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ID = 28980
United States of America (USA)
Brand: Marathon (tubes), Northern Manufacturing Co.; Newark, NJ
Developer: Marathon (tubes), Northern Manufacturing Co.; Newark, NJ 
Tube type:  Triode, vacuum 
Identical to 630_Marathon
First year 1927 Saga of the Vacuumtube, Tyne page 345

Base UX-Base (4 Pins (2 thick, USA 1924, UX) 2 Sidecontacts
Was used by Radio/TV-reception etc.
Filament Vf 5.5 Volts / If 1 Ampere / Indirect

Early AC tubes for conversion of battery radios. The filament was connected to side terminals on the tube base. Usually sold with a Marathon AC kit, consisting of a cable with the necessary clips to connect the heaters. This tube had an amplification factor of 28, anode impedance of 40,000 Ohms and mutual conductance of 680 micromhos.


Literature Saga of the Vacuumtube, Tyne   Page 345
630_Marathon: Fin Stewart
Fin Stewart


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