[time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...
kb8tq at n1k.org
Mon Nov 17 20:31:30 EST 2014
> On Nov 17, 2014, at 7:48 PM, Charles Steinmetz <csteinmetz at yandex.com> wrote:
> Bob wrote:
>> The 58503 is a Z3801 with a pretty instrument style package put around it - right?
>> If so, it might / should have a 10811 in it rather than an MTI OCXO.
> I think there may be other minor differences between the 58503 and the Z3801, including a newer GPS engine, but I'm not positive what they all are. They are clearly very similar.
> The 58503 should have either a dual-oven 10811 or the Symmetricom look-alike. (The Symmetricom has a 5MHz crystal and a doubler -- it looks exactly like a DO 10811 except for lacking an HP sticker.) I bought a 58503 from one of the usual far-eastern suspects, which was advertised expressly as having a 10811. When it arrived, I saw that it had the Symmetricom OCXO. I fired off a message to the supplier complaining that I did not receive the promised 10811, and he offered to part-refund the purchase price or exchange the oscillator. Because of the high transaction cost of exchanging, I elected to take the part refund thinking I would swap in one of the DO 10811s I had on hand. But after only a week of running, the Symmetricom was better than all of the 10811s I own!
It’s the -155 to -160 dbc / Hz phase noise limit that can be tough to hit with a 5 MHz doubled to 10 MHz. Getting below -166 dbc / Hz at 100 Hz offset on a 5 MHz is quite unusual.
> (Interestingly, my best 10811 is not a DO unit -- it is a SO 10811 that came out of an HP5345A that was originally part of a 5390A frequency stability analyzer.)
> Note: My experience should NOT be read as a claim that the Symmetricom oscillators are better than 10811s. My sample of the Symmetricoms is way too limited to make any claims. But this particular Symmetricom happens to be a very fine OCXO.
If it’s a 5 MHz it *should* have ADEV that is as good as / better than just about all the 10811’s out there.
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