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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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19th Nov 2021, 10:09 pm | #1 |
Hexode
Join Date: Jan 2007
Location: Beckenham, London, UK.
Posts: 373
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CRT Identification Please
I have a 14 inch rectangular crt. Externally it looks very much like the MW 36-44 with the same valve base except that the base material is metal rather than plastic. Internally it looks also to be a simple triode gun. It differs from the MW 36-44 though in that its gun is straight down the axis of the neck. In other words, it doesn't look like it's designed for an ion trap. Any ideas please? Thanks.
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19th Nov 2021, 10:22 pm | #2 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: CRT Identification Please
Possibly a GEC with a triode gun assembly. Made about 1953.
DFWB. |
19th Nov 2021, 10:27 pm | #3 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,567
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Re: CRT Identification Please
MW36-67?
Adrian |
19th Nov 2021, 10:57 pm | #4 |
Hexode
Join Date: Jan 2007
Location: Beckenham, London, UK.
Posts: 373
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Re: CRT Identification Please
Thanks David and Adrian. I can't see anything about MW36-67 online. Can you point me to a data sheet please?
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19th Nov 2021, 11:05 pm | #5 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,567
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Re: CRT Identification Please
On the frank.pocnet.net site
https://frank.pocnet.net/sheets/030/m/MW36-67.pdf Also an advert in Wireless World November 1956 pages 80 and 81 https://worldradiohistory.com/UK/Wir...6-11-S-OCR.pdf Adrian |
19th Nov 2021, 11:17 pm | #6 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: CRT Identification Please
GEC 7203A? Advert in the July 1956 Practical Television magazine.
DFWB. |
19th Nov 2021, 11:24 pm | #7 |
Hexode
Join Date: Jan 2007
Location: Beckenham, London, UK.
Posts: 373
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Re: CRT Identification Please
Thanks. I see both suggestions are aluminised non-ion trap tubes, so I guess it could be either
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20th Nov 2021, 11:13 am | #8 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
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Re: CRT Identification Please
Hello Steve, I would go with David here. It could of course be the monitor tube but they must be very rare.
The 7203A is an excellent tube, pin sharp with excellent contrast as fitted in my GEC BT1746 from 1956. The pic needed a bit of adjustment shift wise but will give some idea. It will replace the MW36-24/44 but being a triode the focus magnet may not be strong enough. John. |
20th Nov 2021, 10:19 pm | #9 |
Hexode
Join Date: Jan 2007
Location: Beckenham, London, UK.
Posts: 373
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Re: CRT Identification Please
Thanks John. Thanks also Adrian for that Wireless World attachment which is well worth reading in itself.
I think the metal base surround makes it more likely to be the GEC tube too. I had thought that my original tube had a partial heater short (which they are prone to), but on checking with a separate power supply, it was drawing the correct 0.3 amps at 6.3 volts. I gave it a boost with my BK and it's come up very well. I will see if it survives, and if not, fit the mystery tube. Thanks again all for the help. Stephen |
22nd Nov 2021, 10:33 am | #10 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,184
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Re: CRT Identification Please
First thing I check for in such a case is whether there's a Mullard-like manufacturing code on it. Either on the socket or in white ink somewhere on the tube.
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22nd Nov 2021, 11:19 am | #11 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
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Re: CRT Identification Please
Hello Maarten,
As you can see from the picture this is definitely a GEC manufactured tube type 7203A. GEC manufactured their own triode aluminised tubes until around 1958. They then employed Mazda [EDISWAN] to supply them with their range of tubes with GEC labels. In fact the labels were identical to the Mazda with just the name changed. GEC did use a few MW36-24 Mullard tubes in the 1954 model BT1746 but I think this was due to supply shortages. GEC produced triode tubes of very high quality but this put them in a difficult position when it came to the replacement market due to the increased focus field needed for triode tubes. This was also the problem with FERRANTI who followed a similar path. The early Mullard 14" rectangular tubes in the UK were the MW36-22, MW36-24 and the last magnetic focus MW36-44. The MW36-22 did not have a grey glass filter screen and is very rarely seen. As far as I am aware Mullard never produced a triode tube for domestic use in the UK and were very late in aluminising generally, the MW53-20 and AW36-20 being examples. Regards, John. |
23rd Nov 2021, 12:53 pm | #12 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,184
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Re: CRT Identification Please
I didn't quite get what was meant with a metal base, but seeing this picture I wouldn't even go looking for Philips codes. I wasn't sure of possible early Mullard developments with aluminisation or triode guns, but clearly not the case.
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