The VMS4 variable μ screened tetrode dates from 1931. It was designed for RF and IF amplification in broadcast superhet receivers.

This M-OV valve is badged as Osram, the consumer brand. Unlike VMS4 the lower part of the envelope does not have an extended waist. The waist being designed originally for the S625 that was designed to be mounted through a screen plate or chassis with the internal screen in the same plane as the external screen.

This exhibit has lost the screw cap to the top cap assembly but the use of the screw top cap was phased out around 1933-4 and so this is an early version of the design.

The Osram branding.

The balloon envelope is 44 mm in diameter and, excluding the B5 base pins, is 124 mm tall.

References: Data-sheet & ¹⁰⁰⁵ Type VMS4 was first introduced in 1931. See also 1931 adverts.

Pin Connections

B5

1

2

3

4

5

tc

g2

g1

h

h

k

a