A high temperature calibration furnace comprising: a core having an elongated central test cavity for testing/calibration of a temperature-sensitive component, the core having at least three electrical heating elements adjacent to the test cavity for heating of the test cavity by a supply of electrical power to the heating elements, the heating elements including a first end heating element adjacent to a first end portion of the test cavity, a second end heating element adjacent to a second end portion of the test cavity opposite the first end portion thereof, and a center heating element between the first and second end heating elements (50, 52); and control circuitry for managing the supply of electrical power to the first, second and third electrical heating elements (50, 52, 54), the control circuitry having operating means for periodically configuring interconnections (68, 70, 72) of the first, second and third heating elements (50, 52, 54) during multiple phases of a duty cycle, including a first phase in which the operating means is capable of configuring the interconnections (68, 70, 72) such that electrical current is passed through the central heating element, a second phase in which the operating means is capable of configuring the interconnections (68, 70, 72) such that current is passed through the first and second end heating elements (50, 52) in series, and a third phase in which the operating means is capable of configuring the interconnections (68, 70, 72) such that current is passed through one of the first and second end heating elements (50 or 52) and also through the central heating element without passing current through the other of the first and second end heating elements (50 or 52). a core having an elongated central test cavity for testing/calibration of a temperature-sensitive component, the core having at least three electrical heating elements adjacent to the test cavity for heating of the test cavity by a supply of electrical power to the heating elements, the heating elements including a first end heating element adjacent to a first end portion of the test cavity, a second end heating element adjacent to a second end portion of the test cavity opposite the first end portion thereof, and a center heating element between the first and second end heating elements (50, 52); and control circuitry for managing the supply of electrical power to the first, second and third electrical heating elements (50, 52, 54), the control circuitry having operating means for periodically configuring interconnections (68, 70, 72) of the first, second and third heating elements (50, 52, 54) during multiple phases of a duty cycle, including a first phase in which the operating means is capable of configuring the interconnections (68, 70, 72) such that electrical current is passed through the central heating element, a second phase in which the operating means is capable of configuring the interconnections (68, 70, 72) such that current is passed through the first and second end heating elements (50, 52) in series, and a third phase in which the operating means is capable of configuring the interconnections (68, 70, 72) such that current is passed through one of the first and second end heating elements (50 or 52) and also through the central heating element without passing current through the other of the first and second end heating elements (50 or 52).