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Dead Bear
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Join Date: Feb 2008
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Name This Tube!

10/10/2008 12:43 AM

So i found this in the trash and don't want to fire it up,

as it could melt my face or just burn out....

any one of you people out in the real world worked with/ seen one of these

it is numbered 7923-62, no this number doesn't produce relevant info on a google

datasheet or tube-site search (which is why I ask)...

the first photo is the face of the tube and the following photos show the many, many

screens; the screens have aligned triangular "striations" or channels, each screens "triangular channels" match shape, but they vary in angle from screen to screen.

it has 20 pins, one of which is unused.

the accompaning circuit is point to point wired, the board has the following labels:

PM tube/ preamp 400314 rev-a (this has also be searched for)

input, output, +/- 15V, com, and dark balance... all lead out of the device...

the circuit does look like its just a preamp....

this maybe part of lab equipment-- I found it in a university dumpster....

the face in its mounting/case--- probly flush mounted, is it just a segmented display?

a side view of the number and the screens

another view of the screens...

thanks so much for any of your help or attention...

and if this cooks out dangerous radiation (its probably just a segmented display or archaic modulator) I will treat it with the magical respect it would deserve.
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JohnDG
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#1

Re: Name this Tube!!!

10/10/2008 1:48 AM

It's a photomultiplier.

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user-deleted-1105
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#2
In reply to #1

Re: Name this Tube!!!

10/10/2008 3:35 AM

Drat you beat me to it.
Have a free photon (to multiply at your leisure)
Del

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JohnDG
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#3
In reply to #2

Re: Name this Tube!!!

10/10/2008 4:26 AM

My erstwhile boss (latterly co-director) worked at Harwell during the war. He claimed the dubious honour of having dropped & smashed one, when there weren't very many around (invented 1936).

PS Ta for the photon. Unfortunately, I dropped it, and it's got mixed up with some others. What colour was it?

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Kris
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#4
In reply to #3

Re: Name this Tube!!!

10/10/2008 4:53 AM

.....if you want, I'll volunteer to crawl around the floor looking for the dropped photon.

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user-deleted-1105
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#5
In reply to #3

Re: Name this Tube!!!

10/10/2008 5:26 AM

Damn it was one of my favourites, given to me by a bloke called Heisenburg...he was a tad unsure of the colour.

Del

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JohnDG
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#6
In reply to #5

Re: Name this Tube!!!

10/10/2008 5:59 AM

I keep seeing a very pretty blue one out of the corner of my eye, but every time I go to grab it - the colour kinda fades, and I'm not sure which one it was .

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#8
In reply to #5

Re: Name this Tube!!!

10/10/2008 8:31 PM

Aaaah, sorry, mate - I had it in a box for a while, but it tunnelled, & Schroedinger's pussycat just et it .

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Milo
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#10
In reply to #5

Re: Name this Tube!!!

10/11/2008 9:56 PM

Actually a great answer.

milo

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Anonymous Poster
#7

Re: Name this Tube!!!

10/10/2008 1:45 PM

For an indepth look into photomultipliers (free handbook), please see this site:

http://www.burle.com/cgi-bin/byteserver.pl/pdf/Photo.pdf
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#9

Re: Name This Tube!

10/11/2008 4:19 AM

Name this tube eh?

How about Leonora? or Betty? or do we think it's a boy tube? the nmaybe Butch or Mikey?

Del (sorry that's the silliest post I've written for days...I shall go curl up in the corner)

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Dead Bear
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#11

Re: Name This Tube!

10/12/2008 1:02 AM

Thanks!
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Anonymous Poster
#12

Re: Name This Tube!

10/13/2008 8:37 AM

You definetly have a "Photomultiplier" tube.

You might try contacting "Electron Tube" or "Hamamatsu" (Google them) and give them the tube number. They might have a cross reference as to who made it. I don't think it is either of theirs though.

It appears that the assembly has a pre-amp. The ballence that you refer to is probably to cancel the dark current that is inherent to PMTs. Also, be aware that PMTs require HI VOLTAGE to operate 800 to sereral 1000 volts. Be carefull.

The front gridded pattern is the photo-cathode and has the negative HV. The photocathode converts light into electrons. The electrons get multiplied by the dynodes that you see in your side view. The Anode is at ground potential, and that is where the pre-amp is attached. Or more correctly a transimpeadance amp. This converts the current into a voltage. If you get this thing running you will have to operate it in complete darkness as even a small amount of room light will saturate the output and it won't appear to be operating. The light necessary to stimulate the cathode could be so little as to be indistinguishable by eye. The over all gain of the PMT can be controlled by adjusting the HI VOLTAGE.

Good Luck & hve fun with this
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Users who posted comments:

Anonymous Poster (1); Dead Bear (1); JohnDG (4); Kris (1); Milo (1); user-deleted-1105 (3)

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