A friend just completed a woodworking project to make a display base for two of my vintage camera tubes. :banana:

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Very Nice:yes:
Is the iconoscope still usable ?
I thought I read they all lost
vacuum years ago.
Ed

Very Nice:yes:
Is the iconoscope still usable ?
I thought I read they all lost
vacuum years ago.
Ed

I'd guess not useable, but I don't know.

That is a great way to display those tubes. Thanks for the idea!

That looks great ! !

I would have them held in place with some FunTac..... I think I would also use it on the
wood to the desktop as well.....

But then I have squirrels and cats runnin around...... Sometimes things go bump....

.

That looks great ! !

I would have them held in place with some FunTac..... I think I would also use it on the
wood to the desktop as well.....

But then I have squirrels and cats runnin around...... Sometimes things go bump....

.

No pets or kids here, so they are not stuck down. If Chicago has an earthquake, I'm out of luck.

"wood to desktop"? - if you mean the uprights to the base, they are tightly screwed (and maybe glued, I didn't think to ask).

The wood base.... So it can't slide.... Yah the little critters had a way of doin' stuff
I would not think possible..... That is a very nice display !

.

Wow.History of TV right there.How beautiful .I hope its on a safe shelf in a display cabinet .

I would like to think he made several and would sell them and save me the time to build one. Is he game for that?

BTW, It is very likely the Ike tube is still usable. They don't naturally "lose" their vacuum.

This is the perfect post to answer a question that was posted to the KTLA-TV alumni website. Here's the question regarding the Iconoscope tube:

David Shipman. "In 1962, as I was helping John DeMuth and Roy White with an inventory in the Maintenance Dept., they had to explain (as if they were speaking to a three year old) why you should only hold one of these tubes face down...anyone know?"

I couldn't answer David's inquiry. Anyone know?

-Steve D.

The light from an AMBIENT source could damage the photosynthetic coating ?!?

Holding the tube face down would prevent any loose particles dislodged from the gun from falling onto the surface of the image plate and damaging it.

This is the same reason that orthicons and vidicons are supposed to be kept face UP.

The light from an AMBIENT source could damage the photosynthetic coating ?!?

Not a bad answer Sandy. The guy who asked the question came up w/this answer:

David Shipman: "When it's held face up, dust may fall onto the target and scratch it...top is the large end, which should be uppermost."

N21XK, You're reply is very similar to the answer given by former KTLA employee David Shipman, who asked the original question.

-Steve D.

The light from an AMBIENT source could damage the photosynthetic coating ?!?

The reason to keep them pointed down is, as stated, to avoid spots from loose particles.

However, when working with common 931a photomultiplier tubes for a flying spot scanner in the 70s, I found that they could be damaged by exposure to bright office fluorescent lighting [edit - before ever being powered up. Taken out of the box in a dimly lighted room and installed in the scanner, they were good, but if exposed to bright light in the process of opening the box or replacing a tube to test another one, they would get worse.]

We had two brands, RCA and Hamamatsu. The Hamamatsu's, out of the box, were less noisy than the RCAs, but could be made noisier if you exposed them to the office lighting. [Edit: IIRC, the RCAs were just noisier whether exposed to bright light or not.] I never made a test to determine if that was because the output was reduced and subsequently we had to turn up the multiplier voltage, or if they were just noisier at the same voltage (i.e., by measuring the voltage required before and after). I suspect that the output of the photocathode was less after exposure and we had to turn up the voltage to get normal output.

Photo-emissive surfaces are made from compounds / alloys that hold their electrons loosely and that seems to involve the compounds holding together loosely as well - characteristics are easily degraded by high temperature, but I have never seen a description of the effect we saw with the Hamamatsu's. I suspect that other tubes like the iconoscope could have the same problem, but if they were always manufactured or handled in a bright environment, no one ever saw the original higher performance.

I would like to think he made several and would sell them and save me the time to build one. Is he game for that?

BTW, It is very likely the Ike tube is still usable. They don't naturally "lose" their vacuum.

Sorry, this took several months of tiny bits of a busy man's spare time, and I don't feel I can impose any more. Plus, the drawings are gone. Maybe you can tell that the dimensions were made precisely for this particular tube - some of the dimensions can vary up to a quarter inch from tube to tube according to the spec sheet.

Very Nice:yes:
Is the iconoscope still usable ?
I thought I read they all lost
vacuum years ago.
Ed

Here's one that is very much usable http://youtu.be/Bs5l39WsnKo.

"Ordinary" PMTs, of which the 931 and similar ones like the 1P28
and even the ones with the photocathode on the front glass,
are not permanently damaged by room light, and the 931 and 1P28
won't be by even straight sunlight. That's turned off of course.
Far red multialkali ones might be by the sun, but I've never seen it happen,
and I've used hundreds of these things.

However!! They can "charge up" and take hours, or for the red ones
even a week or two, to fully recover their original low light
dark current performance. Just let them sit in the dark for an hour
before using if you're fussy.

Here's the "official" answer: Has anyone ever had a window break in their car? No matter how much you vacuum or clean you almost always find a glass shard that mystically appears! RCA was always big on this prospect and most plumbicons would come shipped with a gimbal to keep the tube UPRIGHT and NOT FACE DOWN for fear that GLASS OR METAL particles (not dust) that may have lodged in the unit could fall down and hit the TARGET. (NO PUN INTENDED) These tubes were all 100% hand made and no matter how hard you clean the assemblies, debris can be present. Iconoscopes usually were never a victim of this unless they were broken or dropped in some way and also were too rugged to be bothered by this phenomenon. Most all image orthicons were labeled to not store or ship face down.

Re: the 931A being sensitive to fluorescent room light.
The early B&K Analyst flying spot scanner CRT produces lots of blue light and a good amount of ultraviolet as well. The 931A is the photomultiplier tube used in these old B&Ks
because it is most sensitive to blue light.
The B&K was running full tilt to produce the B&W TV test pattern image and even after many years the test signal is still quite contrasty and visually noise free.
Just trying to reconcile the "damage from room light" and the use of the 931A in the B&K Analyst that continues to work well even now.

Re: the 931A being sensitive to fluorescent room light.
The early B&K Analyst flying spot scanner CRT produces lots of blue light and a good amount of ultraviolet as well. The 931A is the photomultiplier tube used in these old B&Ks
because it is most sensitive to blue light.
The B&K was running full tilt to produce the B&W TV test pattern image and even after many years the test signal is still quite contrasty and visually noise free.
Just trying to reconcile the "damage from room light" and the use of the 931A in the B&K Analyst that continues to work well even now.

The optics were quite different - the video player used the blue/UV phosphor too, but had small lenses to focus the raster on an area of microfilm less than 3 mm x 4 mm, so the 931A may have been running at higher gain. Don't really know.

" ...

However!! They can "charge up" and take hours, or for the red ones
even a week or two, to fully recover their original low light
dark current performance. Just let them sit in the dark for an hour
before using if you're fussy.

This may be what we were seeing. Still it's curious that the two manufacturers were different.

Very nice display, those tubes look "off the assembly line" brand new! :) Reading through the replies asking whether the Iconoscope is still any good, I personally think if there's no whiteness around the getters then it's still under vacuum and would likely be good for use, my RCA 1846 Iconoscope tube I recently got working in my homemade camera is outputting a picture. I was advised with vintage tubes that have been doormat for decades to fire up the tube heater at 3V for 2 hours and then 5V for 1 hour to rejuvinate them and so I did that with my 1846 and it's working! :) Those not aware of my homemade Iconoscope camera here is the link to my thread on it http://videokarma.org/showthread.php?t=263849 .