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QCX40 slightly low on power #qcx #lpf

Ted 2E0THH
 

I would welcome any input here.

I have been measuring the power output on my QCX40. It is a Rev 4 board with blue capacitors for C26 and C27 (not sure if they are ceramic or tantalum).
I am using a home built variable PSU with the radio feeding into the QRPlabs 50 ohm dummy load and measuring both voltage and power with the QCX test equipment tools. 
I read:
8v 0.86w
9v 1.11w
10v 1.37w
11v 1.65w
12v 1.93w
13v 2.25w
14v 2.58w
15v 2.96w
16v 3.32w

After reading nearly ever post on the subject including those of Hans and especially the trouble shooting guide I elected to remove 1 winding from L1 and L3. (now 20 turns instead of 21). On remeasuring, I was very surprised to find the readings absolutely identical!

I am not sure where to go from here and indeed if I should go anywhere.

Any advice most gratefully received.

73s Ted
M7ECH