The Decca model 919 is a two wave-band AC superhet released in 1935. All the controls are operated from a single knob (actually two concentric controls). The inner control is volume and mains on/off, and pulls out to change the wave-band. Provision is made for connecting a gramophone pick-up.
When the set is used on "gram", the tuning (outer) control is turned to its minimum wavelength stop, where it operates a switch to silence the radio.
The valve line-up is:
MX40 Frequency changer
AC/VP1 (or VPM46) IF amplifier (IF = 130kHz)
AC2/PenDD Detector and output
A11D (or equivalent) Mains rectifier
The circuit is reasonably conventional, although AVC is applied to the frequency changer only on the long wave-band. The second IF transformer in the anode of the IF amplifier is single tuned.
The loudspeaker is mains energised, with the field coil providing HT smoothing.
The electric gramophone pick-up is connected into the grid circuit of the IF valve when the radio operates on "gram".
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