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BTW, could we keep this thread focused on using the RD16HHF1 discussion and move the SMD/SMT discussion to a new thread?
Thanks for the great measurements on the pre-drivers, Glenn. Makes it clear the IRF510s aren't the only problem, which corroborates Jerry's excellent LTSpice work.
Allison, you are quite correct. RD16HHF1 vs IRF510 is more a personal preference for me; both will certainly work well with the right changes. I agree that redesigning the pre-drivers and finals is the best way to go to get flatter gain across the bands whether using the RD16HHF1 or the IRF510. Personally, I'm OK with replacing everything from C80 to KT1 pin12 in my uBitX, but I understand that others may want a simpler solution. That's the beauty of having an open design you can tinker with. What changes would you recommend to the transformers, and what transistor would you recommend for the pre-drivers to get flatter gain across the 1.8Mhz - 50MHz range?