[Elecraft] KPA500 Problem

[Scott Manthe]

Is this behavior present on all bands or just 40 meters? You might try 
using the KPA500 without the control cable, as well.

73,
Scott, N9AA


On 9/21/12 8:01 PM, Phillip Shepard wrote:
> I put my new KPA500 (s/n 1057) together earlier this week and have been
> loving it, although it has seen only light use so far.
>
> However, that changed this afternoon.  I used it briefly on 40m LSB a few
> hours ago and all was fine.  About 35w of drive for 550w out.  I just
> retuned the antenna to the low end of the band, yielding a 1.0:1 SWR at the
> K3 in the standby mode of the KPA500.  When I switched the amp to operate
> and keyed the transmitter (tune control), the amp power LEDs jumped up to
> about 500w and then went to 0.  Subsequent keying  show a very high SWR at
> the K3 (65 to 99:1) and the K3 puts out no power as does the KPA500.  I
> tried a dummy load with the same result.  If the amp is in standby mode the
> K3 acts right and the power and SWR LEDs on the KPA500 act right (100w out
> at a low SWR).  Putting the amp into operate mode acts like the input SWR is
> very high.
>
> I tried tightening up the cables at both ends (BTW, I am using the control
> cable between the rig and amp for maximum integration, and the K3 knows to
> reduce the power out when the amp is in operate).
>
> I hope I am doing something wrong, and the fix is simple.  Any suggestions
> of where to begin?  Thank you.
>
> 73,
> Phil, NS7P
>
>