The VR40 is the PX25 (PP5/400) in military uniform.
This early audio power triode was one of the first to give a significant output. 26 Watts to the loudspeakers of the time was suitable to fill a small hall. With transformers of the period being less efficient than later designs an audio power amplifier using a pair of these valves was a substantial piece of equipment, and heavy.
The ratings given are for class AB1 push pull for a pair of such valves. Under these conditions the grids would require 108 Volts peak to peak to achieve full output.
The balloon envelope has a maximum diameter of 60 mm and excluding the B4 base pins it is 133 mm tall.
Pin Connections
B4 |
1 |
2 |
3 |
4 |

|
a |
g |
f |
f |
Absolute Maximum Operating Conditions
Triode |
Vh |
Ah |
Va |
Vg |
mAa |
Pout |
D |

|
4.0 |
2.0 |
500 |
-54 |
82 |
26 |
4% |
This exhibit was last updated on 02 March 2005 |
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