[Elecraft] PA Transistors Maintenance in K2

[Don Wilhelm]

Mel,

That is NOT true for the KPA100 power transistors - and it is not 
because of initial torquing.  The thermal pads take both time and heat 
to fully conform to the heatsink and any irregularities in the 
transistor surface.

BTW, with the KPA100, Elecraft has "done their job" when the parts are 
put into the box.  This is not sold as an assembled item - the builder 
must assemble it.

I tighten those screws on every KPA100 that I service.  I am amazed at 
the number I find loose.

73,
Don W3FPR

On 10/28/2017 3:24 PM, Mel Farrer via Elecraft wrote:
> Ted,
>   If the people at Elecraft have done their job and mounted the transistor properly with the correct torque on the mounting hardware procedure, no additional maintainance is required. I have been in the industry for a LONG time .  Three things to remember in the mounting of any RF or high power device.  Flat surfaces, minimual mating gu, and required torque. Lack of any of these will kill a device if not correct.  I have never required retorqueing parts, with one exception.   In 000 copper wire terminals, the copper does relax and needs to be retorqued to achieve a gas tight seal connection, but that is in industrial application.  Small RF devices only need the initial torque to be correct.