Eddystone S870 Receiver



 This is another of those AC/DC Eddystone receivershat depend on complicated mechanical arrangements to keep the live chassis from contacting the outer case. Because an earth connection is made through a condenser C4, it's highly desirable to use a third mains wire, the safety earth connection which ensures the outer case or the aerial/earth wires can never be live.


 A couple of top views of the chassis showing the 4 valves plus rectifier. A twin gang tuning condenser shows the set has no RF stage in front of the frequency valve.Note extra wiring that's been added for an external speaker. The speaker wiring is isolated from the chassis but has a condenser C47 so some measure of tingling could be felt by an unwary user.


The receiver uses a set of valves which are satisfactory with series connected heaters: 12BE6 Frequency changer, 12BA6 IF amplifier, 12AT6 audio amplifier/Detector/AVC, 19AQ5 audio output and a 35W4 HT rectifier. The total heater requirement is 90 volts so the remainder for 110 volt operation is 21 volts. This is accommodated by using a pair of dial lamps, a ballast resistor and a thermistor.

Under the chassis you can see a sizeable flywheel and a neat arrangement of coils and beehive trimmers.


   Being an AC/DC receiver means no mains transformer and so voltage sellection is done via a high wattage ballast resistor. This is designed to work correctly given the current consumed by the circuit.

   The manufacturer's plate tells us that this set is an S870 from around 1956 rather than the later "A" version from around 1963.

 Return to Communications Receivers

 Return to Reception