The WD-11 vacuum tube, a triode, was introduced by the Westinghouse Electric corporation in 1922 for their Aeriola RF model radio and found use in other contemporary regenerative receivers (used as a detector-amplifier) including the Regenoflex and Radiola series.
|Socket:||UV4 (also known as WD-4-Pin)|
|EIA/RETMA Base Diagram:||4F|
|Description:||Detector Amplifier Triode|
|Filament:||Directly-heated 1.1 V||0.25 A|
|Plate (anode) Voltage:||90V||135V maximum|
|Plate Current||2.5 mA||3.0 mA|
|Plate Resistance:||15.5 kilohms||15 kilohms|
|Amplification Factor (mu):||6.6||6.6|
|Transconductance (gm or S):||0.425 mA/V||0.44 mA/V|
|Power Output: (Po):||0.007 W||0.04 W|
|Grid-plate Capacitance (Cga):||3.3 pF|
- RCA Receiving Tube Manual RC-13. 1937. p. 98.
- RCA Receiving Tube Manual RC-14. 1940. p. 157.
- "Miniwatt" Technical Data (6th ed.). Australia: The "Miniwatt" Electronics Division of Philips Electrical Industries Pty. Limited, N.S.W. 1958. p. 56.
- "WD 11". Retrieved 7 January 2013.
The WD-11's design was somewhat ill thought out, when the filament burns out it has a tendency to contact the plate, feeding high voltages back through the heater circuitry. It was replaced just a year later by higher performance tubes which were less likely to encounter this problem, Westinghouse Electric's WD-12 and General Electric's UX-199. No radios using the WD-11 tube were designed after 1924, RCA ceased production and issued a service bulletin describing how to retrofit existing sets to use the newer UX-199 triodes.
Because of its rarity it has become one of the most valuable vacuum tubes in the world. New-old-stock units have sold for as much as US$180 and used tubes for over $100, more than the original price radios that use them. Collectors rarely, if ever use these tubes for fear of burning them out.
Sets that use the costly WD-11 and UX-199 tubes can be modified to use the 1A5/GT octal power pentode (Which cost around $2.50) by wiring a 5.1 ohm resistor between the pins of the filament and fabricating an octal-to-four pin adaptor. The pin for the 1A5's suppressor is left unconnected and the screen connected to the plate.
The type 12 (also known as RCA-12) is electrically identical to the type 11, but with a more common UX4 base.
Here is a link on how to modify other tubes to use in place of a wd11: