$f_0$ of either circuit away from their intended values will degrade performance unless the shift $\delta f_0$ is roughly within the coupling bandwidth, or approximately $f_0/Q$ using the quality factor Q of the lossy primary. This leads to the rough limit $|\delta f_0 / f_0| \lesssim 1/Q$, beyond which the shift impedes energy transfer. Quantitatively, the curve in Fig. 3(b) corresponds to $Q \approx \omega \tau / 2 = 13.3 \pm 0.2$, which is similar to a typical SGTT value.[@skeldon:1997ETAL] Thus for a comparable SGTT, the limit $|\delta f_0 / f_0| \lesssim$ 7.5%.

As a result, slightly adjusting the capacitance or inductance of the secondary, for example, typically ruins SGTT performance and either reversing or compensating for this in the primary is needed to restore operation. In contrast, both may be adjusted freely without requiring any other circuit changes to maintain operation with the Marx coil. As a demonstration, Fig. 4 shows the MC operating after the solenoid was removed, as in Figs. 1(d) and 2(b). This reduced the output frequency to about 110 kHz, corresponding to $\delta f/f_0 \approx -61$%, far outside the rough limit of $\pm$7.5%. Additionally, this led to spark discharge off the MC components due to 