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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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15th Feb 2024, 9:57 pm | #1 |
Heptode
Join Date: Oct 2019
Location: Täby, Sweden
Posts: 709
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Yet another unknown valve ...
I am going through the stash trying to organise them into useful and otherwise.
Anyone have a suggestion for this one? The base is B8G. There is a paxolin wafer on the pins and a mica sheet against the base. The inside of the glass is some sort of grey coating. The letters are not really disinguishable. X or K, M and then a 4. |
15th Feb 2024, 10:03 pm | #2 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,400
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Re: Yet another unknown valve ...
KT81, or possibly A1820? (Which I suspect is the same valve anyway....). Try measuring the heater current, would be around 0.95A for these.
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15th Feb 2024, 10:16 pm | #3 |
Heptode
Join Date: Oct 2019
Location: Täby, Sweden
Posts: 709
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Re: Yet another unknown valve ...
Thanks! I will try that.
Here is another, Arcturus brand. The text on the base reads (I am 90% sure) N 5 R 4 Metal base, with one pin missing. I have found another with the vague bit of a marking on the side, 6 something, 7 GT, 6J7GT I am thinking. |
15th Feb 2024, 10:22 pm | #4 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,400
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Re: Yet another unknown valve ...
Maybe 6J7GT or 6K7GT? Not enough pins or internal connections for 6K8GT. Or maybe the 12V editions thereof.
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24th Mar 2024, 1:19 pm | #5 |
Heptode
Join Date: Oct 2019
Location: Täby, Sweden
Posts: 709
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Re: Yet another unknown valve ...
Thanks for the replies. As luck would have it the thread next to this one was identifying a 6K7GT which looked identical.
Here is another that I cannot find a match for. This one has an ID, but I can't find anything online about what it is used for. Any clues appreciated! I am thinking something linked to Telecoms repeater service? |
24th Mar 2024, 1:29 pm | #6 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,998
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Re: Yet another unknown valve ...
Tungsram did use Pnnn codes in the 30s, but I can't help beyond that.
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24th Mar 2024, 1:57 pm | #7 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,289
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Re: Yet another unknown valve ...
This eBay listing suggests it's equivalent to a K45, but there's no info on that either:-
https://www.ebay.co.uk/itm/404644868050
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
24th Mar 2024, 2:22 pm | #8 |
Octode
Join Date: Jul 2008
Location: Gloucestershire, UK.
Posts: 1,043
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Re: Yet another unknown valve ...
Hello,
Whilst the first valve is most probably a KT81, there is also the KT101. http://www.r-type.org/exhib/ach0004.htm The P310 appears to be equivalent to a 310A see data here. https://frank.pocnet.net/short/054/1/172.pdf Yours, Richard Last edited by Mr Moose; 24th Mar 2024 at 2:27 pm. |
24th Mar 2024, 3:34 pm | #9 |
Heptode
Join Date: Oct 2019
Location: Täby, Sweden
Posts: 709
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Re: Yet another unknown valve ...
Many thanks for that!
This is another odd one. I am fairly certain it is a 309A, but I don't understand the modern box for such an antique looking valve. I am going through the collection, hoping to get some boxes filled with stuff to get rid off. Vari-mu pentodes are always going to be fearing the reaper's blade, but coming in a box this size does not help their case ... |
24th Mar 2024, 3:39 pm | #10 |
Heptode
Join Date: Oct 2019
Location: Täby, Sweden
Posts: 709
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Re: Yet another unknown valve ...
This one looks like a directly heated triode, on a B4 base?
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24th Mar 2024, 5:23 pm | #11 |
Octode
Join Date: Jul 2008
Location: Gloucestershire, UK.
Posts: 1,043
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Re: Yet another unknown valve ...
Hello,
The B4 triode appears to have the old british military stores number 10E/9856 which is a PX4. http://www.r-type.org/exhib/aba0002.htm Yours, Richard Last edited by Mr Moose; 24th Mar 2024 at 5:35 pm. |
25th Mar 2024, 1:43 pm | #12 |
Heptode
Join Date: Oct 2019
Location: Täby, Sweden
Posts: 709
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Re: Yet another unknown valve ...
Well, that is better than yet another ECH21!
Thanks! |