The VMS4 variable μ screened tetrode design dates from 1931. It was designed for RF and IF amplification in broadcast superhet receivers. This exhibit is a later example employing the shouldered envelope to allow for a mica sheet to provide support at the top of the envelope. The first VMS4 valves followed the pattern of the first single ended SG valves in having a waist above the base cap that extended to the point where the screen grid began within the glass. Thus it could be mounted horizontally through a metal plate or chassis for maximum screening. See S215.
The printed Osram name.The classic envelope is 45 mm in diameter and, excluding the B5 base pins, is 119 mm tall.References: Data-sheet & 1005 Type VMS4 was first introduced in 1931. See also 1931 adverts. |
