Mike,
Within 2-3w based on RF ammeter reading of 1.40 amps that match
I^2*R=100w. 50-MHz 50w and HF-100w Bird elements were within 1w
agreement at 50w output on 6m. And long use of the meter on many
bands with multiple rigs.
Of course Bird rates +/- 5% of full reading which would be +/- 5w but
then if 72w reading were actually 77w then the amp is outputting 117w
on 20m. Also Bird appears to be good agreement with the KVPA-100 Bar
meter which reads 70 on 6m, and the power meter on my Drake MN2000
antenna tuner shows same output as the Bird.
Input SWR of the amp is 1.4 on 6m vs 1.0 on HF which may suggest
something. I am going to swap out coax lines everywhere and
re-measure. But I had also assumed the Astron was running 14.2v from
measurement years ago when installed, so may have shifted down with aging.
72w vs 80w is nitpicking but I had hoped it would show specs on all
bands considering its cost. Interesting that 6m takes nearly twice
the drive power that is needed on HF. Perhaps the limiting factor is
the matching transformers. If so that is a disappointment.
6m band is most demanding with often weak-signal conditions so every
watt is important. I traded my 150w Mirage 6m amp to buy the
KXPA-100 realizing that it was rated at nearly half the output on
6m. I plan some improvements to my 6m station this year which will
compensate: 1) adding a second 6-element yagi, 2) finishing a 1100w
6m amplifier which can be run at 800w on SSB with 8w drive from my
KX3. But the KXPA-100 will likely be used for normal daily use and
QRO reserved for extreme DX operating (including eme and ms).
If I find the issue was with coax cables I will report that after
testing. Also will provide measurements after raising Astron 50A to 14.2v.
73, Ed - KL7UW
How accurate do you believe the Bird to be?
73, Mike NF4L
73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
dubus...@gmail.com
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