Well might you ask! Fig. 1 illustrates the rotary coil turret inside the RF front-end compartment of a Radiometer Model AFM2 Modulation Meter. The coils and trimmers are adjusted to calibrate the tuning dial; there is one pair per range. Turning the bandswitch rotates the turret , switching in the LO tank corresponding to the selected frequency range. The air-variable capacitor to the right of the turret is the instrument's main tuning capacitor.
Verily a thing of beauty.
Copyright © 2011 A. Farson VA7OJ/AB4OJ, including images. Last updated: 11/27/2015