So above 3.675 it works fine?  Weird. When you say it was happening
previously, is that also with the KPA1500? First I would try another amp and
watch the SWR. I would also try bybassing any lightning protection devices
and coax relays so you just have coax and an antenna connected to the amp.

GL
John KK9A





Peter Dougherty W2IRT wrote:

HI guys, 
I'm still having a serious problem on 80m with my KPA1500.

With the amp inline I'm getting high reflected power fault everywhere below
about 3675. My antenna (an inverted vee) is resonant at 3550, and the SWR is
below 2:1 from 3500 to 3630. 

 

This was happening in the past as well, and prompted me to completely
rebuild the antenna last summer. The antenna is fed with 100' of brand new
Davis BuryFlex feedline, a brand-new 5kW-rated Balun Designs 1:1 current
balun, new 12 AWG copper-clad steel wire, even new heavy ceramic insulators!


Without the amp everything's fine. I can push 100W through to the antenna
all day; the SWR LEDs on the amp (bypassed) show two green and that's it.
It's fine on every other band, including 80/75 phone. 

 

With the amp in, If I drop the drive to 10W or less, the amp is happy and I
get about 450 Watts out. But the instant I drive it with ~15 Watts (when the
K3s kicks the high power module in, and I hear the internal relay click, I
get the HI SWR warning and the amp faults. 100% repeatable. Doesn't matter
if the tuner is in or out..there's NO way to get high power out of the KPA
on 80 CW. 


More details: If the KPA's tuner is bypassed it just faults instantly. If
the tuner is placed inline and I find a match, I can get about a second's or
two's worth of power before the SWR LEDs start lighting up, then the fault
happens.

Any idea what's going on here? This is unbelievably frustrating

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