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Vintage Radio

The Astor P7G 8-Transistor AM Portable Radio

By Rodney Champness

Domestic transistor radio manufacture in Australia commenced in the late 1950s. The first sets were built in much the same way as valve radios. Point-to-point wiring was common (ie, they didn’t use printed circuit boards) and in some cases, the transistors were plugged into sockets just like valves had always been installed.

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By contrast, the Japanese started with crude printed circuit boards (PCBs) right from the onset of transistorised receiver manufacture. As a result, Australian manufacturers initially lagged behind the Japanese in their construction techniques before adopting phenolic printed circuit boards.

Like many, I wasn’t initially all that keen on PCBs as it was often difficult to be sure which track a particular component was wired to. Instead of following point-to-point wiring, you had to try to work out the connections by examining both sides of the board and this could be rather difficult on a tightly-packed board.

Apart from that, early PCBs also suffered from a number of drawbacks. They were somewhat hygroscopic (ie, they absorbed moisture), were easily charred if components overheated and the copper tracks lifted off the board if too much heat was used during soldering.

Hairline cracks in the tracks were also common and caused many intermittent faults. They were almost impossible to see and if a serviceman suspected such a problem, the cure was to run solder right along the suspect track. This sometimes involved laying a very thin wire strand along the suspect track and soldering it at various intervals until the fault vanished.

These servicing techniques largely overcame the problems with early boards. And of course, as time went by, the various issues were addressed and the quality and durability of the boards improved.

Japanese receivers

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Most of the circuitry is built on a main PCB, with a separate small board used for the RF stage. These are mounted on a metal chassis, along with the tuning gang, dial-drive mechanism, loopstick antenna and the loudspeaker.

The performance of the early Japanese transistors receivers wasn’t all that good. They were noisy and not very sensitive and that situation continued for many years.

Of course, the Japanese were catering for a world market where listeners generally lived close to local radio stations. By contrast, many Australians lived some distance away from radio stations, so sensitivity was important.

As a result, Australian manufacturers produced many sensitive, low-noise receivers to suit the domestic market. However, despite their technical superiority, they eventually lost the battle for market share due to the low cost of imported receivers. As a result, domestic receiver production slowed and eventually ceased in the 1970s.

There was no point making receivers if no one bought them, even if they were superior in many respects!

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