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EF39/6K7 – Remote-cutoff RF pentode for use as an IF amplifier or as a superheterodyne mixer (1st detector). Also used in test equipment. Also used in test equipment. EF4, EF22 and EF41/6CJ5 with an Octal base with control grid on top-cap
A General Electric 12AE10 double pentode. Pentode tubes were first used in consumer-type radio receivers. A well-known pentode type, the EF50, was designed before the start of World War II, and was extensively used in radar sets and other military electronic equipment. The pentode contributed to the electronic preponderance of the Allies.
EF50. In the field of electronics, the EF50 is an early all-glass wideband remote cutoff pentode designed in 1938 by Philips.It was a landmark in the development of vacuum tube technology, departing from construction techniques that were largely unchanged from light bulb designs. [1]
1A4-p – Remote-cutoff pentode; 1A4-t – Remote-cutoff tetrode; 1A6 – Pentagrid converter up to only 10 MHz due to low heater power (2 V/60 mA) and consequent low emission in the oscillator section; also occasionally used as a grid-leak detector; 1B4-p – Sharp-cutoff pentode; 1B4-t – Sharp-cutoff tetrode; 1B5 – Dual detector diode ...
The 954 and 956 types are sharp and remote cut-off pentodes, respectively, all with indirect 6.3 V, 150 mA heaters. Types 957, 958 and 959 are for portable equipment and have 1.25 V NiCd battery heaters. The 957 is a medium-μ signal triode, the 958 is a transmitting triode with dual, paralleled filaments for increased emission, and the 959 is ...
The EF86 [1] is a high transconductance sharp cutoff pentode vacuum tube with Noval (B9A) base for audio-frequency applications. It was introduced by the Mullard company in 1953 [2] and was produced by Philips, Mullard, Telefunken, Valvo, and GEC among others. It is very similar electrically to the octal base EF37A and the Rimlock base EF40.
Triodes: triodes cut off when applied grid bias is too low. This will be a negative voltage under ordinary conditions. Tetrode, pentode etc.: There is some degree of interaction between the grids, and values will vary from one device to another. Anode voltage also affects cutoff voltage. Prolonged periods in cut-off leads to cathode poisoning.
Examples of this format are "PL302" and "EF183". From about the start of the 1960s an extra digit was needed for new devices. Either a digit 1 was inserted before the 8 or other base-defining digit (e.g. an EF184 is a Noval pentode), or a three-digit sequence was used. For example, a PL500 is a power pentode in a Magnoval base.