[time-nuts] Wenzel 245MHz OCXO Low noise power supply and mountingenvironment

John Miles jmiles at pop.net
Thu Sep 23 02:35:58 UTC 2010


> I am not able to measure Phase Noise as per spec, I am looking for
> assistance from this group on the best method for measuring phase noise
> and stability using what equipment I do have in my Lab. I have a
> TDS2022B with FFT, HP 53131 and Tek492BP. My standard's reference is
> one of Tom's Thunderbolt with John's mods ( 10811 ) and a good quality
> linear power supply.

I think that seller had >1 of those oscillators, didn't he?  If you buy one
more and phase-lock them together, your 492BP can measure the PN, per the
guidelines at the very end of the GPIB Toolkit FAQ.  All it will take is a
mixer and an opamp.  You'll be able to see down to 1 kHz, if the 492BP's
minimum RBW is 100 Hz.

Without another oscillator to compare it with, I don't see any economical
way to measure it.

Supply-wise, an ordinary LM317T is quiet enough to avoid degrading a ULN
oscillator (much), so it should be OK for a Sprinter-class part like these.
A Zener+emitter follower is the next step.  Most likely you will not need to
go to the trouble of building a noise-cancelling shunt element.  Avoid the
temptation to use a large choke and electrolytic as a filter -- this will
tend to crowd all of the available power-supply noise into a small hump
around the LC network's resonant frequency.

You can get the original spec sheet by emailing sales (at) wenzel.com with
the part #.  If the info is proprietary to a customer who's still in
business, they may not release it to you, but they're always nice about it.

-- john, KE5FX




More information about the time-nuts mailing list