Tandem subs for perforating gun systems

A tandem sub for a perforating gun system, comprising:

• a tubular housing comprising a longitudinal first end, a longitudinal second end opposite the first end, a central passage defined by an inner surface that forms a seal bore defining a minimum inner diameter of the central passage and an annular receptacle, wherein the housing is connectable to an outer housing of a perforating gun;
• and
• an electrical pass-thru assembly configured to electrically connect to the perforating gun and comprising a longitudinal first end, a longitudinal second end opposite the first end, an electrically conductive signal bar, and an electrical insulator surrounding a periphery of the signal bar;
• wherein the signal bar has a longitudinal first end defining a first electrical contact of the tandem sub and configured to establish an electrical connection with a first electrical component separate from and external the tandem sub, and a longitudinal second end opposite the first end and defining a second electrical contact of the tandem sub that is longitudinally opposite and electrically connected to the first electrical contact and configured to establish an electrical connection with a second electrical component separate from and external the tandem sub, wherein the signal bar is rigid along the entire longitudinal length thereof extending from the first end to the second end;
• wherein the insulator has an outer surface sealingly contacting the seal bore of the housing when the pass-thru assembly is installed in the housing;
• wherein one of the first end and the second end of the pass-thru assembly longitudinally overlaps the receptacle of the housing when the pass-thru assembly is installed in the housing whereby a radial gap is formed between the outer surface of the insulator and a portion of the inner surface of the housing defining the receptacle.