[PJL]

I need to make some plug-in coils for this beast. It dates from 1925 and has an unusual tuning method. The coil sits over 'gyroscope' tuning mechanisms which rotate the inner ring between perpendicular and parallel to the coil. Each gyroscope operates a switch which connects a capacitor in/out of circuit so that the rotation on either side of the perpendicular position cover different frequencies. The 'gyrscope' is not connected to anything so I assume the tuning is by changing inductance from the introduction of the shorted turn which explains why they need the 'rejector'.

The tuning dials are marked Aerial and Anode. The Aerial appears to use the aerial capacitance for resonance and switches a series capacitor in/out. The Anode I am still checking but I think this is more conventional with two capacitors in parallel one being shorted by the switch.

The capacitors are wirewound! The big black box contains a conventional tuned circuit used as the 'rejector' for strong stations. It's very dirty (you can see where I have washed the rejector cover) and the cabinet is a bit scratched about but it has potential!

Valves in place were an eclectic mix of Mullard PM3. Cossor Point One RC, Unmarked, and Mullard AC104, but I will swap these out for 2V PM series. The grid resistor is 3M and should be 1ohm (1920's for 1M!). The interstage transformers are both good. All the square wires look to be in place.

Where to start? The coils are pretty big so I would have thought about 30 turns will be more than enough. I am just drawing out the circuit.