Holes in the anode plate?

lazthegaz · 14th July 2004, 08:21 AM

Could any of you, respected tube gurus, tell me what purpose holes serve in the anode plate of tubes? Some tubes have them, others don't. I have some ECC83's with holes, some without.

I've been thinking long and hard, but cannot see the purpose of them. Except that you can see the cathode glow, which is nice...

SHiFTY · 14th July 2004, 08:26 AM

I suspect it doesnt serve any functional purpose, but is useful in the manufacturing process. Maybe its to allow inspection after assembly of the valve?

smoking-amp · 14th July 2004, 11:25 AM

Many of the beam tetrodes with aligned screen grids have inspection ports for the assembler to see the screen grid and G1 wires for aligning them, by bending the lead wires. (This reduces screen grid current and aids in forming the dense electron beamlets for secondary emission suppression.) Look thru the opening and see if you can't see the G1 and G2 wires easily. Some tubes even have a little trap door in the plate that is closed after the alignment.

Don

http://www.mif.pg.gda.pl/homepages/f...D62/index.html

http://www.mif.pg.gda.pl/homepages/f...RCA/index.html

14th July 2004, 08:21 AM	#1
lazthegaz diyAudio Member Join Date: Jun 2004 Location: East Anglia	Holes in the anode plate? Could any of you, respected tube gurus, tell me what purpose holes serve in the anode plate of tubes? Some tubes have them, others don't. I have some ECC83's with holes, some without. I've been thinking long and hard, but cannot see the purpose of them. Except that you can see the cathode glow, which is nice...

14th July 2004, 11:25 AM	#3
smoking-amp diyAudio Member Join Date: Dec 2001 Location: Hickory, NC	inspection portals Many of the beam tetrodes with aligned screen grids have inspection ports for the assembler to see the screen grid and G1 wires for aligning them, by bending the lead wires. (This reduces screen grid current and aids in forming the dense electron beamlets for secondary emission suppression.) Look thru the opening and see if you can't see the G1 and G2 wires easily. Some tubes even have a little trap door in the plate that is closed after the alignment. Don http://www.mif.pg.gda.pl/homepages/f...D62/index.html http://www.mif.pg.gda.pl/homepages/f...RCA/index.html __________________ Ohms Law V = I R

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14th July 2004, 08:26 AM	#2
SHiFTY diyAudio Member Join Date: Jul 2002 Location: New Zealand	I suspect it doesnt serve any functional purpose, but is useful in the manufacturing process. Maybe its to allow inspection after assembly of the valve?