Sensibly equivalent¶ to:
The VT-104 is a double diode triode with heaters designed to operate from the 12.6 volts available in a vehicle. The VT-104 is the USA Government designation for the commercial 12SQ7.
The diodes are for AM signal detection and AGC detection whilst the triode section is for first audio amplification. This is typical for a valve used in a radio superhet receiver.
Apart from the 12.6 volt heaters the valve characteristics are equal to the 6SQ7.
The reverse of the envelope has the makers name and the country of origin.
The thin metal tube envelope is 25 mm in diameter and, excluding the IO base pins, is 50 mm tall.
References: Data-sheet & 1040. Type VT-104 was first introduced in 1939.
Absolute Maximum Operating Conditions¶
Updated November 24, 2013. shape:thin.metal.tube construction:pinch type:double.diode.triode age:1940.1950 base:io heater:12.6v pins:8 pin:1.m pin:2.g1 pin:3.k pin:4.a(d2) pin:5.a(d1) pin:6.a pin:7.h pin:8.h