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MPT4

Sensibly equivalent to:
7A2 MP/Pen Pen4VA
See also:
The Azide Process - 1935 Advert
    
Extras ▼

 

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.
See also MPT4 for more details.
The interesting point about the grids is their shape.
The the suppressor grid is close to the anode. The inner grids are held on supports away from the cathode but are shaped to form a small cage around the cathode and close in.
The balloon envelope is 56 mm in diameter and, excluding the B5 base pins, it is 117 mm tall.
References: Datasheet & 1043. Type MPT4 was first introduced in 1931.

 

Pin Connections
B5
1
2
3
4
5
sc
a
g1
h
h
k,g3
g2

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
4.0
1.0
250
200
-10.5
32.0
5.5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 07, 2015.
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