The “VU” is a uniquely designed UHF tuning capacitor using completely original concepts. With it, conventional “lumped constant” circuits, rather than tuned cavity techniques, can be efficiently used up to 500 megahertz. In addition to employing the capacitor sections in series to eliminate the rotor wiper, the design also utilizes Pyrex balls to form precision bearings and to completely isolate the rotor. Thus, noise generated by rubbing metal-to-metal contacts and variable resistance paths in the bearings has been totally eliminated. Circuit connections are made to threaded studs on each stator. This permits vacuum tube and inductor to be mounted adjacent to and on opposite sides of the capacitor to minimize circuit inductance. The symmetrical design is ideal for tuning circuits operating up to 500 megahertz.
Rotors and stators are of brass with plates soldered in precisely located grooves and then silver-plated to increase the “Q” of the capacitor. The insulation is silicone treated steatite. All lengthwise frame members are of brass to minimize temperature effects. Base mounting brackets are provided.
The capacity characteristic approaches a straight line frequency curve as indicated by nominal values in the table. Air Gap is .0168″ nominal. Tested at 700 V. R.M.S., 60 hertz, between rotor and each stator.