GB1047156A - Radio frequency signal generator for a moving object detection system - Google Patents

Abstract

1,047,156. Circuit assemblies. PINKERTON ELECTRO - SECURITY CORPORATION. Aug. 4, 1964 [July 26, 1963], No. 30477/64. Heading H1R. [Also in Division H4] In a R.F. signal generator for a radar system (see Division H4), a double triode oscillator valve 20, Fig. 3, is mounted on an insulating board 48 together with a U-shaped inductor 26 which, with a variable capacitor 28, forms the tuned-anode tank circuit of the oscillator (Fig. 2, not shown, depicts the circuit) and a second U-shaped inductor 36 coupled to inductor 26 is mounted parallel thereto on a second insulating board 50, which is fixed parallel to board 48 and normal to a shielding chassis base 52, the valve 20 and the inductors 26, 36 being maintained in their mutually spaced locations by a rigid insulating member 56 which receives the tip 58 of the valve envelope in a hole therein, and which has passages through which inductors 26, 36 pass. The timed-grid tank circuit of the oscillator comprises a centre-tapped inductor 24 and the interelectrode capacitance of valve 20, for which 22 is the grid resistor. The anode H.T. for valve 20 is applied via a decoupling circuit comprising a R.F. choke 32 and a shunt capacitor (not shown) to a conductive lug 54 on board 50, the centre-point of inductor 26 being soldered to lug 54. The induced signal in inductor 36 is passed via a capacitor 60 and a porcelain feed-through insulator 64 to an aerial (not shown), the load on the aerial being variable by adjustment of a variable capacitor 62 which is mounted on a side wall 46 of the chassis and is accessible through a hole in the chassis-cover (not shown). Detection of an object produces modulations of the radiated signal which are detected by a crystal diode 6 and passed via a filter comprising a capacitor 74 and a choke 76, and a feed-through capacitor (not shown) in side wall 44 of the chassis, to an amplifying and indicating network (Fig. 2a, not shown).