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Phil Allison
Guest
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 Posted:
Fri Sep 23, 2005 12:07 pm Post subject:
Holes in Plates ? |
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** Why do some (not all) plate structures in power tubes have holes.
A quick survey of my stock showed:
6V6GTA Sovtek = no holes
5881 Sovtek = 4 vertical slots
6L6GC Sylvania = no holes
6CA7 Sylvania = 6 round holes
6550C Svetlana = 6 horizontal slots
6L6 WXT Sovtek = 6 round holes
EL34 EH = 4 horizontal slots
Please do not say it is for ventilation or cooling !!!
........... Phil
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izozaya
Guest
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| Posted:
Fri Sep 23, 2005 12:14 pm Post subject:
Re: Holes in Plates ? |
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I believe it is for uniforming plate current flow across a larger
surface of the plate, and thus to prevent hot-spots.
Just a (reasoned) guess! |
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Phil Allison
Guest
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| Posted:
Fri Sep 23, 2005 12:16 pm Post subject:
Re: Holes in Plates ? |
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"izozaya"
| Quote: |
I believe it is for uniforming plate current flow across a larger
surface of the plate, and thus to prevent hot-spots.
Just a (reasoned) guess!
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** Sure they are not just port holes for the electrons to look out ?
.......... Phil |
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izozaya
Guest
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| Posted:
Fri Sep 23, 2005 12:23 pm Post subject:
Re: Holes in Plates ? |
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Maybe. Some claim that stressed electrons take away some of the
subtleties and nissances of the sound, and paint them with this magic
lacquer, one by one.
Seriously, given the construction of the tetrode/pentode, electron tend
to hit the plate in a non uniform way (the center of the plate
typically collects the largest part of them, and that's why hot spots
appear there). I think that eddy currents along the plate can be forced
to take a longer an more uniform path on the plate surface using these
holes. No it does not cool, but will certainly help to have a more
uniform temperature and infrared radiation of the plate.
Any Western Electric engineer here? |
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Yves Monmagnon
Guest
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| Posted:
Fri Sep 23, 2005 7:32 pm Post subject:
Re: Holes in Plates ? |
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I've heard about visual grids alignment ? ?
"Phil Allison" <philallison@tpg.com.au> a écrit dans le message de news:
3phnu4Fais66U1@individual.net...
| Quote: |
** Why do some (not all) plate structures in power tubes have holes.
A quick survey of my stock showed:
6V6GTA Sovtek = no holes
5881 Sovtek = 4 vertical slots
6L6GC Sylvania = no holes
6CA7 Sylvania = 6 round holes
6550C Svetlana = 6 horizontal slots
6L6 WXT Sovtek = 6 round holes
EL34 EH = 4 horizontal slots
Please do not say it is for ventilation or cooling !!!
.......... Phil
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Phil Allison
Guest
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| Posted:
Fri Sep 23, 2005 7:48 pm Post subject:
Re: Holes in Plates ? |
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"Yves Monmagnon"
| Quote: |
I've heard about visual grids alignment ? ?
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** My preferred theory at present.
............ Phil |
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Jim McShane
Guest
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| Posted:
Sun Sep 25, 2005 7:17 pm Post subject:
Re: Holes in Plates ? |
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Phil Allison wrote...
| Quote: | "Yves Monmagnon"
I've heard about visual grids alignment ? ?
** My preferred theory at present.
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The square holes in SED 6550C are to allow use of a
screen alignment tool/fixture. Prior to use of the tool
during assembly the SEDs had problems with screen
misalignment.
My source for that info is Eric Barbour, who was
chief engineer at the old Svetlana USA during the
time they were fighting the screen problem.
I don't know if that means all the holes in all the
different tubes out there are for the same reasons,
but it seems some are for production and assembly.
Jim McShane
Need Tubes? Got a H-K Citation (Pre) Amp?
Check http://pages.prodigy.net/jimmcshane
Repro knobs for Citation gear in stock! |
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Phil Allison
Guest
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| Posted:
Sun Sep 25, 2005 7:21 pm Post subject:
Re: Holes in Plates ? |
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"Jim McShane"
| Quote: | Phil Allison wrote...
"Yves Monmagnon"
I've heard about visual grids alignment ? ?
** My preferred theory at present.
The square holes in SED 6550C are to allow use of a
screen alignment tool/fixture. Prior to use of the tool
during assembly the SEDs had problems with screen
misalignment.
My source for that info is Eric Barbour, who was
chief engineer at the old Svetlana USA during the
time they were fighting the screen problem.
I don't know if that means all the holes in all the
different tubes out there are for the same reasons,
but it seems some are for production and assembly.
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** Seems to be the only hypothesis that fits ALL the facts of the matter.
Thanks for that info, Jim.
............... Phil |
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