Transformers running with gain

[Jdo300]

Hello,

Are there any coil setups for transformers that when tuned or combined in wierd ways run with gain? I heard that coupled inductors for CB radio antennas do this, but are there any effects similer to this for transformers? I heard an account from someone who said that two out of tune AC transformers tended to create big voltage spikes sometimes as the frequencies collided and created a lot of hash.

Thanks,
Jason O

[NoTime]

Gain of what?

[Averagesupernova]

Any step-up transformer has voltage gain at the expense of current. Any step-down transformer has current gain at the expense of voltage. Also, both cases have loss as nothing is 100% efficient. NO transformer EVER has power gain.