Abstract: A tunable oscillator develops a signal having a frequency variable over a range of frequencies in response to a control signal. A frequency determining resonant circuit includes two voltage-variable capacitance diodes in an arrangement for adjusting at least one endpoint of the frequency range. As a result, the relationship between the magnitude of the control signal and the frequency of the oscillator signal can be adjusted while avoiding mechanically adjustable reactive elements. The disclosed arrangement is suitably employed with resonant circuits other than those in oscillators.

Abstract: To lock out certain channels in a scanning receiver, a counter in the scanning control circuit is manually stepped to the channel to be locked out and a signal is recorded in a memory at that point by depressing a switch while the memory is addressed by the circuitry which causes scanning. When the scanning circuit thereafter reaches the same channel, the address of that channel causes a readout from the memory which electronically inhibits the scanning of the locked-out channel. With minor modification, the circuitry may accommodate other electrically recorded switching operations such as band switching operations and priority operations.