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.
Two supplementary sets of coils, E and F, were offered separately, addressing ranges between 960–2050 kHz and 480–960 kHz. Prior to each radio leaving the factory, a technician would fine-tune a set of A, B, C, and D coils for that specific model, which took nearly 4 hours.