|Mullard DM70 Tuning Eye Tube
|Written by AnubisTTP on 2011-06-12
The DM70 is a small low power tuning eye tube intended for use in battery powered radios. DM70 tubes have a plate voltage of only 45 volts, a tiny amount compared to larger eye tubes like the 6E5, which requires a plate voltage in excess of 200 volts. The tube also requires a very low 1.4 volt filament voltage, and can be easily destroyed from excess voltage. The DM70 has a rather unusual display pattern, the tube's side viewed phosphor target is masked by an exclamation point-shaped stencil. In operation, the 'bar' portion of the exclamation point will shrink to the top of the tube and the 'dot' portion will grow dimmer at the grid voltage is varied.
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Mullard DM70 low voltage tuning eye, normal operation.