[time-nuts] HP CBT Cutaway?

Tom Van Baak tvb at leapsecond.com
Sat Aug 20 11:02:52 EDT 2005

I had a 5061A CBT opened for me a while back
using a Dremel tool. It took some time and
patience. All the magnets did unavoidably get
filled up with metal case filings but the result
was quite nice regardless.

The HP CBT factory told me the right way to
do it is to put the CBT in a lathe and cut off
the two end caps at their circular seams.

Apparently you do not have to worry about Cs
getting in contact with air (moisture). All the
spent Cs is captured by the getter and any
remaining Cs is deep in the oven assembly
and the pin hole is so small that there is no

I have detailed photos of the inside of both a
5061 and 5071 tube if you're interested. Send
me email offline.


----- Original Message -----
From: "Jim Miller" <timenuts at jcmco.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Friday, August 19, 2005 13:12
Subject: [time-nuts] HP CBT Cutaway?

> Hi,
> Has anyone ever seen a cutaway of an HP 5061 CBT? I recently bought a
> "Serviceable" 5061A from Gov. Liquidation that turned out to be
> nothing but an empty, gutted carcass containing only the CBT and the
> time of day clock option.  To add insult to injury, the CBT's leads
> had been close-clipped 1/2" away from the tube body.
> In order to make some lemonade from a lemon, I'd like to cut open the
> CBT outer case to expose the innards as a show-and-tell piece for
> time-and-freq presentations at the local ham club and high school
> electronics demonstrations.  Any suggestions on where to make the
> incisions in the case? Is it worth the trouble? I have a machine shop
> that can do the cutting.
> Thanks,
> Jim

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