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Clubs, Groups and Societies For discussions about various clubs, groups and societies relating to our hobbies, such as the BVWS (incl RetroTechUK), BATC, RSGB, APTS, CLPGS, THG, TCC, BECG, MCR21 etc. This is NOT an official forum for any of these organisations. |
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17th Feb 2018, 6:00 pm | #1 |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,988
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BVWS Capacitors
Most know the BVWS sell the yellow 630v metallised polyester film capacitors to BVWS members at events around the country. But do or will they stock 1000v rated ones for tone correction use?
John. |
17th Feb 2018, 8:24 pm | #2 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,935
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Re: BVWS Capacitors
Not that I have ever seen.
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G8JET BVWS Archivist and Member V.M.A.R.S |
17th Feb 2018, 9:09 pm | #3 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: BVWS Capacitors
Why does 'tone correction' require 1000v capacitors?
Andy |
17th Feb 2018, 9:14 pm | #4 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,935
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Re: BVWS Capacitors
I think Andy,because folks have stated that is what is needed across sound tx,s.Spikes I guess.
I have I admit used less rated before without problems.
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G8JET BVWS Archivist and Member V.M.A.R.S |
17th Feb 2018, 9:53 pm | #5 |
Octode
Join Date: Jun 2004
Location: Reading/Fakenham, UK.
Posts: 1,324
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Re: BVWS Capacitors
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17th Feb 2018, 10:35 pm | #6 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: BVWS Capacitors
OK, I hadn't thought about directly across the output transformer, I was thinking about filter components in tone control circuits, so low-level signals.
Andy |
17th Feb 2018, 11:07 pm | #7 |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,988
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Re: BVWS Capacitors
I have a Pye PE80 on the bench at the moment Tone correction caps are shown as 300v AC which I think would equate to around 900v DC, hence the 1000v DC needed. I would guess that it would be same for most valve sets.
John. |
17th Feb 2018, 11:12 pm | #8 |
Heptode
Join Date: May 2003
Location: Devizes, Wiltshire, UK.
Posts: 650
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Re: BVWS Capacitors
In many cases, perhaps most cases, the capacitor across the output transformer of a normal commercial radio will be found as an old waxy rated at 500v DC.
Dependant on the manufacturer and the range being used (hunts black/brown, Metalpack, Sprague etc.) the voltage rating on the cap will be the most appropriate in the specific range. You must remember manufacturers did deals with component suppliers to get the keenest price for the required component and even changed the design in some way to fit in with getting this best price break for quantity purchases. The BVWS range was specifically chosen at 630v DC so as to be as useful as possible to restorers. They don't have to be 630v and in fact the 400v range would probably sufficed for most things. There are no plans for the BVWS to stock 1kv rated caps. Mike...
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Mike Barker. |
17th Feb 2018, 11:25 pm | #9 |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,988
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Re: BVWS Capacitors
Thank you Mike.
John. |
18th Feb 2018, 9:43 am | #10 |
Dekatron
Join Date: Jun 2013
Location: East Sussex, UK.
Posts: 3,326
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Re: BVWS Capacitors
Often seen 1000 volt ceramics used with that type of tone control.
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18th Feb 2018, 12:14 pm | #11 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
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Re: BVWS Capacitors
Stick two in series if you're that worried. A short circuit failure across the primary won't hurt anything anyway. Beware of anode-chassis connected ones, though!
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20th Feb 2018, 2:24 am | #12 |
Dekatron
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 5,000
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Re: BVWS Capacitors
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