The EFP60 like the EE50 is a secondary emission pentode originally designed, like the EE50, for television purposes.

Secondary emission (more accurately, secondary current flow) is almost never a good thing. It occurs unavoidably in the tetrode is the principal reason why the pentode was developed. It was exploited in photomultiplier tubes, as a way to multiply a very feeble initial current.

The EE50 dates from 1938 and was a product of the quest for RF valves for television. The EFP60 has a post WW2 CV number and was used in the 1950s for high speed (50MHz) computing circuits. The EF50 quickly replaced the EE50 for TV and RADAR in the late 1930s.

From a 1957 paper by R M Walker et al titled 'An Experimental 50 Megacycle Arithmetic Unit' comes the following.

The EFP-60 has a nominal secondary-emission ratio of five, a transconductance from grid to plate of 25 ma/volt, a transconductance from grid to dynode of 20 ma/volt, and a transconductance from grid to cathode of 5 ma/volt.

The grid base of the tube is 3.5 volts when the plate and screen voltage are +275v and the dynode voltage is + 150v. The maximum allowable plate, dynode and screen dissipations are 2 watts, 1 watt and 0.4 watt, respectively.

Two useful features of the EFP-60 are that the dynode may be used as an active output element and that the tube has current gain as a grounded-grid amplifier. Since non-inverting amplification is obtainable from grid to dynode or from cathode to plate, a variety of multivibrator circuits may be built with a single EFP-60 tube.

By using the grid and dynode as the input and output electrodes, respectively, in EFP-60 amplifier configurations, it is possible to use positive pulses throughout the system. The advantages which derive from this unique feature of the EFP-60 tube are evident when one considers the requirements for handling negative pulses at these speeds and impedances. A cathode follower, for example, would have to be operated with a quiescent current of 50 mA in order to be able to drive 10-volt negative pulses into a 200 Ohm coaxial line. This feature also allows one to operate all amplifiers in a normally cut-off condition. This minimises power dissipation and allows unwanted low-level signals to be eliminated.

The wide glass tube envelope is 32 mm in diameter and, excluding the B9G base pins, is 57 mm tall.

 
Pin Connections

B9G	1	2	3	4	5	6	7	8	9
	h	k(in)	g1	k(out)	k(sec)	a	g3,s	g2	h

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	gm	μ
	6.3	0.37	250	150	-2	20.0	1.5	25.0	110

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 02 February 2008 {find valves by name}