K3 power output instability

[w7xu]

I'm experiencing a problem with instability in power output from
my K3/100.  No word back from Elecraft yet (it's only been a few
days), so I thought I'd try here.

The problem is that at relatively low power output levels
(approximately 10 to 40 watts), the power output does not remain
constant.   If I engage TUNE, the power will vary plus/minus 3 or
4 watts, then jump up briefly by as much as 10 watts or more
before resuming smaller excursions.  Although the power
variations are brief, they cause the grid protection circuit in
the amp to trip.  This behavior seems to be independent of mode
and frequency.

The above problem persists with different feedlines and occurs
with the amp out of line and transmitting into a dummy load as
well.  At higher levels of output, the power level is stable. The
radio is of relatively recent manufacture (S/N 5839) and I have
the latest downloads installed.  I have another K3 that does not
exhibit this problem.

Any ideas?

Thanks & 73,

Arliss   W7XU
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Don Wilhelm-4]

Arliss,

I would suggest that you run the Transmit Gain Calibration and see if
that improves the situation.

73,
Don W3FPR

On 3/13/2013 9:10 PM, Arliss wrote:

> I'm experiencing a problem with instability in power output from my
> K3/100.  No word back from Elecraft yet (it's only been a few days),
> so I thought I'd try here.
>
> The problem is that at relatively low power output levels
> (approximately 10 to 40 watts), the power output does not remain
> constant.   If I engage TUNE, the power will vary plus/minus 3 or 4
> watts, then jump up briefly by as much as 10 watts or more before
> resuming smaller excursions.  Although the power variations are brief,
> they cause the grid protection circuit in the amp to trip.  This
> behavior seems to be independent of mode and frequency.
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html