Brass medium screw base with skirt, domed glass insulator. A glass plate mounted in the center with a metal plate on each side. A coil (ballast?) is inside the stem. Tipped, T-shaped envelope. Stamped on side: "Osram Schriftgfimmlp", near base: "303[circled 1]6-8W.210-230V."; stamped on base skirt: "2.22".
VT-2 tube with envelope. Audion is being used generically here. Brass 4-pin base (gold tips on tines) with bakelite insulator, two plates and grids with one emitter. Stamped on the shell: "Pat. in U.S.A. / 1-15-07 Two patents / 2-18-03 4-27-15 / 12-19-16 / Pat. Applied For". Reference: Tyne, "Saga of the Vacuum Tube" 100-103, 286-287; https://www.radiomuseum.org/tubes/tube_vt2.html.
A plastic four-pin base with binding post on side. Tipless S-shaped envelope mostly silvered on inside. Stamped on one side: "Mullard / Pentone / Registered Trade Mark / PM24 / BVA". BVA is British Valve Association, a trade consortium. On other side: "Registered Trade Mark / Radio Mullard Valve / Protected By Patent / KB / Dummy." "A" molded on base near one pin. Philips-Mullard, See Reference: Tyne, "Saga of the Vacuum Tube," page 377-379.
Sold by Electro Importing Co., manufactured by H. W. McCandless & Company. An audion-type triode mounted on a wooden base. Five binding posts on base. Tube contains 2 filaments, 1 grid, 1 plate. Label on bottom reads: "M-13523-V.17 / Assembler - No. 15 / Finished this instrument / Any Defect should be / Promptly Reported to / Electro Importing Co. / 233 Fulton St., N.Y.C. / [F]oreman's / Ins[pection?]". Reference: Tyne, "Saga of the Vacuum Tube," 107-114, 185-188.
VT-2 tube with envelope. Audion is being used generically here. Brass 4-pin base (gold tips on tines) with bakelite insulator, two plates and grids with one emitter. Stamped on the shell: "Pat. in U.S.A. / 1-15-07 Two patents / 2-18-03 4-27-15 / 12-19-16 / Pat. Applied For". Reference: Tyne, "Saga of the Vacuum Tube" 100-103, 286-287; https://www.radiomuseum.org/tubes/tube_vt2.html.
An audio frequency vacuum triode in original box. A 4-pin plastic base with tipless S-shaped envelope, partly silvered. Stamped on base: "RCA / Radiotron / UX226". References: Tyne, "Saga of the Vacuum Tube," page 319; https://www.radiomuseum.org/tubes/tube_ux226.html.