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VT25

Sensibly equivalent to:
AT35 CV1025 DET25 E1175
See also:
The VT25
    
Extras ▼

 

The VT25 transmitting triode has a large four pin square base. The design is elegant and appears quite delicate as in fact it proved to be in this form.
The filament is broken but was a single inverted V. Later versions were re-designed around an M shaped oxide coated filament.
Also on the envelope is the old stores code of 10E/7312.
See VT25 for more details.
The Crown and A M for the UK Air Ministry.
The sticker declares that this valve is for ground use only. Note that one base pin has lost the outer expanded metal petals.
The pressed anode and grid extending outside the anode.
Looking down through the top mica one can see the filament tension spring and the shape of the grid winding.
The wide glass tube envelope is 57 mm in diameter and, excluding the L4 base pins, is 160 mm tall.
Reference: Data-sheet & 1005.

 

Pin Connections
L4
1
2
3
4
a
f
f
g1

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
7.5
1.9
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated June 17, 2020.
shape:wide.glass.tube construction:pinch type:triode age:1930.1940 base:l4 pins:4 pin:1.a pin:2.f pin:3.f pin:4.g1
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