The WD40 is a vari-μ RF pentode and a pair of single diodes all sharing a common cathode and fitted with a B9 base cap. It was designed for all AC mains radios and the heater is the then UK standard for indirectly heated valves at 4.0 Volts at 1.0 Amps.The WD30 was designed for use with series heater chains operating at 300 mA and was released in 1935.
The Marconi brand printed onto the zinc metal screening paint that has started to peel off.Reference: 1043. Type WD40 was first introduced in 1935. See also 1935 adverts. |
Pin Connections
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | tc |  h | k,g3 | a(d1) | a(d2) | m | g2 | a | nc | h | g1 |
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Absolute Maximum Operating Conditions¶
| Vh | Ah | Va | Vs | Vg | mAa | mAs | gm |
| 4.0 | 1.0 | 250 | 100 | -1.0 | 7.7 | 1.0 | 2.6 |
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Updated January 06, 2022.
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