Place a watt meter between the transceiver and the KPA500 and measure the TX output into the KPA. I think you will find the transceiver output is low at those times.
This is fairly common in the K3/K3S world when the tx needs to be recalibrated. I would suggest that your 7610 may need recalibration as well. The KPA500 is a linear amplifier - it has fixed gain. The only thing in the KPA500 that could change the gain is a 3db pad in the front end that is invoked when the controller sees something amiss, but not so bad as to declare a fault (yet). You would see a flashing red LED on the KPA when this is invoked. Since you didn’t mention a flashing LED on the KPA, I can only assume the pad is not being invoked. This then points at the driving tx for low output. 73, Jack, W6FB > On Apr 16, 2025, at 1:01 PM, Phil Zminda via Elecraft > <elecraft@mailman.qth.net> wrote: > > In the last few days I have noticed that when operating FT8 using my > KAT500/KPA500 combo with an IC-7610, my output seems low on the first or > second transmit cycles after switching bands. If I am chasing DX I usually > run about 120 to 160 Watts, which is about 6 to 8 Watts on the transmitter. I > am seeing only 50 or 60 Watts on the amp when I first transmit. After a > couple cycles it goes to the higher output and is stable after that. > > When changing bands, I switch the radio, with the amp in Standby, then switch > bands on the amp before transmitting. Sometimes I use Tune in WSJT-X running > just a few watts with the amp in Standby for the amp to automatically switch > bands. My antennas have low SWR on most bands, so the tuner is often in > Bypass. > > This seems to have just started and most often occurs on 20 Meters using a > GAP 20 Meter Mono-band. > > I also run CW and some SSB but don’t notice the power meter as much as on > FT8. I don’t thing it’s happening there. > > Has anyone seen this or a similar problem? > > Phil N3ZP > ______________________________________________________________ > 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 jackbrin...@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
