Apco Manufacturing Company, Providence took over the Auto Parts Company of Providence on June 1st 1917 with the capitalization of the new company of $200,000 as compared to the $30,000 of the Auto Parts Company. 1
Apco itself was started 8 years earlier by Thomas F Wilson with it's main business being a large line of specialties for Ford cars.
The 1921 3 and 1924 4 Providence House Directories list Apco's address at 1200 Eddy St. In 1924 there were two trademarks granted to Apco for Battery Charges (193,794 - May 17th) and Current Rectifiers (204,580 - December 30th) 2 In the 1925 Rhode Island Radio Fan's handbook, Apco was listed as making Battery Chargers and Apco Rectodyne, a radio battery eliminator.
In 1927 the company merged with the Frank Mossberg Company (Founded in 1899), a maker of automotive specialty tools, becoming Apco Mossberg which is still in businees today.
APCO plant in Providence. 1926
APCO Twin Tube
The Apco Twin tube was produced by the Apco Manufacturing Co. of Providence, Rhode Island, ca. 1925 5 . We see mention of the tube in a a Radio Broadcast article in July 1926 7 and in an article on new products in August of the same year. 6 .
Apco Twin Tube
From the collection of
Bill's Vintage Tube Site
Bill Condon's discription of the Twin tube is: "The Apco Twin has a single triode section but uses an "M" style filament that is center-tapped. Metal tabs on the base allow selection of either half of the filament, or both halves at once. Using one half resulted in '01A performance. If both halves were used at once, the tube could be used as an output tube."
Then in the "Saga of the Vacuum Tube" book the discription says: "The Apco Twin Tube was made by the Apco Manufacturing Company of Providence, Rhode Island, in the period 1925-1926. It contained two complete sets of 201A-type elements. These were connected in parallel ex-cept for one end of each filament. When the first filament failed, the second one could be brought into service by slightly unscrewing one of the filament prongs so that a switch arm could be moved from one contact to another. This brought the second filament into the circuit. Each filament took 0.25 ampere at 5 volts. The base was of the UX type and the only identification on the tube was an oval black paper label on the glass bulb with the words "Apco Twin Tube." At the left of the trade name "5 volt" and to the right ".25-amp" were printed—all in dark red on the black label."
So it looks like there were two versions of the APCO Twin tube.
Click to enlarge
The Antique Wireless Association Old Timers Bulletin, June 1974.
1 Hardware Review, June, 1917
2 Index of Patents Issued From the United States Patent Office, 1924
3 1921 Providence House Directory
4 1924 Providence House Directory
5 The Multivalve Tube and its Applications
6 Radio Broadcast August 1926
7 Radio Broadcast July 1926