[time-nuts] HP 106B on Ebay

[Tom Van Baak]

I second what Corby says. I have a number of hp 106, starting with one 
from eBay in 1999. Quite rare. When they work they are somewhere between 
very good and unbelievable. But most have issues. They are all very old 
by now and one trouble I've seen is that the double ovens don't work 
like they used to, which pretty much ruins their performance.

So when you power it up it's a good idea to continuously log frequency 
(10 s gate is ok) for the first day or two and by looking at the 
wiggles, slopes, and slope changes, you can tell if the inner and outer 
oven are working right, or if one is dead, or if due to old age they are 
fighting each other.

The daily ageing rate should slow down gradually. At some point (maybe 
months) environmental effects will exceed the ageing rate. These 
standards were meant to be powered up forever, in laboratory conditions. 
I had one that was far better than rubidium or cesium short-term, and 
almost rivaled rubidium long-term. It died of oven failure.

Some photos, warm-up, and long-term plots:

http://leapsecond.com/museum/hp106a/

http://leapsecond.com/museum/hp106b/

If you have questions feel free to ask us on- or off-list. And again, if 
at all possible collect data from the very first power-up.

/tvb


On 3/21/2020 4:47 PM, cdelect at juno.com wrote:
> If whoever bought it needs advice I have repaired a couple of them.
>
> It does not have a dewar.
>
> Both the units I worked on had low to mid parts in 10 -13th from 1 to 100
> Sec.
>
> They do take 3 to 4 hours to warm up so don't be impatient.
>
> Aging wont slow down for several weeks.
>
> Cheers,
>
> Corby
>
>
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