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Bottlehead Forum Welcome! Need support, you got it. Or share you ideas and experiences. |
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Bottlehead Forum Welcome! Need support, you got it. Or share you ideas and experiences. |
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In Reply to: B7 transformer as step-up input posted by Klas on April 16, 2003 at 17:18:07:
The impedance on the input is whatever is loading it on the secondary divided by 5.48. The 5.48 comes from SQRT(15K/500), square root of the turns ratio.If you have just the grid of the 71A, then it's capacitance mainly, being the capacitance of the 71A grid times 5.48. More capacitance means less impedance. In this application, with some stray capacitance, that's about 40 pF on the secondary. Therefore it's about 220 pF on the primary. At 20 KHz, 220 pF has an impedance of 36K ohms.
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Follow Ups
- Re: B7 transformer as step-up input - Kürt §†rå¡n 07:53:50 04/17/03 (1)
- Minor correction - Kürt §†rå¡n 08:00:18 04/17/03 (0)
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