Sensibly equivalent¶ to:
The MX40 is a 1934 Osram frequency changer of heptode construction and some of the grids are clearly visible in the picture.
The British radio industry was slow in adopting the superhet for a variety of reasons one of which was that British valve manufacturers were slow in developing the specialised types of valve required in an efficient, low-cost set.
The American radio industry showed the way and the MX40 is simply a home-brewed copy of the American 'pentagrid converter' frequency changers popular there in the early 1930s.
The oscillator voltage was designed to be 10.0 V peak to peak.
The balloon envelope is 43 mm in diameter and, excluding the B7 base pins, is 115 mm tall.
References: Data-sheet, 1040 & 1043. Type MX40 was first introduced in 1934.
Absolute Maximum Operating Conditions¶
Updated December13, 2012. shape:balloon construction:pinch type:heptode age:1930.1940 base:b7 heater:4.0v pins:7 pin:1.g2 pin:2.g1 pin:3.g3.g5 pin:4.h pin:5.h pin:6.m.k pin:7.a pin:tc.g4