AC Test Set

This is an electrodynamic AC Test Set model 44371/2.

This instrument was offered in various types, depending on the range values and frequency range. DC voltages could also be measured but the current ranges were limited to AC only, due to the internal current transformer.

This transformer also featured a calibration winding that could be added in-phase or in anti-phase - or left out altogether - for fine calibration adjustment of the instrument.

Very similar instruments and using the same model number sequence were also offered by H W Sullivan. An example of a late Sullivan version can be found here.

This particular AC Test Set is still in good working order.