On Tue, Nov 29, 2022 at 06:19:45PM +0000, Michael Carter wrote: > The original 100 watt PA (KPA3) used RF BJTs as the finals, > whereas the KPA3A used RF MOSFETs (LDMOS).
I took it apart a few weeks ago. I did not note what transistors are in it. I will be taking it apart again when I have time in the next week or so. It all looked good. I can detect no burned smell of any kind nor did I see anything obvious. I did clean things up and put it back together. It does have the gold pin update. > similar problem revealed the fault to be in one > of the RF chokes (the red toroids on the 100 watt > PA board) that feed DC to the PIN diode switches. > The problem was a broken wire on one RF choke. I did look at these but in retrospect I did not look closely at the wires on each. I will do that when I take it apart again. I do see it drawing current in transmit and that seemed to go up as I turned up the power control. I did not note the amount of current shown on the K3 display but I will look at this further in a few days. Thanks for all the good advice so far - once I am back with the radio I will dig into it a bit more. -- George Fremin III - K5TR [email protected] http://www.kkn.net/~k5tr ______________________________________________________________ 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 Message delivered to [email protected]
