Frank, you're absolutely right. I was so busy laughing about Bill's
leakage that I missed the previous statement about the fuse not blowing
until the unit went into transmit. I'm in full agreement that the
transistor could not have a hard short and if the bias was excessive...
it certainly could blow the fuse instantly.

Professor
www.telstar-electronics.com


Frank Gilliland wrote:
On 19 Nov 2005 18:22:33 -0800, "Professor"
wrote in
. com:

Collector-Emitter leakage... LOL
What he's got is a shorted transistor. That's got nothing to do with
leakage.

Professor
www.telstar-electronics.com


Bill Eitner wrote:
The transistor that heats up immediately is
bad (excessive C-E leakage).
snip


.......oh brother.

Hint #1: The amp doesn't blow a fuse until it's keyed. If the
transistor was shorted the fuse would blow on power-up. It's not a
shorted transistor.

Hint #2: Excessive quiescient collector current is not definitive of a
C-E leak, nor is it even a likely possibility since the gain of the
transistor would be almost nil, and keying up isn't likely going to
increase the current enough to blow the fuse.

Both of you voodoo-techs missed the obvious and most likely problem:
excessive base bias current. The cause could be a bad bias supply
and/or base shunt, or the other transistor (assuming a push-pull amp)
being blown wide open.