RE: K2/100 current consumption problem - update
Posted by
Don Wilhelm-3 on
URL: http://elecraft.85.s1.nabble.com/K2-100-current-consumption-problem-tp375119p375124.html
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
>
>
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