Re: uBitx 12 MHz Crystal Filter transformer terminations

DuWayne Schmidlkofer
 

The same  transformer is used throughout the circuit.  In this case the leads marked with x are not connected to anything.  The filters are in effect terminated by a center tapped transformer. This gives a 2 to 1 winding  ratio, squaring these to get the impedance ratio you get a 4 to 1 ratio.  One end of the filter goes through this transformer center tap to a 50 ohm pi attenuator R114 -R116.  The other end of the filter is terminated by the impedance of the bidirectional amplifier it connects to.

DuWayne KV4QB




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DuWayne  KV4QB

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