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beery · 7th Aug 2019, 2:08 pm

Hi all,
in the circuit of the timebase that is in my last post, you can see that the screen feed resistor of the line output valve (R8) is labelled 3K3? The reason why becomes clear when you look at the attached photo of it...

Anyway, you can just make out that the very left hand part of this resistor is still intact. By measuring its resistance and width I was able to extrapolate it. This produced a value in the range of 6K to 8K, so I have ordered a 6K8 14W resistor to try.
It is interesting to note that the screen feed is not decoupled unlike in the Baird Countryman (which is probably where the flyback EHT line output transformer comes from). The pre-war T18 circuit is of no use here either as it uses a triode for the line output.

Cheers
Andy

7th Aug 2019, 2:08 pm	#84
beery Heptode Join Date: Jun 2006 Location: Ware, Hertfordshire, UK. Posts: 988	Re: Baird Garrick Hi all, in the circuit of the timebase that is in my last post, you can see that the screen feed resistor of the line output valve (R8) is labelled 3K3? The reason why becomes clear when you look at the attached photo of it... Anyway, you can just make out that the very left hand part of this resistor is still intact. By measuring its resistance and width I was able to extrapolate it. This produced a value in the range of 6K to 8K, so I have ordered a 6K8 14W resistor to try. It is interesting to note that the screen feed is not decoupled unlike in the Baird Countryman (which is probably where the flyback EHT line output transformer comes from). The pre-war T18 circuit is of no use here either as it uses a triode for the line output. Cheers Andy Attached Thumbnails __________________ www.youtube.com/user/andyvalve100