Jim, I don’t think this is the same problem as you had. The receive signal on my K3 does NOT drop off when placing the amp in OPER. With my antenna switched over to the IC-705 (not the K3), the received signal does drop off when the amp is placed into OPER mode. Thus, I’m pretty certain that R7 and the PIN diodes are OK - the K3 is not affected.
Jim / K7TXA >>>>> > Jim, Andy et al, > > I weighed in on this thread last evening from memory in response to Andy's > comment, above. By age 77, I should have learned not to rely on memory. As > it turns out, my memory was faulty. > > So, even though it appears many have pointed Jim to a useful, unrelated > solution, I will now provide the correct information about the issue and fix > with my KPA500 almost one year ago. > > At first glance, my symptoms were nearly identical to what Jim is reporting: > With ALL control cables between the K3s and the KPA500 completely > disconnected (only the input and output coax cables connected to the amp), > every time the amp is manually switched from "STBY" to "OPER" the receive > signal on the K3s dropped about 20 dB. > > As many suggested, the problem was in the T/R circuit. In my case the > culprit was R7. This 51 Ohm resistor was toast -- completely open. My fix > was to parallel a pair of 1/4 Watt, 100 Ohm resistors across the R7 pads. > Problem solved. The KPA500 has been on good behavior since. > > Hopefully, this information might be useful to someone in the future. > > Jim - WS6X > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to w6...@me.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
