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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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17th Jun 2018, 8:55 pm | #41 | |
Heptode
Join Date: Jan 2006
Location: Todmorden, West Yorkshire, UK.
Posts: 870
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Re: Mystery valve
Quote:
(I don't think Mullard made them for the German companies, by the way) but neither of them resemble the mystery valve. I do, however, have several ECL85s which are virtually identical to it. |
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17th Jun 2018, 8:57 pm | #42 |
Hexode
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 363
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Re: Mystery valve
This is what I have managed to find out with my valve tester, strange I know but this is how it seems to be. The pinout tallys with a PCL85, 18 volts heater voltage across pins 4 and 5 and the pentode tests as such the difference then is that pin 1 is definitely the junction of the two heaters. 1 and 4 is the triode heater which takes 6.3 volt at 300ma, 1 and 5 is the pentode heater taking 12.6 volt at 300 mA, the two anodes are connected together internally. When you just feed the 6.3 volt heater you can test the triode, when you feed the 12.6volt on its own you can test the pentode.
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17th Jun 2018, 9:14 pm | #43 |
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
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Re: Mystery valve
So it appears to be a special, built from a PCL85.
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17th Jun 2018, 9:19 pm | #44 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,394
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Re: Mystery valve
How curious. Could it have been a niche-purpose modulating, gating or level-shifting valve based on PCL85 structure and jigs to minimise initial investment? Perhaps for a mobile (whether land, air or sea) application where 12.6V nominal heater stringing was needed. There were a few weird and wonderful valves cooked up for machine control interface and computer applications, too. We need that time machine!
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17th Jun 2018, 10:39 pm | #45 |
Hexode
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 363
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Re: Mystery valve
The only clue about these that I have is that the person I bought them from was selling them for his son who was a radio amateur, Am I right in thinking that they must have been used individually by switching in the individual heaters? With the anodes connected together if both heaters were in operation would the two valves be in parallel?
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17th Jun 2018, 10:53 pm | #46 |
Hexode
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 363
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Re: Mystery valve
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18th Jun 2018, 2:51 am | #47 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
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Re: Mystery valve
Would it be for a two power radio transmitter?
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18th Jun 2018, 11:29 am | #48 |
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
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Re: Mystery valve
Might be more useful in a guitar amp, but this would not have been the original purpose.
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18th Jun 2018, 12:34 pm | #49 | |
Hexode
Join Date: Apr 2008
Location: Ramsgate, Kent, UK.
Posts: 252
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Re: Mystery valve
Quote:
A centre tapped heater of 6.3/12.6 Volts suggests to me an ECC81/2/3 heater setup were you wire in series (across the ends) for 12 Volt and parallel (between CT and ends) for 6 Volt supply. I believe that 6 volt batteries were still being used on vehicles at that time (and still are?). I will not hazard a guess as to the actual intended use for this oddball, suffice to say that as the world of electronics applications was expanding rapidly during that time, it could be almost anything. Only one real clue here, it must have been something worthwhile (or high budget military?) to interest a company like Mullard/Philips . . . I would forget the amateur radio connection, that is probably just a red herring. |
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18th Jun 2018, 2:17 pm | #50 |
Guest
Posts: n/a
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Re: Mystery valve
Triode part as a mute function leaving the pentode as the amplifier?
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19th Jun 2018, 11:53 pm | #51 |
Hexode
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 363
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Re: Mystery valve
Just one further comment on this ,Does anyone know when Mullard stopped making valves what happened to all the records of the company,For instance when Blackburn closed was everything dumped or was there any attempt saving anything for historical purposes/posterity.
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20th Jun 2018, 2:26 pm | #52 |
Dekatron
Join Date: Nov 2010
Location: Oxford, UK.
Posts: 4,980
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Re: Mystery valve
It all is here http://brimaruk.com/menugbvp/great-b...valve-project/ being restored in order to remanufacture valves again.
A lot was scattered overseas - they tracked it down and raised enough money to get it all shipped back. Craig |
20th Jun 2018, 4:47 pm | #53 |
Hexode
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 363
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Re: Mystery valve
I have seen this venture and hope it comes to fruition, I was wondering about the what must have been the vast amount of documentation in their records, whether any of this was saved from disposal, something like was done with Marconi etc. Graham.
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20th Jun 2018, 8:14 pm | #54 |
Heptode
Join Date: Jan 2006
Location: Todmorden, West Yorkshire, UK.
Posts: 870
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Re: Mystery valve
Mullard was completely taken over by Philips in 1928(!) so any documents might be in the Philips Company Archive in Eindhoven. Their email address is:
pca@philips.com but the problem is you have no designation for the valve. I suggest you scrutinise the valve's bulb with a magnifying glass, possibly with a light behind it which might show up the permanent ink marking of the code (if there is one). |
2nd Jul 2018, 6:28 pm | #55 |
Triode
Join Date: Apr 2018
Location: Nijmegen, Netherlands (You know from that bridge)
Posts: 35
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Re: Mystery valve
Im quite certain that is a PCL805, identical pinout but slightly different guts
Last edited by Thatvalveguy; 2nd Jul 2018 at 6:37 pm. |
3rd Jul 2018, 2:49 am | #56 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,199
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Re: Mystery valve
Sometimes it helps to breath a bit on the code. The first line could start with VX for a PCL805 but if it's a development type it could well have another code.
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3rd Jul 2018, 4:30 am | #57 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,864
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Re: Mystery valve
Two other possibilities: An oscillator with a built-in reactance valve for FM/AFC? or a training exercise. Someone being trained in development, say, gets to do a design using existing subcomponents and then build it and test it.... then take the result home. I've got a few very oddball items made while in the training school at Rolls Royce. They could get someone who didn't know quite confused. New R&D engineers at HP in the 80's got given a project to do as training. The guy running it used cheap hobbyist counters and function generators as models. The new graduates had to make their own PCB versions of the traced out circuit which they stuck in HP standard cabinets, doing all the schematics, drawings for metal parts, transformers etc. At the end they got to keep the thing. Of course it worked no better than the original bought from a wireless world advertiser. Some of these must be floating around and could cause confusion. I thought that copying another firm's circuit was very dodgy. We should have designed something ourselves for legal reasons, but the guy running the training programme chose this way and said it made an illustration of the difference in price! Who knows what apprentices and trainees made in other firms?
I pre-dated this scheme and just got started straight into designing stuff for real. David
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3rd Jul 2018, 8:42 am | #58 |
Dekatron
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,311
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Re: Mystery valve
I thought the whole point of this thread was that the mystery valve has a different pinout. The PCL805 has the triode anode connected to pin 1. The mystery valve has a heater tap connected to pin 1. Therefore the mystery valve isn't a PCL805. Or am I missing something ?
Cheers, GJ
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3rd Jul 2018, 4:57 pm | #59 | |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,199
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Re: Mystery valve
Quote:
A development type wouldn't have had normal type number. It would have been referred to in the documentation (if any) as M<number>PCL or possibly by its manufacturing code. Last edited by Maarten; 3rd Jul 2018 at 5:09 pm. |
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3rd Jul 2018, 10:12 pm | #60 | |
Hexode
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 363
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Re: Mystery valve
Quote:
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