This tube is identical to the CT199 made by the parent company in the USA and is probably an import from them. The tube box is clearly marked Cleartron London and Birmingham. Page 17 of the "British Radio Valves The Classic Years:1926 - 1946" lists a CT199 with a B4 base. This might be an error.
Abmessungen (BHT) inkl. Stifte/Spitzli
x 84 x 25 mm / x 3.31 x 0.98 inch
Gewicht
26 g / 0.92 oz
Literatur
-- Collector info (Sammler) Banneitz, TB der drahtl. Telephonie u.Telegr. 1927
Wireless World (The), London (WW, 79) Cleartron Advertisement: September 30 1925
