A year earlier, the company began to manufacture octal radio lamps in a metal housing and this contributed to the simplification of the chassis design and its reduction in cost, as there was no need to shield the lamps from radio interference. As a result, the set of radio lamps (6K7,6A8,6J7,6K7,6H6,6E5,6F5,6F6,5Z4), which the company used in this model became the most popular in the world for the next 10 years.