[Elecraft] max power suggested on PSK with K2/100

[Fred Jensen]

John Wiener wrote:
> I just worked KJ5XF who suggested that running 50W PSK would fry the 
> finals.  I thought 50 was about max for safe PSK.
> What's the latest on this?

My KPA100 top got too hot to leave your hand on at 50W in a RTTY 
contest.  I put a square of sticky backed velcro on it, the mating 
square on the center of a 12V muffin fan, and now the heatsink stays 
cool at 90W on RTTY.  I still run the K2/100 at 50W since I'm driving an 
amp to 500W and need to protect it too, and at 50W, the heat sink is cold.

The heat transfer rate issue is still there ... the PA transistors will 
be hotter than the HS ... but with the HS cold, the transfer rate is 
increased a lot.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2007 CQP Oct 6-7
- www.cqp.org

PS:  The fan blows down onto the HS, but you all probably knew that.