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ID = 19493
Tube type:  TR-switch 
Identical to 721A = CV3595 = RK-721A
Similar Tubes
Other characteristic (electr. data):
  721B ; REL64
First year 01.Apr.1942 - - Manufacturers Literature

Base Top contact with a cap.
Was used by Radar

Disc-seal TR/ATR tube, with keep-alive electrode connected to a cap. External cavity at 2.7 to 3.3GHz frequency. Developed to protect solid state diode mixers against RF pulses generated by the magnetron transmitter, this TR switch incorporetes an igniter, the keep-alive electrode, that gives a bias ionization and improves spike protection of the receiver. The copper discs are shaped and supported by a special glass ring, to obtain a low temperature coefficient and a resonance drift with temperature as close as possible to that of the magnetron. The tubes were pretuned before exhaust, placing them in a special cavity and deforming the copper discs with a tool.

Manufactured by WE, Sylvania and Bomac.

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Tube prices 2 Tube prices (visible for members only)
Information source Tube Lore (I)   
- - Manufacturers Literature   BSTJ, The Gas Discharge T/R Switch
  721A: Manufacturer's Literature
Emilio Ciardiello
721A: TreLe
Trev Levick

721A: RR
Reinhard Riek


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