RADIO ENGINEER Sir Ernest Fisk play­ed a vital role in founding Amalgamated Wireless Australasia (AWA) and later served as its Managing Director and Chairman. In practice then, the Fisk Radiola 50G was really an AWA receiver.

Produced in 1939, this battery-powered receiver used either a 2V wet cell or an air cell (via a resistor) to power the filaments. These had a total current drain of 0.6A but this increased when the dial lamps are switched on. However, this extra drain was only short term, as a switch has to be held in to actuate the lights.

This view shows the excellent condition of the loudspeaker. The 761 bias battery measures 2V (down from 4.5V) and is overdue for replacement.

There’s not a lot of information on the air cells that were used in this set, other than that a resistor was needed to drop their output voltage to 2V. What little information I can glean indicates that they have a terminal voltage of around 1.4V, so two would have been used in series in this receiver.

The high tension (HT) of 135V was taken care of by three 45V batteries connected in series, the current drain on this line being 13-15mA. In addition, there was a separate bias battery (type 761) which applied -1.5V, -3.0V and -4.5V to various sections of the receiver.

By the way, a variant of the model 50G, designated the 50GV, was also available. Its circuit was almost the same but was modified to use a 6V vibrator power pack.