is one of the first FM transmitter circuits that I engineered back in
the late 80's that used an IC 3046 chip. Back then CAD software was
non-existent and everything was hand drawn. The fm transmitter circuit
shown below is the original, scanned drawing that I pulled from my
I had originally produced this fm transmitter circuit to
function and hide between the fm and vhf bands.
My chain of thought
was, why troubleshoot a problem with the active components when I could
just replace them all in a second by pulling and replacing the chip!
Its frequency shown based on coils L1, L2 and L3 was configured for
120 MHz. The frequency can be changed or even adjusted up or down by
removing the 22pf capacitor shown at L1 and replacing it with an
adjustable 4.5 to 22 pf capacitor.
Shown below is my original drawing. Enjoy, John.