[Premium-Rx] Mini-circuit amps

[Ben Dover]

Hello Scott.

In my multicoupler I got to near unity gain by putting an attenuator pad on
the amplifier output, and did so for a very specific reason besides gain
adjustment.

With the pad placed on the output, it acts as a matched load on the amp, just
in case there's any instability from an unmatched load. That in itself will
improve the overall noise figure preformance of the amp.

Most Minicircuits splitters are resistive / inductive hybrids and tend to
serve the same function, but the pad looks like PURE resistance to the amp, in
addition to providing isolation from the splitter's inductive component.


As far as varying gain by varying supply voltage is concerned, I wouldn't try
that approach. Gain migh vary SLIGHTLY, but the available amp headroom is
going 
to vary much more quickly.

73's,

Tom, W9LBB


PS- STILL very happy with the 8718 here! It's one hell of a receiver!


At 09:42 PM 11/12/2005 EST, you wrote:
>  Because it was all cheap :)
> 
>   I've considered an attenuator on the output of the amp, but was also
>curious whether the gain might be usefully varied by reducing the supply
>voltage, and what effect that might have on noise figure (which is OK at
>less than 3db) or 3rd order IMD (which ain't very good already at about +14
>db).
> 
> Thanks for any ideas.
> 
> Scott _______________________________________________  Premium-Rx Mailing
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