Anonymous asked in Science & MathematicsEngineering · 1 month ago

Did vacuum tubes like 1U4 in portable dc radios last longer than their ac counter parts?

For example, the 1U4 cut off pentode is used as an I.F. amplifier in portable radios and has a filament voltage of only 1.4 volts, draws only 50 mA and doesn’t glow or get warm during operation.  Striking contrast to the 12BA6 in the American 5 at 12 v ac, 150 mA, glows and gets almost too hot to touch.  Just wondering if the electrical differences increased the lifespan?

1 Answer

  • Jim
    Lv 7
    1 month ago
    Favourite answer

    Anytime you can get metal red hot, the quicker it goes bad with vibration.

    So you're right, a cooler temp and lower current should last longer. But vibrations are still the enemy!

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