[hpsdr] Norton Amplifiers and Noise Performance

[Bob McGwier]

With OIP3's as high as you can get with Norton amplifiers,   *A* way to 
do this would be to always have the amplifier in line and switch in well 
designed attenuators as needed.   Then the IIP3 will go up as you 
increase the attenuation.   On 160 meters you can't use a low noise 
figure if you life depended on it but at 6 meters,  a good noise figure 
would be nice.

An alternative viewpoint we could take is IF we can get -130 dBm MDS at 
6 meters without a  preamplifier,  then we might just chuck it and tell 
the user to take his 40 dBm IP3 front end and add gain as needed.     
With that kind of front end they will have one of the highest performing 
6 meter systems around.

Trade offs,  trade offs.....  always making life interesting.  Also,  
ignoring the designer of Mutek front ends (Chris) is a thing one does at 
their own peril.

Bob



Ray Anderson wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>   
>
> ------------------------------------------------------------------------
>
>  
>
>
>  
>
> Chris-
>
>  
>
> Thanks for your insightful comments regarding Norton amps and noise 
> performance. I fully understand your inability to get into specifics 
> due to proprietary considerations.
>
>  
>
> It is looking like we may be able to obtain very good performance on 
> the HF bands without the need for a preamp, however on 6 meters some 
> noise figure improvement may be beneficial to the system performance. 
> I may look into the feasibility of a switchable preamp so that the 
> circuit may be used when necessary, but may removed when not.
>
>  
>
>  
>
> 73    Ray   WB6TPU
>
>  
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> HPSDR Discussion List
> To post msg: hpsdr at hpsdr.org
> Subscription help: http://lists.hpsdr.org/listinfo.cgi/hpsdr-hpsdr.org
> HPSDR web page: http://hpsdr.org
> Archives: http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/


-- 
Robert W. McGwier, Ph.D.
Center for Communications Research
805 Bunn Drive
Princeton, NJ 08540
(609)-924-4600
(sig required by employer)



 1153939608.0