Throw it away.

Make a dipole for the longest frequency you desire to operate on.

Formula is 33 / 66

Make the one leg 33% of the length of the frequency and make the other side so that when combined to the first leg equals 66% of the total length for the dipole.

I use the term dipole antenna loosly - because a true dipole antenna is only one half of the wavelength at the resonant frequency...

It will then be resonant somewhere on all frequencies above the center cut frequency as long as the Q of the coil is high.
Don't use a low Q coil balun...