开云体育

Nick, that makes sense and I'm sorry to hear what happened on your board.

Your measured S21 looked good enough for the US standard assuming no harmonic is stronger than the fundamental and the 40m 2nd harmonic is weak enough. I guess the latter is the unknown here. (and there is always a small chance of one of the push-pull transistor blows without the operator not noticing for some time)

For my high band filter, I use elliptic function filter to achieve steeper transition band without modifying the board. I can simply add a 2012/0805 SMD cap on the bottom side. But I'll first build the filter on barrack and measure with NanoVNA V2 before I build the kit though.