Abstract: Mixer which has, in place of four conventional diodes, the collector - emitter spaces of transistors polarized to earth and supplied at their bases by the local oscillating signal across a coupling system and as a result giving performance levels like those obtained with diodes, but with a lower local oscillating power.

Abstract: The output electrode of a field effect transistor of a high-frequency input stage is connected to a capacitively coupled input (gate) electrode of the field effect transistor of a mixer stage through one of a pair of bifilarly wound coils provided on a ferrite core, while the second of these coils connects the same input of the mixer stage to the output of a local oscillator in such a way that two signal paths leading towards the mixer stage, respectively for the high-frequency signal and the oscillator signal, go through coupled coils in opposite winding directions. The result is that the path for signals in either direction between the local oscillator and the input stage are of much higher impedance than the paths for signals proceeding to the mixer stage respectively from the input stage and from the local oscillator.

Abstract: A mixer/oscillator circuit comprises a mixer stage to which an oscillator stage is connected, an emitter follower circuit being connected between the oscillator stage and the mixer stage.

Abstract: A control system is described for use in a television receiver adapted to receive multi-band television signals and which has a direct-access type tuning system. In such a tuning system, the receiver employs at least one local oscillator, the output of which is applied to a prescaler for dividing down the frequency of the oscillator signal. Frequently, the oscillator signal fluctuates in amplitude as the oscillator is tuned from channel to channel and from one frequency band to another frequency band. To compensate for such amplitude fluctuations, the control system confines the amplitude of the oscillator signal to an amplitude range which the prescaler can reliably handle and applies the amplitude-controlled oscillator signal to the prescaler.