The TH4A is an indirectly heated triode hexode frequency changer with the 1930's standard 4.0 V heater. The box it came in matches the HL2 box referenced to above.The triode is employed as the local oscillator and the hexode for the mixing process, the input signal being coupled to the control grid via the top cap for maximum separation of the circuits.The classic envelope is 45 mm in diameter and, excluding the B7 base pins, is 126 mm tall.References: Data-sheet & 1043. Type TH4A was first introduced in 1938. See also 1938 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 | gm |
| 4.0 | 1.5 | 250 | 100 | -2 | 3.5 | 5.5 | 0.85 |
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Absolute Maximum Operating Conditions¶
| Va | mAa |
| 100 | 1.5 |
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Updated January 07, 2013.
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