MX40 @ The Valve Museum

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MX40

Sensibly equivalent^¶ to:

15A2 41MPG A80 A80A CV3576 FC4 FCH MH4105 VHT4 X42

See also:

Pentagrid Converters - Replacing a Triode Hexode - Valves at Olympia 1934

Extras ▼

Osram The John Lawrence Collection Other MX40 exhibits

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. See also 1934 adverts.

Pin Connections

B7	1	2	3	4	5	6	7	tc
	g2	g1	g3,g5	h	h	m,k	a	g4

Absolute Maximum Operating Conditions^¶

Heptode	Vh	Ah	Va	Vs	Vg	gm
	4.0	1.0	250	80	-3	0.5

Thanks to Frank Philipse for supplying the above PDF datasheet.

Updated May 09, 2023.

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