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

Luis Cupido cupido at mail.ua.pt
Thu Aug 14 06:55:24 EDT 2008

Related to this, I have a question in my mind for sometime.

How close to a decent phase-noise setup are we if
we down convert and use a low frequency spectrum analyzer ?
(downconverting with the best XTAL LO we can imagine).

My target is microwaves and millimeter waves so I have to
down convert anyway, Or then I have to live with what my
spectrum analyzer show me (a tek 492, in my case).


Rephrasing the question, how much better are the low frequency
spectrum analyzers comparing to the microwave spectrum
analysers (in phase noise I mean)?

Any comments ?

Luis Cupido.

P.S.(I know that I'm limites to 100Hz RBW with my 492... and
I would like also to measure closer than that )

John Miles wrote:
> 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

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