[Elecraft] KPA500 - key down current on CW

[Roy Morris]

There is a 4 watt discrepancy between the 39 watts dialed in the K3 and the 
43 watts that is shown on my PowerMaster meter.  The PowerMaster coupler is 
attached directly to the output of the K3 (using a double male connector) 
with a 5 foot length of RG8 coax to the input of the KPA500.  The 
PowerMaster reading is probably more accurate than the dialed in power. 
This could be factored into the efficiency equation.
Calibration of the K3 power is not linear.  Roy Morris  W4WFB