"Portable" radios first started to appear in numbers in the
1930s, although a few innovative portables did appear as early as the mid 1920s.
These early sets were quite bulky and heavy and by today’s standards, were
portable in name only.
This is the view inside the Global miniature portable. The components are tightly packed together.
Some of those original sets used 2V valves and required a 2V
wet cell (A battery) for the filaments. They also required around 135V from a
dry battery pack (B battery) for the high-tension (HT) plate and screen
voltages. Certainly, people had to be serious about their desire to have radio
"wherever they went". Radio stations of the time were fairly low-powered and
programming was limited, which restricted the usefulness of early portable
In addition, the battery requirements were quite onerous. The
wet cell required regular maintenance and care, including measuring the specific
gravity of the electrolyte, keeping the top clean and dry, recharging it at
regular intervals and making sure the set was not tipped over.
Tipping the cell (battery) over meant that acid would leak out
of the battery and damage the set as well as the battery itself (sulphuric acid
is quite corrosive). By contrast, the better designs used dry batteries for the
filaments, usually two 1.5V cells in series. The 2V supply for the valve
filaments was obtained simply by connecting a resistor in series with this 3V
The dry batteries used for the HT supply required no special
maintenance. However, they were heavy and expensive to replace.