[Elecraft] Strange KPA500 problem on 6M

[HankP]

Are you sure its only putting out 200 watts on 6 ??? MIne started acting that way a few weeks after I assembled it , was perfect whenI first ran thru the tests but later started doing exactly waht you describe . With an external Array Solutions Powermaster wattmeter and good dummy load it was in fact putting out more than 500 watts when the meter said 200 watts or so. Look at votlage and current and see how they compare with say 10 meters . FWIW - mine runs about 14.2 amps and 62.4 volts on 28.025 mhz for 500 out and on 50.1 mhz about 15.8 amps at 61.5 volts. Wattmeter reads withing about 10 watts or so compared to my AS Powermaster . SWR of my dummy load with all the assorted cabling using ANT3 port after letting it tune with the DL runs about 1.1 on 6 and 1.2 on 10 KPA500 readings - the Powermaster says its a tad better . All I can figure is its little digital brain got confused in mine and the 6 meter calibration went to pot - I re set it and it has been fine ever since. Manual tells how to do that . Anyhow something to look at . 73 Hank K7HP ----- Original Message -----
> Bottom line: I can’t get more than 200 watts out of my new KPA500 on
> 6M. It faults (HI SWR FAULT) when I try to increase the drive in order
> to get more output.
> But I get full power on 6 with a dummy load.
> Bad antenna? Don’t think so. Here’s my setup:
> 3 element M2 6M beam fed with high cost, low loss coax. Very low SWR
> and works great until I try to get more than 200 watts out of the amp.
> I also have an R8 vertical and an HF dipole, both of which tune up on
> 6 with my new KAT500.
> When running the amp at 200 watts, the swr indicator shows low swr
> with the KAT500 and any of the 3 antennas. As soon as I increase the
> drive with any of the 3 antennas, I get the fault.
> When running the amp without the KAT and the beam hooked directly in,
> same fault when increasing drive.
> The beam looks good in an MFJ antenna analyzer as does the R8.
> So, I think the amp must be extremely sensitive to anything other than
> a pure 1:1 load as provided by the dummy load.
> Your thoughts?
> Carl, K8NU
> Carl Yaffey K8NU
> Recording studio.
> cyaffeyNO_SPAM at gmail.com
> 614 268 6353, Columbus OH
> http://www.carl-yaffey.com
> http://www.grassahol.com
> http://www.bluesswing.com
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