[Elecraft] PA Transistors Maintenance in K2

[Ron D'Eau Claire]

The K2 is a kit built by the customer, not Elecraft. 

With respect, my experience is different from Mel's. In many years working electronics field and shop service industry have found that re-tightening hardware subjected to thermal stress is commonly required by manufacturers. Manufacturers routinely do that after a "burn in" period of testing before the unit leaves the factory. Elecraft customers are instructed to do it on some gear after a period of use. 

The rarity of failures in spite of many thousands of rigs in service suggests that Elecraft's recommendations are good ones. 

BTW, when Elecraft has found that a better than metal-to-metal thermal conduction is needed, they use thermal pads instead of thermal compounds. The pads are entirely adequate and avoid customers handling messy compounds. 

In commercial work, when a manufacturer specifies using a thermal compound, I use GC Type 44. It is a non-silicon based compound and so does not 'migrate' from where it was placed. My small tube has plenty left and it predates the computer "age" -  bought it sometime in the 1970's. Like the old Wildroot Cream Oil for hair they mean it when they say a "little dab will do ya" yet it remains flexible and never hardens. 

73 Ron AC7AC 

-----Original Message-----
From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Mel Farrer via Elecraft
Sent: Saturday, October 28, 2017 12:24 PM
To: Cameron Francey; Dauer, Edward; elecraft at mailman.qth.net
Subject: Re: [Elecraft] PA Transistors Maintenance in K2

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.

Mel, K6KBE