Ballast Tube and Resistor Numbering Codes
      Mike at MDBVentures.com
      http://www.MDBVentures.com

There are two basic systems for designating ballast tubes and resistors.

The earlier system (system A) is identified as starting with a letter. 
The second system (system B) is identified as starting with a number.

Type A and B ballasts are designed for use with 
0.3Amp series wired tube circuits.

-------------------
System "A" Ballasts

  B  K  Y  49  C  J  G  <--- example ballast code
  -  -  -  --  -  -  -
  1  2  3  4   5  6  7  <--- code letter position
  -------------------- 

  1 : Position 1 is optional. When the letter "B" is present
      it indicates that a ballast type pilot lamp (low cold start 
      resistance) must be used in the circuit. 

  2 : Position 2 is optional. When present it identifies the type 
      of pilot lamp that must be used.
      There are three possible letters, K, L or M. 
      K = #40 or #47 - 6.3Volts 0.15Amp brown filament support bead.
      L = #44 or #46 - 6.3Volts 0.25Amp blue filament support bead.
      M = #50 or #51 - 6.3Volts 0.20Amp white filament support bead.

  3 : Position 3 identifies the type of base and pin connections.
      There are three possible letters, X, Y or Z.
      X = 4 pin base and metal shell.
      Y or Z = octal base, metal or glass shell. 

  4 : Position 4 identifies the ballast voltage drop at 0.3Amps. 

  5 : Position 5 identifies the internal wiring of the ballast. 
      The letters A through K are used. 

  6 : Position 6 is optional. When the letter "J" is present it 
      identifies if a jumper is present between pins 3 and 4. 

  7 : Position 7 is optional. When the letter "G" is present it
      identifies the ballast has a glass bulb and octal base. 

--------------------
System "B: Ballasts
  
  200 R 44 <--- example ballast code
  --- - -- 
   1  2 3  <--- code letter position
  --------

  1 : Equivalent resistance at 0.3Amps.
      As an example, 200=200ohms, 200 x 0.3A = 60Volts

  2 : Position 2 when followed by a number indicates the type of 
      pilot lamp that must be used. If there is a letter "R" with
      out a following number, there is no pilot lamp connection.
      There are three possible letters, R, L or M. 
      R = #40 or #47 - 6.3Volts 0.15Amp brown filament support bead.
      L = #44 or #46 - 6.3Volts 0.25Amp blue filament support bead.
      M = #50 or #51 - 6.3Volts 0.20Amp white filament support bead.

  3 : Position 3 is optional. When present it indentifies the 
      internal wiring of the ballast. The possible numbers 
      4, 8 or 44.

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