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KT81Sensibly equivalent¶ to:See also:
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The KT81 is the first M-OV kinkless tetrode audio power valve with a pressed glass foot. We can not find details of how it performed in the market place, but it was not a valve produced for many years. The KT81 appeared in 1947 and by 1951 this valve was being described as an obsolescent Type.Produced by M-OV this example is branded Osram and our other KT81 exhibit is branded Marconi.
The detail photograph shows the M-OV identification on the envelope.The wide glass tube envelope is 31 mm in diameter and, excluding the B8B base pins, is 68 mm tall.References: 4018 & 1040. Type KT81 was first introduced in 1947. See also 1947 adverts. |
Pin Connections
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |  h | a | g2 | ic | ic | g1 | k | h |
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Absolute Maximum Operating Conditions¶
| Vh | Ah | Va | Vs | Vg | mAa | mAs | gm | Pout | D |
| 6.3 | 0.95 | 250 | 250 | -4.4 | 40 | 7.5 | 10.8 | 4.3W | 8% |
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Updated December14, 2020.
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