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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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26th May 2020, 12:23 pm | #1 |
Hexode
Join Date: Sep 2013
Location: Wembley, London, UK.
Posts: 395
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Cossor valve 220 O.T.
Hello to all. I would be grateful if some Forum Member could give me some advice on this valve. I removed this valve from a Cossor, Model 30 and was puzzled by the area around the base pins. There is a hole there, as if an extra pin had been removed. I am able to insert an insulated wire through this hole, and right up, inside the glass envelope. I was wondering if that is the way it should be. Thanks in advance. All the best. John.
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26th May 2020, 12:40 pm | #2 | |
Octode
Join Date: Jan 2004
Location: Southport, Merseyside, UK.
Posts: 1,156
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Re: Cossor valve 220 O.T.
Quote:
John |
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26th May 2020, 12:47 pm | #3 |
Nonode
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 2,171
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Re: Cossor valve 220 O.T.
When you say you can insert a wire and see it in the glass envelope, can you see it in the 'pinch' tube or actually in the envelope with the anode?
What colour is the getter deposit? |
26th May 2020, 1:32 pm | #4 |
Octode
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
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Re: Cossor valve 220 O.T.
The 220 OT is a battery (2v 0.2A) Tetrode on a B5 base, so only has 5 connections.
Nothing has ever been in the 'spare' hole. Why it is there... no idea.
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Never Leave Well Enough Alone... |
26th May 2020, 2:59 pm | #5 | |
Octode
Join Date: Jan 2004
Location: Southport, Merseyside, UK.
Posts: 1,156
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Re: Cossor valve 220 O.T.
Quote:
John |
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26th May 2020, 2:59 pm | #6 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,879
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Re: Cossor valve 220 O.T.
Its position is similar to below where the side screw terminal might go on the side of the base of a B5 Pentode.
It might be there to make it easier to connect the side terminal on the base when used on a Pentode during manufacture. Easier to make 1 base rather than many if you don't need the hole nothing lost. Just an observation. Cheers Mike T
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Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
26th May 2020, 7:02 pm | #7 |
Hexode
Join Date: Sep 2013
Location: Wembley, London, UK.
Posts: 395
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Re: Cossor valve 220 O.T.
Hello to all. Thanks for all your advice. I took another photo. Hopefully, the red wire can be seen 'inside' the valve. I just don't know if it should have access to there. All the best' John.
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26th May 2020, 7:11 pm | #8 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,879
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Re: Cossor valve 220 O.T.
Hi John
Yes that's the pinch. If you watch how this style old valve is made it will become obvious. https://www.youtube.com/watch?v=_-JzxX75oYc&t=1116s from about 12 minutes in Cheers Mike T
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Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk Last edited by Cobaltblue; 26th May 2020 at 7:22 pm. Reason: added link |
26th May 2020, 7:37 pm | #9 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
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Re: Cossor valve 220 O.T.
The pins look like they could do with some solder.
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26th May 2020, 8:18 pm | #10 |
Hexode
Join Date: Sep 2013
Location: Wembley, London, UK.
Posts: 395
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Re: Cossor valve 220 O.T.
Hello to all. Thanks for all your various replies and advice. The 'Modern Aladdin's Lamp' video was totally interesting. Thanks to Mike T for highlighting it. All the best. John.
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26th May 2020, 8:25 pm | #11 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,643
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Re: Cossor valve 220 O.T.
At a guess it's to stop an air pocket disturbing the shellac (?) adhesive whilst it cures.
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26th May 2020, 9:53 pm | #12 |
Guest
Posts: n/a
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Re: Cossor valve 220 O.T.
As my chidhood neighbour (he was in photo recon in WW2) said to ladies looking at the "pee hole" in old biplanes "What's that hole for?", answer "Lightness madam, lightness". I think the shellac idea is good but the pins have holes down them anyway.
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