[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.
ct1dmk.

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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