At the Center for Pulsed Power and Power Electronics, previous coaxial ferrimagnetic Nonlinear Transmission Lines (NLTL) relied solely on pressurized Sulfur Hexafluoride (SF6) as high-voltage insulating dielectric medium . While the use of SF6 provides the necessary electric insulation, there are drawbacks including gas storage and pressure fittings that increase system size and add to the design complexity of the NLTLs themselves. Hence it was deemed necessary to evaluate solid dielectric materials as an alternative. Initial attempts utilized a standard high voltage (HV) epoxy to pot the NLTL assembly. This method was effective at producing magnetic precession in the NLTL; however, there was a reduction in output power due to the high loss tangent of the epoxy. Sylgard 184, commonly used in solar cells, has also found use as an HV potting material. Per datasheet, its loss tangent is an order of magnitude lower compared to standard HV epoxy at 1 kHz. Samples of HV epoxy and Sylgard 184 were tested in a microwave cavity resonator at 3GHz, which yielded their respective loss tangents. The performance of an NLTL potted with Sylgard 184 is compared to that of the HV epoxy NLTL and the earlier SF6 insulated NLTL.