[time-nuts] So what’s inside that Cs Beam Tube anyway?
djl
djl at montana.com
Mon Oct 31 21:45:03 UTC 2016
Echo, Magnus. Thanks, Skip! Easy now to see the incredible expense of
building one of these! Kinda Kludgy; Love the s/s spot welded keepers on
the screw heads, e.g.
My really dumb question is, why isn't there Cs plated on everything? Or
is the Cs contained in the rf cavity only? I think I see a window on one
end...
Thanks again, Don
On 2016-10-31 15:20, Magnus Danielson wrote:
> Hi Skip,
>
> Many thanks for taking the effort and describing what we see.
> Good thing to tinker around with, if you have one. Good conversation
> piece. :)
>
> Cheers,
> Magnus
>
> On 10/31/2016 09:54 PM, Skip Withrow wrote:
>> Hello Time-Nuts,
>>
>>
>>
>> I recently acquired a stock of dead cesium beam tubes, and my
>> curiosity got
>> the best of me, so I have cut one open. After watching lots of
>> YouTube
>> video of burning and exploding cesium I was a little leery at first.
>> The
>> first step was to make a very small hole just to let a small amount of
>> air
>> in, no flames or heat so I let it sit for a while for any reactions
>> with
>> air to take their course. Next I proceeded to cut off the ends, and
>> after
>> that the bottom of the unit, finally I trimmed the top off as far as I
>> could. Pictures are linked below for your enjoyment. I have attached
>> two
>> of the before and after at low resolution.
>>
>>
>>
>> 1. http://www.rdrelectronics.com/skip/CS-tube/cstube1.jpg
>>
>>
>>
>> This is the before picture of a tube (not the actual one opened). It
>> is HP
>> part number 05061-6077. The band around the center of the tube is a
>> mu
>> metal shield that is removed by removing the screws along the seam.
>> Unfortunately
>> 11 of the 14 tubes that I received had the cables cut as shown
>> (ouch!).
>>
>>
>>
>> 2. http://www.rdrelectronics.com/skip/CS-tube/cstube2.jpg
>>
>>
>>
>> This is a shot of the deconstructed tube. The cesium oven is on the
>> left,
>> the microwave cavity is in the center (under a metal cover), and the
>> detector is on the right.
>>
>>
>>
>> 3. http://www.rdrelectronics.com/skip/CS-tube/cstube3.jpg
>>
>>
>>
>> This is the oven end of the tube. The oven (with the cesium) is the
>> copper
>> vessel. The ion trap assembly is at the top (with magnet). The first
>> beam
>> magnet is between the oven and the microwave cavity. One thing that I
>> can
>> say is that HP brought the art of spot welding to a new level. Note
>> the
>> stainless steel strips welded over the screw heads (and lots of other
>> things).
>>
>>
>>
>> 4. http://www.rdrelectronics.com/skip/CS-tube/cstube4.jpg
>>
>>
>>
>> This is the detector end of the tube. I believe the hot wire ionizer
>> is
>> the broken metal strip. The electron multiplier/detector is in the
>> metal
>> box above it. The second beam magnet sits between the microwave
>> cavity and
>> the electronics at this end of the tube. I don’t think I broke the
>> filament, this was probably the failure mode of this tube. Also note
>> that
>> all the wiring insulation is ceramic tubing, since insulation that out
>> gasses in vacuum is a no-no.
>>
>>
>>
>> 5. http://www.rdrelectronics.com/skip/CS-tube/cstube5.jpg
>>
>>
>>
>> This is the bottom view of the tube for completeness. I have not yet
>> removed the cover that is over the microwave cavity (and has the
>> C-field
>> coil around it).
>>
>>
>>
>> 6. http://www.rdrelectronics.com/skip/CS-tube/cstube6.jpg
>>
>>
>>
>> This is the top of the tube with the potting compound removed. I was
>> surprised to find a couple of embedded resistors. I guess the good
>> news is
>> that it would be easy enough to remove the potting and solder on new
>> wires
>> if deemed useful.
>>
>>
>>
>> 7. http://www.rdrelectronics.com/skip/CS-tube/cstube7.jpg
>>
>>
>>
>> This is just a close-up of the broken hot wire ionizer (and all the
>> spot
>> welds).
>>
>>
>>
>> 8. http://www.rdrelectronics.com/skip/CS-tube/cstube8.jpg
>>
>>
>>
>> This is a close-up of the ion trap where the +3500V connects. I’m not
>> a
>> physics expert, but didn’t think about a magnet being involved. I
>> don’t
>> think any of the drawings that I have seen have ever mentioned it.
>>
>>
>>
>> So, enjoy. I will most likely be throwing the rest of the tubes up on
>> ebay
>> at some point. If there is strong interest in having them cut open
>> first
>> please let me know. I intend to cut up some wood to make an
>> appropriate
>> stand and add this one to my tube collection.
>>
>>
>>
>> Sorry for the long post, but I hope you found it informative.
>>
>> Regards,
>>
>> Skip Withrow
>>
>>
>>
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Dr. Don Latham
PO Box 404, Frenchtown, MT, 59834
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