Abstract: A downhole toroidal coupled telemetry apparatus is disclosed in which the secondary winding comprises a plurality of turns wrapped around a generally annular core member.

Abstract: A logging telemetering system comprising a toroidal coupled telemetry apparatus including a primary winding carrying bore hole data, wrapped around at last one torroid core mounted within a drill collar. The toroid core is further wrapped with at least one secondary turn which is connected to the drill collar for enhancing the efficiency of inducing a current carrying the borehole data in the drill string for transmission to the surface. One half turn of the secondary winding is provided by an insulated portion of the drill collar, and the balance of the secondary winding is composed of an electrically conductive strap wound around the toroid core.

Abstract: An insulated drill collar gap sub assembly for a toroidal coupled telemetry system including a first annular sub member (150) operable to be connected at one end to a drill collar and a second annular sub member (156) operable to form a part of a drill collar sub. The first and second annular sub members have interconnecting structural members (54, 58) operable to structurally interfere. The interconnecting structural members are dimensioned to form a continuous gap (160) between mutually opposing surfaces and a dielectric material (162) fills the gap to electrically isolate the first annular sub member with respect to the second annular sub member. A bearing member (164) is positioned between the first annular member and the second annular member and is coated with a dielectric insulation (166) to facilitate the formation of a drill collar gap sub assembly of structural and electrical integrity.

Abstract: A downhole digital power amplifier comprises a device which, through digital means, provides a sinusoidal, variable frequency, variable power and variably phase-shift modulated output for the transmission of data from a downhole sensor arrangement to an uphole receiver. Selection and variation of frequency, power and modulation are made through digital inputs. The device provides these functions at extra low frequencies (ELF) low-to-high power output, and varying phase-shift keying.

Abstract: A heat sink/retainer clip (54) capable of resiliently holding objects, such as printed circuit boards, in tubular members, such as telemetering tools. The heat sink/retainer clip comprises two portions (56, 60) which extend across the tube from opposite sides thereof and two portions (58, 62) which engage the inner periphery of a tube (48). The clip is made of a resilient material, and the outer radii of the second two portions is slightly greater than the inner radius of the tube, so that the clip is distorted by the tube, during assembly, to resiliently grip the object between the first two portions.

Abstract: An insulated point gap assembly for a toroidal coupled telemetry system wherein a drill collar (38), operable to be connected to a lower portion of a drill string (32), carries a toroidal core having primary windings (88) and secondary windings (130). An aperture (154) is laterally fashioned through the drill collar. A conductor (150) is connected to one end of the secondary and extends through the aperture and the other end of the secondary is connected to the drill collar. The conductor is surrounded by an electrical insulation member (152). In a preferred embodiment, an axially extending sleeve of insulating material (156) is applied about the drill collar at the location of the conductor (150) to further isolate the conductor 15 from the drill collar.

Abstract: An insulated drill collar gap sub for a toroidal coupled telemetry system comprising a first annular sub member (100) operable to be connected at one end to a drill collar and a second annular sub member (104) operable to be connected at the other end to the drill collar. The first and second annular sub members have longitudinally extending interconnecting structural members (106, 118) operable to structurally interfere. The interconnecting structural members are dimensioned to form a continuous gap (116) between mutually opposing surfaces and a dielectric material (118) fills the gap to electrically isolate the first annular sub member (100) from the second annular sub member (108). A bearing member (124) is positioned between the first annular member and the second annular member but is insulated from at least one of said annular members to facilitate the formation of a drill collar of structural and electrical integrity.