Inside the mag mount is a tuning circuit for 146 MHZ!! So, it's not
simply cutting the length from 49 inches to another value. It will
require changing the tuning inside the mag mount.

So, scaling the 49 inches from 146 MHZ to 223 MHZ yields a length of 32
inches for 5/8 wavelength at 223 MHz. But, you still have to solve the
retuning of the internal circuit.

W1MCE


Darrin wrote:

I found an old mag mount 2 meter antenna, and want to convert it for
use on 224MHz. The whip is 49". Is there a simple formula to figure
out how short to cut it?