Rob French (KC4UPR)
I do have a V5 board. To be clear, I have not yet made any modifications to the transmit chain... the only thing I have done is adjust RV1 to increase the output power on 80M to about 12W. Before I did that, the pot was set at about half way, so it would be easy enough to turn RV1 back to a half-turn, and it should pretty much be what it was from the factory, +/- a few tenths of a watt. I could then take reasonable "before" measurements.
I can't tell by looking what Q90 is (tiny little thing...), but based on the official V5 schematic, it should be an SMD 2N3904. The rest of the pre-driver/driver transistors (6 of them) are all 2N3904, by the looks of them.
My power meter is built into an automatic antenna tuner designed for up to 150W. So I'm sure it's not super accurate.
Thanks for all the feedback!