The TX21 is a triode hexode frequency changer for use on 200 mA heater chains. It is thus suitable for both the AC and DC mains that existed in the 1930s.
The B7 base and pins.Thanks to Mark Mallison for sending the images.The wide glass tube envelope is mm in diameter and excluding the B7 base pins, is mm tall.Reference: 1043. Type TX21 was first introduced in 1936. See also 1936 adverts. |
Pin Connections
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | tc |  a(t) | g1(t),g3 | g2,g4 | h | h | m,k | a | g1 |
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Absolute Maximum Operating Conditions¶
| Vh | Ah | Va | Vs | Vg | mAa | mAs | ra | gm |
| 21.0 | 0.2 | 250 | 80 | -1.5 | 5.5 | 6.0 | 1M | 1.0 |
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Absolute Maximum Operating Conditions¶
| Va | Vg | mAa | gm |
| 150 | -1.5 | 4.0 | 1.2 |
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Updated April 16, 2022.
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