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Old 1st Dec 2017, 10:49 am   #1
Argus25
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Default 1937 RCA Projection TV "gun"

I recently found this in some of my archived magazines. It is amazing how far advanced RCA were with this technology at the time. The final anode voltage on the especially made CRT in this "gun" was 10kv. The construction is certainly very futuristic for the time, building it into the cylinder to make it like a gun.

When did the first projection sets turn up in the UK ?
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Old 1st Dec 2017, 11:43 am   #2
Peter.N.
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Default Re: 1937 RCA Projection TV "gun"

Looks a lot better than the Philips and Decca systems from the '50s and they used 25 kv.

Peter
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Old 1st Dec 2017, 12:15 pm   #3
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Default Re: 1937 RCA Projection TV "gun"

European 1950ís projection TVís
https://www.radiomuseum.org/forum/pr...sion_sets.html

Slightly bigger version of the 1937 type.
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Old 1st Dec 2017, 12:35 pm   #4
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Default Re: 1937 RCA Projection TV "gun"

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Originally Posted by Peter.N. View Post
Looks a lot better than the Philips and Decca systems from the '50s and they used 25 kv.
My parents' Philips was poor because it lacked dc restoration but I must say I was impressed by Trevor Goodenough's Decca 1000 projecting an image equally as large as the RCA image.

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Old 1st Dec 2017, 4:08 pm   #5
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Default Re: 1937 RCA Projection TV "gun"

This displayed picture on the second page of the article doesn't look quite right to me. If you look carefully at the shadow of Dr Law's head, the outline of the model's shoulder continues as a darker shadow. Methinks this was a printed picture being simply illuminated by a light being shone on it.
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Old 1st Dec 2017, 4:45 pm   #6
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Default Re: 1937 RCA Projection TV "gun"

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Originally Posted by Nuvistor View Post
Slightly bigger version of the 1937 type.
Wow, that one looks massive.

I found a little more information on the 1937 gun version in Fink's television book. The CRT apparently runs 2mA beam current and they mention a figure of 5mA too and 10kV, so it has about 20 to 50 watts screen power. No a wonder the CRT phosphors had a habit of aging relatively quickly. It also has a focus coil wound to prevent spherical aberration. I'm sure a scan collapse on one of those projection CRTs would destroy the phosphor is short order.
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Old 1st Dec 2017, 6:08 pm   #7
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Default Re: 1937 RCA Projection TV "gun"

Fascinating.... also remember the mechanically-scanned projection TVs of the same era: Scophony being the most well-known example:

https://blog.scienceandmediamuseum.o...scanner-motor/
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Old 1st Dec 2017, 9:02 pm   #8
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Default Re: 1937 RCA Projection TV "gun"

I have heard it said of Eidophor projectors, that by rights they shouldn't really work at all!
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Old 1st Dec 2017, 9:12 pm   #9
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Default Re: 1937 RCA Projection TV "gun"

A business acquaintance of my dad had a colour CRT projection TV in his lounge. The screen was integral to the set like a RPTV, but it was front projection with the tubes mounted in a trough at the front.

Impressive for the mid '70s.

I can't recall the make or model, but I suspect I am about to be told
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Old 1st Dec 2017, 10:53 pm   #10
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Default Re: 1937 RCA Projection TV "gun"

Perhaps: Sony Videoscope KP-5040 1981 50"

https://www.youtube.com/watch?v=Pm0oLFr0j2s

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Old 1st Dec 2017, 11:08 pm   #11
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Default Re: 1937 RCA Projection TV "gun"

Quote:
Originally Posted by Argus25 View Post
Wow, that one looks massive.

I found a little more information on the 1937 gun version in Fink's television book. The CRT apparently runs 2mA beam current and they mention a figure of 5mA too and 10kV, so it has about 20 to 50 watts screen power. No a wonder the CRT phosphors had a habit of aging relatively quickly. It also has a focus coil wound to prevent spherical aberration. I'm sure a scan collapse on one of those projection CRTs would destroy the phosphor is short order.
Some flying spot telecine scanners had air-blast cooling on the CRT face- I wonder if this was ever used on projection sets, or maybe the noise would have been too obtrusive in a viewing/listening environment.
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Old 2nd Dec 2017, 2:14 am   #12
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Default Re: 1937 RCA Projection TV "gun"

In a film which features the original low definition pre-war German TV system

https://www.youtube.com/watch?v=0oqJBVg7MxI

at 5:20 there is a short scene showing what seems to be a projected live TV image. No details given, but at that time the Germans did develop an intermediate film system for projecting live TV that used a conventional movie projector to produce the image.

Attached is leaflet describing Decca's large screen projection TV from 1954. I wonder what the life of its tube was?
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Old 2nd Dec 2017, 9:21 am   #13
Peter.N.
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Default Re: 1937 RCA Projection TV "gun"

The Philips set had an elaborate protection circuit should a timebase fail, the problem was you had to somehow overcome it to fault find. Yes I can confirm that a time base collapse without the protection system will destroy the screen phosphor instantly.

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Old 2nd Dec 2017, 9:56 am   #14
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Default Re: 1937 RCA Projection TV "gun"

Tube life was actually very good. The problems arose when one of the timebases failed and the protection circuit had an unknown fault.

This was quite rare but most engineers fitted an old burnt screen tube [Mullard MW6-2] for chassis fault finding and when all was working ok the good tube was refitted.

I have a number of projection receivers. I brought this beast back to life for the Dulwich museum. John.
https://www.vintage-radio.net/forum/...d.php?t=120026
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Old 2nd Dec 2017, 10:39 am   #15
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Default Re: 1937 RCA Projection TV "gun"

Quote:
Originally Posted by emeritus View Post
In a film which features the original low definition pre-war German TV system

https://www.youtube.com/watch?v=0oqJBVg7MxI

at 5:20 there is a short scene showing what seems to be a projected live TV image.
I think that Telefunken Karolus system was actually a filament lamp matrix display rather than a projection system.

http://www.sarganserland-walensee.ch...kow/nipkow.htm

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Old 2nd Dec 2017, 11:29 am   #16
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Default Re: 1937 RCA Projection TV "gun"

I’ve seen the Eidophor projectors in use around 1980. They were very large and gave brilliant pictures fed from 2” video tape. The screen used was a cinema type about 30 feet across.
I worked for a dealer that sold the Sony projectors at that time and they cost about £7000. The Eidorphor was about £200,000. So not going to be a domestic product, plus you would need a spare room to house the projector and it’s associated equipment.
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Old 2nd Dec 2017, 11:45 am   #17
Dave Moll
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Default Re: 1937 RCA Projection TV "gun"

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Originally Posted by Peter.N. View Post
The Philips set had an elaborate protection circuit should a timebase fail... Yes I can confirm that a time base collapse without the protection system will destroy the screen phosphor instantly.

Peter
The Decca also has this feature - for the same reason.
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Old 2nd Dec 2017, 2:05 pm   #18
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Default Re: 1937 RCA Projection TV "gun"

Thanks for the link to the Karolus display, most interesting. I had wondered if the lack of flicker that you usually see when a TV appears in shot in a cine film, meant that the picture was produced by special effects. The persistence of filament lamps could account for the the lack of flicker, meaning that it was indeed a straight shot of a Karolus display.
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