I heard from a few people who have problems connecting a cw paddle to a serial port. Some are using USB adapters. Some blamed contact bouce and some blamed dirty contacts. With serial port keying, none of the paddle wires is at ground potential - all 3 wires are floating. So the large metal frame of the keyer base is also floating and picking up hum.
Someone reported connecting two 0.5 MFD capacitors across the paddle contacts solved the problem. Someone else said connecting three .001 MFD capacitors between paddle wires and ground solved the problem. Both persons were keying VOIP tones, so no RF was involved. When I designed my home brew, touch paddle keyer, I used two 5 volt reed relays (with internal diode) to key the equipment, whether it be a serial port or a transceiver. One relay is for dits and the other relay is for dahs. These relays have less than 1 millisecond of lag, and consume just 10 ma. at 5 volts. The contacts are rated for 0.5 amps at 200 volts. It would be a simple experiment to try hooking up these relays with a battery. http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=306-1020-ND http://ve3efc.ca/keyer.html -- Doug McCormack, VE3EFC _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kb.flex-radio.com/ Homepage: http://www.flex-radio.com/
