Abstract: A device is disclosed for the heat processing of cables, wires, fibers, and the like which is small, light, and configured to be disposed temporarily directly on the cable to be heated in situ. Typically the device comprises a heat generation element or elements and supporting shells arranged so as to form an elongated cavity, a housing to provide an insulating enclosure around the cable so as to form a heated chamber, temperature sensing means to monitor the heating for closed-loop control, and means to enable the heater to hold itself onto the cable or wire in situ. Power and control means with electrical processing capability are provided to supply power to the heater, monitor the temperature inside the heater cavity, and govern the time and temperature which the device applies to the cable or wire in order to process it, for instance to apply a heat shrink sleeve.