[Elecraft] PA transistors

Vic Rosenthal [email protected]
Wed Nov 6 14:33:00 2002


I have four 2SC2879 transistors, such as are used in the KPA100 PA.  When I
measure the forward voltage drop of the emitter-base jucnctions I get:

#1: 0.592v
#2: 0 v
#3: no continuity
#4: no continuity

question 1: I presume this means that only #1 is good?  

question 2: Is it necessary to replace both transistors with a matched pair in a
push-pull circuit like the KPA100?

question 3: Assuming #3 and #4 are bad, what conditions cause this kind of
failure?

No, they're not from my KPA, but from my %!$@% high-power final.  The problems
I've had with this make me want to go back to 100 watts maximum!

Vic K2VCO