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B&W TV Different Phosphor colours.

 
slidertogrid
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I have been sorting through the sets in my collection recently and getting them wired to a signal source so I can give them a run without having to heave them onto the bench. As I get older it seems someone is turning the gravity up each year! 
I have two Philips 20" sets one single standard and the other dual standard. They both have very good tubes, the bottom set has a Brimar tube which appears to be a replacement new tube rather than a regun. The top set has the original Red label Mullard.
There is a marked difference in the colour of the pictures,

Philips 210 and 310

the Brimar tube is very black and white whereas the Mullard has the usual blue tinge to the picture. The difference in more apparent than it looks in the photograph. I think it is the Brimar that is unusual. I have seen differences before but never this apparent, probably emphasised by the fact that the two sets are together.
I will have to check the label on the Brimar I wonder if it was a special tube made for monitors or the like?

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Topic starter Posted : 30/04/2022 12:53 pm
Cathovisor
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Posted by: @slidertogrid

I will have to check the label on the Brimar I wonder if it was a special tube made for monitors or the like?

It could have been, Rich. I know we had Brimar tubes at work that were "Illuminant D" and they looked much like what you have there.

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Posted : 30/04/2022 1:26 pm
Lloyd
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I have noticed this too, one test that shows it up really well is shining UV light at them, they show up different shades of green and blue!

 Regards 

Lloyd 

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Posted : 30/04/2022 3:52 pm
Jayceebee
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If you look very closely at a Mazda CRT phosphor you can see it's a blue/yellow mix but it still photographs towards blue, the Brimar you have there looks a bit special. How does the corner focus compare to the Mullard? The square cornered tubes weren't great in that respect.

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Posted : 30/04/2022 10:09 pm
Jayceebee
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At the end of the 70s and early 80s there was still quite a demand for monochrome sets for the diehards. The decent 1500s left were treated to some TLC and a new CRT.

I think everyone knows about the Polish Unitra tubes with a phosphor similar in constituency to the surface of the moon. After these dried up we were sourcing tubes from the CCCP, these had a type number with Cyrillic characters and had a very short life, next to a Mazda the display was almost sepia.

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Posted : 01/05/2022 2:28 pm
slidertogrid
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@jayceebee Thanks for the info, that is interesting. I didn't realise there were such different screen Phosphors used in domestic tubes. I realised that screen colours had changed over the years but not that different colours were used at the same time. I didn't take a lot of notice of the Brimar label when I had the back off as at that time I hadn't noticed the unusual Phosphor colour. I will put the set back on the bench and have a better look at the label.

Both tubes look very good with good focus right into the corners despite both sets not having been run for some time. The 20" tube in the white A640 was more like what they are usually like after a long period of disuse with a bit of defocussing being worse at the edges when I first started using it, but after a prolonged run on 7.5 Volts it has come up a treat and looks very good now. ( He says keeping his fingers crossed! )

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Topic starter Posted : 01/05/2022 10:11 pm