Run the 5 and 50 watt TX power calibration on the K3. It's in the K3 utility program.
73, Guy K2AV On Sat, May 6, 2017 at 12:51 PM W1GO (Joe) <[email protected]> wrote: > > Elecraft faithful, > > Any guidance with trouble shooting a KPA500 / K3 issue would be helpful. > > Problem: KPA500, primarily in SSB, “redlines” (600W+ LED) after a few > seconds of transmission / speech. This seems to be independent of band. > With the KPA in standby, the K3 output power holds rock steady as indicated > in the KPA. > > Conditions: > - Only about 20W of drive in SSB can result in the “redlining” … To > eliminate the redlining, I have to turn drive down to about 18W. … about > 20W in CW provides about 500W fairly solid. > - The K3 is powered by a 70A supply that does not sag much upon K3 > keydown (14V to ~13.7V indicated on K3) > - KPA is powered off 240 … I tried two different KPA transformer taps as > I noticed with yellow tap the supply voltage right about 60V and > occasionally a little below on key down. Supply voltage stays well above > 60V with red tap but same “redlining” of the KPA. > - Have tried various mic gain compression settings using dynamic mikes. > Without amp in-line I do fine with gain 30, compression 20 (10db). I’ve > gone as low as gain 15 / compression 15 (~5db) with no impact. > - I’ve tried various TXG VCE rating from -1.5 to 1.5 … no impact. > - ALC on … ext ALC off …. varied these to see if there would be an > impact. None. > - SWR (to different antennas) is <1.7 w/o KAT500 and <1.3 w/ KAT500 > > > What I’ve tried / done: > - Gain / compression changes as above > - Checked K3 supply voltage and no significant voltage drop on key down > - Changed power supply to a 35A powering K3 with no change > - Varied KPA transformer taps to ensure supply above 60V > - Changed coax between K3 and KPA and KPA and KAT500 > - Tried with two different antennas / coax runs and had same result > - Varied TXG VCE from -1.5 to 1.5 > - Performed gain calibration on K3 > > > > I’ve had the KPA for about 9 months but primarily operated CW so not sure > if this is a recent occurrence. Any other suggestions would be appreciated. > > Many thanks, all, and have a wonderful weekend. > > > > Kindest regards, > > Joe > W1GO > > ______________________________________________________________ > 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] -- Sent via Gmail Mobile on my iPhone ______________________________________________________________ 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]
