The Western Electric 'Weco' valve came in three sub-types, green spot, orange spot and the red spot version that we have. The filament is given as 0.8 to 1.1 Volts at 0.25 Amps. The anode voltage was quoted as 15 to 30 Volts for the orange spot, and 30 to 60 Volts for the other two types. The red spot was designed to operate with a grid bias of -3 to -5 volts and used as an RF amplifier. The green spot was designed as a detector with the grid at -7 to -10 volts. Finally the orange spot type was specified as an audio amplifier and to be biased to -3 to -5 volts. All three types were introduced in 1925, had an rA of 25K Ohms, a mutual conductance of 0.22 mA/V and an amplification factor (μ) of 5.5.

A visual inspection reveals a glass top support for the fixing rods. The filament is a single vertical wire down the centre of the tubular anode cavity. The grid is wound as a helix in a wire much thicker than the filament.

The side markings show patents in 1915 and 1921.

We have also been told that these valves were used in early Western Electric microphones.

The thin glass tube envelope is 15 mm in diameter and, excluding the base pins, is 63 mm tall.

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	μ
	1.0	0.25	60	-3	1.0	25,000	6

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 01 February 2008 {find valves by name}