Bird Electronic Corporation

Ralph P Trefney

A device for monitoring operating conditions of an RF transmitter, including the RF power output thereof, and the reflected voltage wave on a transmission line therefor, and for promptly switching the transmitter off whenever a faulty condition is detected. The device includes two voltage comparators that receive voltage signals representative of transmitter power output and the magnitude of the reflected voltage wave on an associated transmission line, and which generate an output signal whenever a respective voltage signal varies a predetermined amount from a preset reference voltage level. The two voltage comparators are activated by a relay operated by the carrier wave of the transmitter so that the comparators function only when the transmitter is operating. The output signals from the two comparators are transmitted together with any other signals indicating a faulty condition, to a NAND gate which outputs an alarm signal whenever at least one fault signal is received. The alarm signal is then processed to switch off the transmitter and, if desired, to simultaneously switch on an alternate backup transmitter. A third comparator associated with the amplifier circuit for the meter that indicates the transmitter power output is used to provide a transmitter-on condition indication once the transmitter reaches a power level of 2% of its output power after being switched on.

Monitor for RF transmitter

A VSWR meter unit for detecting and measuring the forward and reflected RF voltage wave signals on a coaxial transmission line. The unit is adapted to be electrically inserted in a tubular or coaxial transmission line, having an outer conductor with a coaxial center conductor therein. A microstrip circuit board is provided within the meter unit and comprises a dielectric board with a ground plane conductor printed on one side and inserted across the outer conductor, and a specially designed conductive path printed on the other side and inserted across the inner conductor. Also printed on the other side of the microstrip board is an inductive sensing loop located within and concentric with a circular loop portion of the conductive path. The sensing loop is closely spaced to the loop portion of the conductive path so as to be responsive to the voltage wave signal on the transmission line. A D'Arsonval meter movement is connected to the conductive loop through a specially designed 180.degree. switch assembly in either a 'forward' or 'reflected' condition through a meter circuit, designed so that the meter provides an indication of the level of either the forward voltage wave signal or the reflected wave signal depending on the condition of the switch assembly.

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Valley View, OH, United States of America

Ralph P Trefney