Royal Radio Tube Co.
3741 Woodland Ave, Cleveland, Ohio

This company was owned by Clara Quinn and made three renewable tubes invented by her in the late 1920's. 

Clara E. Quinn was a fairly accomplished engineer (unusual for a woman in the 1920's). She worked in the lamp making factory of GE at "NELA Park", Cleveland, from as early as 1899 and had several patents in later years, from 1936 to 1950, relating to refrigeration. She was a single parent, being widowed in 1910. She was also a qualified accountant. 

It was reported in the "Radio Retailer and Jobber" in June 1929 and Popular Science, May 1930 that she had invented a tube which had a renewable filament. Syndicated newspapers around the US also carried this story. She is shown in several photos holding one of the tubes. In addition to the Quinn Radio Tube Co., she formed the Royal Radio Tube Co. Three tubes are known to have been utilised to have the newly developed replaceable filament. These were the 171A, 226 and 227.

The renewal process inviolved three years of experimentation before a successful element was perfected. The new filament was referred to as a "darning needle" in some articles and consisted of a small triangular bakelite plate with two filament pins in place. These were connected to the new filament which was of well insulated high resistant wire in a hairpin form. The filament was designed to burn in the open air ad in turn would heat the cathode. The filament assembly was held in place by a small screw. 

The patent for this tube was applied for on October 9th, 1928 and issued as No 1,877,708A on September 13th, 1932. The applicant was Walter J West and the assignor was the Lucian Tube Corp. A summary of this patent is shown on page 594 of the Official Gazette (from the U. S. Patent Office). Nothing in the reference material located shows any connection between West and Quinn or Quinn and Lucian. 

The July 1929 issue of "Radio Retailer and Jobber" does link the Royal Radio Tube Co. and Lucian Tube Corp. in their failed joint attempt to buy the Federal Radio Corp. of Buffalo, NY. If successful, the new tubes were to have been used in Federal radios.