For several years I used a very simple interface with just DC isolation and
full Ground connection between my computer and radio for Digital modes.
Realizing that I was living on borrowed time before something blew, I decided to
do a full galvanic isolation interface. At the same time my ARC experimented
with a computer-based contest interface (CQ_caller aka voice recorder/player and
CW interfacing), requirering some way of signaling the computer what to do from
push-buttons and/or footswitches.
Another very good design with "hard" CW keying can be found here: http://www.cqrlog.com/?q=webfm_send/86/3
This is my design:
T1/T2 are 600Ohm LF transformers (salvaged from discarded telephone equipment); IC1/IC2 are optocouplers (same source)
(Click on picture to get a full resolution version)
The operational prototype boxed and ready to go! (In daily use in my schack)
I also constructed a "Soap-on-a-Rope" mini-version for portable use, omitting the pushbutton interface:
The cable between the interface box and the radio is attached via a 5-pin DIN plug, and is thus easily exchangeable if a another
radio needs attachment!
Both interfaces are used with several Digimode programs (WSJT, CW-Get and -Type, MMTTY, PSK31, W95SSTV, WINMSDSP 2000 and others) and have been in nearly daily use for almost a year.
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Last modified 09.10.2011, Peter Frenning