[eagle] Re: 70 cm Receiver Spur Source Found

Jim Sanford wb4gcs at amsat.org
Sun Jun 10 17:53:26 PDT 2007


All:
Slightly off topic . . . .

Somewhere in this discussion, Juan has asked basically, "what is 
acceptable phase noise at what offset?"  This is similar to a question I 
asked Bob McGwier some months ago, as I contemplate various options for 
my 6m to 10 GHz terrestrial station.  The question arises because so 
many texts have different opinions and the manufacturers each choose a 
different offset for their specs, carefully avoiding evaluation of the 
phase noise of their device on whatever communications mode.

I think I remember Bob's answer as -110dbc at 10 KHz offset.

If I remember Bob's answer correctly (Which I may NOT, Bob, please 
correct me) then the picture Juan shows, which is the composite of his 
signal generator, his SDRIQ, and the U-band downconverter doesn't look 
too bad -- close, but maybe not close enough, but maybe so.  John, Matt, 
& Phil:  What is your evaluation of this phase noise on our intended 
uses of the receiver?

Thanks & 73,
Jim
wb4gcs at amsat.org


Juan Rivera wrote:

> All,
>
>  
>
> The source of the spurs in the 70 cm prototype receiver is the CAN-Do 
> module.
>
>  
>
> *This is the receiver IF output as designed*
>
> *(powered from pins 39 and 40 of the CAN-Do Module)*
>
>
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