This disclosure relates to an amplifier incorporating various devices for detecting parameters such as average power, peak power and signal voltage to be used to provide the feedback signals for automatic level control of an RF amplifier whose output signal is passed through an antenna coupler to an antenna. These detection devices allow normal operational level setting as well as minimizing the chance of overloads resulting in amplifier circuit failure during tuning conditions.

Protected amplifier apparatus

Noise potentials and radiation in an ultrasonic nebulizer are reduced by separating the oscillator and power supply and shielding the former, with one of the DC power lines to the oscillator passing through an aperture in the metal casing that shields the oscillator, while the other power supply line is connected to that casing. Oscillator control may be achieved by an unshielded variable resistor coupled by conductors of extended length to the oscillator by a filter circuit.

Ultrasonic atomizer unit utilizing shielded and grounded elements

An adaptive power amplifier system for use with VSWR loads includes an adaptive power supply that indirectly monitors the power dissipated by a RF power amplifier and adapts bias conditions of solid state components in the RF power amplifier to protect the components from excessive power dissipation typically experienced with VSWR loads, even while maintaining full forward power output.

VSWR adaptive power amplifier system

Power amplifiers, which include a feedback element, may be protected from excessive operating power levels by adjusting the feedback element to reduce the drive signals to the power elements. This is accomplished by sensing the output power of the power amplifier to produce a sensing signal. When the sensing signal exceeds a predetermined threshold, a feedback element is adjusted to produce an increased feedback signal. The increased feedback signal is subtracted from an input signal, thus decreasing the drive signal. With the drive signal reduced, the output power is reduced proportional to the adjustment of the feedback element.

Method and apparatus for protecting power amplifiers from excessive operating power levels

A linear sensitivity voltage controlled crystal oscillator of the type including a resonator coupled to a negative resistance generator. The resonator comprises a crystal connected in series with a voltage variable capacitance device. The response of the resonator is linearized by the addition of an inductance across the voltage variable capacitance device. A resistor is shunted across the crystal to prevent oscillation at spurious resonances of the resonator.

Daniel J Mahoney

Papers

Frequency modulated crystal oscillator including voltage variable capacitor

Semiconductor protection system