[Elecraft] K3/100 TX problem on 20m

[Michael Carter]

Hi Paul,

For comparison, here are the 50 watt TX gain values from the
calibration I did last November when I installed
the KPA3A 100 watt PA in my K3 (s/n 67xx):

1900 kHz TXGain HP  10
3750 kHz TXGain HP  06
5336 kHz TXGain HP  08
7150 kHz TXGain HP  08
10125 kHz TXGain HP  08
14200 kHz TXGain HP  05
18110 kHz TXGain HP  05
21200 kHz TXGain HP  03
24930 kHz TXGain HP  03
29000 kHz TXGain HP  05
52000 kHz TXGain HP  04

Do you know if your 100 watt PA module
uses RF bipolar transistors or MOSFETs
(the KPA3A uses MOSFETs; the original KPA3
uses bipolars)?
I don't know if the MOSFET version has higher gain
than the bipolars, but I suspect not.

I've been in a separate conversation
with Hal, W7YNC, who is an LDMOS RF amplifier
designer professionally.  There is some
uncertainty about whether the higher TX gain
parameters mean higher TX drive signal
amplitude or the converse.

In any event, your TX gain values don't
have wild swings from band to band,
although the difference between 20
meter and 30 meter gains is substantial.

Perhaps some others who have done
TX gain calibrations recently (or could
repeat them) on K3 units with the
bipolar PA transistors could post
their results?

73,
Mike, K8CN