NO, I"m suggesting that he disconnect the FB and drive the transistor with a sig-gen ( which will fully swtich the transistor ) and measure the output of the FB coil. The FB coil is typically just a few turns; just enough to get the process started, and the transistor's regeneration does the rest. But it might require more than a few mV, it all depends on the voltage gain of the transistor. Maybe even a small trasistor to drive the 3055 would help alot. That would increase the overall gain and make up for the low amount of FB being injected.