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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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7th Nov 2017, 11:26 am | #21 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: 405 colour on my Pye CTV
I'm busy reassembling the scanning coils, as long as there are no interruptions in the shop all the CRT neck components will be refitted today.
Reference to the April 1956 Wireless World, page 185. The Mazda 6P1 frame output valve receives it's anode supply from the 400 HT rail. Pye must have invested a lot of resources into developing this set because unlike other UK made CTVs it doesn't have that "prototype" look about it. DFWB. |
7th Nov 2017, 9:38 pm | #22 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: 405 colour on my Pye CTV
In fact the frame output stage does already receive it’s HT via a 3.3Kohm resistor from the 360 volt supply. According to my notes the decoupled HT supplied to the transformer primary is 290 volts. I’ll take a chance and short out the 3.3K resistor and supply the frame output stage with the full HT. Let’s see what happens.
DFWB. |
7th Nov 2017, 11:56 pm | #23 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: 405 colour on my Pye CTV
Played safe and connected a 2.7Kohm resistor across the existing 3.3Kohm frame timebase HT supply resistor. Sure enough there is a slight improvement to the linearity but mainly at the top of the picture. Also, there is plenty height available now before the picture cramps at the top. See second attachment.
Also noted is that the HT voltage is only 320 volts, and that's the voltage measured a the anodes of the two PY81 booster diodes. I reckon I should hit the frame output stage with the full 320volt HT supply. DFWB. Last edited by FERNSEH; 8th Nov 2017 at 12:26 am. |
8th Nov 2017, 12:38 am | #24 | |
Heptode
Join Date: May 2009
Location: Birmingham, West Midlands, UK.
Posts: 708
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Re: 405 colour on my Pye CTV
Quote:
An ITV series 'Adventures of Sir Lancelot' in the 50s had some of the episodes made in colour and these vary in their presentation (although these may been corrected these days for the DVD) as because in both here and the US they were using the show to experiment with different film makes and grades that they could use on a CTV system.. they discovered that Technicolor was a big NO NO as the contrast ratio was just too vast for early equipment to cope with...consequently any film you saw on TV in those days that said it was 'Technicolor' was actually a TV spec Eastman mono/colour print. |
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8th Nov 2017, 10:28 pm | #25 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: 405 colour on my Pye CTV
One of the three heater chains has gone open circuit. It's the chain that supplies the valve heaters of the receiver section. Will investigate and report back later.
DFWB. |
10th Nov 2017, 10:17 pm | #26 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,337
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Re: 405 colour on my Pye CTV
The extract from a BUSH TV leaflet from early 1952 (undated, but it refers on an unscanned page to a TV22 that was expected to be the cheapest TV exhibited in the forthcoming Manchester exhibition of April 1952) suggests that, at that time, UK TV manufacturers were concerned that people might be delaying buying new TVs in anticipation of colour, the BBC's colour TV transmissions then being expected to start in 4 year's time, ie circa 1956. Interesting that it refers to UK manufacturers knowing all about colour before the Americans! Could they be referring to Baird's experiments?
Re Pye, closed circuit colour TV is mentioned on the last page of an undated leaflet about their (black and white, Image Orthicon tubed, as used in their Type 2014 camera) underwater camera. I think it may date from circa 1952-54. The article in the link below refers to the prototype camera (made by Marconi) having been used by HMS Reclaim in 1951. http://arl.g3w1.com/arl_underwater_viewing_systems.htm This suggests that Pye's closed circuit colour TV system was a well established product by the time Pye's production underwater camera was produced. Last edited by emeritus; 10th Nov 2017 at 10:44 pm. |
10th Nov 2017, 11:02 pm | #27 |
Dekatron
Join Date: May 2003
Location: Edinburgh, UK.
Posts: 3,274
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Re: 405 colour on my Pye CTV
I suspect that rather than Baird's two colour systems they were more likely to have in mind the field sequential systems with add-on colour filters offering fully compatible transmission for existing sets.
Leastwise the colour television system depicted for the public in a children's encyclopedia that I had in the 1950s clearly showed field sequential. Peter Last edited by peter_scott; 10th Nov 2017 at 11:14 pm. |