"However, what I'm seeing is that when the amp is in OPER mode, my receive signal strength drops way, way off to the point I have to go full AF volume to hear signals. If I put the amp in STBY, signal levels go back to normal."
These exact symptoms have been associated in past reports with a failure of the TR switch PIN diodes. Jack's idea of incorrect band can be easily confirmed, or eliminated, by looking at the KPA500 band display. Andy, k3wyc >>>> 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 arch...@mail-archive.com
