[time-nuts] 5 MHz Frequency Doubler

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Oct 26 06:14:19 EDT 2006


Christopher Hoover wrote:
>  
> Hey 'nuts,
>  
> I'm looking for a good design for a 5 MHz frequency doubler.
>  
> The Wenzel Blue Tops HF doubler is said to be  based on a low phase
> noise, public-domain NIST design:
>  
>
>  <http://www.bluetops.com/Modules/lnhd.htm>
> http://www.bluetops.com/Modules/lnhd.htm
>  
> The LNHD is a fixed-frequency HF doubler based on a public-domain design
> developed by the National Institute of Standards and Technology (NIST
> <http://www.boulder.nist.gov/timefreq/> ) for superlative phase noise
> performance.
>
>  
> Can anyone point me at a this design?  I haven't had any luck finding it
> on the web.
>  
> I'm open to suggestions on other doubler designs, as well.  
>  
> -ch
>  
>  
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>   
The secret is to ensure that there is adequate local RF feedback (source 
series resistor) during each half cycle to ensure that the flicker phase 
noise is suppressed whilst allowing the gate drive to switch the current 
between  the JFETS. J310 n channel JFETs or similar devices should be 
satisfactory. Matching the JFETs is useful but a trimpot can be used to 
compensate for residual JFET mismatch.

Bruce



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