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

[Gerald Molenkamp]

Hi John,

Actually he had 10+ for sale at $25 each free postage. Later that same
day with a sudden spike in sales, the silly seller put them up to $80
and went back on several sales at $25. Now he has swapped them out with
Vetron at $49 each and the excuse was the other Wenzel failed his tests.
See 270629163153

Yes, I ended up buying 2, I will look at your suggestion ( mixer and
opamp)

I recall we had a chat about the 492BP with your p/n toolkit, it was
limited down to around -88dBc/Hz @ 10KHz, mainly due to the Yig's
quality.

I found a white paper on Tektronix site about using FFT on the TDS to
measure power supply noise, may give that a go tonight.

Regards


Gerald
VK3GJM



-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of John Miles
Sent: Thursday, 23 September 2010 12:36 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Wenzel 245MHz OCXO Low noise power supply
andmountingenvironment


> 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


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