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ID = 20803
United States of America (USA)
Brand: Common type USA tube/semicond.
Developer: Raytheon Mfg. Co.; Cambridge, MA 
Tube type:  Reflex Klystron   SHF/EHF (>3 GHz) 
Identical to 5721 = RK5721 = QK205
Similar Tubes
Other class quality (otherwise equal):
Multiple differences or of other kind:
First Source (s)
19.Oct.1948 : Electron Tube Registration List 702
Successor Tubes ZV1011  

Filament Vf 6.3 Volts / If 0.58 Ampere / Indirect / Specified voltage AC/DC
Description 2.5 to 12.0 GHz, external cavity reflex klystron. 125 mW average output. 4 pin 'Peewee' base.
There are errors in the literature equating the 5721 to the E83CC. There is a misprint in table 345 of the 1994 Vade Mecum and also in the index to the Franzis Tabelle No 11. This is a confusion with 5751. 
Information source Universal Vade-Mecum, Electron Valves and Semiconductor Devices   
- - Manufacturers Literature   
Tube Lore (I)
5721: Private collection
Emilio Ciardiello

5721: Manufacturer's Literature
Emilio Ciardiello

5721: Manufacturer's Literature
Emilio Ciardiello

Usage in Models 4= 1955?? ; 1= 1968?

Quantity of Models at with this tube (valve, valves, valvola, valvole, válvula, lampe):5

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