[time-nuts] Passive Frequency Doubler (was Latest measurements on my FTS 4050/S24)

[Christopher Hoover]

> A handy passive frequency doubler can be made just using a 
> double-balanced mixer.  Feed 5 MHz into the X and R ports 
> connected together and take 10 MHz out of the L port.  You'll 
> loose a few db and the waveform becomes rather triangular but 
> if your goal is to sync the internal oscillator in a counter 
> to an external standard it works just fine.  Mixers are often 
> available on eBay for a very modest price.
> 
> Regards,  Brooks

Thanks for the suggestion.  I've got a Mini-Circuits mixer in
my junk box somewhere; I'll give it a try.

The FTS 4050/S24 circuit is a Mini-Circuits half-wave doubler,
followed by a passive LPF and then cleanup by a discrete buffer.

Since I posted originally, I've wound a 1:4 transformer, 
Roughly matched a pair of diodes and stuffed it all into a 
Hammond box.   It works OK.  I haven't tried matching an
LPF yet.

-ch