Butch, The HEXFET used in the K3 KEY OUT circuit has a diode to protect against negative voltage excursions. I do not know how much negative voltage it will stand, but it is possible you exceeded the limit. That diode conducting is the reason your amp was keyed every time you plugged it into KEY OUT.
You can check to see if the K3 KEY OUT still works OK with an ohmmeter - you should have an open circuit during receive - then use TX TEST and again check the resistance at KEY OUT - it should be near zero. Yes, an external relay would be a good solution, or modify the amplifier in some way to key it by grounding a positive voltage. Checking the specs for the devices on both ends of the cable before plugging that cable in is always a good idea. 73, Don W3FPR Butch Schartau wrote: > I want to use a Collins 30L-1 amp with my K3, when I plug the 30L-1 amp > control cable into the K3 KEY OUT jack, the 30L-1 keys. The 30L-1 is keyed > by grounding it's key line (pulling -160 DC to ground). The K3 specs says > +200 VDC, at 5 amps, I guess the K3 does not like the minus voltage on the > 30L-1 key line, any suggestion other than an external relay? > > Butch K0BS > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
