Colour from Alexandra Palace

[Panrock]

I understand that the first BBC colour tests, starting in 1954 and using NTSC, were mounted from Studio A at Alexandra Palace.

This was around the period during which the London signal was switched from AP to CP(Crystal Palace). Presumably the AP transmitter became redundant for a while before removal, and might other work then have been found for it...?

There's a rumour floating around that colour was actually transmitted from the Alexandra Palace tower on Channel 5. Is there any truth to this? Could the final 405-line transmissions from AP actually have been in colour?

Steve

[ukcol]

Hi Steve

There is some info about early BBC colour transmissions in this old thread.

https://www.vintage-radio.net/forum/...ead.php?t=5255

[Ray Cooper]

"BBC Engineering 1922-1972" by Edward Pawley has this to say about AP colour:

Much work was done in Designs Department in testing equipment produced by Marconi’s for scanning slides and 16-mm films, colour pictures from which were
radiated by a standby 5-kW transmitter at Alexandra Palace. (The early colour transmissions were double-sideband and continued to be so until the Crystal Palace station opened in 1956. When radiating DSB colour, the 5-kW transmitter at Alexandra Palace gave an output of only 3 kW). The signals were also sent round the SB system to Manchester and back, with surprisingly good results.

No mention of channel used. But here, 'a standby 5-kW transmitter' probably means 'the standby 5-kW transmitter': namely, the standby for the 17kW main transmitter. The wording is interesting: it implies that the standby tx was in fact used as a conventional VSB transmitter at the time (hence, any pre-war receivers that were left and still receiving on the 'wrong'
sideband would have had pretty grim pictures) and for these colour tests was re-tuned to give a double-sideband response. Why, one wonders? After all, any colour service would have had to have worked using a VSB system. Any valid reasons for needing to use DSB will be gratefully accepted...

And, if the gear being used was in fact the service standby, I don't think they would have wanted to use channel 5: it would take hours to re-tune one of these things back to Ch.1, and the legitimate Ch.1 viewers might get a bit impatient if the main TX had developed a wobbly.

Finally, if you wanted to radiate even 3kW worth of channel 5 test transmissions, you'd have needed a separate aerial array: the existing Ch.1 setup would have been of no use whatsoever. I have never heard of any such aerials being fitted to AP: but that's not to say that they weren't. Again, any further contributions eagerly awaited.

[Station X]

I have moved the posts in this thread relating to a Pye 405 line TV to a new thread here:-

https://www.vintage-radio.net/forum/...ad.php?t=15531

Please keep both threads on topic.

[DoctorWho]

I have a variety of clips af tele-recordings from the colour 405 tests of the 50's (mainly black and white of course), I get the impression that viewers with regular 405 sets on Channel 1 could look in, in black and white of course, so I strongly suspect that Channel 1 was used.

[Dave Moll]

I certainly have childhood memories of seeing this on the screen:
http://www.pembers.freeserve.co.uk/T...ur-Redrawn.jpg
... in monochrome, of course. So, it would have been on the normal broadcast channel. As this was in Oxford, it may have been from AP or CP (more probably the latter) before Oxford's own Beckley transmitter was commissioned.

(above image borrowed from Alan Pemberton's web site).

[Chrisw]

Hi all. i recall reading about these transmissions years ago in the 405 Alive magazine that was then current.
If I have it correct.... viewers could watch the transmissions in black and white but they suffered from "Dot Crawl" from the colour part of the NTSC encoding. I thought that all the sets that were used were made by Bush but of course that would not have stopped Pye building a few for demo purposes. In the book "The Setmakers" it mentions on more than one occasion that the guy in charge of Pye hated our 405 system and always demanded we followed Europe and went 625 so again if Pye made some 405 NTSC sets its another bonus.
It must have been a fantastic time and sadly forgotton now that back then we did have colour tests taking place while most the Country had no ITA service.
I have a Pratical Televison mag of I think mid 50s that details these tests, I must look it up again.
Finally these tests remind me of a small tale concering a TV Dealer in Northampton which I think is true..This dealers Brother in Law worked for Bush and obtained one of these sets for private demo purposes. The set was put in the shop window and after normal viewing would be turned on in all its glory for the public to see.
The increase in traffic accidents outside the shop for the few days that the set was running resulted in the local Police ordering the owner to remove the set or face a court appearence.....sorry to rattle on folks...
Just remembered I think that all the tests were from AP (mast and studio) while normal transmissions took place from CP.

[Ian - G4JQT]

In the early 1980s I worked with a BBC engineer who had worked at Tatsfield, the BBC’s old technical receiving site, when they were carrying out 405-line NTSC tests from AP or CP - I can’t remember which now.

He said (and this may be apocryphal) that one of the test scenes was a bowl of fruit, but the engineers at Tatsfield just couldn’t adjust the hue control to get the colour of all fruit correct. After some time messing with the receiver, they had worked out what was going on.

They phoned up the studio and petulantly told them to remove the mauve-pained orange and put a proper one in if they wanted to continue with the tests.

Ian

[ppppenguin]

This sounds like a local variant of the "blue banana" that appeared, possibly as an urban myth, during early NTSC trials in the USA.

[FERNSEH]

GEC must have made many experimental CTVs. An article about the the model TT4 appeared in the Febuary 1959 Practical Television informing the readers about the excellent results the companies research group were experiencing from their latest colour receiver.

From the text:

Fringe conditions:

"The GEC team has now been able to ensure good colour reception even with a poor signal. By paying special attention to the syncronising of the sub-carrier oscillator. Using the GEC Reseach Mobile Laboratory for testing in the Brighton fringe area it was in fact found that colour reception was slightly more acceptable tn the corresponding picture on a monochrome receiver"

DFWB.

[ORTF_&_Co]

Originally Posted by Ray Cooper

"BBC Engineering 1922-1972" by Edward Pawley has this to say about AP colour:

No mention of channel used. But here, 'a standby 5-kW transmitter' probably means 'the standby 5-kW transmitter': namely, the standby for the 17kW main transmitter. (...) And, if the gear being used was in fact the service standby, I don't think they would have wanted to use channel 5: it would take hours to re-tune one of these things back to Ch.1, and the legitimate Ch.1 viewers might get a bit impatient if the main TX had developed a wobbly.

Finally, if you wanted to radiate even 3kW worth of channel 5 test transmissions, you'd have needed a separate aerial array: the existing Ch.1 setup would have been of no use whatsoever. I have never heard of any such aerials being fitted to AP: but that's not to say that they weren't. Again, any further contributions eagerly awaited.

I quite agree with Ray. I can't imagine how AP pre-war designed aerials could have been so easily adapted to such a different channel ! How could have they retuned the aerials system in order to reduce the stationary wave rate ? (I don't know if that's the correct translation for our French 'Taux d'onde stationnaire" aka T.O.S.).

Frequency range between channels B1 (41-45 MHz) and B5 (63-67 MHz) is so wide that I can't understand how these colour transmissions (which were already rather difficult to operate at that time) could have been correctly broadcast under such bizarre conditions !

[ppppenguin]

Originally Posted by ORTF_&_Co

....stationary wave rate ? (I don't know if that's the correct translation for our French 'Taux d'onde stationnaire" aka T.O.S.).

Voltage Standing Wave Ratio or VSWR.

[ALANS ANITAS]

When I worked for Rediffusion Research (58-61) the modified RCA colour set being used for developing colour reception equipment used a Pye 45mhz radar if unit, so it was chanell 1 from Crystal Palace. All those EF50's and the 2 metre long luminance delay line, and the 29 pots in the convergence panel. Brings back many happy memories.

ALAN

[CheapSlider]

According to a document on the BBC site The BBC Colour Television Tests: An Appraisal of Results


The colour studio was at Alexandra Palace with land line links to Crystal Palace. Tests were done on Ch 1 from Crystal Palace and from Alexandra Palace.(page 41, table 1)

BBC research at Kingswood Warren did some local low field trials using a low power (500W vision, 125W sound) transmitter working on Ch 5 (page 12)

Some more info in A New Survey of the BBC Experimental Colour Transmissions

There were also tests made on the links to other transmitter sites. Although the signals were being sent up and looped back down. one could speculate if some of these colour tests were radiated from any of these distant transmitters (with or without permission).

[Panrock]

So that must be it... colour tests from Kingswood Warren on Channel 5. I wonder how high up Kingswood Warren is, and how far afield 500 watts from there would have 'served' ...

Steve

[mickjjo]

The attached article from Wireless World September 1954 seems to confirm that the B.B.C. were transmitting a colour sub-carrier on 45 Mc/s from Alexandra Palace during July 1954. .

Regards, Mick.

[Panrock]

Thanks Mick. Interesting in that article about the non-standard subcarrier frequency then (allegedly) being tried...

S