Re: Can harmonic happen at 1/2f?

Please put your inductor standing up; the PCB pads down below are overloading the inductor. If possible, raise it 2-3 mm off the board. Hopefully your problem will disappear.

My FM transmitter has its coils spaced above the circuit board.

Oh yeah! Trust me on this one.

The weirdest one I ever saw was a non harmonic spur caused by an RF signal bouncing off of an amplifier input, and generating the spur. Took a while to find that one.