Folks -
I just completed the KPA-100 amp for K2 #5540 and everything is great
except for one problem. My memory tells me that I have seen
something on this before
on the reflector but I cannot remember the solution.
Anyway, I am seeing unstable power control on 40M SSB. 40M CW seems
fine (although the power control "hunts" a little more than it does
on the other bands). The power output on my peak reading Bird
will exceed 150W on voice peaks - on the other bands, the peak is at
or below the power control setting. Input current hits about 20 amps
(normally it is pulling about 15 amps, except
it pulls about 18 amps on 17 meters CW or SSB - but power control is
stable there). I tried SSB into the dummy load on 30M since it is
the same LPF, but power control is FB there.
By backing the power control down below 60 watts, the peaks can be
reduced, but it is still hitting 40% or more over the setting -
again, ONLY on 40M SSB.
There are no high current or any other errors showing up. My KPA-100
came with the resistor mod, and it is installed. I have already
performed the R98 mod on
the base K2 which did help stabilize the power "wiggles" on 40M CW,
but did nothing to tame SSB. All of this is into a verified good
dummy load. I have seen the same
high peak power that the Bird is showing on my LP-100 meter also.
Has anyone seen this before?
Thanks,
Bill
K4DXU
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