[time-nuts] How can I generate a very clean 1 W signal @ 116 MHz ?

Charles Steinmetz csteinmetz at yandex.com
Mon May 30 20:28:49 EDT 2016


Tim wrote:

> If you want to make it time-nutty, there's the NIST JFET "push-push"
> frequency doubler we've talked about here in the past.

As I noted during the push-push doubler discussion, a push-push FET 
doubler works much better if one does not run the FETs to cutoff.  This 
is because the FETs do not operate as switches, but rather as 
common-base amplifiers.  Running them into cutoff does nothing except 
generate large amounts of undesired odd-order and higher even-order 
harmonics in addition to the desired second harmonic.

I posted a schematic with graphs, comments, and discussion on Didier's site:

<http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Frequency_doubler_push_push_JFET_schematic_description_discussion.pdf>.

The on-list discussion is included.

The posted design focuses on doubling 5MHz to 10MHz, but I tested the 
prototype with 50MHz input (100MHz output) using J310s and 2N4416s, and 
it worked fine.

Best regards.

Charles




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