3a. Tune (match) the input for lowest in-system noise figure.
This is in general not a match for maximum power transfer.
3b. Be sure the active device(s) is/are biased for optimum
noise figu collector/drain voltage and standing current.
4. Be sure there are not any unnecessary noise
contributions from components other than the
active devices in the amplifier.
If you want to consider the system as a whole,
4. Lower the loss between the antenna and the preamp
(eliminate feedline, for example).
5. Be sure that the preamp has enough gain that it
sensibly sets the system noise figure. (Be sure
that its gain gets the signal seen at the next stage
high enough that the next stage contributes
insignificant noise to the system.)
.... etc.

But beware of trading other things for noise figu beware of
poor intermod or desense performance, for example.

Cheers,
"Me" aka Tom


"You" wrote:
In article .com,
" wrote:

Does anyone have any idaes on how to lower the nf in a uhf preamp?


1. Lower then temprature of the device, by dumping it in Liquid Nitrogen.
2. Use a device with a lower Noise Figure, as the active element.

Daaa.....