Jeff
great question on what's a good transmit path design.? since I have the K2 manual here --
predriver is a 2n5109, feeding a (;3 transformer on a FT37-43
driver is a 2SC2166 NPN feeding a 12:8 transfomer on a FT37-43
maybe some soft equalization network here ?? that's all I see that might seek to flatten RF performance
the PA is push-pull pair of 2SC2166 into a transformer to achieve the desired output power to feed 50 ohms
these devices fit the original K2 price target but not now the primary, global uBITX users.
the FT817 uses different PA devices for VHF/UHF than HF I think.? I imagine the VHF/UHF PA module may cost more than a uBITX.? obviously the climb for HF to 50 MHz requires more savvy PA devices.?
on the uBITX PA, when details are revealed on the IRF510 PA designed by Allison and Hans for the QSX there will be something of value here for v5, and to see if we can improve use of the v4 board.?
73 Curt
