Spark Gap Transformer Type R

Thordarson Electric Mfg. Co. ; Chicago (IL)

  • Year
  • 1917 ?
  • Category
  • Radio part (not a module) 
  • ID
  • 247921

 Technical Specifications

  • Wave bands
  • - without
  • Power type and voltage
  • Alternating Current supply (AC) / 110 Volt
  • Loudspeaker
  • - - No sound reproduction output.
  • Material
  • Various materials
  • from
  • Model: Spark Gap Transformer Type R - Thordarson Electric Mfg. Co. ;
  • Shape
  • Tablemodel, with any shape - general.
  • Notes
  • These high voltage transformers were the "heart" of many amateur spark stations providing the necessary potential to charge sending condensers and create the damped waves which were the main component of spark signals. The primary of the transformer is keyed via the AC line with perhaps a primary choke also in the circuit for extra protection. The secondary is connected (usually through kickback preventer) to the closed circuit (usually an oscillation transformer primary, charging condenser and rotary spark gap.) The closed circuit is coupled to the antenna via the oscillation transformer secondary. On a 1/2KW transformer the secondary voltage is about 12KV. The levers control a sliding section of the core that can be moved in or out, creating an adjustable "magnetic leakage gap" which served several purposes. Initially, it allows some control over the power output of the spark transmitter but it also serves to limit the high primary current that flowed during the discharge at the spark gap (this discharge was a momentary short on the secondary) and also to help prevent transmission at two frequencies (called double wave emission - this can also be a product of excessive coupling in the oscillation transformer.) The Type R sold for $21 in 1917, just before the WWI Navy ban on receiving and transmitting. This ban was not lifted until April 1919 for receiving and October 1919 for transmitting.

  • Price in first year of sale
  • 21.00 USD
  • Author
  • Model page created by Alan Larsen. See "Data change" for further contributors.

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