Did you check your signal on a spectrum analyzer? When I cranked up RV1
for maximum power output my 3rd order IMD fell pretty drastically.
I'm using 13v on the PA and 12.4v on the main board.
Based on your data for using 13.8v with the factory setting it might be
worth it for me to reset my power supply to 13.8v and use two dropping
diodes to take it down to 12.6v on the main board.
I've ordered a second ubitx and when it gets here I'm going to try
changing out all the driver transistors to see what happens to the
power output and the 3rd order IMD.
On Sat, 24 Mar 2018 13:58:25 -0700
"Tim Young" <tyoung@...
The attached jpeg shows the results of testing (CW transmission) with
the out of the box RV1 setting and with RV1 set for maximum output.
Looks like the results are similar to what has been reported. My
primary interest is in 20M,40M and 80M emcomm QRP (bug out radio). I
was pleased with the power levels at 13.8VDC. I will be using a 12VDC
to 13.8VDC regulator to insure maximum voltage input at all times.