Now I'm really confused. I observed the power drop when operating
several times, as described below. However, I just ran a test, both with
an antenna and a dummy load, and saw only a very small change in output,
perhaps 50 W, which is inconsequential. I even tried simulating CW
operating in QSK mode. I can't think of anything else which has
changed. In each case, I'm reading the power output on the KPA1500
display, but it appears consistent with the P3 TX monitor. Any ideas?
BTW, the specs I've seen for LDMOS FET's like the ones I presume are
used in the KPA1500 show quite a small variation in gain with
temperature. Feedback should reduce that further. That would be
consistent with my test results, but not the operating ones.
I'll do some more "real" operating in a couple days and report the results.
73,
Scott K9MA
On 5/30/2018 15:19, K9MA wrote:
I'm using the K3 with the Elecraft interface cable. I've noticed the
the CW drive power required by mine varies considerably, both with
temperature and SWR. If I set the K3 output for a KPA1500 output of
1500 W output initially, the output will drop to perhaps 1100 W when
the temperature stabilizes at around 65 C. (I've ruled out any change
in antenna impedance, etc.) A similar change occurs if the SWR goes
from 1:1 to 1.2:1 when changing frequency or switching antennas. I
haven't changed the ALC from the default setting. Has anyone else
noticed this?
73,
Scott K9MA
--
Scott K9MA
[email protected]
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