[Elecraft] K2/100 current consumption problem - update

[W3FPR - Don Wilhelm]

Fraser,

If you have a 'scope handy, try cranking the power up to 100 watts on 160
and 80 and observing the CW envelope - if you see what looks like weak
modulation on the top and bottom of the envelope pattern, you have a low
frequency oscillation.  If you do have that oscillation, the 'cure' has been
discussed on this reflector - on the KPA100, put a 1K resistor across RFC3,
and change R4 from 100k to 39k.

I have worked on KPA100s having this modulation problem, but never related
it to current draw before, but it is worthy of investigation.

73,
Don W3FPR

> -----Original Message-----
>
> Thanks Geoff, the TR bias HV is 139V on RX.  On TX at 70W out it's about
> 118V on 160m and 80m.  With power flat out it's 113V on 80m and 109V on
> 160m.  So I think that's ok.
>
> The voltage on U7B pin 5 and 6 is identical on 160m and 80m at
> full power at
> 675mV, so I think the PA bias current is behaving.
>
> G3VTT suggested the transformers, but they have the correct
> number of turns,
> including the po/swr sensor T4.
>
> Thanks / 73 Fraser G4BJM
>
>