On Wed, Sep 5, 2018 at 11:09 AM, Lev likely copied:
4. RF transistors (BFS17P)
Yes, we could use something better than 2n3904's in places.
Though using buckets of $0.02 2n3904's/mmbt3904's (at lower gain where
appropriate) has a cost and stocking advantage.
If used right but they are not good at high currents.
The BFS17P is a really weak device. Max collector current of 25ma,
FT of 1.4ghz, 15V mac collector voltage. Good enough for q90 only!
I suspect very few have an idea of how amplifiers in RF power chains work.
What missed is RF from the power amp has a path into the IF and that should
not be so tuned or filters are a bandaid.
If it were simple...