Re: P3 noise floor base line question.

Posted by Alan Bloom on Feb 06, 2011; 5:22am
URL: http://elecraft.85.s1.nabble.com/P3-noise-floor-base-line-question-tp5997094p5997113.html

That sounds about right.  With the preamp on the K3 is more sensitive so
the noise level drops.  With the attenuator on the K3 is less sensitive so
the noise level rises.

Another way to look at it is to realize that the P3 compensates for the K3
attenuator and preamp to keep signal levels the same.  So when you turn on
the preamp, the P3 lowers its gain so that signals show at the same S
level.  That makes the noise look lower.

Alan N1AL

> K3+P3.   when the K3 is set up into a dummy load, with the pre amp OFF.
> the
> noise base line is at S1/2 (between S0 & S1)  on the P3.
> Then switching in the ATT the noise floor climbs to S2,
> With the ATT switched in and the PREAMP on,  the noise floor goes back to
> S1.
> With just the Preamp On the noise floor goes to S0
> It does this on all bands
> Is this right?  or am I just nit-picky
>
> Ed K7WIA
>
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