[time-nuts] Re: Custom Quartz crystals

[Richard (Rick) Karlquist]

On 8/14/2022 11:47 AM, Bob kb8tq via time-nuts wrote:
> Hi

> 3) If you are really headed to 10’s of GHz, you might want to think
> through the entire chain. In some cases a 120 MHz crystal is a
> better bet than 60. Your far removed phase noise can / will be better
> with 2X ( or 3X or maybe even 4X) the “starting” frequency.
> 


A few years ago, I designed a ~6.84... MHz source
(you can guess what it was used for).  It used
an NEL 10 MHz VCXO multiplied to VHF and used
to phase lock an Abracon VCXO.  A microwave DRO
was offset by a synthesizer to make the output
frequency.  The DRO was divided down and
compared to the Abracon VCXO to phase lock it.
I looked at a lot of possible architectures and
this was the best one we could come up with.
It was not actually all that expensive except
for the NEC oscillator.

Rick N6Rk