[Elecraft] K3 TX Power

[Ray Coles]

For the last few months I have been focussing on datamode operation, and
putting a lot of hitherto unobtainable DX in the log as a result.

I have noticed a problem with my K3 on all bands related to TX power. My rig
is a K3/100 plus a KPA500/KAT500 combo which remain on STBY for digital
modes of course.

My problem is: I dial in a power-setting on the K3 and for the first (let's
say JT65) transmission the actual transmitted power as measured by: the K3
itself, the KPA500 and my inline MFJ duelling banjo wattmeter is always much
less. If I dial in 100W I would get 20-30W during my first transmission,
30-50W on the second, and 75-80W on the third. On the 4th or 5th minute of
transmission it will reach the dialled in power setting. The SWRs are all in
the 1 to 1.5 range and I can see no external problems.

This is not good because I would really prefer it the other way around, once
someone has responded they will stick with you, but if they don't hear you
on the first call, you're toast.

To offset the problem I turn the power up to 100W and cross my fingers that
they will hear my first (weak) transmission. Unfortunately by the time I am
done, I am putting out more power than is healthy for other users who may
find that the weak signal they are working is pushed down by their AGC due
to my strong signal in the same window.

Attempts to adjust the power during a QSO fail, with a minor downward
adjustment (say from 100 to 80W) resulting in the true output power
plummeting to 20W and the cycle starting over.

This doesn't seem to be any kind of "warm-up" issue (my first suspicion) but
maybe some kind of logic or control feedback issue.

Has anybody else experienced this? Is it me? 

 

Ray Coles, C.Eng. M0XDL

10 Littlemoor Road,

Weymouth DT3 6AA

Tel: +44 (0) 1305 833699

Mob: 07831 516517