Experimental or developmental tubes, including types with very limited production
1DP1_Series Miniature CRT, orange screen. National Union custom made variant. Custom
2J21 Very early X-band magnetron, late 1941. Used in the early production of APS-3 airborne set. Superseded by the 2J21A and then by 725A. Rare
2J21A Improved version of 2J21. Rare
3C27 Millimicropup UHF power triode. National Union developmental. Superseded by 3C27B
3C27B Millimicropup UHF power triode. As 3C27 plus finned grid radiator. National Union developmental. Superseded by 3C37.
3C36 NU R1003 UHF power planar triode registered in 1946 to National Union. Extremely rare, this is the only known sample. Very rare
10AL1 British developmental S-band klystron likely build at the Bristol Signal School. Believed to be a transition type from the American WE 707A to the new low-profile family including CV237 and CV238. Probably EMI, 1941. Unique
175HQ Bell pentode amplifier for submarine telephone repeaters. Designed for utmost reliability, with more than 50 centuries reported data MTBF. Bell internal use only. Extremely rare
227 EIMAC VHF power triode used in early naval sets. Superseded by 227A. No data found. Rare
455A Western Electric ultra hi-rel amplifier for transatlantic telephone repeater. Succesor of 175HQ, was used in the 128 channels transatlantic SD system. Extremely rare
2154 Mullard Large window photocell
2242B Amperex photomultiplier
6090 National Union beam-switch demultiplexer. Decodes 18 sequentially transmitted channels. Rare
6324 Beam-switch selector. Intended to sequentially transmit 25 channels over a single carrier. Rare
A63-10 Diode, power. Unknown, likely a damper diode
A-103A RCA Undocumented sample of split-anode early magnetron, It can be dated around the early 1930s. Extremely rare
A-1306B RCA RCA, believed to be a developmental beam-deflection switch, usually intended for fast pulse forming circuits. Coming from a British Marconi warehouse Extremely rare
A-2212 RCA RCA developmental UHF power triode, pulse operation. Probably a prototype of 4C33. Coming from a British Marconi warehouse. Unique
C-100A Amperex-Collins electrostatic deflection oscillator designed according a 1915 patent of Robert Goddard. About 1936 Very rare
C-100D Amperex-Collins negative resistance oscillator. In 1938 replaced the C-100A. Also made the 6.3 V filament version, C-100D Extremely rare
C31007-G13 RCA developmental photomultiplier. Probably custom spectral response.
Catkin Prototype GEC developmental 'Catkin' power prototype. Special finned radiator. Looks a variant of the NT39 / CV1222 transmitting triode. Unique
CV8 Vacuum diode intended to operate as TR switch. Never in operative use, replaced by DS103 / CV94 Rare
CV11 - 10E/501 Very early British reflex klystron, NR89 'Sutton tube', about 1940. AS fas as we know, this looks to be the only NR89 survived today. See also 'Sutton tube prototype'. Coming from a British Marconi warehouse. The only surviving sample today on the web. Extremely rare
CV14 Silica valve', high emission variant of NT57T transmitting triode. Only experimental use around 1941. Very rare
CV87 - KRN2 Early British X-band klystron. About 100 units made between September 1942 and January 1943. Very rare
CV114 Early X-band TR cell. Devised early in 1942 at TRE and built at GEC. Very rare
CV150 / PK150 Experimental power pulse klystron designed by EMI to replace  NT98 magnetron in airborne missions over Germany. 1942 Extremely rare
CV208 Double Stem Very early production of GEC X-band strapped magnetron. Soon replaced by the single stem variant, compatible with BTH CV209. Extremely rare
CV208 Single Stem GEC variant, compatible with BTH CV209 Rare
CV209 BTH X-band strapped magnetron. Internal code MX57, it was interchangeable with CV108 Rare
CV214 Waveguide-flanged X-band magnetron Rare
CV230 Heil oscillator. Likely developed by Fremlin at STC for a possible use as local oscillator in radar receivers due to its low voltage operatio. Eventually the decision was taken in favor of the NR89 klystron. Also known as DV55 or V230C/1D. Extremely rare
CV2368 Saturated diode, intended as noise generator up to 500 MHz. Flying-lead base. MOV
CW10 Not really experimental, rather extremely rare. Split-anode magnetron, likely designed by E. Megaw. Used in very early experiments on microwave radio-localization. Mid 1930s. Extremely rare
DV27 Developmental S-band Heil oscillator. Likely developed as local oscillator in radar receivers and abandoned in favor of NR89 reflex klystron. Later used in secret experiments to test the principle of FM barrage radar jammers. Unique
DV57 Similar to DV27 above, designed to operate in the X-band. On the attached label is given as 3 cm equivalent of DV55 or CV230 No data or information found. Coming from a British Marconi warehouse Unique
E-1189 Prototype GEC internal developmental prototype, likely used in the preliminary life and performance tests run before manifacturing the sample No.12, the one brought to America by the Tizard Mission. July 1940. Very unique
ET1 Electrometer amplifier. Not experimental, rather very rare. Mid 1930s. Rare
GC-873 Amperex Undocumented samples of electrostatically controlled thyratron. The control element is the metal mesh around the glass bulb. Similar as per construction to the C-100A oscillator that Amperex made for Collins in 1936.  Rare
GRD7 Ferranti laboratory cylindrical diode. As temperature-limited diode used to demonstrate the Richardson emission law. Also used to demonstrate the Hull effect Rare
LMS 12 Extremely rare sample of a German magnetron operating at 3 cm. Made just before the end of the war for the microwave Berlin D radar set. Very unique
LMS 13 Extremely rare prototype of German magnetron operating around 18 GHz. 5 kW pulse power. Very unique
LWG5 Developmental prototype of power UHF triode, doorknob style. Presumably made by STC around 1940. Coming from a British Marconi warehouse Unique
Magnetic Field CRT Sensor CRT operating as probe to observe flux lines of magnetic fields. About 1937. Very rare
Magnetron 8 segments GEC developmental interdigital magnetron. 8 segments electrode structure. Late thirties. Unique
Magnetron 12 segments GEC developmental interdigital magnetron. 12 segments electrode structure. Late thirties. Unique
Omegatron Philips developmental Omegatron sensor for mass spectrography. Unique
Q85033 Early 10 cm developmental strapped magnetron. Likely built at Birmingham by the Sayers group. About 1941. Unique
QK174C C-Band CW magnetron, frequency-modulated through electron beams oriented to the cavity gaps. Raytheon Very rare
R1003 National Union NU internal code for 3C36 UHF power triode Extremely rare
R-1790 RCA Orbital beam VHF amplifier. Developmental prototype of 1630 giant acorn Extremely rare
REL Type 8 Canadian Rogers copy of the British 'Sutton tube' reflex klystron. 1941
RM 4025 Extremely rare prototype of German Siemens & Halske internal resonator magnetron, operating around 3 cm. Very, very unique
RT-323 Toshiba VHF Japanese transmitting triode, designed for Tachi No.7 mobile warning set. 1942 Extremely rare
SMC-11A Developmental klystron frequency tripler. Sperry
Sperry Early Prototype Very early Sperry production sample, still resembling the prototypes developed at Stanford by Varian brothers. About 1939. Very rare
Sutton prototype Unbased bulb of 'Sutton tube'. Presumably build in the developmental phase of the associated resonant cavity. Mid 1940. Very rare
T-310A JAPAN VHF/UHF Japanese transmitting triode. Likely derived from German LS180 and intended for Tachi 24 radar. Nothing found. Very unique
Thyratron, Developmental Looks to be a small developmental hydrogen thyratron. Probably made by EEV. Unique
TY04-30 Early prototype of Mullard doorknob UHF triode similar to WE 316A. Later replaced by TB04/8. About 1937 / 1938. Very rare
UHF Planar triode Looks to be a quite crude prototype predating the 416A.  Unique
VX6012 Trigatron spark gap, experimental Unique
VX6122 British Mazda experimental power diode, rectifier. 12 filamentary diodes in parallel Very rare
XL 7900 / 03 Vibrating capacitor, intended as input stage in amplifiers for very feeble currents, as low as 500 electrons per second. Very rare. Very rare
Last edited on Mar 10, 2018
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