Radio Valve Data: 1915-1960

Note	Definitions
(1)	The letters indicate the three types of filaments found on these valves. B = bright emitter, D = dull emitter, O = oxide-coated.
(2)	The year shown is when it is believed the type was first issued. This date is accurate for most types but cannot be guaranteed for them all.
(3)	For details of the valve bases and connections to caps or flying leads see pages 20-21.
(4)	These valves may be found with any of the following trademarks: GEC, Marconi, Marconi's W.T. Co. and Osram.
(5)	The earlier naval valves, which usually also had an anchor symbol printed on the glass bulb, omitted the 'N' from the type.
(6)	These valves were manufactured by several companies.
(7)	The Western Electric valves carried the Standard or STC trademark from the end of 1925. Note, however, that the STC types are always preceded by the number 4; thus, the Western Electric 101 becomes STC type 4101.
(8)	The anode and inner grid were usually supplied with the same voltage.
(9)	The outer grid is equivalent to the control grid of the triode valve.
(10)	The CA, CT, D and N were all later variants of the C valve.
(11)	The TN was a later development of the T type. Both these, and the type LT, were transmitter valves.
(12)	The last item on the list is believed to be a type T or TN.
(13)	Three types of filaments were used: platinum, platinum-iridium and tungsten.

Base	Envelope Base Caps
Horned	Two top caps for connections to the anode and grid. Mullard R8. (Navy NR8) & Horned.
4C	Two pointed end contact caps and two flat side contact caps. Marconi-Osram low-capacitance types, such as the Q and V24.
4C/1	Similar to 4C, but with a moulded base. Mullard S series.
5C	Two pointed end contact caps and three flat side contact caps. Marconi-Osram FE1 and FE2.
Side Contacts
4-SCt (std.)	Four side contacts on moulded base (standard size). Used on 'Round' type CA.
4-SCt (large)	Four side contacts on moulded base (large size). Used on 'Round' type T.
Post Office
PO-1	Large moulded base with four L-shaped brass feet. Used on V.A. no.1 and V.A. no.2.
PO-2	Similar to UV base but pins spaced at 0.5 in. Found on some early Post Office types.
Misc
S2	Two-contact base plus central hole for grid connection. On MOV type MT3
S3	Three-contact Service base used on some Army transmitting valves. For medium-power types such as AT50 and AT100.
L4	Large four-pin. Medium-power valves.
Peanut	Miniature moulded base with four bottom contacts. Wecovalve.
UV	American Shaw base having four short pins, equally-spaced, and a locating lug on the metal shell. Used by Western Electric and STC types.
T5	Special five-pin base. Not to be confused with the later British B5 type, which has a centre pin. Found on Thorpe four-electrode types.

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