Abstract: A heating device for use in laboratories and the like comprising an oven housing having a magnetron tube, power control circuitry for the magnetron tube, a timer for determining an amount of pulse power for the magnetron tube, a settable heating time switch with display, a settable venting time switch and display, and magnetron tube resistance heating structure directly, physically attached thereto with thermostatic control therefore for accurately, and by a predetermined amount, heating the magnetron tube prior to operation of the overall heating device. Because the temperature of the magnetron tube is very accurately maintained all of the changeable operating controls for the magnetron respond predictably and with a high degree of accuracy, and therefore when the heating device is used in laboratory applications for heating and drying a plurality of samples individually, each sample can be predeterminedly heated and dryed in a predicable manner like the previous samples.