ESI Electro Scientific DT72A Dekatran Standard Decade Transformer

The DT72A Decade Transformer Standard is a laboratory standard, transformer-type ac decade voltage divider having 0.1 ppm resolution with a seven-dial readout. Direct-reading current division with very high accuracy can also be achieved. The accuracy of each transformer is verified by precise calibration tests. The primary standard of voltage division is a special NBS calibrated transformer divider (calibration not included).  Llinearity is established by comparison with this divider. Tests show linearity of the DT72A to be about 0.1 ppm at 400Hz

Frequency: 50-20,000 Hz

Range: -0.01111111 to +1.1111110

Resolution: 0.00001% (0.1 ppm)

Max rms Input Voltage: 0.35 (f in Hz) or 350V, whichever is less

Max Input Current (DC): no DC current should be permitted, DC input of 20 uA will decreas AD input voltage rating aobut 10% and increase distortion slightly.  200 uA will cause near saturation of core, and serious errors.

Imput Impedance: approx 500kOhm at 400 Hz, typoical range of measured values for various dial settings, frequencies, and voltages shown in curves.

Max Phase Shift: approx 0.05 mrad/kHz for settings above 0.1