Some of the first battery portables used a 2V wet cell and either two or three 45V batteries to power them. They were awkward, heavy sets and were ill-suited for portable use – not surprising considering that they were no more than adapted domestic home sets.

However, the public was keen to really get "with it" in those halcyon days of radio development. Experimenters and manufacturers could see that there was a market for compact, portable receivers and they set about producing specialised designs.

The advent of valves specifically designed for use with 1.5V dry batteries and 90V high-tension (HT) rails meant that the battery size and cost could be reduced. As a result, a new range of battery-powered portable radios appeared in the 1930s using octal-based valves, such as types 1P5GT, 1A7GT and 1D8GT. These sets were more convenient to transport, smaller and less costly to run than their predecessors.

But that wasn’t the end of the improvements. At the end of World War II, the appearance of miniature 1.4V filament valves such as the 1T4, 1R5, 1S5, 3S4 and 3V4 meant that portable receivers could be made just that little bit smaller again. In addition, the intermediate frequency (IF) transformers were now more compact thanks to the use of improved ferrite materials and iron dust cores and shields.

Batteries like the Eveready No.482 45V unit were also introduced around this time. This unit featured a layer method of construction for the individual 1.5V cells, resulting in a battery that was more compact than its predecessors.