A gap sub, comprising: a tubular drill collar sub, the drill collar sub including a conductive hollow cylindrical pin body and a conductive hollow cylindrical box body (101, 102), the cylindrical pin body and the cylindrical box body (101, 102) configured to mate via an electrically-isolated threaded connection; at least one end of the cylindrical box body (101, 102) terminating with a threaded box connection, the threaded box connection including a threaded box end profile, the threaded box end profile including a planar annular box end surface on a distal end thereof, the box end surface oriented on a plane substantially transverse to a longitudinal axis of the cylindrical box body (101, 102); at least one end of the cylindrical pin body terminating with a threaded pin connection, the threaded pin connection including a threaded pin end profile configured to mate with the threaded box end profile, a first non-conductive coating deployed on threads on at least one of the threaded pin end profile and the threaded box end profile; characterized by the cylindrical pin body transitioning into the threaded pin end profile via an isolating portion, the isolating portion including a shoulder formed in the cylindrical pin body, the shoulder including a planar annular shoulder face, the shoulder face oriented on a plane substantially transverse to a longitudinal axis of the cylindrical pin body and separated from the threaded end profile by a ring cutout and a recess; an isolating ring made from conductive material, the isolating ring including first and second planar annular ring faces, a second non-conductive coating deployed on at least one of the first and second annular ring faces; the isolating ring further including cylindrical inner and outer ring surfaces; the isolating ring sized to fit over the threaded pin connection and onto the ring cutout, the isolating ring further configured to separate the shoulder face from the box end surface when the threaded box end profile is threadably engaged on the threaded pin end profile, and the ring cutout is sized and shaped to receive the isolating ring after the second non conductive coating has been applied thereto; and the recess formed in the isolating portion such that the recess prevents the cylindrical box body (101, 102) from making contact with the cylindrical pin body nearby the isolating ring when the threaded box end profile is threadably engaged on the threaded pin end profile with the isolating ring located therebetween. a tubular drill collar sub, the drill collar sub including a conductive hollow cylindrical pin body and a conductive hollow cylindrical box body (101, 102), the cylindrical pin body and the cylindrical box body (101, 102) configured to mate via an electrically-isolated threaded connection; at least one end of the cylindrical box body (101, 102) terminating with a threaded box connection, the threaded box connection including a threaded box end profile, the threaded box end profile including a planar annular box end surface on a distal end thereof, the box end surface oriented on a plane substantially transverse to a longitudinal axis of the cylindrical box body (101, 102); at least one end of the cylindrical pin body terminating with a threaded pin connection, the threaded pin connection including a threaded pin end profile configured to mate with the threaded box end profile, a first non-conductive coating deployed on threads on at least one of the threaded pin end profile and the threaded box end profile; characterized by the cylindrical pin body transitioning into the threaded pin end profile via an isolating portion, the isolating portion including a shoulder formed in the cylindrical pin body, the shoulder including a planar annular shoulder face, the shoulder face oriented on a plane substantially transverse to a longitudinal axis of the cylindrical pin body and separated from the threaded end profile by a ring cutout and a recess; an isolating ring made from conductive material, the isolating ring including first and second planar annular ring faces, a second non-conductive coating deployed on at least one of the first and second annular ring faces; the isolating ring further including cylindrical inner and outer ring surfaces; the isolating ring sized to fit over the threaded pin connection and onto the ring cutout, the isolating ring further configured to separate the shoulder face from the box end surface when the threaded box end profile is threadably engaged on the threaded pin end profile, and the ring cutout is sized and shaped to receive the isolating ring after the second non conductive coating has been applied thereto; and the recess formed in the isolating portion such that the recess prevents the cylindrical box body (101, 102) from making contact with the cylindrical pin body nearby the isolating ring when the threaded box end profile is threadably engaged on the threaded pin end profile with the isolating ring located therebetween.