[Elecraft] Which wattmeter do I believe?

[John Pfeifer]

Just finished building KX-1 #1207 with 30m board and ATU.  Nice little rig!

After adjusting C9 on the KXAT-1 per the manual, I decided to compare the 
power output measurements obtained via the internal power sensor, a DL-1 
dummy load + DMM, and using my OHR WM-2 QRP wattmeter.  BTW, the supply 
voltage is 12.5v and I substituted a 33-ohm resistor for R30.  Output before 
I changed R30 was about 1-watt lower across the board.  Here are the final 
measurements, as built:

Band     DL-1+DMM     Internal      WM-2
20m        2.6           3          3.7
30m        3.7           4          4.7
40m        3.4           4.1        4.3

Which wattmeter should I believe?  I tend to think the DL-1 plus my Fluke 
digital multimeter would give me the most accurate reading, but....

Also, no matter how I fiddle with the spacing on L3, 20m output is always 
1-watt less than on 30 and 40m.  I guess this is in line with what other 
folks have reported.

tnx & 73,
John Pfeifer - WL7M