Dave,
Here is a link to the author's implementation of a DIY Kit that produces 50 watts with a 13.8volt power supply and 5 watts input:
You could try to modify the uBitx PA section to match this (as far as I can tell the DIY kit uses IRF520 MOSFETs).? The issue would be that the driver does not put out 5watts, so an intermediate drive would need to be added.? This was verified in a number of trials by others more skilled in RF design than am I.? If you just add the DIY amp after the uBitx amp, then you will need to reduce the output of the uBitx power amp to less than 5 watts.? This can be done with RV1.? You could do surgery on the board to use the built-in LPF, though I would add a second LPF assembly that is rated for greater than 50watts.? There are DIY kits on eBay for those filters.
As to separating the v6 PA supply from the rest of the radio, the 3 pin power connector is still provided, but you will need to cut a trace on the board to separate the supplies.? I HAVE NOT DONE THIS, so please verify for yourself!!? Tracing the runs on the PC board point to the jumper trace between the two power pins on P1 being on the top side of the board under the connector.? You would need to remove the connector, cut the trace, and then solder the connector back on the board.? Again, this is visual only, I have not removed the connector to verify.
Hope this is helpful.
73
Evan
AC9TU
