Battery tube
A battery tube is an electron tube that has been specially developed for portable devices such as battery-operated tube receivers , two-way radios such as the SCR-536 hand -held talkie or hearing aids . Battery tubes generally have a directly heated cathode.
Battery tubes operate with anode voltages of 30 to 135 V and heater voltages of 2 V or less. Low-voltage tubes for car radios, on the other hand, worked with anode voltages of 6 to 12 V, the heating voltage was 6.3 V with a current consumption of usually 300 mA.
history
The high vacuum triode Pliotron from 1913 had a directly heated tungsten cathode and required a heating voltage of 4.1 V with a current consumption of 1050 mA. At that time it was unusual to operate receivers from the (then so-called) light network . The devices were operated with accumulators and batteries.
Over the years, ever more powerful tube types with ever lower heating capacities have been developed. The triode UV201A from 1922, for example, required heating of only 5 V and 250 mA due to the thorium filament that had been introduced in the meantime.
Another big step was the introduction of the oxide cathode . The 1T4 (equivalent type in Europe: DF91) from 1940 only required 1.4 V heating voltage with 50 mA current consumption and already had the modern 7-pin miniature socket . It was used, for example, in the SCR-536 hand -held talkie .
At the forefront of this development was the DF67 intended for hearing aids from 1950. It managed with a heating voltage of just 0.6 V and a current consumption of 13 mA.
The Regency TR-1 transistor radio was available from November 1954 . The bipolar transistor replaced the tube in portable devices due to its lower power consumption, lower operating voltage, theoretically unlimited service life and mechanical insensitivity.
The electrically most similar successor to the tube as a voltage-controlled amplifier is the field effect transistor (as shown in the upper right picture).
Circuit details
→ Main article: Electron tube # heater
In the case of directly heated tubes, the cathode is at ground potential. The automatic Gittervorspannungserzeugung is therefore not possible. The grid base circuit with cathode as input electrode or anode base circuit with cathode as output is also not possible.
Heating with alternating voltage is possible with directly heated tubes, but has disadvantages and is therefore rarely found.