Capacitors are passive devices that are used in almost all electrical circuits for rectification, coupling and tuning. Also known as condensers, a capacitor is simply two electrical conductors separated by an insulating layer called a dielectric. The conductors are usually thin layers of aluminum foil, while the dielectric can be made up of many materials including paper, mylar, polypropylene, ceramic, mica, and even air. Electrolytic capacitors have a dielectric of aluminum oxide which is formed through the application of voltage after the capacitor is assembled. Characteristics of different capacitors are determined by not only the material used for the conductors and dielectric, but also by the thickness and physical spacing of the components.
Capacitor - 100pF, Variable, Single Section
This capacitor is used as a tuning capacitor in a variety of RF test equipment and ham radio gear. It's combination of low price, high maximum voltages, fairly large capacitances, and low-leakage L-4 grade ceramic have made it a popular configuration. Single section 100pf, screwdriver or knob adjustable, full rotation.
Capacitor - 365pF, Variable, Single Section
Single section 365 pf variable capacitor, also referred to as a tuning capacitor. A compact, rugged, economical unit used in wide variety of low-voltage applications. This capacitor's almost cubical shape makes more efficient use of space and delivers a remarkable amount of capacitance for its volume.
Capacitor - 3x365pF, Variable, 3 Section
Three section variable or tuning capacitor. Each section is 365pF. 3 1/4 long frame 1/4" x 1" shaft. This capacitor is the largest condenser currently in production and can deliver a total capacitance of almost 1100 pF.