[Elecraft] Tuning K3 with linear amp

[Bruce McLaughlin]

I am still exploring my new K3 (it's less than one week old.  I discovered
an odd issue while tuning it with my Commander HF 2500 amp.  With the ATU
off and the power lowered to about 3 watts I activated the tune function.
While watching the output on my Coaxial Dynamics wattmeter I gradually
raised the K3 output power while tuning the amp.  When I got to around 13
watts drive from the K3, the wattmeter was showing a carrier power of 1 KW
from the amp.  The drive power of 13 watts indicated on the K3 was unusually
low for an indicated output of 1 KW carrier.  When I then spoke into the
mike and flipped on the peak reading circuit on the watt meter, it showed
only 500 to 600 watts pep which was low in my experience.  Usually with an
indicated carrier power of 1 KW I should at least get around 1400 or more
indicated peak power on modulation.  I gradually increased the drive from
the K3 until the peaks showed 1 KW or a bit more.  When I again checked the
output of the K3 it showed a bit more than 23-25 watts which is what I
usually get with my other radios.

This behavior is different than my other radios.  It appears to require a
low drive level to show 1 KW carrier output from the amp but with a low peak
reading.  I suspect something is happening with the ALC but I'm not sure.  I
should mention that I have yet to load any firmware updates.  It has
whatever version it had when it left Aptos on May 2.  Could that be a
factor?

Bruce - W8FU