With the easy and cheap availability of parts by Internet mail order, it’s easy to forget that acquiring electronic components was once a more tedious process, and it was common to use salvaged parts because they were what you had. Scouring a panel from a dumpster-find TV for the right resistor may now be a thing of the past, but it’s not entirely dead. [Ryan Flowers] was lucky enough to score a box of old CB radios at a garage sale, and takes us through a teardown in search of parts he can use to make a QRP amateur radio rig. Delving into aged electronics is right up our street!

An IF amplifier was high-tech back in ’75.

A possibility for a 27 MHz CB rig is to convert it to the neighbouring 10 m amateur band, but since these were all AM rigs, a mode that sees very little amateur use, it was better to part them out. It’s an interesting study in the evolution of radio design, as an entirely analogue design of mostly discrete components is revealed.

Careful inspection of the photographs reveals a Fairchild uA703 5-transistor IF amplifier chip in a metal can, but that’s about as high-tech as it gets. Unexpectedly there is a huge bank of crystals rather than the frequency synthesiser that would have been standard only a few years later.

He comes away with the chassis, switches and pots, and the RF inductors and crystals from the PCB. Those miniature Toko inductors used to be a common sight, but are now something of a rarity. If you fancy a wallow in semiconductors from this era we’ve previously taken a look at the vintage Fairchild catalogue, in which the uA703 is on page 398.




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