Eimac Type 8533 Planar Triode Connections?

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Discussion Overview

The discussion revolves around identifying the connections for the Eimac type 8533 planar triode tube, specifically the filament, cathode, grid, and anode (plate) connections. Participants explore the challenges of working with a tube that has no pins, as the connections are made directly to the metal and ceramic housing.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant seeks help in identifying the connections for the Eimac type 8533 planar triode tube, noting the absence of pins and reliance on the data sheet.
  • Another participant suggests checking tube-tester manuals and experimenting with current limiting resistors to identify connections without damaging the tube.
  • It is noted that the tube housing is metal and ceramic, complicating the identification of the connections.
  • One participant inquires about the intended use of the triode, which is revealed to be for switching high voltage at a specific frequency.
  • There is a discussion about the suitability of IGBT devices for the application, with concerns raised about their switching speed compared to the triode.
  • A participant recalls the order of connections as filament, cathode, grid, and plate, suggesting that the plate connection has the largest separation from the others.
  • Another participant mentions contacting the ARRL for additional information on the tube and socket availability.
  • The original poster later confirms that they successfully identified the connections and powered the tube, indicating it functions properly.

Areas of Agreement / Disagreement

While there is a general agreement on the identification of the connections by the end of the discussion, the initial uncertainty and various suggestions indicate that multiple views and approaches were considered throughout the thread.

Contextual Notes

Participants expressed uncertainty regarding the exact identification of the connections initially, and there was a reliance on experimentation and external resources for clarification.

Who May Find This Useful

Individuals working with vintage or specialized vacuum tubes, particularly those interested in high-voltage applications or custom tube fixtures.

wmingin
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Hello All!

Can anyone identify the filament, cathode, grid, and anode (plate) connections of a Eimac type 8533 planar triode tube? I need to maufacture a custom fixture/holder to power this tube and
the connections are apparently to the actual metal/ceramic housing of the tube.

I have the data sheet but it gives no connection info.

Thanks very much!
B.
 
Last edited:
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How many pins are there? The filament should be obvious. Do you have access to tube-tester manuals? They may tell you. If it were me I would simply try some things using current limiting resistors so the tube is not damaged. Sooner or later it would make sense.
 
Hello, and thanks for the quick reply!

The problem is that there are no pins!

The tube housing is metal and ceramic (no glass) and the connections are directly to the metal housing.

I would guess the filament is easy, just look for 2 points with low resistance, but the anode, cathode and grid are stumping me.


B.
 
What are you using the triode for?
 
Hi, thanks for the reply.

Im using the triode to switch high voltage (3kv), at 200 khz.

Regards,
B
 
How about IGBT devices or similar.? Not sure if they will manage that switching speed??


http://www.dynexsemi.com/products/igbt/3300.htm

(Looking at the spec for one device they give input capacitance at 1 MHz.)


E-mail Wilson Valves... He has sent me circuit diagrams for free.


http://www.satcure-focus.com/audio/page3.htm
 
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I need a super fast rise and fall (< 10ns)...rules out most semiconductors.

Sometimes old tech is still superior.
 
There are still areas where valves rule and probably will continue to do.
 
It's been a long time since I did anything with this, but IIRC they just went in order.
Filament filament cathode grid plate.
The plate connection having the largest separation from the other contacts.

Perhaps if you contacted the ARRL they might have some more info on the tube and socket availability.
http://www.arrl.org/
 
  • #10
Thanks VERY much to all who helped!
Problem solved.
Cathode / Heater at bottom
Grid at second ring
Plate / Anode at top.
I powered it up, It functions properly, and I'm still alive!
 

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