FM Isolation Transformers

Isolation transformers couple FM power across the base insulator of an AM broadcast station transmitting tower, with little or no effect on the AM base impedance and no mismatch into the FM antenna feed line.  An isolation transformer is especially desirable for feeding high impedance AM radiators or towers that are part of a directional array where “bazooka” isolation systems would have adverse effects.

FM Isolation Transformers are used to pass power to an FM antenna mounted on a base insulated, series fed, AM tower. ERI manufactures five (5) different models of FM Isolation transformers. These include the broadband Model 404 rated to 10 kW FM power, the high power Models 425, 426, and 427 which are rated from 25 kW to 50 kW FM power, and the broadband Model 430 which is designed to support multichannel combined FM systems with combined FM power up to 70 kW.