My FM transmitter just arrived. This is a fine unit. And, if you don’t have to worry about FCC’s rules, you can (from “NC” on Amazon.com):
- Open up the box, by removing 3 screws (one screw is in battery compartment and the other 2 are under those circular rubber feet which are adhesive and once removed can be refitted afterwards)
- Locate the variable resistor marked VR2 on the circuit board. (For those non-technical this is like a volume control that is operated by inserting a tiny screwdriver and turning fully clockwise). Turn VR2 to the fully clockwise position.
Viola! The power output will increase by about five fold.
If you want to go even further, then
- sit it on a grounded metallic surface, such as a metal tray to form a ground plane.
- increase the length of the antennae to about 75 cm (29 inches) which is the correct quarter wavelength at these frequencies.
But frankly, you are unlikely to need this once you turn up the boost.