Murphy A30 Receiver

 This Murphy superhet radio from 1936 has a look which is typically Murphy. Their sets looked quite different to those of their competitors and this had been the case from their first to their last wooden-cased radio.

 

 Behind the rear cover the layout looks perfectly symetrical. The valves currently fitted are, from left to right... all have 4-volt heaters.. AC/TP RF amp/mixer/oscillator (B9 base), AC/VP IF amp (B7 base), AC.2.PEN.DD audio output (B7 base) and an MU14 rectifier B4 base (marked also MWT and CV1039). This rectifier has a much better rating than the original balloon-shaped UU3 which it's replaced.

Wiring has cloth covered cabling so when the many years have passed won't result in short-circuits like the rubber insulated variety.

 

 The set has a clear, nicely printed, dial showing long and medium wavelengths.
 
 

 Here are the various labels and markings on the set. The maker's label shows that this model was designed for 200-250 volt, 50-100Hz.

Although the serial number is given on the label two different numbers are to be found on the rear of the chassis.

 

 

 
   
 Note the terminals marked "FIELD". This connects the loudspeaker energising field coil L13 so that it's in series with the HT current to the valves. The coil is fed by the earthy end of the HT supply which will have the advantage that its potential is much the same as that of the chassis.

 

The internal loudspeaker carries plugs so it can be disconnected if an external speaker is used.

 

 

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