Medium-Mu Triode
The 227 / UY-227 Vacuum tube is a glass type used as a
voltage amplifier or detector in
AC-operated receivers. It requires a five-contact socket.
H.W. Freeman, of Westinghouse Electric & Manufacturing
Company, in an article published in December 1922,
described an indirectly heated cathode tube which was
double ended. A.M. Nicolson, of Western Electric,
constructed indirectly heated cathode tubes in 1914
(see Chapter 6). In July 1925 samples of Freeman's tube
were submitted to RCA. In April 1926 more samples were
obtained. In June 1926 the designation UC225 was
assigned to this tube, and RCA placed orders for 1000
tubes at each of the three tube factories. During
November Westinghouse suggested the use of a five-pin
base to eliminate the necessity for the adopted for
detector applications, and the five-pin base was
aproved. With the adoption of this base the desigantion
UX225 was changed to AY225 and then for commercial
reasons to AY227, and finally to UY227. On May 21, 1927,
the UY227 was announced in New York newspapers. ... The
first UY227s had sheet-metal anodes and were subject to
grid emission difficulties. Westinghouse engineers
suggested that the use of a mesh anode would eliminate
this trouble, and the change was soon made. Shipments
to RCA began early in the Summer of 1927. ~ Written by
Tyne page
Electrical Data:
Heater Voltage ................................ 2.5 V
Heater Current ............................... 1.75 A
Preferred Substitutes ..... 27, 227, 227E, 57T227, A245, AX227, C227, C245, C-427, CX345,
D227, DE-1, ER227, EY227, GSY227, GY227, LS227, NU-27, P227_USA, SLY227, T27, UY227,
UY-227_Japan, Y227, Y227AC.
Substitutes ... 56