An investigation of multijunction thermal converters

The relative ac-dc differences of a group of multijunction thermal converters (MJTC´s) have been determined over the frequency range 30 Hz–10 kHz. These MJTC´s are of different ranges and were obtained from several sources. Differences were observed at low frequencies when converters of various ranges were intercompared. For voltage measurements, the use of matched resistors in series with the MJTC heater resistors greatly reduced these errors and contributed to the reduction of other errors as well. It is believed that the average ac-dc difference of this group is less than 0.3 ppm at 160 Hz and 0.5 ppm up to 10 kHz.