[Elecraft] 80m KPA1500 High reflected power problems

[Don Wilhelm]

Peter,

If your antenna end insulators are covered with ice and snow, it is 
entirely possible that the ice/snow covering will not show conductivity 
with low power, but will become conductive at high power.  That will 
make whatever material you are using to support the antenna ends a part 
of the antenna radiator - effectively lengthening the antenna.

Shake the snow and ice from the end insulators and/or use longer end 
insulators and there is a good chance your problem will go away.

73,
Don W3FPR

On 3/9/2019 10:17 PM, Peter Dougherty wrote:
> John, I know there were some issues with my old tube amp, but it did load
> enough to get me 275-odd DXCC entities with 1500W on 80 CW. The KPA has
> never been used in the past on 80 since I was having antenna trouble (one
> end was down all winter and it just got fixed today).
> 
> Everything's snow covered out the back so I don't want to play around at the
> coax switch at the moment. I'll try bypassing the switch when it's a bit
> warmer and the snow is gone.
> 
> Of note, last year with the weird SWR, the "old antenna" (same physical
> space and height, just all different materials) was cut to 3750 and I used a
> tuner for the bottom end. I found the tuner kept giving me "unable to find a
> match" when I tried tuning with high power from my tube amp. I figured
> replacing every factor in that chain would fix the issue; the only thing
> that's the same is the antenna switch and the physical orientation of the
> wires themselves. New amp, new coax, new balun, new wire, insulators and
> even the support ropes were changed out.
>