With any crystal oscillator, no matter how good they might be, or how well
calibrated to start with, if that's all you have there will always be the
issue of not knowing how well it is calibrated ongoing unless you find
someone else to check it.
Although rubidium oscillators have much better long term stability this is
still an issue, and buying any of the surplus oscillators, or surplus
oscillator based products, from China is definitely taking pot luck.

Some of that kit is very good, and there are indeed bargains to be had,
but the same product from the same seller can give you a good result one week
and a duff one the next, and don't be fooled by the Chinese listings
showing lots of fancy test gear, experience shows that isn't any guarantee of
quality or competence.

It's a bit of a chicken and egg situation and you really need quite a well
equipped timing lab to start with before chancing your arm on something
that is just treated like scrap before it gets into the hands of the Ebay
sellers.

Although more expensive you would be well advised to consider a 10MHz GPS
frequency reference, the Trimble Thunderbolt for example is well thought of
with software freely available to monitor its performance, and once
installed properly there are no ongoing calibration issues.

Regards

Nigel
GM8PZR

Hi all:
I'm hoping to ref. a Rigol DSA815, a Rigol DG1022A sig gen and an HP 8753D
VNA....to a good 10Mhz ref.
I see a heap of them here:
http://stores.ebay.com/Flyingbests-Equipment/High-reliability-OCXO-/_i.html?
_fsub=908870013&_sid=282770553&_trksid=p4634.c0.m322
http://stores.ebay.com/Flyingbests-Equipment/High-reliability-OCXO-/_i.html?_fsub=908870013&;_sid=2
82770553&_trksid=p4634.c0.m322

IDK what voltage is optimal or which unit to chose (*sine/square, single
or double OXCO) and need some advice on this.
tx