Fig. 302 - The breedboard assembling.
The first factory made receivers was built using the breedboard approach. Therefore, soon due to the evolution of electrical components as the resistors, capacitors, transformers, loudspeakers and the thermionic valve, the breedboard
Fig. 303 - A typical electro-mechanical assembling showing the allocation of the tunining scale or dial.
technique was replaced by the metal chassis that improved so much the receiver’s components electro-mechanical assembling.
Originally the metal chassis was made employing several mechanical processes, such as: stamping, punching, bending and soldering; finally, for aesthetic and protection purposes, it was coated with an electroplated zinc layer. Fig 302
Essentially the chassis design should be mechanically and electrically practical in such away to improve the receiver operation. In this way,
Fig. 303A - An early type of dial or tuning scale.
the tunning scale or dial should be allocated for an easy reading. Due to circuit innovation the tunning scale was provided with the first mechanically operated tunning indicators, later replaced by the
Fig. 304 - The transistor era brought a new technique in the electro-mechanical assembling – the printed circuit board.
well-known magic eye, requiring more functional and rationalized design. Fig. 303
Yet, the receiver’s control ergonomy was deeply related with the cabintet design for an easy operation through the use of proper knobs.
In the early 1950’ transistor started a revolution in the electro-mechanical assembling due to the miniaturization of components as well as the introduction of the printed circuit technique. Fig. 304
Therefore the aforeseen innovations gave birth to a new family of materials, since then a perenial research task in the electronic industry. Fig 305

Fig. 305 - The on line radio receiver electro-mechanical assembling.