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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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Thread Tools |
4th May 2023, 2:42 pm
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#1 |
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Octode
Join Date: Aug 2008
Location: Rayleigh near Southend-On-Sea, Essex, UK.
Posts: 1,880
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ECL86 exposed...!
Hello,
Just a little one for the interesting pile… In the past there have been discussions, whether the ECL86 was a beam tetrode or a pentode… Sadly, a Mullard ECL86 valve got damaged in transit, however, looking on the bright side, it enabled me to remove the anode to expose the innards to get sight of the beam plates confirming it’s a beam tetrode. I must marvel at the internal construction of this valve. Pictures attached. The poor ‘ole ECL86 didn’t die in vain! Terry |
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4th May 2023, 4:53 pm
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#2 |
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Dekatron
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,082
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Re: ECL86 exposed...!
Thanks! I'd always believed the ECL86 was a beam tetrode, irrespective of how the Mullard data sheet described it.
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4th May 2023, 5:11 pm
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#3 |
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Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: ECL86 exposed...!
Pentode and tetrode in here:
http://www.r-type.org/exhib/abv0085.htm Are the plates connected to anything? Lawrence. Last edited by ms660; 4th May 2023 at 5:39 pm. Reason: extra info |
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4th May 2023, 5:12 pm
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#4 |
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Heptode
Join Date: Jan 2008
Location: Shrewsbury, Shropshire, UK.
Posts: 841
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Re: ECL86 exposed...!
Sad, but look at it this way, it's never going to have grid-current problems!
David. |
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4th May 2023, 5:17 pm
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#5 |
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Hexode
Join Date: Apr 2007
Location: Milton Keynes, Buckinghamshire, UK.
Posts: 329
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Re: ECL86 exposed...!
It doesn't appear to be a true beam tetrode though, the control grid & screen grid aren't aligned with each other...
Mark |
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4th May 2023, 6:13 pm
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#6 |
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Octode
Join Date: Aug 2008
Location: Rayleigh near Southend-On-Sea, Essex, UK.
Posts: 1,880
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Re: ECL86 exposed...!
It did cross my mind they used beam plates instead of grid wires to enable the manufacture of the valve, given the physical size and target anode dissipation.
The plates along with the internal screening connect the the cathode. Terry |
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4th May 2023, 7:56 pm
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#7 |
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Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,831
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Re: ECL86 exposed...!
There's a certain odour to the insides of a valve - exactly what is it?
__________________
A digital radio is the latest thing, but a vintage wireless is forever.. |
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13th May 2023, 6:49 pm
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#8 |
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Nonode
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 2,870
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Re: ECL86 exposed...!
It's a sharp distinctive odour that you always remember afterwards!
For an output valve to be a true beam tetrode the control and screen grids need to be aligned to funnel the electron streams into the beams as per the original RCA diagram, so I would class the ECL86 to have pentode characteristics! The ECL82 is described in Mullard's data as a "triode–pentode" but a "beam tetrode" in Mazda's data and most diagrams draw the ECL82 as a triode–beam tetrode. The PCL85/PCL805 uses metal plates for G3 with otherwise a pentode construction as well. However, the smaller ECL83/PCL83 is a true pentode with a wound suppressor grid, as is the EL84! Chris Williams
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It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed! |
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13th May 2023, 7:21 pm
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#9 |
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Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,015
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Re: ECL86 exposed...!
Isn't the distinctive pong "Essence of Getter Oxide".
Bottle it and sell it. Oh- but that would be second time around. |
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13th May 2023, 7:29 pm
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#10 |
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Octode
Join Date: May 2003
Location: Belper Derbyshire
Posts: 1,935
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Re: ECL86 exposed...!
The smell would be the near instant reaction of the barium getter to a barium oxide compound. You can get a similar smell filing pure aluminium as this oxidises quite fast.
It is interesting that if you (accidentally) break a valve and put a drop of water on the getter ring, it fizzes as if turned to lemonade. Obviously a reaction of the remaining barium metal still present in the getter ring. Obvious precautions needed as I have no idea of what these compounds would do to you !! Christopher Capener
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Interests in the collection and restoration of Tefifon players and 405 line television |
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