G.E.C. AVC 5
Pictured above is the G.E.C AVC5, or BC3540. As the model name of the receiver suggests, this was the first radio from G.E.C to incorporate Automatic Volume Control (AVC) circuitry. The set is housed in a horizontal cabinet of a pleasing design. The grain of the veneer is very prominent, and veneer cross banding has been applied to the edges of the cabinet front. Particularly effective is the fretwork speaker grille, with GEC's "jagged" speaker cloth behind it. Like the Superhet 5 seen previously, GEC is still using the brass tuning scale surround. However the tuning scale itself is a kind of acetate much like that favoured by Ekco around 1934/5, and is showing similar signs of contracting over time.
The stations names are marked on the scale, and a separate lamp illuminates behind the scale depending on whether MW or LW is selected, with green for medium wave and red for long wave. A band of coloured light about 1" high moves up and down the scale as the tuning knob is turned, and centrally positioned within the block of colour is a single white line that highlights the actual station tuned in. The block of colour is very vivid as hopefully can be seen in the photograph above (bearing in mind a flash was used for the picture which normally washes out illuminated light).
One interesting feature of the circuit is that although an AC only set, with apparently no AC/DC version available, "Universal" valves are utilised by the circuit designer. The Osram "30" series of valves have been used which all have 13v heaters, the heaters being connected in parallel and fed from a 13v tapping on the mains transformer. (obviously not the MU14 rectifier ). Valve line-up is X30, W30, DH30, N30, MU14. Note that the W30 and N30 are Osram "Catkin" valves. "Catkins" were a short-lived valve construction type, the concept only lasting a year or two. However the N30 output valve "Catkin" may also be seen in the photo below right. Also shown in the picture above right is the knob to disconnect the internal speaker, this being provided on the back of the receiver. A frame aerial could be wound on the back of the receiver around the disks seen on the cabinet back.
Continue for the G.E.C. AC Mains 4
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