CW keying interfaces

Peter G. Smith
Wed, 25 May 1994 17:11:24 -0700 (PDT)

Hi Walt -- Well, the problem here isn't RF, but as someone reminded me, I 
haven't checked with a high-impedance voltmeter to find out just what is 
actually going on at the input to the interface.  It's not RF, though, 
because it occurs with the rig not making any...

It would be a real service if you could test and then publish a design 
for an opto-isolator keying interface here.  I could probably work one 
out, but somebody who is truly circuit-literate could do it a lot quicker.

73, Pete
NOTE: New Address

On Wed, 25 May 1994 Waltk@PICA.ARMY.MIL wrote:

> Pete,
> At hi pwr levels any xsistor-based switching system has failed here from time
> to time. The optoisolator trick is indeed the way to go. Keeping the RF out
> of the computer is  a matter of keeping RF off the keying line. That is a
> tall order in my station - miles of cabling for computer, coax, control and
> rotator line, etc. Once, while remotely keying the rig from my 75M vertical
> (250' away) I blew out the COM3/COM4 add-on board in the PC. I now disconnect
> the keying line from the rig to the computer altogether. I suspect you are
> getting RF into the LPT port, as I have experineced. During CQWW, if I set
> power level >1000 W and/or turned beams at the shack (only 80' away) CT would
> go into CW-lock mode, as you're experiencing with N6TR. Thanx for mentioning
> the optoisolator trick, I have to do that here B4 the contest season begins.
> ..............................................................................
> 73 de Walt Kornienko  -  K2WK          Frankford Radio Club
> Internet:          Snail: RR1 Box 919, Lafayette, NJ 07848
> DX PacketCluster: K2WK > W3MM          Packet: K2WK@NX2P.NJ.USA.NA
> ______________________________________________________________________________