Re: Pre driver and driver transistors

ajparent1/kb1gmx <kb1gmx@...>
 

Over the last three years (see the old and very large thread) the following were tried...

MPSA10,
2n2222a
2n3866
2n5109

The BF959 is a low power VHF transistor and would be a poor performer
except as replacement for Q90  maybe, the BFR106 was better.   The BF959
gain falls off fast above 20ma, undesired for high peak current applications.

Desired characteristics are:
Pdiss greater than 800mw (most metal cans do better than plastic).
Vcc max not less than 30V
Max collector current not less than 200ma.
Ft more than 800mhz , and does not decrease at high current.

I tried a few UHF parts I had for the 1W region with Ft of 5ghz and
they did not like the board layout (undesired oscillation). One issue 
is get enough gain at 30mhz and it is unstable due to layout.

Allison
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