[Elecraft] K2 Linear Amp Driving Power

[Steve Kavanagh]

Roy:

I assume you are probably making these
measurements/observations on CW, in which case I can't
add to what has already been suggested. 

However, if you are testing in SSB mode, there is
another possibility.  Some K2/100's have trouble
keeping the power down on SSB, especially on 80m.  The
ALC action is just not aggressive enough in these
units....they probably have a bit higher gain through
the transmit chain than most, resulting from
particularly "hot" transistors, etc.  This is
particularly obvious near the 10 W crossover between
the QRP final and the KPA100.  If I recall correctly,
mine gives about twice the output at the 11 watt
setting as it does at the 10 watt setting, even after
a mod to make the ALC more aggressive (which is
adequate to stop more serious over-power/distortion
problems at higher power settings).  

To check look at the K2 output power display; if you
see 30 watts peak on SSB on the display then you may
actually be getting around 30 watts rather than the 12
watts you have it set for. This problem does not
affect CW however; the actual/displayed power output
should be very close to the requested value.

73,
Steve VE3SMA

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