The AC/VMSG12 is a mystery. The only information found so far is that contained on the bulb. So it appears to be a variable μ screen grid valve or tetrode with a 4.0 Volt heater. The 4.0 Volt suggest indirectly heated. The screw top cap connection suggests early to mid 1930s.The valve appears to be designed for use in a superhet receiver in the UK where the 4.0 Volt heater was standard.![](../pics/abh0081a.jpg)
The screw top cap connection.The classic envelope is 49 mm in diameter, and excluding the B5 base pins is 133 mm tall.Reference: Observation. |
Absolute Maximum Operating Conditions¶
| Vh | Ah | Va | Vs | Vg | mAa | mAs | ra | gm | ![](../static/key.gif)
| 4.0 | - | 200 | - | -1 | - | - | - | - |
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Updated September 10, 2013.
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