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L21Sensibly equivalent¶ to:See also:
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The L21 is a triode designed to operate the filament from a 2 Volt accumulator. It was suitable for low frequency amplification and especially as a driver for the B21 Class B output valve. The Class B valves required a positive grid drive and thus required more than voltage from the driver.
The B4 base cap and pins.Thanks to Mark Mallison for sending the images.The balloon envelope is 41 mm in diameter and, excluding the B4 base pins, is 85 mm tall.References: Data-sheet, Data, 1040 & 1043 Type L21 was first introduced in 1933. See also 1933 adverts. |
Pin Connections
| 1 | 2 | 3 | 4 |  a | g1 | f | f |
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Absolute Maximum Operating Conditions¶
| Vh | Ah | Va | Vg | mAa | ra | gm | 
| 2.0 | 0.1 | 150 | -6.0 | 2.2 | 8,900 | 1.8 |
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Updated January 01, 2025.
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