UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Baird T18

Heatercathodeshort · 13th Feb 2007, 10:19 am

Hello Trevor,
The BRIMAR C12B 12" crt is made by CINTEL. It is a very unusual tube of high quality and was used in the KB EV30. It is rated and was operated at 10kv, very high for a 12" tube of its day and will produce a brilliant picture of incredible contrast and brightness.
The neck is rather longer than most tubes of this type and you may find that the focus unit will have to be moved further along the neck.
I replaced a Mazda CRM121B with one of these tubes in a DEFIENT fitted with the Plessey chassis. I had to fit shunts across the focus magnet and move the assembly. [I can't remember if it was back or forward] I also had to extend the 'bowler hat' due to the length of the neck. That was in 1961 and I was 13 at the time.....
This would suggest that the field needs to be reduced but I expect it is operating at half its original eht so it will be very much an experiment.
Hope this may help. Regards John.

13th Feb 2007, 10:19 am	#2
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Baird T18 - focus problem. Hello Trevor, The BRIMAR C12B 12" crt is made by CINTEL. It is a very unusual tube of high quality and was used in the KB EV30. It is rated and was operated at 10kv, very high for a 12" tube of its day and will produce a brilliant picture of incredible contrast and brightness. The neck is rather longer than most tubes of this type and you may find that the focus unit will have to be moved further along the neck. I replaced a Mazda CRM121B with one of these tubes in a DEFIENT fitted with the Plessey chassis. I had to fit shunts across the focus magnet and move the assembly. [I can't remember if it was back or forward] I also had to extend the 'bowler hat' due to the length of the neck. That was in 1961 and I was 13 at the time..... This would suggest that the field needs to be reduced but I expect it is operating at half its original eht so it will be very much an experiment. Hope this may help. Regards John.