Philips model 291A, 1939
This radio features a drum dial and a complex system of bandspread tuning. It is very popular with contemporary collectors with ‘ham’ pretensions.
The main SW bands each have 2 regions that can be 'spread'. When the main tuning is tuned to the proximity of one of these, a cam switch energises a green lamp. The tuning control can then be pulled out, lighting a red lamp and selecting bandspread.
The position of the main tuning control determines which bandspread region for the applicable main SW band is selected. The separate bandspread tuning knob, actuating a second tuning capacitor, then fine tunes the oscillator. At that stage the main tuning capacitor is still active and can be used to peak the RF and antenna tuned circuits.
Variable IF bandwidth and sensitivity are selectable.