My B&W Iconoscope TV camera project

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My B&W Iconoscope TV camera project

Postby aussie_bloke » Thu Jan 24, 2013 11:18 am

G'day all.

This is my latest project I have embarked on and it is a very ambitious one too, I am going to build an Iconoscope tube B&W TV camera! :D Those who have followed my NBTV camera thread will be already aware of it as I gave a sneak preview. Anyways thought I'd do a bit of work on the camera first before posting anything so over the past couple of weeks I've been doing a bit of work here and there with the camera and so far made a bit of progress, so now thought I'd start making the thread.

So starting from the beginning, I am a proud owner of an early 1940s RCA 1846 military grade Iconoscope TV camera tube http://troysvintagevideo.0catch.com/1846iconoscope.html which looks to be in great condition and still under vacuum (no white spots at the getters) and I intend on making a working camera from it.

So I have been gathering up as much data as I can on iconoscope cameras and tubes from various sources and have been contacting those with greater knowledge of cameras for assistance including Yoshio Osaki who successfully built a solid state Iconoscope camera http://www.youtube.com/watch?v=Bs5l39WsnKo . He couldn't provide me with the official schematics due to misplacing them but kindly provided me with some sketched schematics and notes from his memo pad he was able to find which includes the camera's power supply and the head amp and the deflection yoke construction data which is a great start :) . He prefers I build the camera first before sharing the data so abiding by his wishes I will get the camera built first before sharing them.

I didn't have any data on the RCA 1846 Iconoscope tube but do have data on the 1848 tube which was what Yoshio went by when constructing his 1846 Iconoscope camera. The 1846 and 1848 are nearly identical in specs and in physical appearance so the 1848 data will be fine for the job. The 1846 is actually the military version of the 1848 tube, 1846 tubes were used in WW2 bomber cameras as a visual aid to guide unmanned remote bomber planes/boats to their targets which on impact the camera gets destroyed, more info on these cameras can be found here http://www.earlytelevision.org/military_tv.html . The 1848 tubes were used in outdoor broadcast cameras and the larger 1850/1850A tubes were used for indoor studio cameras.

Now to the construction side of things, I started off racking my brain on a suitable enclosure to house an Iconoscope camera system in, I was initially going to make an enclosure out of wood but then I looked at an empty old computer tower case (initially housing a classic 90s IBM 486 DX2-66) and thought it would make a perfect enclosure due to it's size and the drive mount at the top being nice and square to sit a lens inside so I went with it.

Before doing anything with the case I decided to make a cardboard model of the Iconoscope tube around the same size to use as reference
so I don't risk damage to the tube from over handling it, so that's what I did as seen in the pics, later I also made a cardboard model of the yoke as well.

Now back onto the tower case. First step was to remove the unwanted metal framework in the case so with a hacksaw I cut it all out. Then I needed to stick a metal platform in the back end near the top for the Iconoscope tube to sit on top so I grabbed a metal cover from a scrapped computer power supply and screwed/riveted it in the back of the case at a suitable position for the tube to fit. Then I had to find a suitable way to mount the tube on the platform so I cut a piece of wood with a curved bight at the top and I lined it with rubber from an ex bike tube and sitting the tube on top it fits like a glove. Due to the limited space between the platform and the top of the case I had to make the wood mount removable and the tube fitted to it externally so I cut some brackets and drilled/screwed them to the platform in a suitable position and the wooden mount and tube slides on between the brackets and I screw the mount to the brackets with bolts and wing nuts. I then had to make a strap to hold the tube onto the wood mount so cutting more bike tube rubber I made the strap and nailed one end to one side of the mount and stuck a screw part way in the other side and on the other end of the strap connected a washer to use as a hook to hook around the screw and that worked, the strap fits nice and snug and gripped around the tube but I made sure it was not He-Man tight of course :lol: . Then next part was to make a mount for the tube's yoke and going by Yoshio's given dimensions of the yoke I made a cardboard model of it and cut another wooden mount with a slanted bight at the top for the yoke to sit in in a slanted position. Due to uncertainty of the height position of the yoke I made the mount height adjustable by cutting elongated holes into the metal piece the mount is going to be screwed to so I can adjust the height of it. And that's where I am up to at the moment with the project.

It's coming along slowly due to the fact I have to make do with resources at hand and cutting/machining/making the parts is a timely process and thinking up suitable parts and looking through metal/plastic/wood scraps adds to time and of course I am doing a lot of other things. So I guess it will be a long term project but no matter what I will keep at it even if its in small amounts.

Here below are pictures documenting my construction progress to date and some pdfs of various Iconoscope tubes:
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Postby Steve Anderson » Thu Jan 24, 2013 7:00 pm

An ambitious project indeed, one I will be watching with keen interest!

If the 5527 were available at a sane price I would be very tempted myself too. But in your case winding all those coils/yokes would simply put me off. But I see the attraction of it.

Am I correct in that you propose using this as a 625 camera?...I don't see any reason why not.

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Postby aussie_bloke » Thu Jan 24, 2013 8:44 pm

G'day Steve.

Yep I intend on making it do 625 lines 50 fields/sec to be compatible with the Australian PAL standard for best quality pictures and for convenience with signal output to my DVD recorder.

Winding the coils, yep a daunting task but when I have the resources and tools handy I am willing to do it, or alternatively I will see if I can get help from my boss of my former job as that company I use to work for winds transformers and inductor coils.

In regards of the 5527 iconoscope tube, not sure if you are aware of this but my friend Richard Diehl from LabGuy's World http://www.labguysworld.com/ has embarked on building a camera from his 5527 tube and on his videolabguy YouTube channel http://www.youtube.com/user/videolabguy he has made a video on his 5527 iconoscope camera project http://www.youtube.com/watch?v=cDDY93zx0Zs . He has built it up to testing stage and tested it out but sadly no picture nor video signal response, details of his project can be found on the oldvtr Yahoo group http://groups.yahoo.com/group/oldvtrs/ just search 5527 and his threads will appear.
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Postby aussie_bloke » Sat Jan 26, 2013 9:27 am

Just a little construction update, just riveted the metal plate at the front of the platform to hold the wooden yoke mount onto. Here below are a few pics showing the cardboard Iconoscope and yoke sitting on the mounts (though very roughly positioned):
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Postby aussie_bloke » Tue Jan 29, 2013 5:04 pm

G'day all.

Got some questions in regards of a suitable lens to project the image onto the Iconoscope. I have placed my slide projector lens in front of the tube but with the back end the end being against the glass front of the tube, the image does not get projected sharply onto the mosaic inside the tube. So what lens would be suitable to project an image sharply onto the mosaic at a greater distance, say anywhere from 150mm to 200mm away from the mosaic? And is there major light reduction when projecting an image from a lens at a further distance like that?
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Postby Steve Anderson » Tue Jan 29, 2013 5:26 pm

Looking at the data for the 1848 tube you're going to need a lens with a focal length of at least 80mm, and that's from its rearmost part. not its optical centre. And it would need to be designed to cover the entire mosaic of over 3" x 2"...that's a big piece of glassware! A 35mm lens just ain't gonna cut it, whatever its focal length, whether for a projector or a camera.

You're into the realm of large-format cameras. Best try and find a 120 film based camera (usually 2" square negs) but the landscape version where you only got eight shots per roll of film. Rare. Expensive.

These lenses were not fast and simply may not be up to the task. Or you've gotta find a lens designed for this type of device.

A good quality magnifying glass might get you going, but you'd have devise some form of iris.

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Postby Viewmaster » Wed Jan 30, 2013 12:10 am

Steve Anderson wrote:A good quality magnifying glass might get you going, but you'd have devise some form of iris.

Steve A.

Just make up a set of black discs, each with a suitable sized hole through each of them it to give you your various 'stop' settings. This would get you going for a start.
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Postby aussie_bloke » Sat Feb 23, 2013 7:29 pm

Steve Anderson wrote:Looking at the data for the 1848 tube you're going to need a lens with a focal length of at least 80mm, and that's from its rearmost part. not its optical centre. And it would need to be designed to cover the entire mosaic of over 3" x 2"...that's a big piece of glassware! A 35mm lens just ain't gonna cut it, whatever its focal length, whether for a projector or a camera.

You're into the realm of large-format cameras. Best try and find a 120 film based camera (usually 2" square negs) but the landscape version where you only got eight shots per roll of film. Rare. Expensive.

These lenses were not fast and simply may not be up to the task. Or you've gotta find a lens designed for this type of device.

A good quality magnifying glass might get you going, but you'd have devise some form of iris.

Steve A.


Thanks for the info Steve and also Albert, I will have a crack at doing that, if I can't find a suitable lens I might try the magnifying glass idea.
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Postby aussie_bloke » Sat Feb 23, 2013 8:04 pm

Okay I have not done any further work on my Iconoscope camera project since I last posted due to not having some necessary resources/knowledge to go to the next step but have now made a page on my website devoted to this project which can be seen here http://troysvintagevideo.0catch.com/ico ... oject.html . I have also uploaded to YouTube 6 video logs I made documenting my construction work progress on the camera, the videos are embedded to my Iconoscope page.

Now Yoshio has suggested I find an old 3 tube colour camera and adapt/modify its circuitry it to run with the Iconoscope tube. Interesting he suggested that as I've read in the CQ-TV magazines that Paul Marshall used the video amp circuitry from a plumbicon tube colour camera for his PYE photicon Iconoscope camera tube. Anyways I am now on the look out for a service manual for say a 3 tube plumbicon camera from around the 70s era so I was wondering if anyone here has any 3 tube camera manuals by chance? I am not so keen on scrapping a working 3 tube camera but I can build the circuitry as long as there's no rare unobtanium parts like specialized ICs and obsolete germanium transistors and the like.

Anyways next step with this project is to collaborate the info I've gathered together and draw some form of block diagram of the camera's circuitry stages and list the given requirements for each section.

I admit when it comes to designing the circuitry for this camera from scratch I don't have a clue, circuit designing has always been above my scope of knowledge, I can follow circuits, trace faults, make some modifications and of course I can construct any circuit provided I have the parts but sadly I don't know how to design circuits from scratch except very basic ones :( despite doing Certificate 3 and 4 Electronics at TAFE and working at an electronics company building power related equipment for over 5 years. So I will be needing a lot of help with designing the circuits for this camera so if anyone is willing to assist me in that area I would so much appreciate it. I will of course be asking the same in other forums too as I am dead set wanting to build this camera!!!

Anyways will keep you's updated with my progress.
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Postby Klaas Robers » Mon Mar 04, 2013 2:54 am

The plumbicon cameras like the Philips LDK3 have a target of 2.5 cm diameter. The lenses for them are designed for this size of picures, so say 35 mm film size. As far as I know the target of an iconoscope tube is much larger, so you need a much "longer" taking lens, a lens that is designed to have quite some space behind its glass ant the focal plane. I would try to find a better lens from a old photo camera that used roll films with a picture size of 6 x 9 cm or 6 x 6 cm, e.g Rolleiflex or Hasselblad.

Can you give an impression of the seize of the target and the distance of the target from the glass of the tube?

In the beginning of TV the cameras did not have a zoom lens, but different lenses on a rotatable disc, a so called Turret.
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Postby Viewmaster » Mon Mar 04, 2013 6:27 pm

aussie_bloke wrote:I admit when it comes to designing the circuitry for this camera from scratch I don't have a clue, circuit designing has always been above my scope of knowledge, I can follow circuits, trace faults, make some modifications and of course I can construct any circuit provided I have the parts but sadly I don't know how to design circuits from scratch except very basic ones :( despite doing Certificate 3 and 4 Electronics at TAFE and working at an electronics company building power related equipment for over 5 years. .


Well Aussie, join my ignorant club. :wink:
You have described my lack of design talent too. I never had any electronic training at all.
It never ceases to amaze me how some folk here can sit down and put, in some cases, 100's of components, IC/C/R/diode/etc together to achieve a working system.
I just pinch bits of cct. from one chap and try to sew it onto another bit from someone else. :shock:
A kinda "Sew and grow." :)

BTW, I take it that you have seen this site all about old TV cameras. It will not help in your actual cct design but might spur you on to do great things with your project.
http://www.tvcameramuseum.org/pye/pyethumb.htm
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Postby AncientBrit » Mon Mar 04, 2013 7:10 pm

Well Albert, speaking from an electronics perspective I'm always amazed how you "mechanical" guys can work to such fine tolerances and visualise in 3 dimensions.

My mechanical work is trial and (mostly) error.

I would say we have a happy balance of talents on this forum.

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Postby aussie_bloke » Tue Mar 05, 2013 9:46 pm

Klaas Robers wrote:The plumbicon cameras like the Philips LDK3 have a target of 2.5 cm diameter. The lenses for them are designed for this size of picures, so say 35 mm film size. As far as I know the target of an iconoscope tube is much larger, so you need a much "longer" taking lens, a lens that is designed to have quite some space behind its glass ant the focal plane. I would try to find a better lens from a old photo camera that used roll films with a picture size of 6 x 9 cm or 6 x 6 cm, e.g Rolleiflex or Hasselblad.

Can you give an impression of the seize of the target and the distance of the target from the glass of the tube?

In the beginning of TV the cameras did not have a zoom lens, but different lenses on a rotatable disc, a so called Turret.


Thanks for the info Klaas. Going by the given dimensions of the 1848 tube in the datasheet, the size of the mosaic is 76mm x 57mm and the distance the mosaic is from the front of the tube is 78mm. So looks like a 6x9cm lens would be ideal for the tube.

Yep am totally aware of the early turret lenses used in the image orthicon and iconoscope type cameras from the mid 40s to the mid 60s as I'm a diehard vintage TV camera nut who has done a lot of research on early TV cameras :D . Actually turret lenses weren't used in TV cameras until I assume about 1946 when RCA released its TK-10 and TK-30 cameras. The iconoscope cameras of the 30s-40s and also the orthicon cameras of the early/mid 40s used a single lens at a fixed zoom.
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Postby aussie_bloke » Tue Mar 05, 2013 10:07 pm

Viewmaster wrote:
aussie_bloke wrote:I admit when it comes to designing the circuitry for this camera from scratch I don't have a clue, circuit designing has always been above my scope of knowledge, I can follow circuits, trace faults, make some modifications and of course I can construct any circuit provided I have the parts but sadly I don't know how to design circuits from scratch except very basic ones :( despite doing Certificate 3 and 4 Electronics at TAFE and working at an electronics company building power related equipment for over 5 years. .


Well Aussie, join my ignorant club. :wink:
You have described my lack of design talent too. I never had any electronic training at all.
It never ceases to amaze me how some folk here can sit down and put, in some cases, 100's of components, IC/C/R/diode/etc together to achieve a working system.
I just pinch bits of cct. from one chap and try to sew it onto another bit from someone else. :shock:
A kinda "Sew and grow." :)

BTW, I take it that you have seen this site all about old TV cameras. It will not help in your actual cct design but might spur you on to do great things with your project.
http://www.tvcameramuseum.org/pye/pyethumb.htm


I pretty much get a schematic and build the circuit from it and trace/mark the schematic as I solder the components and wires into the circuit board to be sure I don't make mistakes although usually I will make a mistake or two or more in constructing a large circuit which was the case with my home-made B&W vidicon camera http://troysvintagevideo.0catch.com/mycamera.html , I smoked some components to begin with then fixed those but then there was an elusive damaged transistor in the vertical scan circuitry I wasn't aware of and was getting bad vertical scan until I later discovered it after numerous failed methods of fixing the vertical scan hehe :lol: .

Yep I am totally aware of the Museum of the Broadcast Television Camera site it's an awesome camera site and I regularly visit it :) , I am in touch with the site owner too, he is assisting me via email in my restoration on my Marconi MKIII camera chain http://troysvintagevideo.0catch.com/marconimk3.html . I've also contributed some photos of my RCA TK-760 to his site http://www.tvcameramuseum.org/rca/tk760/p1.htm .

Anyways just drawn a very simple block diagram of the Iconoscope camera outlining the main blocks of the system which is pretty much the basics of any tube camera system:
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Postby Viewmaster » Wed Mar 06, 2013 12:39 am

aussie_bloke wrote:G'day Steve.

Yep I intend on making it do 625 lines 50 fields/sec to be compatible with the Australian PAL standard for best quality pictures and for convenience with signal output to my DVD recorder.

.


When UK TV broadcast different lines per frame, some TV's had the ability to switch to either system .
I did wonder if by switching in two different time bases etc you could make it a dual 625/NBTV 32 line camera?
Maybe defocus the electron beam slightly for 32 lines to 'cover' the large picture area.

Just a thought..... Maybe first time ever that an Iconoscope has been used for NBTV !
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