Adjustable frequency sweep circuit for backward wave oscillator

Claim 1

A DRIVING CIRCUIT FOR A BACK WARD WAVE OSCILLATOR, SAID OSCILLATOR HAVING A HELIX AND AN ELECTRON BEAM FORMING MEANS FOR DIRECTING A BEAM OF ELECTRONS THROUGH SAID HELIX ALONG IT AXIS, SAID BEAM FORMING MEANS HAVING A CATHODE AND AN ANODE, SAID DRIVING CIRCUIT COMPRISING: A DIRECT CURRENT SOURCE OF CONSTANT POTENTIAL HAVING ITS POSITIVE TERMINAL CONNECTED TO A POINT TO REFERENCE POTENTIAL; A DIRECT CURRENT CONNECTION BETWEEN SAID HELIX AND SAID POINT OF REFERENCE POTENTIAL; A PENTODE HAVING ITS ANODE CONNECTED TO SAID POINT OF REFERENCE POTENTIAL; A CONSTANT CURRENT IMPEDANCE CONNECTED BETWEEN THE CATHODE OF SAID PENTODE AND THE NEGATIVE TERMINAL OF SAID SOURCE; A DIRECT CONNECTION BETWEEN THE CATHODE OF SAID BACKWARD WAVE OSCILLATOR AND THE CATHODE OF SAID PENTODE; MEANS FOR APPLYING AND ADJUSTABLE BIASING POTENTIAL BETWEEN THE CONTROL GRID AND CATHODE OF SAID PENTODE FOR ADJUSTING THE DIRECT POTENTIAL OF THE CATHODE OF SAID BACKWARD WAVE OSCILLATOR RELATIVE TO SAID HELIX; A POTENTIAL DIVIDER COMPRISING A FIRST RESISTOR, A SECOND RESISTOR AND A ZENER DIODE CONNECTED IN SERIES IN THE ORDER NAMED BETWEEN SAID POINT OF REFERENCE POTENTIAL AND THE CATHODE OF SAID PENTODE, SAID SECOND RESISTOR HAVING AN ADJUSTABLE INTERMEDIATE CONTACT; A DIRECT CONNECTION BETWEEN THE ANODE OF SAID BACKWARD WAVE OSCILLATOR AND THE ADJUSTABLE TAP ON SAID SECOND RESISTOR; AND MEANS FOR APPLYING A SAWTOOTH ALTERNATING VOLTAGE WAVE BETWEEN THE CONTROL GRID OF SAID PENTODE AND THE NEGATIVE TERMINAL OF SAID SOURCE.