[Elecraft] XV50 cooling

[Tom W8JI]

> Would that not depend on whether or not the source 
> impedance presented to the input device has been optimised 
> for lowest noise figure or for optimum power transfer? If 
> the former then the question arises how rapidly does the 
> noise figure change with small deviations from an optimum 
> noise "match", even if the effective loaded Q of the input 
> circuitry is suitable to pass the six metre band.

The two primary sources of noise are from current flow in 
the input device and thermal noise. I'm not sure what 
portion of the two exist in the XV50, but almost certainly 
the semiconductor characteristics would change far more 
rapidly than the impedance of relatively broadly tuned 
matching circuits.