Please be aware that using an Iso-coupler or installing any antenna on an AM tower can change the impedance of the tower and trigger the need for a proof, especially if you're doing this on a tower that's part of a directional antenna system.? The Iso-coupler will add a shunt capacitance to the tower and the antenna can also change the base impedance and current distribution of a tower.??
An ISO-coil can add a shunt inductance and may need a parallel capacitor to detune it at the stations operating frequency.
Be careful when fooling with AM towers.
Burt, K6OQK
Burt K6OQK