I doubt that Radio Shack has one with Duty Cycle range.

As far as the thermo couple goes, they are all the same. All a thermocouple consists of is two dissimilar metal wires, one iron and one constantine. When I worked in a burn in house we would simply tin the ends of thermocouple wire which was these two wires in the same sheath and twist them together. It was absolutely as accurate as the thermocouples that we could pay more money for. So, electrically they are all the same as long as they will plug into the meter.

Good luck,