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POVT32B

Sensibly equivalent to:
CV1640
    
Extras ▼

 

The POVT32B is a telephone repeater triode. The envelope is marked VT32B for Valve Telephones. To avoid confusion with the RAF VT for Valve Transmitting the later data gives the Post Office procured valves the prefix POVT for Post Office Valves Telephone. The advent of the CV register changed the designation to CV1640.
The commercial code was 4102D. The original Western Electric 102D design dates from 1925 and the 4 prefix in the Type designation denotes that manufacture was in the UK by STC.
Originally the spherical envelope was fitted with a metal skirted base. This exhibit is of much later manufacture but follows the original electrode construction.
See also the experimental M25 for similar construction that was also believed to be derived from Western Electric.
In 1946 STC produced the 31/142A as a replacement for the 4102D.
The British STC company (Standard Telephones and Cables) was, before the 1925 take over of the parent Western Electric company by International Telephone & Telegraph (ITT), a subsidiary office of Western Electric. For years after the separation STC relied on Western Electric technology.
The envelope is also marked W421. The location pip for the UV valve-holder is embedded in the Bakelite base cap.
Construction features a vertical glass rod that supports the electrodes.
The sandwich construction has a single inverted V oxide coated filament in the centre with ladder grids either side and the outside electrodes of the triode are two plain sheet anode plates.
Looking along the electrodes the inter-electrode distances can be seen. The glass rod is intact unlike so many valves made with this support structure where an external impact breaks the rod near the base. Exhibit M4205E has a broken support.
The ladder grids are made from individual wires (rungs) welded to the side supports.
The balloon envelope is 59 mm in diameter, and excluding the UV base pins is 98 mm tall.
Reference: Data-sheet.

 

Pin Connections
UV
1
2
3
4
g1
f
f
a

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
Vg
mAa
ra
gm
μ
2.0
0.97
190
-
1.5
60,000
0.5
30
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated April 18, 2021.
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