For mechanical contractors, fabricators, and maintenance/repair personnel who work in the field and demand a full-featured stick/TIG welding power source, the Maxstar 150 STH is available. This DC stick/TIG inverter features built-in high-frequency or LiftArc TIG arc-starting capabilities, four pre-set pulsing programs, and the company's Auto-Line primary-power-management technology. The Maxstar 150 STH weighs 13.7 lb., has a 5 to 150-A welding range, and offers a powerful per-pound for any unit in its class. It includes adaptive Hot Start to improve stick-arc starts, selectable trigger configurations for weld --se-quence control, a built-in gas solenoid valve to reduce torch weight, and a design that reduces open-circuit voltage to 15 V when not welding. High-frequency starting is noncontact starting that eliminates tungsten or material contamination. Welding codes in some applications, such as process piping in the nuclear power industry, require non-contact starts. When in the pulsed mode, the machine pulses the welding current between the set amperage and a value that is 50 percent of that. Pulsing frequency is fixed at 0.5 pulses per second, 1.0 pulse per second, 2.5 pulses per second, or 60 pulses per second. Pulsed TIG welding reduces total heat input to prevent warping or burn-through in heat-sensitive applications. It also improves bead aesthetics, helping create the stacked dime look. The unit can connect to 115-30 VAC single-phase power, ±10 percent without linking mechanisms of any kind. It also maintains a steady arc even if the primary power varies when welding. It over-comes dirty power, and the unit draws 35 percent fewer amps than other machines, which reduces nuisance tripping, especially when connected to 115V primary.