440 FM rx-noise figure, what is good enough?

[exces3]

for 440 Mhz FM,
suppose you had 5 db of feedline loss,
with a preamp, --> noise figure
of 7 or 8 db.. in a real situation, is that good enough
or not? what would be equivalent sensitivity?

73

 

[WA8ZYT]

You always want the lowest noise figure possible, no matter what the mode. 7 or 8 db noise figure is absolutely horrid. A preamp with a GASFet will give you .5 db noise figure.

Also, 5 db of line loss it quite bad, you are loosing 75% of your signal at that level.

I try for 1.5 db or less line loss on VHF frequencies. I have 7/10ths db loss on my 6 meter array.

Some great preamps:p amateur

 

[exces3]

OK, after some research,
my new question is ...

what is the effective noise
temperature of an antenna for 440 mhz?

half of the antenna pattern looks at the earth,
which is effectively a black body radiator at 290K.and half of the pattern looks at the sky, which is much RF colder.

or not, is manmade noise going to change
that significantly?