They predominantly designed and manufactured domestic radio receivers—of which their two main brands were distributed through their nationwide chain of Columbus Radio Centres (Columbus) and through Turnbull & Jones nationwide branches (Courtenay)—although they were also known for test equipment, intercommunications devices, RACOL wire and the TANZA recording label and more.

In November 1926, William Marks (formerly Markov), a Russian Émigré with an honours degree in Electrical Engineering, stepped ashore in Wellington, New Zealand.

[2] In 1929, Marks went into business for himself, opening a small shop in Cornhill St, Wellington, supplying basic radio parts and equipment, building amplifiers, rewinding transformers and other related activities.

At the same time, they opened a nationwide chain of Columbus Radio Centres to retail and service these new sets.

[20] Over the next year, the lab staff would discover ways to make it more cost-effective, and give it rock solid stability.

Radio Corp would make a wide range of products including Sten Guns, EPS (Emergency Precautions Scheme) helmets, two different models of amenities receiver (the AEW1 and AEW2), and the ZC1 military transceiver.

[11] With the resumption of peace, the company would pick up where they left off in 1942, producing models they had previously developed mixed with some new designs.

[25] The RACOL line would survive not only two changes of ownership of the company, but several subsequent brand owners—on into the present day.

Marks' son, Alex (who had worked closely with his father over the previous few years), would take over the Managing Director role.

This first record was very well received by the New Zealand public, selling over 50,000 copies,[27] quite an achievement for a new label in such a small country.

This was seen by many in the firm as a betrayal of the company's founding family, and many key staff members would leave in the coming few years.

[35][36][37] The Columbus name was originally used as their export brand, but after a brief and unsuccessful foray into Australian retailing, those efforts were abandoned.

[43][44][45] 1937 would be the final year of Radio Corp production for all brands except for the two they owned (Courtenay and Columbus)—and as a consequence, Anderson would resign from the board and close his company.

The Pacific name and branding would be picked up by one of the other major New Zealand manufacturers, Akrad Radio Ltd in Waihi.

Hope Gibbons would go on to be New Zealand agents for Stewart Warner, and according to board meeting notes, discontinued their CQ radio line in early 1937.

Philips would have models made through until 1936, when they opened their first factory in Wellington and began to make their own radios.

From 1934, Wyn appears to have made his own radios, possibly in the old W. Marks Ltd premises in Cornhill St.

The business was known as The Billings Radio Construction Company Ltd, and also seems to have been tied up with the Moderne brand and its owner, 'Mack' MacDonald.