The big question is, how is the PTT connected? Does that operate off
of DCD or DTR on a serial port? If so, note that the voltage coming
out of a serial port's handshake lines can be as much as +/- 15 volts
and still be within the RS-232 spec. I find it hard to believe that
+/- 15 volts on the PTT pin of the radio is OK.

Typically, one uses the RTS (request to send) line of the serial port
for PTT purposes. This depends on your PSK31 software package.

Using an optocoupler, rather than connecting directly, is probably a
good idea. A lot of PCs these days use pseudo-RS232 voltages (either
+5 and ground, or +5 and -5) but it's probably best not to take
chances that your rig might object to higher voltages.

Do any of you know if VOX will work in PSK31 mode?

If you're going into the MIC input, probably so.

If you're going into an auxiliary-audio input, it may not. On my
TS-2000, the auxiliary audio input doesn't support the VOX circuitry
and doesn't work with the software-based "activate PTT" command over
the RS-232 port - it only works with the auxiliary input's "PTT"
ground-to-transmit line.


--
Dave Platt AE6EO
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