I can't count the times I've explained that circuit too - thanks for putting
it on the web again Don. When I was starting to do this stuff, N1RCT's
pages were the place to go for info. The circuit is also described in the
instruction manual for K6STI's RITTY program using a 2N2222.
** Many might not realize it, but N1RCT's interface page is still available
at http://www.w5bbr.com/pttfsk.html. It's the same as what Don has
described, although I don't think Dick had CW shown on his on his. Take a
look at it if you haven't already!
> I built them into a little plastic (wish it had been metal) box with three
> phone plugs.
I used a plastic RS box with a metal front. I put the components on a piece
of RS circuit board. I put 4 stereo jack on the front. If you use the
convenient RS ground plus 2 conductor cable, you can make 2 cables, 1 each
from 2 com ports on your computer to the 2 input stereo connectors. Then
you can use the 2 stereo output connectors to go to your rig(s). This makes
it convenient if you cange modes or rigs, you don't need to remake the com
port end of things - Just change the output en that attaches to the rig.
(For an FT-1000MP or Icom 756PRO (I or II), you don't even need the resistor
at all in the line from the TxD line of the com port to the rig's FSK
input.) YMMV So with 2 transistors and 4 resistors, you can make
interfaces for 2 radios. Sorry Rigblaster, it's cheaper this way!
Using the stereo connector, you can have ground + PTT and CW or FSK. I have
a CW cable that I just plug in when I want to operate in a CW contest.
Can you say <$5 and happy? ;-) 73