Problem with 2sc1973 is they may be hard to get and its still a 300mhs ft.? Might as well use 2n2222a.
The Bf199 is likely better save for its 25V CE breakdown is kinda low but the 1100mhz FT would be better.
I'd not use it for the 25V breakdown spec.
RIght now I'm not pulling transistors at random.
Q90 a 2n2963A in a smt form is being tried at 19 ma I think the current is too
high and I may reduce it further to 10-15ma. It only has to produce 2mw of power
max so running more than 200mw of power is excessive. At 15ma its about 185mw
being dissipated.? Why waste power.
Q911/912:
What I think we should use for pre-driver something with a 500 to 1ghz FT, .6 w or
better per device.? ?The HFE at higher current (30-50ma) must not sag. Even at
that the stage only need produce less than 100mw (more like 70).? ?One device
is not stressed doing that.??
Q92/93/96/97:
What I think we should use for driver something with a 500 to 1ghz FT, 1 w or?
better per device.? ?The HFE at higher current (50-100ma) must not sag.
THis stage is push pull and two need to be able to push about 1 watt
and there are many that can do that as two rather than 4.? It also can run
class AB1 at about 10 to 20ma per device since its push pull.? The
device current as is with 3904s is 27ma (very high) per device on mine.
Candidates I know of but not tested are:?
MPSH10 but I have to try them.
2n2222A? its worked in the past but the FT is barely enough.
2n3553//2n3866/2n5109 are likely good for driver (2 not four).
And no, don't go out and buy them unless your experimenting on your own.? Do report
your results!? More data points may be important.
Before the CW key oddity happened? I was testing a lone (1 not wo) and the predriver
and was getting the same or more power. makes sense as we only need maybe
70 mw of power there.? Not tested enough so everyone sit down please till it is.
I have? no reason to change the IRF510s.? For 10-12W its just right.
Allison
