Colpitts oscillator circuit

High-frequency power for industrial use is generated by a standard oscillator circuit operating under Class C conditions (that is, modified Colpitts, modified Hartley, tuned anode/tuned grid), using industrial triode valves, usually with ceramic envelopes and air- or water-cooled anodes. 

Fig. 13 Oscillator circuit with inverting amplifier (a), with a Colpitts structure (b), and with non-inverting amplifier (c)...

Dielectric systems usually employ negative grid triode tubes, although some systems operating in the 50 to 100-MHz range use beamed power types. RF circuits are usually simple, self-excited oscillators of the Hartley, Colpitts, or tuned plate-tuned grid type. These circuits usually consist of coils and capacitors or coaxial lines. The load to be heated may actually form part of the tank circuit capacitance, it may be separately tuned or inductively or capacitively coupled to the oscillator, or it may be a combination of these, which is directly connected to the oscillator and also... 

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