The M55HG is a current regulator or barretter. Pins four and six are omitted and the iron wire inside is connected to pins 1 and 8. On test the resistance of this eight lengths of coiled wire was around 200 Ω.
The wire is wrapped around a mica sheet. The classic envelope is 38 mm in diameter and, excluding the IO base pins, is 89 mm tall.Reference: Observation. Type M55HG was first introduced in 1937. See also 1937 adverts. |
Pin Connections
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |  f | - | - | - | - | - | - | f |
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Updated February 21, 2022.
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