[time-nuts] Designing and building an OCXO and GPSDO

[John Miles]

If you don't want pushbutton convenience, you can measure the close-in phase
noise with not much more than a $5 mixer and $2 opamp.  It will take a lot
of "sweat equity," and you will need to build two of whatever you're
measuring, or buy/borrow a known-cleaner source at the same frequency.

TSC analyzers are great but they are not the only way to go.  Actually their
biggest advantages lie in their size/weight and the fact that the reference
doesn't have to be at the same frequency as the DUT.  Other than that, their
performance is not necessarily better than a homebrew single-mixer
quadrature PLL or an 11848A.

-- john, KE5FX


> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of SAIDJACK at aol.com
> Sent: Wednesday, August 13, 2008 4:40 PM
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] Designing and building an OCXO and GPSDO
>
>
> Yup, I agree.
>
> I wish I did have one of those TSC5120A's!
>
> Or "at least" an E5052A/B.
>
> bye,
> Said
>
>
> In a message dated 8/13/2008 16:03:00 Pacific Daylight Time,
> bruce.griffiths at xtra.co.nz writes:
>
> SAIDJACK at aol.com wrote:
> >    Thanks  Bruce,
> >
> >
> >
> >    it would be interesting to  see how the different topologies affect
> >    phase noise and  stability etc, and what kind of performance can be
> >     achieved.
> >
> >
> >
> >     bye,
> >
> >    Said
> >
> >
> >
> Said
>
> One way to evaluate the merits of various oscillator circuits  would be
> to build an example of each and then measure their phase noise  and ADEV.
>
> To keep the number of variables and costs down all  oscillators should
> use the same 10MHz fundamental crystal.
> The  oscillators should not be enclosed in their own oven, however an
> enclosure  with a long thermal time constant can be used.
> The oscillator output should  be +7dBm into 50 ohms.
> No EFC and probably no trimmer cap (however this  requires that a
> TSC5120A or similar be used to measure the ADEVand phase  noise).
> Power supply should be standardised at  +12V.
>
>
> Bruce
>
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