Two other sets of coils, E and F, sold separately, covered 960–2050 kHz and 480–960 kHz, respectively. Before each radio left the factory, a technician custom calibrated a set of A, B, C, and D coils for that particular radio, a process that took nearly 4 hours.
In addition to the standard coils, two other sets were available, E and F, which catered to frequencies between 960–2050 kHz and 480–960 kHz. Before each radio was shipped out of the factory, a technician would personally adjust a set of A, B, C, and D coils for that particular model, requiring almost 4 hours.