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Just going to mess with the RX filtering on the QDX-M for 630M.

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Does anyone know the measured input impedance there?? It has lots of variables if you calculate and I don't want to re-invent the wheel.

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I have an assortment of MCL RF Transformers and will probably use something like the 8:1 ADT8-1T+ or lesser step-up.

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Thanks,? N0UU

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The input impedance of the Tayloe circuit varies widely with frequency. For signals at the clock frequency it goes very high, infinite in the ideal.

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As the input signal deviates from the clock frequency the QSD input impedance falls rapidly, ultimately reaching a low value limited by the MUX channel resistance. It follows the bandwidth curve that the QSD develops?

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This behavior is not intuitively obvious. Far from it! It was confirmed in my simulations and also via Steve Dick's correspondence with Dan Tayloe himself.

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IMO a resistive pad could be used to limit the impedance excursions and make the performance of a preceding filter more predictable.

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Good question, OM ..JZ KJ4A?