[Elecraft] Silvery Thermal Pads

[Vic K2VCO]

Roy Morris wrote:
> When I removed the KPA100 PC board to do the KPA100 Upgrade the
> thermal pads of Q1 and Q2 stuck to the transistors.  I noticed that
> the bottom of these pads were silvery where they joined the heat
> sink.  Some of the black part of the pads remained with the heat
> sink.  I will replace these thermal pads.  Should I attempt to clean
> off the heat sink surface where these pads left their residue?  

I think so, certainly.  I used isopropyl alcohol to clean it.  Anything 
that interferes with heat transfer is undesirable.  I even went so far 
as to remove the burrs around the mounting holes in the heat sink and on 
the transistors.

By the way, I did the upgrade because I had observed the KPA100 'taking 
off' on 40 meters with a particular antenna and the KAT100 in line. 
This happened although I had done the previous KPA100 upgrade, installed 
the improved shield, and had been very careful with the location of the 
RF choke across the output.  This problem was solved by the latest upgrade.
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco