The 25L6 is an octal-based

vacuum tube A vacuum tube, electron tube, 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. The type kn ...

of the

Beam tetrode A beam tetrode, sometimes called a beam power tube, is a type of vacuum tube or thermionic valve that has two grids and forms the electron stream from the cathode into multiple partially collimated beams to produce a low potential space charg ...

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. Th ...

s - such as those of the

All American Five The term All American Five (abbreviated AA5) is a colloquial name for mass-produced, superheterodyne radio receivers that used five vacuum tubes in their design. These radio sets were designed to receive amplitude modulation (AM) broadcasts in the ...

type - and was also found in large numbers in early

computers A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These 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 6L6 is the designator for a beam power tube introduced by Radio Corporation of America in April 1936 and marketed for application as a power amplifier for audio frequencies.J. F. Dreyer Jr."The Beam Power Output Tube" New York: McGraw-Hill, ''Ele ...

, which has the same

basing diagram In electronics, a pinout (sometimes written "pin-out") is a cross-reference between the contacts, or ''pins'', of an electrical connector or electronic component, and their functions. "Pinout" now supersedes the term "basing diagram" that was the s ...

, 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 whose ...

s in

key punch A keypunch is a device for precisely punching holes into stiff paper cards at specific locations as determined by keys struck by a human operator. Other devices included here for that same function include the gang punch, the pantograph 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 Vacuum tubes

See also

References