14-10-2016, 10:27 AM
A diathermy having a vacuum tube in a tuned plate, tuned grid oscillator circuit. A coil is placed in the tuned plate circuit for applying short wave signals to a patient undergoing treatment. The tube has at least a control grid connected to the tuned grid circuit and a screen grid. A circuit is coupled to the screen grid for enabling a signal to be fed back from the plate circuit through the screen grid to the control grid and comprises an impedance for coupling the screen grid to a source of control signals for controlling the power delivered by the coil to a patient undergoing treatment.
