The familiar Western Electric 216-A first appeared in 1922 as a component of the W.E. 7A amplifier set. The initial design was taken from the 101-D, with the only difference being in the filament voltage. The 101-D was intended to run at 1 amp at about 4.5 volts, but the 216-A was designed for operation at 5.5 - 6.0 volts at 1 amp. The higher voltage rating allowed this tube to be run from a storage battery without a rheostat or dropping resistor. Gold tips were not used on the pins, as were the normal telephone tubes.
Fig. 1 shows the first version of the 216-A. The flat plates, glass arbor, and general internal construction is that of the 101-D. In Fig. 2 the base markings of this same tube are shown. The base used was that of a 208-A, with the number marked out. One patent date, 4-27-15, has also been milled out. The actual type number, 216-A, is stamped into the wax fill in the bottom of the base. This construction was only used briefly, and the tube shown is rather scarce. The second version is pictured in Fig. 3. The internal structure has been redesigned to a form somewhat like that used in the VT-1, but with wider spacing between the elements. The base is the same as shown in Fig. 2, but with one additional patent date, 10-5-20, marked out. The type number is stamped in the wax fill and is also printed on the paper label wrapped around the glass just above the base. The paper band also carries a notice restricting the use of the tube to the "Western Electric Loud Speaking Telephone Outfit". This version of the tube, while not common, is seen from time to time but can be overlooked if the base markings are not checked.
The 216-A finally got its own base design when the tube in Fig. 4 was released. The type number was stamped in the base and two new patent dates added, 6-24-19 and 1-27-20. The paper band with the license notice is still used, and the number is also stamped in the wax fill. This tube, and the next to be described, are the types normally encountered by collectors. Unlike most Western Electric tubes, the 216-A was available for sale to the general public and is now one of the easier of the early W.E. tubes to find. The next version was like that of Fig. 4 but with new base markings. The patent date 6-13-22 has been added, and the paper band has been deleted. The license notice was stamped into the base as shown in Fig. 5.
The last version is shown in Fig. 6. The base has been changed to bakelite with incised markings. This construction appeared in 1926 and featured a redesigned grid; the original ladder grid being replaced by a newer oval shaped element. The base pins were changed to brass and made longer, but a shell type UV socked was still needed. Gold tips were added to the pins, an improvement that none of the earlier versions employed. Manufacturing was stopped in the late twenties as shown by a Bell Labs table of vacuum tubes dated 4-22-29. This document listed the 216-A as "no longer made". At some later date further production was made, as other W.E. records indicate that manufacturing was discontinued in 1944.