25 amps at 14 volts is 350 watts. That is an awful lot for a radio that is supposed to be putting out only 20. I would expect at most 2 to 3 watts drain at 20 watts TX output. Something is definitely going on here. may load While I don’t suspect the antenna, have you tried testing into a good 50 ohm dummy load to see if you can duplicate the issue? You might also look for bad solder joints between the PA transistors and the antenna. And, just in case, check to make sure there are no bad (arcing) connectors in the antenna path.
Perhaps W3FPR might be around on the Easter Sunday for some suggestions? - Jack, W6FB > On Apr 16, 2017, at 7:51 AM, Steve Kavanagh via Elecraft > <elecraft@mailman.qth.net> wrote: > > This one cropped up just today, with no significant change in my home station > setup, using a K2/100 on 40m using a low inverted Vee. > > Sometimes (typically every other or every third time, but randomly), when > pushing (and holding) the tune button with the power set to 11 watts or more, > I get a high reflected power message on an antenna which is matched at low > power. The power supply voltage reads about the normal 14V and the ammeter > in the power supply is pinned at 25 A (or more) when this happens. An > external SWR meter reads lots of reflected power. Everything unplugged from > the rig except the power cable and the coax to the external SWR meter/antenna > tuner/antenna. It's fine on a dummy load. > > I'd suspect a simple RF feedback problem, except that with 100 watts of CW > everything is perfectly normal. The problem occurs only when using the tune > button around the nominal tune-mode 20 watts, so the external SWR meter > reading implies that the PA is probably oscillating at some frequency where > the antenna is not matched. I haven't tried any other bands yet, but since > there does seem to be RF feedback involved, I'm not sure they will tell me > much of a diagnostic nature. > > Any ideas as to what might be happening and how to stop it? > > 73, > Steve VE3SMA > ______________________________________________________________ > 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
