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ID = 81798
United States of America (USA)
Brand: Raytheon Mfg. Co.; Cambridge, MA
Developer: Bell Labs; Murray Hill, NJ. 
Tube type:  TR-switch 
Identical to RK-721A = 721A

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.


Text in other languages (may differ)
RK-721A: My Collection
Bruce Morgenstern


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