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: Data-sheet & ¹⁰⁴⁰ Type W30 was first introduced in 1934. See also 1934 adverts.

Pin Connections

B7

1

2

3

4

5

6

7

tc

m

g1

g3

h

h

k

g2

a