The EK3 octode frequency changer is set on the short lived side contact base. Our other EK3 has an envelope of reduced diameter and the paint damage clearly shows the effects of excessive heating.
The local oscillator formed using a grid as anode would need to supply 17 volts peak to adequately modulate the main electron flow. The signal input to g4 is applied to the top cap for maximum circuit isolation. The frequency of use would be a few megahertz at best.
The metallising paint has a reticulated surface. The black paint for the identification lettering adheres well.
The classic envelope is 56 mm in diameter and, excluding the Ct8 base pins, is 115 mm tall.
References: Datasheet, 1040 & 1043. Type EK3 was first introduced in 1938.
Absolute Maximum Operating Conditions¶
Updated August 11, 2015. shape:classic construction:pinch type:octode age:1930.1940 base:ct8 heater:6.3v pins:8 pin:1.m pin:2.h pin:3.h pin:4.k pin:5.g2 pin:6.g1 pin:7.g3.g5 pin:8.a pin:tc.g4