[Elecraft] K3 Wattmeter Calibration

[Roy Morris]

Hello Bill,
Thank you for the info on the measured power output.  My findings were very close to yours.  I set the power demand to 50 watts and then set the high power wattmeter calibration CONFIG:WMTR HP to 50.  The actual output was very close to the WMTR HP = 50 setting.  I am really not surprised that the actual output at 100 watts is less than the demanded output because there is probably a DAC conversion involved in the power output circuit where any error beyond 50 watts is multiplied. 
My measurements were made with an LP-100 (calibrated by Larry) into a Bird 8201 Termaline load.  The coupler was attached directly to the K3 output connector.  I did not write down the actual output with 120 watts demanded, but our findings are very close.  These are my findings at 100 watts demanded:

  1875   97.1
  3781   97.9
  5371    98.1
  7223    97.1
10107    94.9
14235    96.6
18115    95.8
21225    95.6
24935    95.0
28350    90.3
29700    91.6
51000    95.2
54000   100.2

Bottom line is that the K3 can deliver over 100 watts output on all bands.  This means the K3 can provide the necessary drive for any linear amplifier.This is a nice contrast to the Omni VII that typically delivers approximately 91 watts on all bands (100 watts on 6 meters) with 100 watts of demanded power.  Since 100 watts is ALL that can be demanded of the Omni VII, 91 watts is the typical maximum power output.  To be fair to the Omni VII it provides enough power to drive most linear amplifiers.
Roy Morris  W4WFB  K3 #323