Sensibly equivalent¶ to:
The W30 is a series two catkin from 1934 and is a 300 mA version of the VMP4. The internal envelope shape is similar to the N30 but the W30 has a substantial outer screening can rigidly attached.
The valve is a variable μ pentode and was used for broadcast radio reception. The 300 mA heater specification was introduced for series heater chains and, therefore, transformerless designs for 'Universal' AC/DC mains sets.
W31 is pin compatible but has a slightly lower specification.
The Osram Catkin label.
The wide metal tube envelope is 38 mm in diameter and, excluding the B7 base pins, is 114 mm tall.
References: Datasheet & 1040 Type W30 was first introduced in 1934.
Absolute Maximum Operating Conditions¶
Updated December17, 2011. shape:catkin construction:pinch type:pentode age:1930.1940 base:b7 heater:300ma pins:7 pin:1.m pin:2.g1 pin:3.g3 pin:4.h pin:5.h pin:6.k pin:7.g2 pin:tc.a