10.1. GENERAL CONSIDERATIONS

Kind of supply voltage:

Radio receivers like most of the electronic nowadays need for good performance a -dc-voltage which is very stabil.

Reason:

Every change of the supply voltage acts on the receiver like an injected signal and this means distortion.

Energy source:

Nowadays mostly batteries or powersupplies from mains.

Amount of supply voltage:

Depending on the kind of “active-components” used in the receiver. For valve receivers “high tension” (75 - 350 V), for transistor receivers (3 - 24 V).

Stages in a power supply:

According to the problems arising in a special case, there are different stages necessary in a power-supply in order to have the constant dc-voltage required.

Chopping is not a topic of this course, therefore the most complicated with here is the supply of a transistorracio by the mains which is shown in blocks in fig. 87.

figure