[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
VOX: 406-626-4304




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