Tubes Asylum

• RE: 805 ? Could it be anything else?? - Alpha Al 09:31:13 10/29/15 (3)
  In Reply to: RE: 805 ? Could it be anything else?? posted by rogerh113 on October 28, 2015 at 20:09:12

  
  
  

  
  Almost certain they are 805's. Here is a pair from my stash, same brand, that are marked CUE-805 VT-143.
  
  I don't know of anything else like these that has a top plate cap.
  

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  • RE: 805 ? Could it be anything else?? - rogerh113 13:01:25 10/29/15 (2)
    In Reply to: RE: 805 ? Could it be anything else?? posted by Alpha Al on October 29, 2015 at 09:31:13

    My thinking as well. I did find a copy of the old United Electronic catalog from about 1945. There is a seemingly identical rectifier tube 217-c (page 125)that seems visually identical to the 805 (at least to my untrained eye). Even the filaments are in the same pin location on the base.
    
    http://www.tubebooks.org/tubedata/United_tubes.pdf
    
    There is a marking on both tubes on the lower ceramic anode support that says '905' and in the catalog price sheet it indicates that United type 805 is corresponding type 905. That seems to specify them as 805. All a bit dodgy - too bad the tubes are not specifically marked. I think the little flag on the metal base might indicate they were made for the signal corps or something, so maybe it was just on the box?
    
    regards -- Roger
    

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    • RE: 805 ? Could it be anything else?? - Ed Sawyer 11:06:09 10/30/15 (1)
      In Reply to: RE: 805 ? Could it be anything else?? posted by rogerh113 on October 29, 2015 at 13:01:25

      yes, they are 805s. As mentioned the 905 on the ceramic spacer is a giveaway (in addition to the other evidence).
      
      the 217-C is similar but usually used a 211 sized plate not a 805-sized plate, the spacing from grid to plate is larger in the 805 than a 211 (or 217-A, 217-C, etc.)
      
      
      

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      • RE: 805 ? Could it be anything else?? - rogerh113 13:34:02 10/30/15 (0)
        In Reply to: RE: 805 ? Could it be anything else?? posted by Ed Sawyer on October 30, 2015 at 11:06:09

        Thank you for your excellent and definitive reply. I will mark this one 'case closed' and move on. I really appreciate you sharing your knowledge.
        
        Best regards -- Roger
        

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• You can check the filaments - andy evans 00:52:11 10/29/15 (1)
  In Reply to: RE: 805 ? Could it be anything else?? posted by rogerh113 on October 28, 2015 at 20:09:12

  If you have a bench supply which shows voltage and current you can bring up the filaments gradually and see what current you are getting and then refer that to the data sheets of likely tubes. Or you could just do this with a multimeter and a small resistor like 10 ohms and measure current across the resistor, using some low voltage source.
  

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  • RE: You can check the filaments - rogerh113 03:32:39 10/29/15 (0)
    In Reply to: RE: You can check the filaments posted by andy evans on October 29, 2015 at 00:52:11

    Thanks, but unfortunately I don't have a bench supply. I am hoping that there is nothing out there physically like it - size, tube shape, 4 pin base, top plate cap, graphite anode, etc.
    
    Thanks -- Roger
    

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