[Linrad] Re: system gain

[Joe Taylor <Princeton.EDU; joe@xxxxxxxxxxxxxxxx>]

Hi John, Dave, and all,

K1VBM wrote:
> In the old days, when every thing was analog, we would say that the 
> system noise figure was set by the first amplifier's noise figure.  

This is just as true today as it was in the old days.  The 
whole point of being sure that you see 15 dB or more 
decrease in noise power, when the DC to the first preamp is 
removed, is to make sure that the first stage does, indeed, 
dominate the receiver noise power.  Otherwise, noise 
contributed by the second (or later) stages may not be 
negligible.  These things have nothing to do with digital or 
analog circuitry.

	-- 73, Joe, K1JT

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