Subj : PSK31
To   : JIM MUNDEN
From : Roy Witt
Date : Sun Aug 06 2000 11:28 pm

Hello JIM.

07 Aug 00 01:25, you wrote to me:

JM> Hello Roy!  Thanks for the reply.  I found that the sound system in
JM> my old laptop is in fact compatible with PSK31, so that solved
JM> that problem.  Unfortunately, it has only one serial port, and it's
JM> connected to my TNC for APRS use.

Does it have a parallel port you're not using?  I found a circuit that can
be used on either DB25 or DB15 connectors.

JM>   None of my radios have VOX capability, and it seems a waste to tie
JM> up a serial port just for a PTT line.  I wonder if there is a circuit
JM> that could be inserted in the sound card's output line to activate
JM> the PTT.  It ought to be fairly simple, not much more than a
JM> switching transistor and a few other components.  Of course, it needs
JM> to be quite fast so none of the signal is lost.

The circuits I found should be fast enough.  There's also a modification
to switching circuit by using an opto coupler that would isolate your old
Swan and keep you 60hz hum out of the puter.

JM>   Hmmm...Time to go surfing again! 73's de Jim

I'll post the URL where I found those circuits.  Can't right now, but will
when I get home this afternoon.


... OSCAR birds don't have feathers!
--- Twit(t) Filter v2.1 (C) 2000
* Origin: KB6PI's Cantina * Santa Ysabel, CA (1:10/22)

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