[Elecraft] 2SC2879 Finals in KPA100

[Vic Rosenthal]

Roy Morris wrote:
>  I don't think the
> mounting surface of the 2SC2879 is a part of the circuit because the
> two mounting screws make contact between the transistor and heat sink
> anyway.  The thermal pads are only used for heat transfer and not for
> circuit isolation.  Am I right about this?  

Yes.

> Or are the two emitter
> pads on the transistor connected internally to the mounting surface
> of the 2SC2879?  Before I put the shield back on I checked the bases
> and collectors of Q1 and Q2 and they checked out fine.  The amp works
> just fine, but I am going to replace the thermal pads to be on the
> safe side.

The pads may *look* like they are worn away, but they are probably not! 
  At least that was my experience.  I replaced them, but when I removed 
the old ones I was sorry that I had bothered -- they were actually fine.

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco