GB1322879A - Anode modulation circuits - Google Patents

Abstract

1322879 Transistor modulator circuits SIEMENS AG 16 June 1972 [30 June 1971] 28201/72 Headings H3R and H3T In a modulator in which a D.C. pulse modulation signal is applied to the anode of a transmitter stage 39 via a transformer, demagnetization of the transformer is effected by applying current to a third winding 5c of the transformer when the modulation signal is zero. An intermittent train of unidirectional pulses (J1 ... &c., Fig. 3, not shown) applied to input 1a are amplified by transistors 10, 12, delayed by delay 3a, and then further amplified before being applied to winding 5a of the modulator transformer. The delayed pulse train is also applied via lead 9 to a network 56, 57, 59 which causes the trailing edge of the delayed pulses to turn on transistors 47, 51 and apply a demagnetizing current to winding 5c. The arrival of the next input pulse then applies a signal via diode 41 to turn on transistor 46 and cut off transistor 51. Saturation of stages 32, 36, 51 is prevented by associated diodes 38a, 38b, 52.