|
MPT4Sensibly equivalent¶ to:See also:
|
|
|
![](../pics/aby0009.jpg)
|
M-OV had trouble designing the MPT4. Not only did it take them a clear two years to produce technically successful copies of Mazda's landmark AC/Pen but thereafter they had to redesign it several times (including the beam tetrode version MKT4) over the next 5 or 6 years.In the end they solved the problem by buying equivalents from other manufacturers and re-labelling them.Part of the problem was that M-OV had invested heavily in the azide process during the late 1920s and were either unable or unwilling to switch overnight to manufacturing oxide-coated cathodes of the rating and quality demanded by powerful, for that time, audio output valves.Another factor was that M-OV were strongly anti-pentode at that time and may have been unwilling to invest in proper, full-scale development in what was, for them, a new and uncharted field. Instead, as is well known, they put their money into circumventing the pentode - by inventing the beam tetrode, with some help from RCA in America.![](../pics/aby0009a.jpg)
The Marconi brand label.![](../pics/aby0009b.jpg)
The screen grid connects to the side contact.![](../pics/aby0009c.jpg)
The Three wire grids can be seen through the top micaThe classic envelope is 50 mm in diameter and, excluding the B5 base pins, it is 104 mm tall.References: Private communication, data-sheet & 1040. Type MPT4 was first introduced in 1931. See also 1931 adverts. |
Pin Connections
| 1 | 2 | 3 | 4 | 5 | sc | ![](../static/key.gif) a | g1 | h | h | k,g3 | g2 |
|
|
Absolute Maximum Operating Conditions¶
| Vh | Ah | Va | Vs | Vg | mAa | mAs | ![](../static/pdflogo.gif)
| 4.0 | 1.0 | 250 | 200 | -10.5 | 32.0 | 5.5 |
|
Updated June 11, 2022.
|
|