A nonlinear transmission line (NLTL) provides a solidstate means of generating high power, microwave pulses. The NLTLs in this study are coaxial transmission lines whose center conductor is encapsulated by ferrite beads. Operational frequency can be controlled by varying the dimensions of the ferromagnetic material, which affects azimuthal magnetic fields and material losses, or by varying the biasing field strength. This research demonstrates frequency agility of an NLTL by documenting the design, construction, and testing of three NLTLs. The NLTL will be one meter long, and to test for frequency agility, three different sizes of ferrites will be loaded onto NLTL with various biasing fields applied. Azimuthal field strengths due to an incident high voltage pulse range from 10-36 kA/m with magnetic biasing fields between 0 kA/m and 50 kA/m.