[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:
> 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
> 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.
> time-nuts mailing list
> time-nuts at febo.com
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.
More information about the time-nuts