|Western Electric Type 201A|
|The Western Electric type
201A tube was introduced in 1917, primarily for sale to the U.S. Navy,
which designated it as the CW-186. It used a 3 contact sheet metal
base which was filled and sealed with a reddish wax compound, as seen in
the bottom picture. The metal base provided the fourth
contact. It was similar in fuction and, possibly, interchangeable
with the DeForest CF-185.
Very typical of early Western Electric tubes was the support structure which consisted of a glass "arbor". Unfortunately, the arbor in this tube is broken near the base, a common problem. While this wouldn't necessarily make the tube unusable, it did allow the elements to move around more than they should, altering the electrical characteristics, and causing shorts.
There is no connection between this tube and the 201A type introduced in the 1920's.