[time-nuts] NIST frequency doubler

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Mon Jul 9 04:57:56 EDT 2007

Peter Vince wrote:
> Hi Bruce,
> 	With a quick search of the NIST site, I couldn't find any 
> mention of this, and the circuit diagram in your GIF was a little 
> small and fuzzy: is that a crystal on the centre-tap of the secondary 
> of the first transformer?  Would it be tuned to the input or output 
> frequency? And would you know the values of the components?
> 	Thanks,
> 		Peter

It just an RF bypass capacitor to ground.
This circuit was embedded in a very small section of a much larger 
paper, so its difficult to find.
You may even have read the paper and not have noticed  the mixer circuit.
The resistor from the centre tap to ground is selected so that the peak 
drain current is around 28mA or so when the RF is applied

RF input ~ 13dBm.
Input transformer 1:4 turns ratio (or thereabouts) centre tapped secondary.
Output transformer 2:1 turns ratio (or thereabouts).
RF bypass capacitor depends on input frequency typically 100nF or so.


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