Patent GB-1111861-A (GB)
Title: Electrical switching apparatus
Filed: 1965-05-12
Abstract: 1,111,861. R.F. couplings. DELTA ELECTRONICS Inc. 12 May, 1965 [15 June, 1964], No. 19985/65. Heading H4A. [Also in Division H1] In electric switching apparatus first and second strip conductors are insulated from a base and are sectionalized to define transverse sets of strip lines, and plungers are mounted on the base at cross-overs between the sets, each plunger being movable between a position in which strip line section continuing contacts on the plunger continue to sections of the strip lines at the cross-over as separate continuous conductors insulated from one another and another position in which contacts on the plunger cross-connect one of the sections of the first strip line to that of the second strip line. The invention is described as applied to the selectable interconnections between aerials and radio apparatus without objectionable crosstalk. Fig. 9 (not shown). The general arrangement is shown in Fig. 1 and a section on line 3-3 thereof is given in Fig. 3, there being three transmitters T1 . . . T3 and three aerials A1 . . . A3 with coaxial connections, e.g. 43. Base 10 has square apertures 13 receiving corresponding plungers 39 and plates 16F, 16R have apertures acting as bearings for the plunger shafts. Insulators 19 carry a strip-line section 20 which is a bar (21, Fig. 5) of silver-plated copper covered by a resilient strip of silverplated beryllium copper (22, Fig. 5) loosely wrapped over the bar, end loops formed by the strip being provided with cuts (25, Fig. 5) affording three yieldable contacts. To minimize inductive heating a conductive rod 25B is bent into a figure-of-eight from the centre of which a stud 25C (Fig. 5) extends into a cooperating aperture in the strip-line. The plunger assembly (Fig. 4) comprises a rod (28) threaded at both ends and extending through an insulator (29) on which spaced square contacts 29F, 29R are mounted with an electric shielding resilient sheet 30 therebetween for closing the square aperture 13 when strip-line sections at the front and rear of the base-plate 10 are engaged by the square contacts. A cross-switch contact is also supported on the insulator (29, Fig. 4) and includes a conductive tube 31 carrying spaced and rectangular contact elements. The various contacts and sheet 30 are correctly spaced by insulating collars. The far end of the plunger carries a disc 40 for operating a microswitch. The shielding element 30 has slots (30A, Fig. 7) affording spring fingers, a dimple (30C) being formed on each finger to engage base-plate 10. The terminal end strip-line section (e.g. 20L, Fig. 8) has a modified resilient strip formation. Microswitches ensure that power is turned off during a switching operation and actuate indicating lights on an annunciator (Fig. 14). A modified plunger with a guide and locking key and cams for microswitch operation is described: a modified front plate (16FA, Figs. 15 to 17) carries the microswitches 45, 47 of Fig. 3 and the plunger includes a shaft core (61) with a threaded bore at each end and a locking sleeve (62), rotatable on the core, prevented from longitudinal movement relative thereto by washers (63, 64) one of which is of nylon to provide a cushioning action between the front plate and the plunger assembly. The assembly of contacts on a rear shaft (26RA) is screwed to one end bore of the shaft core and the operating knob (67) is fixed to the locking sleeve by a pin, it being arranged that an operator's hand cannot engage the shaft core. The locking sleeve has elongated cams (68, 69) spaced by the thickness of the front plate, one cam (68) being adapted to pass through a slot (70) in the front plate to permit axial movement of the plunger assembly. The outer surface of the front plate carries arcuate stops (68S, 69S) which limit movement of the locking sleeve (62) to 90 degrees, and the cams (68, 69) operate respective microswitches 45, 47 via spring- biased actuating arms (45A, 47A) carrying camlifted rollers. Power from a transmitter is thereby positively disconnected before the plunger is moved to change the aerial-transmitter connection and the indicator is operated by switch 47 when the plunger is in the crossconnecting position.