[Elecraft] K3 and KX3 questions for Wayne

[Edward R Cole]

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:
     dubususa at gmail.com