and Tx boxes; 
these are the software commands MMTTY will use to control the radio's 
PTT switching.

MMTTY can also use RTS on this serial port for hardware PTT switching 
(with the help of the K3's CONFIG:PTT-KEY set to RTS-OFF), but there is 
a potential problem with this: If the DTR/RTS box is checked and the Rx 
and Tx Command boxes are not empty, MMTTY will use both software and 
hardware PTT methods in parallel, which is not a good idea. Several 
users who have done this have experienced having their K3 stuck in 
transmit (i.e. failing to switch back to receive when the software 
commands it to do so). This appears to be due to a "race condition" in 
the firmware when software and hardware commands are issued to the radio 
simultaneously. The work-around is to eliminate one or the other of the 
two parallel methods, i.e. to use either software (TX; RX;) commands or 
hardware (RTS or other PTT input), but never both methods at once.

73,
Rich VE3KI



VE3VS asked:

> I use the latest MMTTY software (AFSK), have the two audio lines connected,
> and use VOX to operate this mode. At the same time, the serial cable from
> the computer to the radio remains connected.
>
> Question - Is there a set-up that will allow the computer to signal PTT
> through the serial cable in order to transmit the RTTY tones, rather than
> enabling the VOX switch?