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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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10th Apr 2018, 7:12 pm | #1 |
Triode
Join Date: Mar 2017
Location: Linlithgow, Scotland, UK.
Posts: 10
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Valve ID Help
Hi. I'm looking for some help identifying the valve shown in the pics.
It is used as the output stage to provide the HT for an old Bush radio. I'm not entirely sure if its actually faulty as yet, as I'm still testing the PSU which has other problems, however I thought if I can at least understand what it is that would help regardless. It has seven pins. I've had a look through the National Valve Museum site which is amazing, but not managed to find this. I'm sure it will be a common type, I'm just not familiar with this era of technology. Many thanks for any help / advice. Hugh |
10th Apr 2018, 7:15 pm | #2 |
Dekatron
Join Date: Jun 2013
Location: East Sussex, UK.
Posts: 3,315
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Re: Valve ID Help
Which Bush radio ?
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10th Apr 2018, 7:17 pm | #3 |
Triode
Join Date: Mar 2017
Location: Linlithgow, Scotland, UK.
Posts: 10
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Re: Valve ID Help
It's an SB21
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10th Apr 2018, 7:19 pm | #4 |
Dekatron
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,310
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Re: Valve ID Help
Could it be an OB2 stabiliser http://www.r-type.org/exhib/aaa0357.htm ? In your second pic above the letters SK I think I can just about make out a faint B2. Take it out into the daylight (if we ever get any !) and see what you can see with a magnifier. It should look something like this
https://www.picclickimg.com/d/w1600/...-Old-Stock.jpg Cheers, GJ
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http://www.ampregen.com Last edited by GrimJosef; 10th Apr 2018 at 7:31 pm. |
10th Apr 2018, 7:19 pm | #5 |
Hexode
Join Date: Apr 2008
Location: Ramsgate, Kent, UK.
Posts: 252
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Re: Valve ID Help
Hi Hugh,
That looks like a Voltage Regulator valve. The type number was printed on the glass just above the SK with white background. Usually if you breath on the glass to form condensation and then look at it at an angle you should be able to make out the type identifier characters which are currently unreadable in you photo. Post what you find here and someone should be able to tell you what the device actually is. Adrian |
10th Apr 2018, 7:22 pm | #6 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,823
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Re: Valve ID Help
Just looking at it it looks a lot like a stabiliser tube like this one.
http://www.r-type.org/exhib/aai0227.htm What model of Bush is this? Your description suggests a rectifier but they look more like this http://www.r-type.org/exhib/aaa0851.htm Its possible someone has stuffed any old valve in the socket. Oops crossed. 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; 10th Apr 2018 at 7:23 pm. Reason: crossed a couple of times! |
10th Apr 2018, 7:24 pm | #7 | |
Triode
Join Date: Mar 2017
Location: Linlithgow, Scotland, UK.
Posts: 10
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Re: Valve ID Help
Quote:
Thanks Adrian also. |
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10th Apr 2018, 7:27 pm | #8 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,823
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Re: Valve ID Help
That valve isn't original to the SB21 so it must be part of a later mains power supply for this 1935 battery set
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 |
10th Apr 2018, 7:30 pm | #9 |
Triode
Join Date: Mar 2017
Location: Linlithgow, Scotland, UK.
Posts: 10
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Re: Valve ID Help
Thank Mike. Yes I should have said that, it's a separate PSU I'm fault finding.
I believe the valve heater output is fine, just the HT. |
12th Apr 2018, 11:00 am | #10 |
Triode
Join Date: Mar 2017
Location: Linlithgow, Scotland, UK.
Posts: 10
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Re: Valve ID Help
Looks like this is a voltage rectifier OB2. Seems the likeliest.
I still can't fully see the markings but there is a resemblance of a B and 2. So thanks for everyone's help, much appreciated. Having looked at the design, I'm going to abandon this PSU and go with a better / safer option probably based on info from here:- http://www.dos4ever.com/battery/battery.html Cheers again. Hugh |
12th Apr 2018, 10:45 pm | #11 |
Heptode
Join Date: Jan 2009
Location: West Lothian, UK.
Posts: 760
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Re: Valve ID Help
Just out of interest - could you post the circuit of the present power supply?
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George |
16th Apr 2018, 11:45 am | #12 | |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,527
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Re: Valve ID Help
Quote:
The 0B2 behaves similarly to a zener diode- it has a relatively stable breakdown voltage over a range of operating currents so it can be used with a suitable series ballast as a shunt type voltage regulator.
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