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Old 19th Nov 2022, 11:44 am   #1
FERNSEH
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Default 819 line projection TV set?

From a 1952 SNCF film on YouTube: "Naisance d'une locomotive".

The TV set looks like a Philips table top projection model, TF701?
Possibly the same dimensions as the model 600A.

https://www.youtube.com/watch?v=pCx_eYQhiu8

DFWB.
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Old 19th Nov 2022, 11:59 am   #2
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Default Re: 819 line projection TV set?

Looks interesting, I presume it would scale up nicely.
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Old 19th Nov 2022, 12:04 pm   #3
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Default Re: 819 line projection TV set?

I think the screen image is superimposed as it dances about relative to the set.

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Old 19th Nov 2022, 12:14 pm   #4
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Default Re: 819 line projection TV set?

Looks too bright for a projection set, and not suffering from coma flare that over-bright CRTs give.

Done in post processing it saves issues with syncing.

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Old 19th Nov 2022, 12:23 pm   #5
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Default Re: 819 line projection TV set?

With a good CRT the Philips 600A can show a bright picture.

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Old 19th Nov 2022, 1:28 pm   #6
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Default Re: 819 line projection TV set?

Hello David,

Interesting film.

I agree with Peter S.
I think the set is a 1950 441 line TX601A/TF601A.
The Philips badge looks replaced by a much larger one for the film. Normally it would be the same as on the (TG)600A.

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Old 19th Nov 2022, 2:46 pm   #7
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Default Re: 819 line projection TV set?

Hello Jac,
in many respects the TF601A will be in terms of circuit design similar to the TG600A. Except for reception from the Eiffel Tower transmitter frequencies, there shouldn't be any great differences.
Carriers were 42Mhz sound and 46Mhz vision. Line timebase optimised for 11,025Hz?
Would the spot size of the MW6-2 CRT be small enough for 819 lines definition?

DFWB.

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Old 19th Nov 2022, 4:07 pm   #8
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Default Re: 819 line projection TV set?

Hi David,

I agree that the circuitry of the 600A and TF601A are extremely similar. (I still must compare the service manuals.)
The LOPTs appears to be different though, but the LOPTs used in early Philips French, British and Dutch sets were usually manufactured locally and looked differently. In some cases the coils were developed and wound in Eindhoven, but the housing was made locally.

I'm certain that I have read somewhere what the (practical) maximum number of lines for the MW6-2 is. It may be 625.
I browsed several publications, but I can't find it now....
I might come across it again though, I'll keep looking.

I think that, by the time that the 819 line standard became practically implemented, there were already direct view tubes of a sufficient diameter available.
Philips used the MW31-xx for several early 819 line receivers.
It would have been quite an effort to make an 819 line set with the MW6-2.
The viewing screen would also have to be made in a much finer version of the Fresnel pattern.

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Old 19th Nov 2022, 8:55 pm   #9
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Default Re: 819 line projection TV set?

Mullard publication "Mullard projection television system" mentions a spot size of 170 µm (@ 100µA beam current). Even if we suppose a size of 150 µm, this only gives about 36 mm / 0.15 mm = 240 video lines max.
If Mullard meant 70 µm, it would mean 514 lines max, which is more realistic, albeit on the low side.
(Philips Technical Review writes about a spot size of 70 µm for the 567 line television system.)

Mullard publication "A Projection System for Domestic Television Receivers" mentions a spot size of 58 µm, which would mean 620 lines max. This looks to be a realistic maximum achievable value.

Given that the optical system is not perfect, and neither will the alignment be, a good picture for the 819 line system does not seem feasible.

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Old 29th Nov 2022, 11:10 pm   #10
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Default Re: 819 line projection TV set?

It might be true that 819 lines were at or beyond the limits of the MW22-6 rear projection tube and Protelgram optics.
But the fact is that Philips did produce an 819-lines Protelgram set, the TS2323A.
For details on the French TV developments see here:
https://www.maximus-randd.com/piets-...n-pt2.html#819.
Whether the set gave the full resolution of the 819 lines is indeed questionable, but at that time - early 50s - I think that was not considered a major issue. As long as one was able to receive the broadcast signals - which required 819-line system compliance - the actual display resolution was secondary, given the often small display screens.
That is also why the Belgian French standard essentially displayed the 819-line system at 625-line resolution.

Regards, Pieter
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Old 30th Nov 2022, 8:44 am   #11
Jac
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Default Re: 819 line projection TV set?

Interesting Pieter.

I certainly missed this.

The picture certainly would not have been great.
In principle it is of course possible to display almost any number of lines, but the picture would not get better with the increasing number of lines.
On the other hand it might have been possible to sell a few extra sets by having the TS2323A in the portfolio.

Never seen a picture of the TS2323A. (Only of the TX2324.)

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Old 30th Nov 2022, 11:04 am   #12
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Default Re: 819 line projection TV set?

Quote:
Originally Posted by Pieter H View Post
It might be true that 819 lines were at or beyond the limits of the MW22-6 rear projection tube and Protelgram optics.
But the fact is that Philips did produce an 819-lines Protelgram set, the TS2323A.
For details on the French TV developments see here:
https://www.maximus-randd.com/piets-...n-pt2.html#819.
Whether the set gave the full resolution of the 819 lines is indeed questionable, but at that time - early 50s - I think that was not considered a major issue. As long as one was able to receive the broadcast signals - which required 819-line system compliance - the actual display resolution was secondary, given the often small display screens.
That is also why the Belgian French standard essentially displayed the 819-line system at 625-line resolution.

Regards, Pieter
The earlier Belgian systems seemed to be a bit of fudge before making things more standard in the late 1960s when they switched to colour.
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Old 30th Nov 2022, 3:25 pm   #13
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Default Re: 819 line projection TV set?

I suspect TS2323A should read TF2323A.
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