[Elecraft] K2/100 output variation

[Don Wilhelm]

Chris,

You cannot make a sound judgement using TUNE.  Evaluate the R98 value change
with actual keying.  If you change bands or change the power level, it will
take a few dot times to settle into the new power setting, that part of your
observation is normal.

The rest of the situation is due to the loop response of the ALC control
loop (that controls the power output) - it is quite with only the base K2,
but adding the KPA100 can cause the loop to overshoot and oscillate -
increasing R98 reduces the time constant of the loop and reduces the
overshoot.

Monitor the output on 10 meters during determining the maximum value for
R98 - too much resistance will reduce the maximum power output on the higher
bands, and yes you can compromise if you are willing to accept the lower
power on 10 meters.

73,
Don W3FPR

> -----Original Message-----
>
> No, that didn't help, Stewart. With the 100 PA disconnected and 5 watts
> requested, I see around 0.5 w difference in actual power and that
> is stable.
>
> Having re-connected the 100 w pa to restore the K2/100 to the state I
> would normally use it, I have put a scope on the output. With requested
> power of 50w, in Tune the readout shows 29w immediately, dropping to 24,
> 21 and 17w, it then toggles between 17 and 22w. I can see this stepping
> on the waveform displayed  on my scope. It also explains what I was
> seeing the other night. Since I was working pile-up style, the overs
> would be short, so each time I went to transmit the power variation in
> the K2 would also vary drive to the amp with the consequent output
> variation of between 100 and 200 w from the amp.
>
> Chris G3SJJ
>
--
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.5.432 / Virus Database: 268.15.28/605 - Release Date: 12/27/2006
12:21 PM