you can resonate the primary winding of the CT with a large low loss cap at 50kHz say, you will need the square wave out of your sig gen and buffered by a couple of emitter followers and a good power supply (15V say) with 470uF right across the xtors, you will have to vary the freq ad the cap to get a match some where in the 50k - 100k Hz region, if you have an ammeter in your psu this will show you resonance, (higher current) you should also see it on the CT secondary...