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IF crystal filter with changeable selectivity
IF crystal filter with changeable selectivity
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机译:选择性可变的中频晶体滤波器
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摘要
An IF crystal filter for a VHF receiver including: a crystal filter (20) having an input (22) and an output (24 a reactive impedance means (26) coupled across the crystal filter input and output for changing the selectivity characteristics of the crystal filter by a predetermined amount; and switching means (32) having a control input responsive to a control voltage, and coupled to said reactive impedance means for selectively shunting the reactive impedance means to ground, whereby to change the selectivity of the filter. IMAGE
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