Regenerative Radios

The principle of regenerative reception was proposed in 1913. Amstrong (USA).

Figure 2.3.

The regenerator is a cascade assembled according to the scheme of a lamp generator with self-excitation, with a resonant circuit in the grid circuit. (Self-excited transistor generator with a resonant circuit in the base circuit). Feedback, as in the generator, is chosen positive, but somewhat smaller than the critical value corresponding to the self-excitation threshold.

Regenerative cascade simultaneously performs three functions:

- high frequency gain;

- detection;

- low frequency gain.

High frequency amplification is due to the action of positive feedback.

Detection (grid or base) is carried out due to the nonlinearity of the characteristic of the grid current of the lamp or the base current of the transistor.

Low frequency amplification is carried out by amplifying the anodic or collector circuit of the detection result isolated on the resistance included in the grid or base circuit.

The resonant circuit in the grid or base circuit is tuned to the signal frequency and performs high frequency selectivity.

Due to the presence of high and low frequency gain, the regenerative receiver has a higher sensitivity than the detector receiver. However, to obtain greater sensitivity of the regenerator, it is necessary to bring the equivalent attenuation of the resonant circuit to zero, in this case the regime is very unstable, and the passband is too narrow.