wrote in message
ps.com...
I am asking because it seems difficult, and maybe impossible. I've
never heard of this high gain before, but I dont' know why I cann't
stack amplifiers and I am looking for somebody who can tell me what
exactly the problem is: you see the NF is nice, and I can get the SNR
if the band is narrow enough.

The problem is that, if you have 140dB gain at one frequency, you need *over
140dB isolation* from your final output back to the original input to
prevent oscillations from occurring.

140dB isolation is very difficult for reasonable amounts of money!