[time-nuts] RF Mixers for oscillator comparison

[Bruce Griffiths]

GandalfG8 at aol.com wrote:
>  
> In a message dated 20/04/2009 08:22:05 GMT Daylight Time,  
> df6jb at ulrich-bangert.de writes:
>
> Minicircuits have a BROAD range of mixers. Among other they built the  
> RAY-3,
> a 23 dBm high level mixer, that I have seen used in  oscillator
> characterization publications. My understanding about the  benefits of high
> level mixers for that purpose is that it allows you to  work with higher RF
> levels which in turn leads to a higher IF level which  in turn may lead to a
> better overall s/n of the system.  
>
>
>
> ---------------
> An Ebay seller is offering some Stellex high level mixers, Item # 
> 260382178618.
> I don't know if these would be of any interest in this  application but 
> perhaps worth taking a look.
> I bought a couple a while ago to try out in a radio front  end but haven't 
> had time to play with them yet.
> There's also a couple of links there to WJ and Minicircuits app notes on  
> mixer usage and measurements.
>  
> regards
>  
> Nigel
> GM8PZR
>  
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>   
Nigel

Those Stellex mixers definitely do have common RF, IF and LO grounds.
Either external RF transformers for the RF and LO ports would be
required to break low frequency ground loops or a low noise differential
input amplifier at the IF port (after the low pass filter) could be
useful in minimising mains related spurs.
The low phase noise isolation amplifier with +27dBm output required to
drive the LO ports would be interesting to design.

Bruce