[Amps] LDMOS PAs and high power low pass filters/diplexers

[Dan Levin]

To do the cooling right, you have to do some math.  You start with the
max allowed junction temp and the junction-to-case thermal resistance
(both specified on the data sheet of the device), and work outward
from there through your heat spreader and heat sync or radiator to
your cooling flow of either water or air.

You can see a "quick and dirty" version for a specific design at:

http://www.k6if.com/ssamp/id2.html .

I also wrote a slightly more detailed "white paper" on the subject
intended for hams building SS amps here:

www.k6if.com/ssamp/cooling.html

The paper isn't complete, but it is better than nothing.

Caveat emptor.  I am not a thermal engineer.  I do not play one on TV.
 I did consult with one at some length about this stuff, but I could
easily be wrong.  Please check your work with someone who knows more
than I do.

                ***dan, K6IF