[time-nuts] Re: HP 10811-60111 Oscillators {External}

[Bob Camp]

Hi

There always has been a pretty wide range of ADEV’s on the 10811’s. One of the fun things
they did at Santa Clara was to screen them for ADEV. Once they found enough “good ones”
for that month, they stopped screening. The ones that made the grade got this or that part number
sufix on them and headed into gear that needed them. 

There are indeed OCXO’s that hit <= 1x10^-13 at 1 second. There aren’t a lot of them, but they do
exist. The ones I’ve seen take a bit of time to get to whatever level the best level is. I have not seen
any 10811’s that are past 3x10^-13 at 1 second. If you are going to go sort crazy, there are a lot of 
“targets” on eBay from time to time. Some of them have significantly better yield than 10811’s. 

The risk with any bulk purchase is ( as noted earlier ) that you are buying the tail end of a group that
already has been sorted. Working this out without buying the lot is pretty much impossible. It is very
much a risky business. 

The whole “sort out 10811s” process is not in any way a new thing. Folks have been doing this for
decades. There are a lot of stories about this or that adventure looking at a population of a hundred
or more examples. 

On the “normal”  10811, the package is not hermetic. It soaks up humidity ( and maybe other stuff )
as it sits in storage. Has this or that one been in storage for a year, a decade, or many decades? There’s
not a really easy way to tell. Burn in is going to dry out the boards and components. If you are interested
in ADEV out to 100 seconds ( or worse yet 1,000 seconds ) the units need to be pretty “dry” to do their 
best.

Fun !!!

Bob

> On Jan 11, 2023, at 10:40 AM, Jim Muehlberg via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Bob, so the ADEV gets better than factory spec - better over time?  The number stated below approaches NIST_F1 at 1s ~2.8E-13. (Not sure if its correct - found on a slide presentation) and apparently exceeds most commercial cesium clocks for time scales less than~10s..
> 
> This is all fascinating since I now have two functional (as far as I know) opt 4 5061As (with, of course, 10811s inside). Plotting the spec for the 10811 and the 5061 in time lab is interesting, as the ADEV for the 10811A does indeed  exceed the 5061 for time scales less than 1s.
> 
> Maybe this is old news to all of you, but it's more than I knew yesterday!
> 
> Jim
> 
> 
> On 2023-01-10 8:57 AM, Bob Camp via time-nuts wrote:
>> Hi
>> 
>> There’s a seller on eBay ( besttestus ) who comes up with batches of 10811’s from who
>> knows where. Some are still attached to option boards for instruments. They just sold out
>> of the latest batch of about 200 or so. I’d guess they will get some back in eventually.
>> Asking price is typically right around $50 or so (with free shipping). They take offers so
>> you can indeed get them to sell you 10 at a whack for around $42 each.
>> 
>> Based on testing more than a few of them, there will be a couple that have significant
>> issues ( < 5%). There will be some that are in spec, but not by as much as when they
>> left the factory ( maybe another 5 %). The rest split into “pretty good” and “really good”.
>> 
>> The fact that the really good ones are still in the group suggests that these are indeed
>> NOS or something like that. A lot of batches you see have the best of the best pulled out
>> and you are just buying “the rest”. I’d guess that Fair is in the same mode, you get the
>> whole lot and can sort time as you wish.
>> 
>> Just how many show up in the sub 6x10^-13 ADEV range varies a bit by lot. To me,
>> anything that’s in the parts in 10^-13 counts as very good. How many would improve
>> if you burned them in for six months or so, who knows….
>> 
>> Bottom line: You probably do better buying closer to the source of the surplus in a
>> case like this.
>> 
>> Bob
>> 
>>> On Jan 9, 2023, at 4:18 PM, DM via time-nuts <time-nuts at lists.febo.com> wrote:
>>> 
>>> To All,
>>> Just a quick heads-up to anyone who might be needing, or just want one for fiddling with, Fair Radio Sales has a fair stock and a pretty good price for the HP 10811-60111 ovenized oscillators (https://fairradio.com/product/10811-60111/) . They are selling them (including the 05328-20027 support assembly) for US $79.00 each.
>>> Both I have bought two of them and both arrived in like new condition, and were fully operational, and required only minor tweaking to bring them to 10.0000000 MHz after running for a couple of months. The attached 05328-20027 support board indicates that they were removed from the HP 5328A or 5328B counters.
>>> Seems to be a pretty good deal for these well-aged oscillators.
>>> 
>>> BTW, Fair Radio is also offering the 10544A oscillators for US $69.00. Both are described as "Tested for output may need adjustment."
>>> 
>>> Cheers,
>>> DaveM
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> -- 
> 
> Jim Muehlberg
> Senior Engineer
> 
> National Radio Astronomy Observatory
> ngVLA Local Oscillator Lead
> 
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