[time-nuts] 5 MHz Frequency Doubler

[Dr Bruce Griffiths]

Robert Atkinson wrote:
> Hi,
> Have a look at,
> < http://www.wenzel.com/pdffiles/diodedbl.pdf >
> Also http://www.wenzel.com/documents/hints.htm indicates that the NIST
> design uses JFET's but I can't find any more details.
>
> Robert G8RPI.
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Christopher Hoover
> Sent: 26 October 2006 07:14
> To: time-nuts at febo.com
> Subject: [time-nuts] 5 MHz Frequency Doubler
>
>  
> 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 design is probably a pair of low noise n channel JFETs configured as 
a push push doubler.
Inputs driven in antiphase so that each FET conducts ffor opposite 1/2 
cycles with the 2 FET drains connected in parallel.
A bypassed trimpot connected between the FET sources being used to 
compensate for FET mismatch.
The low frequency design probably uses a common source design whilst the 
VHF version employs a pair of common gate devices.
An RF transformer connected between the the common drain and the 
positive is used to drive the load.

Bruce