I've posted messages here with info about a circuit for keying CW (or PTT)
from TRlog using opto-couplers to isolate the PC from the radio, but the
schematic had a Radio Shack part number that is no longer available from
them. It turns out that the new Tech America stores and DigiKey (mailorder)
both carry the same series of opto's, and they are the same pinout (6-pin
DIP package) as the old part shown on the schematic that's on my web site.
I've updated the drawing with numbers that are available now (4N25, 4N35,
and 4N37), but nothing else has to change.
The 3 parts have similar specs and only cost about $0.50 at Tech America.
If anyone wants a copy of the ASCII schematic let me know, the qsl.net web
site is still awkward to access. It only takes 4 parts in a DB-25 (or DB-9)
shell to protect your COM or LPT ports from RF..
The schematic is at: http://220.127.116.11/ae0q/contest/
The www.qsl.net DNS isn't working yet, but using the IP numbers works OK..
73 -- Glenn
Another month ends... All targets met, all systems
working, all customers satisfied, all staff eager and
enthusiastic. All pigs fed and ready to fly.
AE0Q / V31RY ex: GM5BKC, ZB2WZ, SV0WY, WA0VPK
email@example.com --SOWP 5558-M, QCWA LM, ARRL LM, NCVA--
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