A source of d.c control voltage is coupled to the input winding via a four terminal capacitor to control {HEAD ~ the impedance} of {TAIL ~ the secondary winding} 
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A source of d.c control voltage is coupled to the input winding via a four terminal capacitor to control { HEAD ~ the impedance } of { TAIL ~ the secondary winding }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL