[time-nuts] HP 5065A rubidium lifetime

Chuck Harris cfharris at erols.com
Sun Mar 21 15:44:51 UTC 2010


As I recall, I removed the aluminum covers in much the same way
as you describe.  I then removed the delicate physics package from
the aluminum cylinders, and used a hot air gun to heat up the parts
enough so that they would press free of the foam.

I recall that the resistance is either in the manual, or can be
easily deduced from the circuitry.  Either way, it isn't very critical.

-Chuck Harris

J. L. Trantham wrote:
> Thanks.
> 
> That is just the type of information I was looking for.  
> 
> I have some pictures of my 'melted' unit with the covers off the end of the
> cell end if anyone is interested.  It is pretty messy after the meltdown.
> There are at least three metal cylinders for sure, an outer one then foam
> between it and the next one, then foam between the second and third one then
> foam inside that between the inner cylinder and the aluminum cylinder that
> is the rubidium lamp assembly. 
> 
> When I started trying to disassemble the unit, I could not get the aluminum
> cover of the lamp assembly to turn loose.  I replaced the three 2-56 screws
> that hold the cover in place with longer ones then used a 1/2 inch thick
> aluminum disc with a center hole placed over the center bolt of the lamp
> assembly, resting on the long screws.  I used one of the nuts and 'torqued'
> it to 'pull' the cover off the lamp assembly cylinder but to no avail.
> However, after the melt down, with everything 'hot', it came off relatively
> easily.  This is what makes me think it had had a prior 'meltdown' and the
> 'goo' had dried as an incredibly strong glue.
> 
> Although mine was destroyed, it did not appear to have a 'twisted pair' type
> winding but rather a single layer.  I had missed that it was a 'parallel
> pair'.
> 
> Thanks,
> 
> Joe




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