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KT66Sensibly equivalent¶ to:See also:
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The KT66 is a very well known audio output beam tetrode valve. This exhibit has a black base cap and the later envelope shape mixing the tubular with the shoulder to hold the top mica. The adverts from the 1940's and 1950's show this later straight sided envelope.The KT66 was essentially a 6L6 redesigned with a larger cathode and a shorter, fatter anode. The KT66 had less rapid acceleration, longer electron paths, and almost no kink. It was ace for audio hi-fi but the electrons took longer to reach the anode and were more open to influence from magnetic, etc, fields on the way. Moreover, under HF conditions the electron stream was not perfectly in phase with the grid signal and this resulted in a loss of output power if used for RF applications.The figures given are for single ended use, but a pair run in ultra linear AB2 push pull will deliver 50 Watts with 2% distortion.The Osram paper label.The top mica showing the wires linking the cathode tube to the beam plates.The classic envelope is 50 mm in diameter and, excluding the IO base pins, is 120 mm tall.References: Data-sheet, 1004, 1005 & 1040. Type KT66 was first introduced in 1937. See also 1937 adverts. |
Pin Connections
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | m | h | a | g2 | g1 | nc | h | k,bp |
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Absolute Maximum Operating Conditions¶
| Vh | Ah | Va | Vs | Vg | mAa | mAs | ra | gm | Pout | D |
| 6.3 | 1.27 | 250 | 250 | -15 | 85 | 6.3 | 22.5k | 6.3 | 7.25 | 9% |
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Updated January 19, 2021.
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