The 25L6 is an octal-based

vacuum tube A vacuum tube, electron tube, thermionic valve (British usage), or tube (North America) is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. It ...

of the Beam tetrode type. It is the Octal base equivalent to th
type '43 power tube
which made early AC-powered loudspeaker radios affordable. It found common application in AC/DC

radio receiver In radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. ...

s - such as those of the All American Five type - and was also found in large numbers in early

computers A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations ('' computation''). Modern digital electronic computers can perform generic sets of operations known as ''programs'', ...

, such as the

UNIVAC I The UNIVAC I (Universal Automatic Computer I) was the first general-purpose electronic digital computer design for business application produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the invento ...

. The tube used EIA base 7AC in common with many other power tubes. The tube was identical in design and ratings with the 50L6 with the exception of having a 25 volt 300 mA heater, whereas the 50L6 has a 50 volt 150 mA heater. The 12L6 and identical 12W6 were made with a 12 volt, 600 mA heater, and the 6W6 was made with a 6.3V, 1200mA heater. There was also a 35L6 with a 35V, 150 mA heater. Because of the slightly lower-power heater, the 35L6 has slightly lower output than the rest of the family. This family is not to be confused with the 6L6, which has the same basing diagram, but has more than twice the power capability of the 25L6. The 25L6 was introduced as a metal tube on November 4, 1936, but most examples of this family were made of glass. The ST14 glass 25L6G came out on March 30, 1937. The T9 size GT version came out on April 11, 1938. There was also a 25L6G in the smaller ST-12 glass envelope. Computer equipment used this tube as a relay driver or to run the

solenoid upright=1.20, An illustration of a solenoid upright=1.20, Magnetic field created by a seven-loop solenoid (cross-sectional view) described using field lines A solenoid () is a type of electromagnet formed by a helix, helical coil of wire whos ...

s in key punch machines. The heater in this case ran off the 24 volt power line in the equipment, resulting in long life and slightly lower power output. The industrial type 6046 is a 25L6GT rated for that application.

References

25L6/50L6 datasheet
- GE Datasheet January 1950 * Sibley, Ludwell, ''Tube Lore'', 1996 {{DEFAULTSORT:25l6 Computer vacuum tubes

See also

References