List of Vacuum Tubes

List of vacuum tubes

This is a list of vacuum tubes or thermionic valves, andlow-pressure gas-lled tubes, or discharge tubes. Beforethe advent of semiconductor devices, thousands of tubetypes were used in consumer and industrial electronics;today only a few types are still used in specialized appli-cations.

1 Heater or lament ratingsMain article: Hot cathode

Vacuum tubes fall into three mainly non-interchangeablecategories regarding their heater or lament voltage(some tubes heaters run at a voltage and current suitablefor either series or parallel operation, e.g., 6.3 V at 300mA).

1. Battery types, with a low-power lament operatedusually from 1 to 2 V (2 V types for lead-acid bat-tery, others for dry battery); all laments in a de-sign are rated at the same voltage and are connectedin parallel. They are usually directly heated to saveheating power (therefore requiring a DC current),except if the (due to the voltage gradient along thelament) poorly dened cathode potential impedesthe function of the device, as is the case e.g. withAM detector diodes with lament voltages of 1.9 Vor more.

2. Types for AC-only equipment with a mains trans-former, or for car radios; all tube heaters are ratedat the same voltage and fed in parallel from a trans-former winding or from the car battery, usually 6.3V(domestic AC-only, and 6V car radios) or 12.6V(mainly 12V car radios). Most are indirectly heated.

3. Types for equipment designed to run on either AC orDCmains power (ac/dc) with no mains transformer;all heaters are connected in series, possibly with anadditional ballast tube (barretter) or power resistorchosen so that the sum of the heater and ballast volt-ages equals the mains voltage. All tubes must berated at the same heater current, typically 100, 150,300 or 450 mA. They are always indirectly heated.

The currents drawn by parallel-connected types, and thevoltages across series-connected types, vary widely ac-cording to the tubes heating power requirements. Oth-erwise identical tubes were manufactured in several vari-ants with dierent heater characteristics[1] (but usually

the same power, e.g. 6.3 V/300mA and 12.6 V/150mA).See, for example, the RCA Receiving Tube Manuals.In half-indirectly heated tubes the cathode and one sideof the lament share the same pin.

2 Tube basesMain article: Tube socket

3 Numbering systems

3.1 North American systems3.1.1 RMA system (1942)

Main article: RMA tube designation

The system assigned numbers with the base form 1A21,and is therefore also referred to as the 1A21 system.First digit Filament/heater power rating:

1 No lament/heater; cold cathode or solid state de-vice

2 Up to 10 W 3 10-20 W 4 20-50 W 5 50-100 W 6 100-200 W 7 200-500 W 8 500W-1 kW 9More than 1 kW

Next character: Function:

A Single element (ballast, barretter) B Two-element device such as:

Diode

1

2 3 NUMBERING SYSTEMS

TR (Transmit/receive) cell, cold-cathodewater vapor discharge tube for use inradar systems, short-circuits the receiverinput to protect it while the transmitteroperates

ATR (Anti-transmit/receive) cell, cold-cathode water vapor discharge tube foruse in radar systems, decouples the trans-mitter from the antenna while not oper-ating, to prevent it from wasting receivedenergy

Spark gap

C Triode D Tetrode E Pentode or beam power tetrode F Hexode G Heptode H Octode JMagnetically controlled types, usually incorporat-ing a resonator (essentially, magnetrons)

K Electrostatically controlled types, including a res-onator (klystrons and inductive output tubes)

L Vacuum capacitors N Crystal rectiers (This designation lived on as theN in the EIA/JEDEC EIA-370 solid state devicenumbers standard, like 2N2222)

P Photosensitive types (phototubes,photomultipliers, camera tubes, image converters)

Q Resonant vacuum cavities R Ignitrons and mercury arc rectiers S Vacuum switches T Storage, radial beam, and deection control tubes(no known examples assigned)

V Flash tubes W Traveling-wave tube X X-ray tube Y Thermionic converter

The last 2 digits were sequentially assigned, beginningwith 21 to avoid possible confusion with receiving tubesor CRT phosphor designations. Multiple section tubes(like the 3E29 or 8D21) are assigned a letter correspond-ing to ONE set of electrodes.Examples

1B23 20 kW, 400 to 1500 MHz Gas-lled, cold-cathode Transmit/Receive Tube (TR cell)

1B41 Gas-lled, cold-cathode 9.5 kV, 450 A sparkgap

1B45 Gas-lled, cold-cathode 14 kV, 450 A sparkgap

1B49 Gas-lled, cold-cathode 12 kV, 450 A sparkgap

1C21 Gas-lled, 25 mA, 100 mA, triodethyratron

1D21 Strobotron, gas-lled, 50 mA, 5 A, lu-miniscent tetrode thyratron for use as a stroboscopelamp

1P21 9-stage Photomultiplier, spectral S4 response,11-pin base

1P25 Infrared image converter used in WW2 nightvision sniperscopes.

1P29 Gas-lled phototube, spectral S3 response, 4-pin base

1P39 Vacuum Phototube, spectral S4 response, 4-pin base

1S22 10 kV, 20 A Vacuum SPDT switch 2C21 Dual transmitting triode, indirectly heated, 7-pin base plus a single top cap for one of the grids

2C22 Transmitting triode, indirectly heated, 8-pinbase plus dual top cap for grid and anode

2C39 Disk-seal-type planar UHF power triode. 2C43 Lighthouse-type disk-seal UHF planar trans-mitting triode, indirectly heated, up to 3.37 GHz,6-pin base

2C51 Dual shielded triode, indirectly heated, 9-pinbase

2D21/EN91 (PL21, PL2D21, CV797) 100 mA,500 mA, 10 A, Gas-lled, indirectly heatedtetrode thyratron, negative starter voltage, miniature7-pin base, for relay and grid-controlled rectier ser-vice, used in jukeboxes and computer equipment.

2E22 53 W Power pentode, 5-pin base with anodeon top cap

2E26 Popular amateur 5.3 W VHF beam powertetrode up to 175 MHz, octal base

2E30 10 W Directly heated beam power tetrodewith deection screens available on separate pin,miniature 7-pin base

3.1 North American systems 3

2E31 Subminiature, directly heated, fully shieldedsharp-cuto RF/IF pentode, 5-pin all-glass pig-tailed, FL

2E32 Similar to 2E31, SL 2E35 6 mW Subminiature directly heated powerpentode, 5-pin all-glass pigtailed, FL

2E36 Similar to 2E35, SL 2E41 Diode, pentode, FL 2E42 Similar to 2E42, SL 2F21 Indirectly heated hexode monoscope, IndianHead test pattern, 6-pin base with dual top caps forgrid4 and anode

2G21 Directly heated triode-heptode mixer, 7-pinall-glass pigtailed

2G41 Triode-heptode converter, FL 2G42 Similar to type 2G42, SL 2J30 to 2J34 300 kW S-band Magnetrons 2J55 and 2J56 40 kW X-band Magnetrons for useas pulsed oscillator

2K25 25 mW 8.5 to 9.66 GHz reex Klystron 2K50 15 mW 23.5 to 24.5 GHz reex Klystron 2P23 Early image orthicon TV camera tube. 3B28Xenon half wave rectier; ruggedized replace-ment for mercury vapor type 866.

3C23 1.5 A, 6 A, Mercury-vapor triode thyra-tron, 4-pin base with anode top cap

3C45 45 mA, 1.5 ARMS, 35 A, Half-indirectly heated hydrogen triode thyratron, 4-pinbase with anode top cap

3D21 Indirectly heated beam power tetrode, 8-pinbase with anode top cap

3D22 Gas-lled, 800 mA, 8 A, tetrode thyra-tron, 7-pin base

3E29 Dual beam power tube used in radar equip-ment; a pulse rated variant of the earlier 829B, 7-pinbase with dual anode top cap.

4B32 10 kV, 1.25 A, 5 A Xenon half waverectier

4D21 (6155, Eimac 4-125A) 125 W Glass VHFbeam power tetrode

4E27 125 W Glass radial-beam power pentode 4J31 to 4J35 1 MW S-band Magnetrons

5C22Half-indirectly heated, hydrogen triode thyra-tron for radar modulators.

5D22 (6156, Eimac 4-250A) 250 W, 110 MHzGlass beam power tetrode

5J26 500 kW, 1.22 to 1.35GHz S-bandMagnetrons 5K70 30 kW S-band reex Klystron 6C21 Triode radar modulator for hard tubepulsers.

7C23 120 kW Power triode for high voltage pulseoperation.

8D21 Internally water cooled dual tetrode used inearly VHF TV transmitters.

9C21 100 kW Water-cooled power triode, directlyheated, 4-pin base with dual top caps for grid andanode

3.1.2 RETMA receiving tubes system (1953)

Main article: RETMA tube designation

RETMA is the acronym for the Radio Electronic Televi-sion Manufacturers Association, originally the RMA, laterRTMA, then EIA (Electronic Industries Association, since1997 Electronic Industries Alliance).

The rst character group is always a number, con-sisting of one to three numerals, and very often rep-resents the heater voltage to the nearest whole num-ber - exceptions including 2.0 Volt lament tubes(such as 1C7-G and 1F4) and series heater tubeswhere the rounding was less exact (such as the 5.9-Volt 5X9 and the 46-Volt 50Y7GT).

These numerals are followed by one or two let-ters assigned to the devices in some sort of semi-chronological order of development and introduc-tion to the marketplace,

and then another single numeral that representsthe number of active elements in the tube (includ-ing any internal shield plus the heater in indirectlyheated tubes - electrodes connected together inter-nally count as one). For example, a 7 could meana heptode (pentagrid converter) such as the 12SA7-GT, or a pentode with two diodes such as the 7E7, orwith one diode and a shield pin such as the 12SF7,or triode with two diodes and a shield pin such asthe 6SR7, or a twin-input triode such as the 6AE7-GT, or a double triode such as the 6SN7-GT. Ex-ceptions include the 35L6-GT (with 5 elements, butnamed for consistency with the 6L6/6L6-G wherepin 1 may or may not be connected to a shield, mak-ing the sixth element).


Sometimes a string of up to three Roman letters canbe suxed to the overall number; these generallydistinguish various revisions and improvements tothe original model or dierent bulb shapes; use isunsystematic, except that for octal tubes G often in-dicated a shouldered glass envelope, GT a tubularglass envelope, and neither of these often a metalenvelope. When discussing a type in general theletters are often omitted; discussion of the proper-ties of the 6SN7 would tacitly include the 6SN7GT,6SN7GTB, etc., but not the comparable 6SL7 fam-ily. By and large tubes with the same basic desig-nation are interchangeable unless the qualities of anenhanced version are required.

Lastly, manufacturers may decide to combine twotype numbers into a single name, which their onedevice can replace, such as: 6DX8/ECL84 (6DX8and ECL84 being identical devices under dierentnaming schemes) or 6BC5/6CE5 (suciently iden-tical devices within the RETMA naming system)and even 3A3/3B2, or 6AC5-GT/6AC5-G (wherethe single type number, 6AC5-GT/6AC5-G, super-sedes both the 6AC5-G and the 6AC5-GT).

Often, but not always, vacuum tube designations thatdiered only in their initial numerals would be identi-cal except for heater characteristics. Exceptions include:the 12BR7 and 9BR7 are unrelated to the 6BR7; the4BL8/XCF80 is the 4.6 Volt (600mA series heater) ver-sion of the 6BL8/ECF80, but the 450mA series heaterversion is the 6LN8/LCF80 rather than 6BL8.For examples see below

3.1.3 EIA professional tubes system

A four-digit systemwasmaintained by the EIA for specialindustrial, military and professional vacuum and gas-lledtubes, and all sorts of other devices requiring to be sealedo against the external atmosphere.For examples see below

3.2 West European systems3.2.1 Mullard-Philips system

Main article: Mullard-Philips tube designation

This system is very descriptive of what type of device(triode, diode, pentode etc.) it is applied to, as wellas the heater/lament type and the base type (octal, no-val, etc.).[2] Adhering manufacturers include AEG (de),Amperex (us), Dario (fr), La Radiotechnique (fr), Lorenz(de), Mullard (uk), Philips (nl), RCA (us), RFT (de),Siemens (de), Telefunken (de), Toshiba (ja), Tungsram(hu) and Valvo (de).

Standard tubes This part dates back to the joint valvecode key (German: Rhren-Gemeinschaftsschlssel) ne-gotiated between Philips and Telefunken in 1933-34.Like the North American system the rst symbol de-scribes the heater voltage, in this case a Roman letterrather than a number. Further Roman letters, up to three,describe the device followed by one to four numerals as-signed in a semi-chronological order of type developmentwithin number ranges assigned to dierent base types.If two devices share the same type designation other thanthe rst letter (e.g. ECL82, PCL82, UCL82) they willusually be identical except for heater specications; how-ever there are exceptions, particularly with output types(for example, both the PL84 and UL84 dier signi-cantly from the EL84 in certain major characteristics, al-though they have the same pinout and similar power rat-ing). However, device numbers do not reveal any similar-ity between dierent type families; e.g. the triode sectionof an ECL82 is not related to either triode of an ECC82,whereas the triode section of an ECL86 does happen tobe similar to those of an ECC83.Pro Electronmaintained a subset of the M-P system aftertheir establishment in 1966, with only the rst lettersE, Pfor the heater, only the second lettersA,B,C,D,E, F,H,K, L, M, Y, Z for the type, and issuing only three-digitnumbers starting with 1, 2, 3, 5, 8, 9 for the base.[3]

Notes: Tungsram preceded the M-P designation with theletter T, as in TAD1 for AD1; Vatea (United Incandes-cent Lamp and Electric Company, Budapest, Hungary)preceded the M-P designation with the letter V, as inVEL5 for EL5.

First letter: heater/lament type

Heater ratings for series-string, AC/DC tubesare given in milliamperes; heater ratings forparallel-string tubes are given in volts

A 4 V heater for 2-cell lead-acid batteriesand for AC mains transformers

B 180 mA DC series heater C 200 mA AC/DC series heater D 1.4 V DC lament for Leclanchcells, later low-voltage/low power la-ment/heater:

0.625 V DC directly heatedfor NiCd battery, series-heated two-tube designs suchas hearing aids. If either la-ment breaks, further drainingof all batteries stops

Wide range 0.9 V to 1.55V DC directly heated for drycells

3.2 West European systems 5

1.25 V DC directly heated forNiCd batteries

1.25 V or 1.4 V AC from aseparate heater winding onCRT horizontal-output trans-formers, in half-indirectlyheated EHT rectiers

E 6.3 V parallel heater; for 3-celllead-acid vehicle crank batteries (mo-bile equipment) and for AC mains orhorizontal-output transformers

F 12.6 V DC parallel heater for 6-celllead-acid vehicle crank batteries

G 5.0 V AC from a separate heater wind-ing on a mains or horizontal-output trans-former for the anode voltage rectier;later misc.

H 150 mA AC/DC series heater I 20 V heater K 2.0 V lament for 1-cell lead-acid bat-teries, later for AC transformers

L 450 mA AC/DC series heater; wasshifted here from Y

M 1.9 V, directly heated N 12.6 V, indirectly heated O Cold cathode (by 1955 this also in-cluded semiconductors as these had noheater)

P 300 mA AC/DC series heater Q 2.4 V, indirectly heated S 1.9 V, indirectly heated T Customized heater U 100 mA AC/DC series heater V 50 mA AC/DC series heater X 600 mA AC/DC series heater Y 450 mA AC/DC series heater,shifted to L to avoid conicts with theprofessional tubes system

Z Cold cathode tube; was shifted herefrom O after the advent of semiconduc-tors

Second and subsequent letters: system type

A Small signal diode B Dual small signal diode C Small signal triode D Power output triode E Small signal tetrode F Small signal pentode

H Mixer hexode, special purpose hep-tode

KMixer heptode or octode L Power output, beam tetrode or pentode M Optical tuning/level indicator N Gas-lled thyratron P Secondary emission tube - mostly usedas third letter

Q Nonode R Resistive element (ballast tube,barretter, photoresistor)

S Special tube (German: Sonderrhre) T Beam deection tube, or misc. W Gas-lled half-wave rectier X Gas-lled full-wave rectier Y Vacuum half-wave rectier (powerdiode)

ZVacuum full-wave rectier (dual powerdiode with common cathode)

E.g. ECCnn is a 6.3 V dual triode; EABCnnhas a single detector diode, a common-cathodepair of diodes, and a triode.

Following digits: model number and base type

For signal pentodes, an odd model numbermost often identied a variable transconduc-tance (remote-cuto) valve, whereas an evennumber identied a 'high slope' (sharp-cuto)valveFor power pentodes and triode-pentode com-binations, even numbers usually indicate lin-ear (audio power amplier) devices while oddnumbers were more suited to video signals orsituations where more distortion could be tol-erated.

1-9 Pinch-type construction valves,mostly P8 bases (P base, 8-pin side-contact) or European 5-pin (B base) andvarious other European pre-octal designs

1019 8-pin German metal octal, G8A 2029 Loctal B8G; some octal; some 8-way side contact (exceptions are DAC21,DBC21, DCH21, DF21, DF22, DL21,DL21, DLL21, DM21 which have octalbases)

3039 International Octal (IEC 67-I-5a),also known as IO or K8A

4049 Rimlok (Rimlock) B8A All-glassminiature valves


5059 Special construction types ttedwith bases applicable to design featuresused[4]"; mostly locking bases: 9-pinLoctal (B9G) or 8-pin Loctal (B8G);but also used for Octal and others (3-pinglass; Disk-seal incl. Lighthouse tubes;German 10-pin with spigot; min. 4-pin;B26A; Magnoval B9D)

6064 All-glass valves tted with 9-pin(B9G) bases

65-69 Sub-miniature all-glass valves withor without bases

7079 Loctal Lorenz, all-glass pigtailed(y-leads in place of pins) subminiatures

8089 Noval B9A (9-pin; IEC 67-I-12a) 9099 Button B7G (miniature 7-pin;IEC 67-I-10a)

100109 B7G; Wehrmacht base; Ger-man PTT base

110119 8-pin German octal; RimlokB8A

130139 Octal 150159German 10-pin with spigot; 10-pin glass with one big pin; Octal

160169 Flat wire submins; 8-pin Ger-man octal

170179 RFT 8-pin; RFT 11-pin all-glass gnome tube with one oset pin

180189 Noval B9A 190199Miniature 7-pin B7G 200209 Decal B10B; Pro Electron-issued

230239 Octal 270279 RFT 11-pin all glass with oneoset pin

280289 Noval B9A 300399 Octal; Pro Electron-issued 400499 Rimlok B8A 500529 Magnoval B9D, Novar; ProElectron-issued

600699 Flat wire-ended 700799 Round wire-ended 800899 Noval B9A; Pro Electron-issued

900999 Miniature 7-pin B7G; ProElectron-issued

1000- Round wire-ended; special nuvis-tor base

2000 Decal B10B 3000- Octal

5000-Magnoval B9D 8000- Noval B9A

For examples see below

Special quality tubes Vacuum tubes which had spe-cial qualities of some sort, very often long-life designs,particularly for computer and telecommunications use,had the numeric part of the designation placed imme-diately after the rst letter. They were usually special-quality versions of standard types. Thus the E82CC wasa long-life version of the ECC82 intended for computerand general signal use, and the E88CC a high quality ver-sion of the ECC88/6DJ8. While the E80F pentode wasa high quality development of the EF80, they were notpin-compatible and could not be interchanged withoutrewiring the socket (the E80F is commonly sought afteras a high quality replacement for the similar EF86 typein guitar ampliers). The letters CC indicated the twotriodes and the F, the single pentode inside these types.A few special-quality tubes did not have a standard equiv-alent, e.g. the E55L, a broadband power pentode usedas the output stage of oscilloscope ampliers and theE90CC, a double triode with a common cathode con-nection and seven pin base for use in cathode-coupledFlip-ops in early computers. The E91H is a special hep-tode with a passivated third grid designed to reduce sec-ondary emission; this device was used as a gate, allow-ing or blocking pulses applied to the rst, (control) grid bychanging the voltage on the third grid, in early computercircuits (similar in function to the U.S. 6AS6).Some tubes can appear to belong to a particular number-ing scheme, but in fact do not. A case in point is the E81Lwhich could be mistaken for a special quality version ofthe EL81 in the Mullard-Philips numbering scheme. Inreality, they are not even similar in characteristics or ap-plication. The E81L is a high slope signal pentode andwas the product of one of many numbering schemes usedby the telephone industry. There is the possibility for con-fusion in such cases, though in this instance an SQ versionof the EL81 was never produced.Many of these types had gold-plated base pins and spe-cial heater congurations inside the nickel cathode tubedesigned to reduce hum pickup from the A.C. heater sup-ply, and also had improved oxide insulation between theheater and cathode so the cathode could be elevated toa greater voltage above the heater supply. (Note thatelevating the cathode voltage above the average heatervoltage, which in well-designed equipment was suppliedfrom a transformer with an earthed center-tapped sec-ondary, was less detrimental to the oxide insulation be-tween heater and cathode than lowering the cathode volt-age below the heater voltage, helping to prevent pyromet-allurgical electrolytic chemical reactions where the oxidetouched the nickel cathode that could form conductivealuminium tungstate and which could ultimately develop


into a heater-cathode short-circuit.)Better, often dual, getters were implemented to maintaina better vacuum, and more-rigid electrode supports in-troduced to reduce microphonics and improve vibrationand shock resistance. The mica spacers used in SQ andPQ types did not possess sharp protrusions which couldake o and become loose inside the bulb, possibly lodg-ing between the grids and thus changing the character-istics of the device. Some types, particularly the E80F,E88CC and E90CC, had a constricted section of bulb tormly hold specially shaped akeless mica spacers.[5]

For examples see below, starting at EAALater special-quality tubes had not base and functionswapped but were assigned a 4-digit number,[2] such asECC2000 or ED8000, the rst digit of which again de-noting the base:

1Miscellaneous 2Miniature 10-pin base (JEDEC F10-61) 3 Octal base (IEC 67-1-5a) 5 Novar/magnoval base (JEDEC E9-75 and E9-23) 8 Noval base (IEC 67-1-12a) 9Miniature 7-pin base (IEC 67-1-10a)

For examples see below, starting at ECZ Cold-cathode SQ tubes had a dierent function letterscheme:[6]

A Long-life amplier tube B Binary counter or switching tube C Common-cathode Counter Dekatron that makesonly carry/borrow cathodes separately available forcascading

E Electrometer tube G Amplier tube M Optical indicator S Separate-cathode Counter/Selector Dekatron thatmakes all cathodes available on individual pins fordisplaying, divide-by-n counter/timer/prescalers,etc.

T Relay triode, a low-power triode thyratron, onestarter electrode, may need illumination for properoperation if not radioactively primed

U Low-power tetrode thyratron, may mean: Trigger tetrode, one starter electrode and aprimer (keep-alive) electrode for ion availabil-ity to keep the ignition voltage constant, foranalog RC timers, voltage triggers, etc.

Relay tetrode, two starter electrodes to makecounters bidirectional or resettable

W Trigger pentode, two starter electrodes and aprimer electrode

X Shielded Trigger pentode, two starter electrodes,a primer electrode and a conductive coating of theglass envelope inside connected to a separate pin

For examples, see below under Z

Professional tubes In use since at least 1961, this sys-tem was maintained by Pro Electron after their establish-ment in 1966.[3]

Both letters together indicate the type:

X High vacuum electro-optical devices XA Phototube XGMiscellaneous XM Character generating cathode ray tube XP Photomultiplier XQ Camera tube XRMonoscope XS Cathode ray charge storage tube XTMemory display tube XV Infrared detector XW Infrared imaging device XX Image intensier or image converter

Y Vacuum tubes YA Diode YD Transmitting or industrial, single or dualtriode

YG Electrometer tube, vacuum gauge YH Traveling-wave tube YJMagnetron YK Klystron YL Transmitting or industrial, single or dualtetrode or pentode

YN Backward wave oscillator YP Electron multiplier YR Crossed-eld amplier YT Pulse modulator tube YY High vacuum rectier

ZGas-lled tubes not employing photosensitivema-terials ZA Cold cathode indicator tube


ZBMicrowave switching tube (TR/ATR cells,etc.)

ZC Trigger tube ZD Surge arrester ZE Glow modulator tube, a linear light sourcefor rotating-drum FAX receivers, lm sound-track recording, etc.

ZF Flash tube ZL Gas laser ZM Cold cathode character display tube orcounter display tube

ZP Radiation counter tube (Geiger-Mllercounter tube or proportional counter tube)

ZQMixed analogue and digital display ZR Plasma display panel ZS Bar graph ZT Thyratron ZX Ignitron ZYMercury-vapor rectier ZZVoltage stabilizer or corona discharge tube

Then follows a 4-digit sequentially assigned number.Optional suxes for camera tubes:Version letter:

B Blue G Green L Luminance R Red T Reticule XMedical X-ray

Letter for variants derived by selection:

D High resolution M Blemish standard


Transmitting tubes The rst letter (or letter pair, inthe case of a dual-system device) indicates the generaltype:

B Backward-wave amplier D Rectier, including grid-controlled types JMagnetron

K Klystron L Traveling-wave tube M Triode (AF amplier or modulator) P Pentode Q Tetrode R Rectier T Triode (AF, RF, oscillator) X Large thyratron (including all hydrogen thyratronsand high-current types)

The following letter indicates the lament or cathodetype. The coding diers between Philips (and other Con-tinental European manufacturers) on the one hand and itsMullard subsidiary on the other.Philips system:

A Backward-wave amplier or Traveling-wave tube: Output power


H Hydrogen lling R Inert-gas lling X Xenon lling

The next letter indicates the cooling method or other sig-nicant characteristic:

H Helix or other integral cooler L Forced-air cooling Q Shield-grid (tetrode) thyratron (thyratrons only) S Silica envelope T Tunable microwave device WWater cooling

The following group of digits indicate:

Microwave tubes: Frequency in GHz Rectifying tubes: DC output voltage in kV in athree-phase half-wave conguration

Thyratrons: Peak inverse voltage in kV Transmitting tubes: Maximum anode voltage inkV

The following group of digits indicate the power:

Backward-wave amplier or Traveling-wavetube: Output power 2nd letter: A - in mW 2nd letter: B - in W

Klystrons: Output power Magnetrons: Pulse output power in kW Continuously transmitting tubes: Maximum an-ode dissipation in W or kW in class C ampliertelegraphy

Pulsed transmitting tubes: Maximum peak anodecurrent in A (number preceded by "P")

Rectiers: Maximum average anode current in mA Thyratrons: Maximum average anode current:

Less than 3 digits: in mA 3 or more digits:

1st digit =0: in mA 1st digit >0: in A

An optional following letter indicates the base or connec-tion method:

B Cables EMedium 7-pin base ED Edison screw lamp base EG Goliath base GMedium 4-pin base GB Jumbo 4-pin base GS Super jumbo 4-pin base NMedium 5-pin base P P-base


Phototubes and photomultipliers The rst digit indi-cates the tube base:

2 Loctal 8-pin base 3 Octal 8-pin base 5 Special base 8 Noval base 9Miniature 7-pin base

The second digit is a sequentially assigned number.The following letter indicates the photocathode type:

A Caesium-activated antimony cathode. Used forreective-mode photocathodes. Response rangefrom ultraviolet to visible. Widely used.

C Caesium-on-oxidated-silver cathode, also calledS1. Transmission-mode, sensitive from 3001200nm. High dark current; used mainly in near-infrared, with the photocathode cooled.

T Multialkali sodium-potassium-antimony-caesiumcathode, wide spectral response from ultravioletto near-infrared; special cathode processing canextend range to 930 nm. Used in broadbandspectrophotometers.

U Caesium-antimony cathode with a quartz window

The following letter indicates the lling:

G Gas-lled V High-vacuum

A following letter P indicates a photomultiplier.Examples


50AVP 11-stage photomultiplier for scintillationcounters, duodecal base

51UVP 11-stage photomultiplier, duodecal base 52AVP/XP1180 10-stage photomultiplier, 13-pinbase

53AVP, 153AVP 10-stage photomultiplier, dihep-tal 14-pin base

53UVP 11-stage photomultiplier, diheptal 14-pinbase

54AVP 11-stage photomultiplier, diheptal 14-pinbase

55AVP 15-stage photomultiplier, bidecal 20-pinbase


56UVP 14-stage photomultiplier, duodecal base 57AVP 11-stage photomultiplier, bidecal 20-pinbase



150CVP 10-stage photomultiplier, bidecal 20-pinbase

57CV Photometric cell 58CG Gas-lled phototube, Red/IR sensitive, all-glass pigtailed

58CV Vacuum phototube, Red/IR sensitive, all-glass pigtailed

90AG Gas-lled phototube, daylight/blue sensitive,miniature 7-pin base

90AV Vacuum phototube, blue sensitive, miniature7-pin base

90CG Gas-lled phototube, Red/IR sensitive,miniature 7-pin base

90CV Vacuum phototube, Red/IR sensitive, minia-ture 7-pin base

92AG Gas-lled phototube, blue sensitive, minia-ture 7-pin base

92AV Vacuum phototube, blue sensitive, miniature7-pin base

61SV/7634 PbS infrared (300...3500 nm)photoresistor, 2-pin all-glass pigtailed

Voltage stabilizers The rst number indicates theburning voltageThe following letter indicates the current range:

A max. 10mA

B max. 22mA

C max. 40mA

D max. 100mA

E max. 200mA

The following digit is a sequentially assigned number.An optional, following letter indicates the base:

E Edison screw lamp base

K Octal 8-pin base

P P-base

Examples

75B1 Voltage reference tube, miniature 7-pin base

75C1 Voltage reference tube, miniature 7-pin base

83A1 Voltage reference tube, miniature 7-pin base

85A1/0E3 Voltage reference tube, Loctal B8G base

85A2/0G2 Voltage reference tube, miniature 7-pinbase

90C1 Voltage reference tube, miniature 7-pin base

95A1 Voltage reference tube, miniature 7-pin base

100E1 Voltage reference tube, A Base

108C1Voltage reference tube, miniature 7-pin base

150A1 Voltage reference tube, P base



150C1 Voltage reference tube, P base




3.2.2 Marconi-Osram system

The British Marconi-Osram designation from the 1920suses one or two letter(s) followed by two numerals andsometimes by a second letter identifying dierent ver-sions of a particular type.The letter(s) generally denote the type or use:

A General professional tube B Dual triode D Detector diode GU Gas-lled rectier GT Gas-lled triode H High-impedance signal triode L Low-impedance signal triode MU Indirectly heated rectier N Power pentode P Power triode QP Dual pentode S Tetrode U Rectier VS Remote-cuto tetrode W Remote-cuto pentode X Triode/hexode frequency-changer Y Optical tuning/level indicator Z Sharp-cuto RF pentode

The following numbers are sequentially assigned for eachnew device.Examples

A1834 = 6AS7-G - Dual power triode, series regu-lator, octal base.

B719 = ECC85/6AQ8 - Dual RF triode, noval base D42 - Single Detector Diode, British 4-pin base GU21=AH221 =RG4-1250 - Half-wavemercury-vapor rectier, Edison screw lamp base

H63 = 6F5 - Hi-mu triode, octal base H610 - AF triode L63 = 6J5 - Low-mu triode, octal base L610 - AF triode

MT7A, MT7B - Large radiation-cooled transmit-ting triodes used in the 1920s and 1930s.

MU14 = UU5 = IW4-500 - Indirectly heated full-wave rectier, British 4-pin base

N77 = 6AM5 = EL91 - Power pentode, 7-pinminiature base

P610 - AF power triode P625 - AF power triode PX4 - AF power triode designed in the 1930s. Ca-pable of providing about 4.5 W of audio

QP21 - Directly heated, dual AF (push-pull) powerpentode, British 7-pin base.

QP240 - Directly heated, dual AF (push-pull) powerpentode, British 9-pin base.

S610 - RF tetrode U52 = 5U4G = 5AS4A/5U4GB - Full-wave recti-er, octal base

VS24 - Directly heated, remote-cuto RF tetrode,British 4-pin base.

W727 = 6BA6 = EF93 = 5749 - Remote-cuto RFpentode, 7-pin miniature base

X41 Triode/hexode mixer designed to be a directplug-in replacement for the MX40 pentagrid con-verter

X61, X61M = 6J8G - British triode/heptode mixer,octal based.

X63 = 6A8 Heptode pentagrid converter, octalbased.

X727 = 6BE6 = EK90 = 5750 - Pentagrid con-verter, 7-pin miniature base

Y61, Y63 = 6U5G = VI103 - Optical tuning/levelindicator, octal base, similar to 6G5

Z77 = 6AM6 = EF91 - Sharp-cuto RF pentode,7-pin miniature base

3.2.3 Mazda/Ediswan systems

Older system First letter: Heater or lament voltage

A 1 V B 2 V D 4 V E 5 V F 6 V


G 7 V

Second letter: Heater or lament current

W 200 mA

X 150 mA

Y 100...140 mA

Z 50 mA

Next number: GainNext number: Internal resistance in k

Signal tubes First number: Heater or lament rating

0Misc. higher voltages

1 1.4 V

6 6.3 V

10 100 mA

20 200 mA

30 300 mA

Following letter or letter sequence: Type

C Frequency changer with special oscillator section

D Signal diode(s)

F Tetrode or pentode

FD Tetrode or pentode and diode(s)

FL Tetrode or pentode, and triode

K Small gas triode or tetrode thyratron

L Single or dual triode, including oscillator triode

LD Triode and diode(s)

M Optical tuning/level indicator

P Power tetrode or pentode

PL Power tetrode or pentode, and signal triode

Final number: Sequentially assigned number

Power rectiers Letter(s): Type

U High-vacuum half-wave rectier UU High-vacuum full-wave rectier

Number: Sequentially assigned numberExamples:

6C10 (6CU7/ECH42) Triode/hexode frequencyconverter, 8-pin rimlock base

6F22 (6267/EF86) Low-noise A.F. pentode, 9-pinnoval base

6F33 Shielded pentode, 7-pin base 6L12 (6AQ8/ECC85) Dual triode, 9-pin noval base 6L19 Dual triode, 8-pin base 6M2 (6CD7/EM34) Dual-sensitivity tuning indica-tor, 8-pin octal base

6P9 (6BM5) Power pentode, 7-pin base 6P15 (6BQ5/EL84) Power pentode, 9-pin novalbase

10PL12 (50BM8/UCL82) Triode/power pentode,9-pin noval base.

U381 (38A3/UY85) Half-wave rectier, 9-pin no-val base.

UU9 (6BT4/EZ40) Full-wave rectier, 8-pin rim-lock base.

3.2.4 STC/Brimar receiving tubes system

First number: Type

1 Half-wave rectier 2 Diode 3 Power triode 4 High-mu triode 5 Sharp-cuto tetrode 6 Vari-mu tetrode 7 Power or video pentode 8 Sharp-cuto RF pentode 9 Vari-mu RF pentode 10 Dual diode 11 Triode and dual diode


12 AF Pentode and dual diode

13 Dual high-mu triode

14 Dual class-B power triode

15 Heptode

16 DC-coupled power triode

17 RF pentode and dual diode

18 Pentode and triode

20 Hexode/heptode and triode

Next letter: Heater rating

A 3.6 to 4.4V Indirectly heated

B 2V Directly heated

C Directly heated other than 2 or 4 V

D All other heater ratings, indirectly heated otherthan 4V

Number: Sequentially assigned numberExamples:

1D6 Indirectly heated, half-wave rectier, 5-pinbase

4D1 Indirectly heated triode, 7-pin base

7A3 Indirectly heated power pentode, 7-pin base

8A1 Indirectly heated RF sharp-cuto pentode, 5-pin base with anode top cap

9A1 Indirectly heated RF/IF remote-cuto pentode,5-pin base with anode top cap

10D1 Indirectly heated, common-cathode dualdiode, 5-pin base

11A2 Indirectly heated, common-cathode dualdiode and triode, 7-pin base

13D3 Indirectly heated, common-cathode dual tri-ode, 9-pin base

15A2 Indirectly heated, heptode pentagrid con-verter, 7-pin base

20D4 Indirectly heated, triode/heptode frequencymixer, 9-pin base

3.2.5 Tesla receiving tubes system

First number: Heater voltage, as in the RETMA schemeNext letter(s): Type, subset of the Mullard-PhilipsschemeNext digit: Base

1 Octal K8A, A08 2 Loctal W8A 3Miniature 7-pin B7G 4 Noval B9A 5 Special, mostly 9 out of 10 1.25mm pins on a25mm-diameter circle

6 Submagnal B11A 7 Duodecal B12A 8 Diheptal B14A 9 Pigtails

Last digit: Sequentially assigned numberExamples:

1M90 (DM70/1M3) Subminiature indicator tube,1.4V/25 mA lament, all-glass pigtailed

4L20 Directly heated RF power pentode; lament2x2.4V / 325mA; Soviet 41, German RL4,2P6with Loctal base

6B31 Dual diode up to 700 MHz; 6.3V/300mAheater, miniature 7-pin base

6BC32 (6AV6, EBC91) Dual diode and triode;6.3V/300mA heater, miniature 7-pin base

6CC31 (6J6, ECC91) 600 MHz dual triode;6.3V/450mA heater, miniature 7-pin base

6CC42 (2C51) VHF dual triode; 6.3V/350mAheater, noval base

6F24Telecompentode, 6.3V/450mAheater, Loctalbase

6F36 (6AH6) Sharp-cuto IF/video pentode,6.3V/450mA heater, miniature 7-pin base

6H31 (6BE6, EK90) Heptode mixer; 6.3V/300mAheater, miniature 7-pin base

6L36 (6AQ5, EL90) Power pentode, 6.3V/450mAheater, miniature 7-pin base

6L41 (5763) Beam tetrode, 6.3V/750mA heater,noval base

35Y31 Half-wave rectier, miniature 7-pin base;35V/150mA series heater; UY1N with 7-pin base


3.3 Japanese Industrial Standards systemFirst letter: Base

B Special D Subminiature G Octal L Loktal MMiniature 7-pin N Nuvistor R Noval 9-pin T Large 7-pin W 7-pin X 4-Pin Y 5-Pin Z 6-Pin

Second letter: Type

A Power triode B Beam tetrode D Detector diode E Optical indicator G Gas-lled rectier H Signal triode, gain < 30 K Kenotron L Signal triode, gain > 30 P Power pentode R Sharp-cuto tetrode or pentode V Remote-cuto tetrode or pentode

Number: Sequentially assigned number

Rectiers: Even number: Full-wave Odd number: Half-wave

3.4 Russian systemsMain article: Russian tube designations

Vacuum tubes produced in the former Soviet Union andin present-day Russia are designated in Cyrillic. Someconfusion has been created in transliterating these desig-nations to Latin.

3.4.1 Standard tubes

In the 1950s a 5-element system (GOST 5461-59, later13393-76) was adopted in the (then) Soviet Union fordesignating receiver vacuum tubes.The 1st element is a number specifying lament voltagein volts (rounded o to the nearest whole number), or, forcathode-ray tubes, the screen diagonal or diameter in cm(rounded-o to the nearest whole number).The 2nd element is a Cyrillic character specifying thetype of device:

D (Russian: ) - Diode, including damper diodes H (Russian: ) - Double diode Ts (Russian: ) - Low-power rectier (kenotron) S (Russian: ) - Triode N (Russian: ) - Double triode E (Russian: ) - Tetrode P (Russian: ) - Output pentode, or a beam tetrode Zh (Russian: ) - Sharp-cuto pentode (alsotransliterated sh or j)

K (Russian: ) - Variable-mu / remote-cutopentode

R (Russian: ) - Double pentode or a double tetrode G (Russian: ) - Combined triode-diode B (Russian: ) - Combined diode-pentode F (Russian: ) - Combined triode-pentode I (Russian: ) - Combined triode-hexode, triode-heptode or triode-octode

A (Russian: ) - Pentagrid converter V (Russian: ) - Vacuum tube with secondary emis-sion

L (Russian: ) - Cathode-ray tube Ye (Russian: ) - Optical tuning/level indicator

The 3rd element is a number - a series designator thatdistinguishes between dierent devices of the same type.The 4th element denotes vacuum tube construction(base, envelope):

- All-metal tube P (Russian: ) - Small 9-pin or 7-pin glass envelope(22.5 or 19 mm in diameter)

3.5 Very-high power tubes designation (Eitel McCullough and derivatives) 15

A (Russian: ) - Subminiature glass envelope (5 to8 mm in diameter) with exible leads

B (Russian: ) - Subminiature glass envelope (8 to10.2 mm in diameter) with exible leads

S (Russian: ) - Glass envelope (greater than 22.5mm in diameter), typically with an octal base

N (Russian: ) - Nuvistor K (Russian: ) - Metal-ceramic envelope D (Russian: ) - Glass-metal envelope with discconnections (for UHF operation)

The 5th element is optional. It consists of a dash ("-")followed by a single character or a combination of char-acters, and denotes special characteristics (if any) of thetube:

V (Russian: ) - Increased reliability and mechan-ical ruggedness (such as low susceptibility to noiseand microphonics)

R (Russian: ) - Even better than V Ye (Russian: ) - Extended service life D (Russian: ) - Exceptionally long service life I (Russian: ) - Optimised for pulsed (i.e. switch-ing) mode of operation

Note: In most cases this means constructiondierences to the basic version, rather thana selection for those characteristics from theregular-quality production at the factory.


3.4.2 Very-high power tubes

There is another designation system for high-power tubessuch as transmitter ones.The 1st element is always G (Russian , for"" generator).The 2nd element (with some notable exceptions such asthe 807) is:

K (Russian: ) - Shortwave tube (25 MHz) U (Russian: ) - VHF tube (25-600 MHz) S (Russian: ) - UHF tube (>600 MHz) M (Russian: ) - Modulator tube I (Russian: ) - Impulse tube

The 3rd element consists of a dash ("-") followed by thedesign serial number:

A (Russian ) - Water-cooled B (Russian ) - Air-cooled


3.5 Very-high power tubes designation(Eitel McCullough and derivatives)

Manufacturers of very-high power tubes use the followingcode:[7]

An initial digit denoting the number of electrodes: 3 Triode 4 Tetrode 5 Pentode

One optional letter denoting the construction type: Glass envelope C Ceramic envelope

One optional letter denoting the cooling method: V Vapor cooled (anode is immersed in boilingwater, and the steam is collected, condensedand recycled)

WWater cooled (water is pumped through anouter metal jacket thermically connected tothe anode)

XAir cooled (air is blown through cooling nsthermically connected to the anode)

A number to indicate the maximum anode dissipa-tion in watts. This can be exceeded for a short time,as long as the average is not exceeded over the an-odes thermal time constant (typically 0.1 sec). Inclass C applications, the amplier output power de-livered to the load may be higher than the devicedissipation

One or more manufacturer-proprietary letters de-noting the construction variant

An optional proprietary digit denoting the gaingroup

Examples:

3CW5000A3 5 kW Ceramic triode, water cooled,variant 'A', gain group 3

3CX100A5 100WCeramic UHF triode, forced-aircooled, variant 'A', gain group 5; often used by radioamateurs for 23cm-band microwave ampliers.


3CX1500A7 (8877) 1.5 kWCeramic triode, forcedair cooled, variant 'A', gain group 7

3CX2500A3 2.5 kW Ceramic triode, forced aircooled, variant 'A', gain group 3

4-65A (8165) 65 W Glass beam tetrode 4-125A (4D21, 6155) 125 W Glass beam tetrode 4-250A (5D22, 6156) 110MHz, 250WGlass beamtetrode

4-400A 400 W Glass beam tetrode 4-1000A (8166) 1 kW Glass beam tetrode popularin broadcast and amateur transmitters.

4CX250B 250 W Ceramic tetrode, forced-aircooled, version 'B', favored by radio amateurs as anal amplier.

4CX250DC 250 W Ceramic tetrode, forced-aircooled, version 'DC'

4CX35000 Ceramic tetrode used in numerous 50-kW broadcast transmitters, forced-air cooled, of-ten in a Doherty conguration as in the ContinentalElectronics 317C series.

5-125B/4E27A 75 MHz, 125 W Glass power pen-tode

5-500A 500 W Glass radial-beam pentode 5CX1500A 110 MHz, 1.5 kW Ceramic radial-beam pentode, forced air cooled

5CX3000A 150 MHz, 4.0 kW Ceramic radial-beam pentode, forced air cooled

3.6 ETL computing tubes designationThe British Ericsson Telephones Limited (ETL), of Bee-ston, Nottingham (not to be confused with the SwedishTelefonAB Ericsson), original holder of the now-generictrademark Dekatron, used the following system:

An initial letter denoting the lling: G Gas-lled V Vacuum

One letter denoting the type: C Common-cathode Counter Dekatron thatmakes only carry/borrow cathodes separatelyavailable for cascading

D Diode, voltage reference, etc. R Readout - Digital indicator

S Separate-cathode Counter/Selector Deka-tron that makes all cathodes available onindividual pins for displaying, divide-by-ncounter/timer/prescalers, etc.

TE Trigger tetrode, one starter electrode and akeep-alive (primer) electrode for ion availabil-ity

TR Trigger triode, one starter electrode only

A digit group: Dekatrons: Stage count Digital indicators: Display cathode count Diodes, voltage references: Nominal voltage Trigger tubes: Ignition voltage

An optional digit group after a slash: Pin count

One letter denoting the type: A Plastic base B Plastic base C Plastic base D Plastic base E Plastic base G 26-pin B26A base H 27-pin B27A base M B7G base P B7G base Q B7G base W Pigtails X Pigtails Y Pigtails

For examples see below underGC,GD,GR,GS,GTE,GTR and VS

3.7 Military naming systems3.7.1 British CV naming system

This system prexes a three- or four-digit number withthe letters CV, meaning civilian valve i.e. commonto all three armed services. It was introduced during theSecond World War to rationalise the previous nomencla-tures maintained separately by the War Oce/Ministryof Supply, Admiralty and Air Ministry/Ministry of Air-craft Production on behalf of the three armed services(e.g. ACR~", AR~", AT~", etc. for CRTs, receiv-ing and transmitting valves used in army equipments,NC~", NR~" and NT~" similarly for navy equip-ments and VCR~", VR~" and VT~" etc. for air force

3.8 Other numeral-only systems 17

equipments), in which three separate designations couldin principle apply to the same valve (which often hadat least one prototype commercial designation as well).These numbers generally have identical equivalents inboth the North American, RETMA, and West European,Mullard-Philips, systems but they bear no resemblance tothe assigned CV number.Examples

CV1986 = 6SN7 = ECC33 CV4007 = SQ version of 6AL5 = E91AA CV4010 = SQ version of 6AK5 = E95F

Note: The 4000 numbers identify special-quality valves.The principle behind the CV numbering scheme wasalso adopted by the US Joint Army-Navy JAN number-ing scheme which was later considerably expanded intothe US Federal and then NATO Stock Number systemused by all NATO countries. This part-identication sys-tem ensures that every particular spare part (not merelythermionic valves) receives a unique stock number acrossthe whole of NATO irrespective of the source, and henceis not held ineciently as separate stores. In the caseof CV valves, the stock number is always of the format5960-99-000-XXXX where XXXX is the CV number(with a leading 0 if the CV number only has 3 digits).

3.7.2 U.S. naming systems

One system prexes a three-digit number with the lettersVT, presumably meaning Vacuum Tube. Other sys-tems prex the number with the letters JHS or JAN.The numbers following these prexes can be specialfour-digit numbers, or domestic two- or three-digit num-bers or simply the domestic North American RETMAnumbering system. Like the British military system,these have many direct equivalents in the civilian types.Confusingly, the British also had two entirely dierentVT nomenclatures, one used by the Royal Air Force(see the preceding section) and the other used by theGeneral Post Oce, responsible for post and telecommu-nications at the time, where it may have stood for valve,telephone"; none of these schemes corresponded in anyway with each other.Examples

VT numbering systems North American VT90 = 6H6 British (RAF)VT90VHF Transmitting triode British (GPO)VT90=ML4=CV1732Powertriode

VT104 RF pentode VT105 RF triode

3.8 Other numeral-only systemsVarious numeral-only systems exist. These tend to beused for devices used in commercial or industrial equip-ment.For examples, see belowThe oldest numbering systems date back to the early1920s, such as a two-digit numbering system, startingwith the UV-201A, which was considered as type 01,and extended almost continuously up into the 1980s.For examples see belowThree- and four-digit numeral-only systems were main-tained by R.C.A., but also adopted by many other manu-facturers, and typically encompassed rectiers and radiotransmitter output devices. Devices in the low 800s tendto be transmitter output types, those in the higher 800s arenot vacuum tubes, but gas-lled rectiers and thyratrons,and those in the 900s tend to be special-purpose and high-frequency devices. Use was not rigorously systematic: the807 had variants 1624, 1625, and 807W.For examples, see below under 800s, 900s and 1600s

3.9 Other letter followed by numeralsThere are quite a number of these systems from dierentgeographical realms, such as those used on devices fromcontemporary Russian and Chinese production. Othercompound numbering systems were used to mark higher-reliability types used in industrial or commercial applica-tions. Computers and telecommunication equipment alsorequired valves (tubes) of greater quality and reliabilitythan for domestic and consumer equipment.For examples, see belowSome designations are derived from the behavior of de-vices considered to be exceptional.

The rst beam tetrodes manufactured in the UKin the late 1930s by M-OV, carried a KT prexmeaningKinkless Tetrode (for examples see below).

4 List of American RETMA tubes,with European equivalents

Note: Typecode explained above. See also RETMA tubedesignation

4.1 0 volt gas-lled cold cathode tubesFirst character is numeric zero, not letter O.

Voltage stabilisers and references. Function in asimilar way to a Zener diode, at higher voltages. Let-

18 4 LIST OF AMERICAN RETMA TUBES, WITH EUROPEAN EQUIVALENTS

ter order (A-B-C) indicates increasing voltage rat-ings on octal-based regulators and decreasing volt-age ratings on miniature-based regulators. 0A2 150 volt regulator, 7-pin miniature base 0A3 75 volt regulator, octal base, aka VR75 0B2 105 volt regulator, 7-pin miniature base 0B3 90 volt regulator, octal base, aka VR90 0C2 75 volt regulator, 7-pin miniature base 0C3 105 volt regulator, octal base, akaVR105 0D3 150 volt regulator, octal base, akaVR150

Other cold-cathode tubes 0A4G 25 mA, 100mA Gas triode de-signed for use as a ripple control receiver;with the cathode tied to the midpoint of aseries-resonance LC circuit across live mains,it would activate a relay in its anode circuitwhile f is present

0Y4 40 I 75 mA Half-wave gas rectierwith a starter anode, 5-pin octal base

0Z4 30 I 90 mA Argon-lled, full-wavegas rectier, octal base. Widely used invibrator power supplies in early automobile ra-dio receivers.

4.2 1 volt heater/lament tubes Tubes with 1.0 to 1.4 volt heaters

1A3 High frequency diode with indirectlyheated cathode. Used as a detector in someportable AM/FM receivers.

1R5/DK91 Pentagrid converter, anode volt-age in the 45-90 volt range.

1S4 Power output pentode Class-A amplier,anode voltage in the 45-90 volt range.

1S5 Sharp cut-o pentode Class-A amplier,and diode, used as detector and rst A.F. stagein battery radio receivers. Anode voltage in the67-90 volt range. (B7G base)

1T4 Remote Cut-O R.F. Pentode Class-Aamplier, used as R.F. and I.F. amplier inbattery radio receivers, similar characteristicsto 6BA6 (B7G base).

1U4 Sharp Cut-O R.F. Pentode Class-A am-plier, used as R.F. and I.F. amplier in bat-tery radio receivers, similar characteristics to6BA6 (B7G base).

1B3GT High-voltage rectier diode commonin monochrome television receivers of the1950s and early 1960s. Peak inverse voltageof 30 kV. Anode current 2 mA average, 17mA peak. Derived from the earlier industrialtype 8016. (International Octal base.)

Tubes with 1.4 volt DC heaters 1A7GT Pentagrid converter 1G6-G Dual power triode. GT version alsoavailable.

1LA6 (loctal) and later 1L6 (7-pin miniature)battery pentagrid converter for Zenith Trans-Oceanic shortwave radio

1LB6 Superheterodyne mixer for battery-operated radios

1LC6 Similar to type 1LA6, but with higherconversion transconductance

1U6 Nearly identical to type 1L6, but with a1.4 V/25 mA lament

4.3 1.25 volt lament subminiature tubesThe following tubes were used in post-WW2 walkie-talkies and pocket-sized portable radios. All have 1.25volt DC laments and directly heated cathodes. Somespecify which end of the lament is to be powered bythe positive side of the lament power supply (usually abattery). All have glass bodies that measure from 0.285to 0.400 inches (7.24 mm to 10.16 mm) wide, and from1.25 to 2.00 inches (31.75 mm to 50.4 mm) in overalllength.Those labeled 8 pin have round bodies and bases with 8sti pins arranged in a circle. Those marked FL haveelliptical bodies and at bases with long, inline yingleads that are soldered into the circuit. Those markedSL are similar to those marked FL, but have short inlineleads that can be soldered or can be mated with a spe-cial socket. (Flying leads can be cut short to t into inlinesockets.)

1AC5 Power pentode, FL 1AD4 Sharp-cuto pentode, FL 1AD5 Sharp-cuto pentode, 8 pin 1AE5 Heptode mixer, FL 1AG4 Power pentode, FL 1AG5 Diode, pentode, FL 1AH4 RF pentode, FL 1AJ5 Diode, sharp-cuto pentode, FL 1AK4 Sharp-cuto pentode, FL 1AK5 Diode, sharp-cuto pentode, FL 1C8 Pentagrid converter, 8 pin 1D3 Low-mu high-frequency triode, 8 pin 1E8 Pentagrid converter, 8 pin

4.5 2 volt heater/lament tubes 19

1Q6 Diode, pentode, 8 pin 1S6 Diode, pentode, 8 pin 1T6 Diode, pentode, 8 pin 1V5 Power pentode, 8 pin 1V6 Triode-pentode converter, FL 1W5 Sharp-cuto pentode, 8 pin

4.4 1 prex for home receiversThese tubes weremade for home storage battery receiversmanufactured during the early to mid-1930s. The num-bers of the following tubes all start with 1, but these tubesall have 2.0 volt DC laments. This numbering schemewas intended to dierentiate these tubes from the tubeswith 2.5 volt AC heaters listed below.

1A4-p Remote-cuto pentode 1A4-t Remote-cuto tetrode 1A6 Pentagrid converter up to only 10 MHz due tolow heater power (2 V/60 mA) and consequent lowemission in the oscillator section; also occasionallyused as a grid-leak detector

1A7-GT Re-engineered version of types 1A6 and1D7-G, designed for use in portable AC/DC/Dry-cell battery radios introduced in 1938. Has 1.4 V/50mA lament.

1B4-p Sharp-cuto pentode 1B4-t Sharp-cuto tetrode 1B5 Dual detector diode, medium-mu triode. Usu-ally numbered 1B5/25S.

1B7-GT Re-engineered version of types 1C6 and1C7-G, designed for use in dry-cell battery radioswith shortwave bands. Has 1.4 V/100 mA lament

1C5 Power pentode (similar to 3Q5 except for la-ment)

1C6 Pentagrid converter; 1A6, with double theheater power and double the frequency range

1C7-G Octal version of type 1C6. 1D5-Gp Octal version of type 1A4-p. 1D5-GtOctal version of type 1A4-t. (Note: This isa shouldered G octal, not a cylindrical GT octal.)

1D7-G Octal version of type 1A6. 1E5-Gp Octal version of type 1B4-p. 1E5-Gt Octal version of type 1B4-t. (Note: This isa shouldered G octal, not a cylindrical GT octal.)

1E7-G Twin power pentode for used as a driverwhen parallel-connected, or as a push-pull output.GT version also available

1F4 Power pentode 1F5-G Octal version of 1F4. 1F6 Duplex diode, sharp-cuto pentode 1F7-G Octal version of type 1F6 1G5-G Power pentode 1H4-GMedium-mu triode, can be used as a powertriode. Octal version of type 30, which is an up-graded version of type 01-A. GT version alsoavailable.

1H6-G Octal version of type 1B5/25S. GT ver-sion also available.

1J5-G Power pentode 1J6-G Dual power triode, octal version of type 19.GT version also available.

4.5 2 volt heater/lament tubes Tubes used in AC-powered radio receivers of theearly 1930s. All have 2.5 volt heaters. 2A3Directly heated power triode, used for AFoutput stages in 1930s-1940s audio ampliersand radios.

2A5 Power Pentode (Except for heater, elec-tronically identical to types 42 and 6F6)

2A6 Twin-diode, high-mu triode (Except forheater, electronically identical to type 75)

2A7 Dual-tetrode-style pentagrid converter(Except for heater, electronically identical totypes 6A7, 6A8 and 12A8)

2B7 Twin-diode remote-cuto pentode (Ex-cept for heater, electronically identical to type6B7)

2E5 and 2G5 Electron-ray indicators (Eyetube) with integrated control triode. (Exceptfor heater, electronically identical to types 6E5and 6G5)

Tubes used in television receivers 2AF4 UHF triode oscillator 2BN4 VHF RF triode 2CW4 VHF RF triode (Nuvistor type) 2CY5 VHF sharp-cuto RF tetrode 2EA5 VHF sharp-cuto RF tetrode 2EN5 Dual-diode


2ER5 VHF RF triode 2ES5 VHF RF triode 2EV5 VHF sharp-cuto RF tetrode 2FH5 VHF RF triode 2FQ5 VHF RF triode 2FV6 VHF sharp-cuto RF tetrode 2FY5 VHF RF triode 2X2 High Vacuum High Peak inverse voltagediode, used as rectier in CRT EHT supplies.Similar to 1B3 and 1S2 except for heater volt-age.

4.6 5 volt heater/lament tubes 5AR4, GZ34 Full wave rectier 5AS4 Full wave rectier 5R4 Full wave rectier 5U4 Full wave rectier 5V4, GZ32 Full wave rectier 5Y3 Full-wave rectier, octal base version of type80

4.7 6 volt heater/lament tubes 6AB4/EC92 High-mu triode (Pinout same as 6C4except for pin 5 not having a connection)

6AB5/6N5 cathode ray tuning indicator 6A6 Twin Power Triode, used as a Class A audiodriver or a Class B audio output. UX6 base. 6.3volt heater version of type 53 which had a 2.5 voltheater. Octal version 6N7.

6A7 and 6A8 (PH4, X63) SuperheterodynePentagrid converter dual tetrode style. Based ontype 2A7, which had a 2.5 volt heater. 6A7 hasa UX7 base with top cap connection for controlgrid (grid 4). 6A8 is octal version with top capconnection for control grid. Loctal version: type7B8.

6AC7, 1852 Television Sharp Cuto R.F. Pentode.(Often encountered in a black metal envelope, notto be confused with the 6CA7.)

6AD6-G and 6AF6-G Magic Eye tuning indi-cators. Both have two pie wedge shadow indi-cators, one each on opposite sides of a single cir-cular indicator target. Both shadows may be usedin tandem or may be driven by two dierent sig-nal sources. Type 6AE6-G is specically madeto drive each indicator with dierent signals. May

also be driven by separate pentodes with dierentcharacteristics. E.g., a sharp-cuto pentode like a6J7 - which would be hyper-sensitive to any signalchangewould drive one shadow, while a remote-cuto pentode like a 6K7 - which would only reactto stronger signalswould drive the other shadow.Both tubes have octal bases. Type 6AD6-G, witha target voltage rated from 100 to 150 volt, is de-signed for AC/DC radios. Type 6AF6-G, with a tar-get voltage rated at 250 volt, is designed for largerAC radios.

6AE6-G A driver triode specially designed forMagic Eye tuning indicator types 6AD6-G and6AF6-G. Has a common heater and indirectlyheated cathode, two internally connected triodegridsone with sharp cuto characteristics, onewith remote cuto characteristicsand two plates,one for each grid. The sharp cuto grid reacts toany signal change, while the remote cuto grid re-acts only to stronger signal changes.

6AF4 UHF Medium mu Triode, commonly foundin television UHF tuners and converters.

6AH5-G Beam power tube for early television use.Same as type 6L6-G, but with scrambled pinout.Used in some Philco sets.

6AK5, EF95, 5654, CV4010, 61 MiniatureV.H.F. Sharp cut-o Pentode (Used in old Ra-diosonde weather balloon transmitters, receiverfront ends and contemporary audio equipment)B7G, (Miniature 7 pin) base

6AK6 Power pentode. 7-pin miniature version oftype 6G6-G. Unusual low-power consumption out-put tube with 150 mA heater.

6AK8/EABC80 Triple Diode, High-mu Triode.Diodes have identical characteristicstwo havecathodes connected to the triodes cathode, one hasan autonomous cathode. Used as a combination AMdetector/AVC rectier/FM ratio detector/A.F. am-plier in AM/FM radios manufactured outside ofNorth America. Triode amplication factor: 70.North American type 6T8 is identical (but for ashorter glass envelope) and may be used as a sub-stitute.

6AL3, EY88 Television Damper/ EciencyDiode

6AL5, EAA91, D77 Dual Diode, Detector. Oftenused in vacuum tube volt meters (VTVMs). Minia-ture version of type 6H6.

6AL6-G Beam power tube for early television use.Same as type 6L6-G, but with scrambled pinout andplate connected to top cap.


6AL7-GT Tuning indicator used in many earlyAM/FMHi-Fi radios. Similar in function to MagicEye tubes. Has two bar-shaped shadows; one growsto indicate signal strength, the other moves to indi-cate center tuning on FM.

6AM6, EF91, Z77, Sharp Cuto R.F. pentode usedin receiver front ends and test gear such as VTVMsand Television broadcast modulation monitors.

6AN7, ECH80 Triode-Hexode Local Oscilla-tor/Mixer (radio)

6AQ5 Beam-power pentode, 7-pin miniature simi-lar of type 6V6.

6AQ8 Dual Triode with internal shield, like6BK7/6BQ7/6BZ7

6AR8, 6JH8, 6ME8 Beam deection tubes foruse as NTSC chroma signal demodulators in analogcolor TV receivers

6AS6 Pentode with a ne-pitched suppressor gridwhich could serve as a second control grid. Used inradar phantastron circuits.

6AS7, 6080 Dual low-mu Triode, low impedance,mostly used for voltage regulation circuits.

6AT6 Dual Diode, High Mu Triode, miniature ver-sion of type 6Q7. Triode amplication factor: 70.

6AU4 Television Damper/ Eciency Diode 6AU6, EF94, 6AU6A, Sharp-cuto pentode 6AV6 Dual Diode, High Mu Triode, miniature ver-sion of type 75. Triode amplication factor: 100.(Triode section similar in characteristics to one halfof a 12AX7.)

6AX4 Television Damper/ Eciency Diode 6AX5 Full-wave rectier. Octal base. Similar instructure to type 6X5, but with higher voltage andcurrent ratings which are comparable to those oftypes 5Y3 and 80.

6B6-G Double-Diode High Mu Triode. Octal ver-sion of type 75. Has top-cap connection for triodegrid. Later octal version, type 6SQ7, has under-chassis connection for triode grid. Miniature ver-sion: 6AV6.

6B7 and 6B8 (EBF32): Double-Diode, Semi-Remote Cuto Pentodes. Based on type 2B7 whichhad a 2.5 volt heater. Type 6B7 has a UX7 basewith a top-cap connection for the control grid (grid1). Type 6B8 has an octal base with a top cap. Thediode plates are most commonly used as (second)detectors and AVC rectication in superheterodynereceivers. Because their control grids have both

sharp cuto and remote cuto characteristics, thesetypes were used as I.F. ampliers with AVC biasto the control grid, and as A.F. ampliers. Thesetypes were also used in reex radios. In a typical2B7/6B7/6B8 reex circuit, the I.F. signal from theconverter is injected into the pentode and is ampli-ed. The diodes then act as detectors, separatingthe A.F. signal from the R.F. signal. The A.F. signalis then re-injected into the pentode, amplied, andsent to the audio output tube.[8]

6BA6, EF93, W727, 5790 Medium Cuto R.F.Pentode (Often encountered in Car Radios)

6BE6, EK90, 5750, X727 Pentagrid Converter (Of-ten encountered in Car Radios)

6BF6 Dual Diode, Medium-mu triode. Miniatureversion of octal type 6R7.

6BG6 Beam tetrode, anode cap. Used in early TVmagnetic-deection horizontal-output stage.

6BK4 High Voltage beam Triode (30 kV anodevoltage). Used as shunt regulator in color TV re-ceivers and measurement equipment such as highvoltage meters

6BK7 Dual Triode with Internal shield betweeneach section, used in RF circuits (Similar to 6BQ7)

6BK8, EF86, Z729 Audio Pentode used inmicrophone preampliers and audiophile equipment

6BK11 Triple triode compactron preamplier; usedin some guitar amps made by Ampeg.

6BL8, ECF80 General-purpose Triode pentodeused in television, audio and test gear

6BM8, ECL82 Triode pentode used as the driverand output stages in audio ampliers, audio outputand vertical output stages in televisions and has evenbeen seen in an electronic nerve stimulator.

6BN6 Gated-beam discriminator pentode, usedin radar, dual channel oscilloscopes and F.M.quadrature detectors (cf. nonode)

6BQ5, EL84,(N709) 5.7 Watts AF Power pentode,noval base

6BQ6-GT Beam Power Pentode, used as a Hori-zontal Deection Output tube in monochrome TVsets of the 1950s. Most commonly used in sets withdiagonal screen sizes less than 19 inches (49 cm).(However, may be found in some larger models.)Larger sets often used similar type 6DQ6. Laterversions of this tube branded as 6BQ6-GTB/6CU6.

6BU8 Split Anode Television Sync Separator


6BX6, EF80, E80F (though not pin compatible)Sharp Cuto R.F. Pentode (TV IF; E80F used inearly computers.)

6BY6 Similar to type 6CS6, but with highertransconductance. 3BY6 with a dierent heater

6BY7, EF85, W719 Remote Cuto R.F. Pentode(TV IF)

6BZ6 Sharp Cuto R.F. pentode used in video I.F.circuits of the 1960s.

6BZ7 Dual Triode. See 6BK7 6C4 V.H.F. Triode 6C6 Sharp Cuto R.F. Pentode. Most commoncommercial uses were as a tuned R.F. amplier, adetector, and an A.F. amplier. Also used in testequipment. Has UX6 base with top cap. Based ontype 57, which had a 2.5 volt heater. Similar to types1603, 77 and octal types 6J7 and 6SJ7.

6C10 High-mu triple triode compactron 6CA4, EZ81 Full Wave Rectier 6CA7, EL34 Audio Power Output Pentode 6CB6 Remote Cuto R.F. Pentode used in videoI.F. circuits of the 1950s and early 1960s.

6CG7 Dual Triode (used in television and some au-dio ampliers including modern solid-state designsoften as a cathode follower, similar to 6SN7)

6CJ6 Line Output Pentode 6CL6 Power pentode 6CM5, EL36, EL360 Audio and Television LineOutput Beam Power Tetrode.

6CW4 Nuvistor tube, high triode 6D4 25 mA, 100 mA Indirectly heated, argontriode thyratron, negative starter voltage, miniature7-pin base; found an additional use as a 0 to 10MHznoise source, when operated as a diode (starter tiedto cathode) in a transverse 375 G magnetic eld.Suciently ltered for atness ("white noise") ina band of interest, such noise was used for testing ra-dio receivers, servo systems and occasionally in ana-log computing as a random value source.

6D6 Remote-Cuto R.F. Pentode. Most commoncommercial uses were as an I.F. amplier or as a su-perheterodyne mixer, aka 1st detector. Also used intest equipment. Has UX6 base with top cap. Basedon type 58, which had a 2.5 volt heater. Similar totype 78. Octal version: 6U7-G.

6D8-G Superheterodyne Pentagrid converter, simi-lar to type 6A8. Octal base with top cap. Has 150mA heater. Used in pre-war 6-volt farm radios.

6DA6, EF89 R.F. Pentode used in AM/FM radiosmanufactured outside North America.

6DJ8, ECC88, E88CC, 6922, 6N23P, 6N11 DualAudio and R.F. Triode (often used in televisionbroadcast equipment, test gear, oscilloscopes andaudiophile gear) similar to 6ES8

6DQ6 Beam Power Pentode, used as a HorizontalDeection Output tube in monochrome TV sets ofthe 1950s. Most often found in sets with diago-nal screen measurements larger than 17 inches (43cm). Smaller sets often used similar type 6BQ6-GT. Also used as Audio Output tubes in Standelguitar ampliers. Later versions branded as 6DQ6-B/6GW6.

6DR8, EBF83, R.F. pentode which will operatewith 12 V anode supply, used as I.F. amplier in carradios which run directly o the 13.5 volt supply.

6DS4 Nuvistor R.F. triode used in TV tuners imme-diately prior to the introduction of solid state tuningcircuits. (RCA TVs equipped with a 6DS4 tunerbore the trademark Nu-Vista Vision.)

6DS8, ECH83, Triode-Heptode Local oscillator-Mixer which will operate with 12 V anode supply,used in car radios which run directly o the 13.5 voltsupply.

6DT6Quadrature detector used in TV audio circuitsof the 1950s and early 1960s.

6DV4Medium-mu nuvistor triode for UHF oscilla-tors; some versions had a gold-plated envelope.

6DX8 Triode pentode 6E5 Magic Eye Tuning indicator. Has incor-porated driver triode with sharp-cuto grid whichmakes it extremely sensitive to any changes in signalstrength. Has UX6 base. Based on type 2E5, whichhad a 2.5 volt heater.

6EM5 Pentode (Television Vertical Output) 6ES6, EF98, R.F. pentode which will operate with12 V anode supply, used as tuned R.F. amplier incar radios which run directly o the 13.5 volt supply.

6ES8, ECC89, E89CC Dual Triode used as cascodeR.F. amplier in television tuners and V.H.F. re-ceiver front ends, also used as general-purpose dualtriode in test gear, similar to 6DJ8

6F5 High-mu triode, equal to triode section of type6Q7


6F6, KT63 Power Pentode. Octal base version oftype 42. Moderate power output rating9 wattsmax. (Single-ended Class A circuit); 11 wattsmax. (Push-pull Class A circuit); 19 watts max.(push-pull Class AB2 circuit). Available in metal(numbered 6F6), shouldered glass (6F6-G), andcylindrical glass (6F6-GT). Sometimes used as atransformer-coupled audio driver for types 6L6-GCand 807 when those tubes were used in Class AB2or Class B ampliers. Also used as a Class C oscil-lator/amplier in transmitters.

6F7 Remote Cuto Pentode, Medium-mu Triode.Has UX7 base with top-cap connection for the pen-todes control grid (grid 1). Most common uses wereas superheterodyne mixer (rst detector) and localoscillator, or as a combination I.F. amplier (pen-tode) and (second) detector or A.F. amplier (tri-ode). Octal version: 6P7-G.

6FH8 Medium-mu triode and three-anode sharpcuto tetrode for use in TV receivers and complexwave generators

6G5 Magic Eye Tuning indicator. Has incorpo-rated triode with remote-cuto grid, which makes itless reactive to low-level changes in signal strength.Has UX6 base. Electronically identical to type 6U5except for indicator. Both types had pie wedgeshadow indicators. At rst, the shadow indicatorfor type 6G5 was fully closed at zero signal andopened as signal strength increased. For type 6U5,the shadow indicator was fully open at zero sig-nal and closed as signal strength increased. Af-ter World War II, type 6G5 was discontinued as aunique tube and all 6U5s were doubled branded ei-ther as 6G5/6U5 or 6U5/6G5.

6G6-G Power pentode. Octal base. Low poweroutput1.1 watt max. output. Has 150 mA heater.Used in pre-war 6-volt farm radios. Miniature ver-sion - 6AK6.

6G8-G Double-Diode Sharp Cuto Pentode (Usedas Detector and rst A.F. stage in Australian 1940sradios)

6GK5Miniature V,H.F. Triode (Used as V.H.F. lo-cal oscillator in some T.V. Turret Tuners)

6GM5 Beam power pentode, identical to 7591 and7868 with a mini-noval pin base

6GV8, ECL85 Triode Pentode (TV vertical output) 6GW8, ECL86 Audio Triode Pentode (audio, TVvertical output)

6H6, D63, EB34, OSW3109. Dual Diode. Octalbase. Most commonly found as a stubby metalenvelope tube. Glass versions 6H6-G and 6H6-GTare also found.

6J5, L63. Medium-mu triode. 6J5WGT Heater cathode type, medium mu triode,identical to 12J5WGT except heater characteristics

6J7, EF37. Sharp Cuto Pentode. Most commoncommercial uses were as a tuned R.F. amplier, a(second) detector, or an A.F. amplier. Octal ver-sion of type 77. This type included a top-cap con-nection for the control grid. Later version, type6SJ7, had its control grid connection on pin 4.

6J8-G Triode-Heptode (radio local oscilla-tor/mixer)

6JU8A 9 mA, Four-diode bridge rectier 6K6-G Power Pentode, octal version of type 41.Low-to-moderate power output rating0.35 to 4.5watts (single-ended Class A circuit); 10.5 watts max.(push-pull Class A circuit).

6K7, EF39. Remote Cuto R.F. pentode. Mostcommon commercial uses were as an I.F. ampli-er or as a superheterodyne mixer, aka 1st detector.Also used in test equipment. Octal version of type78. This type included a top-cap connection for thecontrol grid. Later version, type 6SK7, had its con-trol grid connection on pin 4.

6K8 and 12K8 American Triode-Hexode mixer,1938

6KM8 Diode and three-anode sharp cuto tetrodefor use in musical instruments, frequency dividersand complex wave generators

6L5-G Medium-mu triode (Similar to type 6J5-G,available only in ST shape)

6L6/EL37 High-powered beam tetrode.

There are several variations. Ex-cept for types 6L6-GC and 6L6-GX, all have the same maximumoutput ratings:

11.5 watts (single-ended ClassA circuit)

14.5 watts (push-pull Class Acircuit)

34 watts (push-pull Class AB1circuit)


6L6 (metal envelope) and 6L6-G(shouldered glass envelope) wereused in pre-World War II radiosand Public Address ampliers.


6L6 and 25L6 were introduced in1935 as the rst beam tetrodes.Both types were branded with theL6 ending to signify their (then)uniqueness among audio outputtubes. However, this is the onlysimilarity between the two tubes.(Type 6W6-GT is the 6.3 voltheater version of types 25L6-GTand 50L6-GT.)

6L6GA Post-war version of type 6L6-G,in smaller ST-14 shape with ShoulderedTubular, (ST), shaped bulb, revision A.

6L6GB Post-war improved version in acylindrical glass envelope. Similar totype 5881.

6L6GTB, Type 6L6 withTubular, (T), shaped bulb,revision B, (higher powerrating, as it happens. The6L6GTB can always replacethe 6L6, 6L6G, and 6L6GT,but a 6L6GTB running atmaximum rating should notbe replaced with anothersubtype).

6L6-WGB Industrial ver-sion of type 6L6GB.

6L6GC Final and highest-powered audioversion of the tube. Max. outputs:

17.5 watts (single-ended ClassA circuit)

32 watts (push-pull Class Acircuit)



6L6-GX Class C oscillator/amplierused in transmitters. Max. output 30watts. (All versions may be used as aClass C oscillator/amplier, but this ver-sion is specically designed for this pur-pose, has a special ceramic base.)

6L7 Pentagrid converter often used in consoleradios of the late 1930s. Similar in structureto pentode-triode pentagrid converters 6SA7 and6BE6, except that a separate oscillatorusuallytype 6C5 - is required. Also, grid 1 is remote cut-o control grid, grid 3 is oscillator input grid. (Intypes 6SA7 and 6BE6, grid 1 is the internal oscilla-tor grid, grid 3 is the control grid.) Because of low

conversion transconductance, radios using type 6L7typically have either a tuned RF pre-amplier stage,or at least two stages of I.F. amplication. (A fewmodels have both.)

6M5 Audio Output Pentode (Used as Class A or Coutput stages of 1950s Australian radiograms) sim-ilar to 6BQ5

6ME4 Tuning indicator 6ME5 Tuning indicator 6ME10 Tuning indicator 6MDE1 Tuning indicator 6MK8 Dual-anode pentode for TV receiver syncseparation service

6N3, EY82 Half-Wave Rectier 6N5/6N5P Tuning indicator 6N7 Twin Power Triode, used as Class A audiodriver or as Class B power output (also 6N7-G and6N7-GT). Max. output (Class B) - 10 watts. Octalversion of type 6A6.

6N8, EBF80 Remote cut-o pentode, dual diode.(detector plus RF or AF amplier in radios)

6P5-G/GT Medium-mu triode, Octal version oftype 76, often used as driver for type 6AC5-G.

6P7-G Rarely seen octal version of type 6F7. 6Q5-G Triode gas thyratron used in DuMont oscil-loscopes as a sweep generator. Identical to RMAtype 884.

6R3, EY81 Television Damper/ Eciency Diode 6R7 Dual Diode, Medium-mu Triode (also 6R7-Gand 6R7-GT). Octal base with top cap. Miniatureversion - 6BF6. Amplication factor: 16.

6S7-G Remote Cuto RF Pentode, similar to type6K7. Octal base with top cap. Has 150 ms heater.Used in pre-war 6-volt farm radios.

6S8-GT Triple Diode, High-mu Triode. Octal tubewith top-cap connection to triode grid. Has threeidentical diodestwo diodes share a cathode withthe triode, one has an autonomous cathode. Usedas a combined AM detector/AVC rectier/FM ra-tio detector/A.F. amplier in AM/FM radios. Typ-ically, all sections of this tube are arranged arounda single heater.

6SA7 First pentode-triode style pentagrid converter.Octal type. Miniature version: 6BE6.

6SB7Y (octal), 6BA7 and 12BA7 (9-pin minia-tures) VHF Pentagrids, 1946

4.8 7 prex loctal tubes 25

6SC7 High-Mu dual triode (Both sections share asingle cathode)

6SK7Remote-cuto pentode (Used in I.F. stages ofNorth American radios) Miniature version: 6BD6

6SL7, ECC35. Twin triode (Used in Television andgeneral electronics)

6SN7, ECC32, B65, 13D2, CV1986, 6042?Medium-mu twin triode (Used in Audio Ampliers,Hammond Organs and Television; extensive use inWorld War II radar) Each section is equivalent to a6J5. Miniature version: 12AU7

6SS7 Remote cuto pentode (150 mA lament ver-sion of the 6SK7, found in some AA6 radios as boththe RF amplier and rst IF). This is the only tubeto have two of the same letters in its type.

6T5 Magic Eye Tuning indicator. Has incorpo-rated driver triode with remote-cuto grid. HasUX6 base. Shadow indicator is fully closed at zerosignal. As signal increases, shadow grows outwardfrom the center, covering the entire circumferenceof the indicator. Electronically identical to types6G5 and 6U5, which may be used as substitutes.

6T7-G Dual diode, high-mu triode, similar to type6Q7. Octal base with top cap. Has 150 mA heater.Used in pre-war farm radios.

6T8 Triple Diode, High-mu Triode. Has three iden-tical diodestwo have cathodes connected to thetriodes cathode, one has an autonomous cathode.Triode amplication factor: 70. Used as an AM de-tector/AVC rectier/FM ratio detector/A.F. ampli-er in North American AM/FM radios. Identical totype 6AK8/EABC80, but with a shorter glass enve-lope.

6U5 Magic Eye Tuning indicator. Has incorpo-rated driver triode with remote-cuto grid. HasUX6 base. Has pie wedge shadow indicator thatis open at zero signal and closes as signal increases.Electronically identical to types 6G5 and 6T5 andmay be used as a substitute for those types. AfterWorld War II, most new 6U5s were double-brandedas either 6G5/6U5 or 6U5/6G5.

6U5G Magic Eye Tuning indicator with triode,International Octal, (IO), base

6U7-G Remote Cuto R.F. Pentode. Most com-mon commercial uses were as an I.F. amplier oras a superheterodyne mixer, aka 1st detector. Alsoused in test equipment. Octal version of type 6D6.Most direct substitute: 6K7. Similar to types 58, 78and 6SK7.

6U8A Split triode-pentode, mini-noval pinbase.Audio preamplier.

6V6 Beam power tetrode, used in single-ended classA audio output stages of radios and sometimes seenin class B audio ampliers (see also: 5V6 and12V6). Electrically similar to 6AQ5/EL90.

6V6G, Type 6V6 with Shouldered Tubular,(ST), shaped bulb.

6V6GT, Type 6V6 with Tubular, (T), shapedbulb.

6V7-G, Dual Diode, Medium-mu Triode. Octalversion of type 85. Amplication factor: 8.3. Sim-ilar to type 6R7.

6W6-GT Beam power pentode, used most often asa Vertical Deection Output tube in monochromeTV sets of the 1950s. Can also used as an AudioOutput tube. This is the 6.3 volt heater version oftypes 25L6-GT and 50L6-GT.

6X4 (EZ90) and 6X5 (EZ35): Full-wave rectierswith indirectly heated common cathode. Type 6X4has a 7-pin miniature base, the 6X5 has an octalbase. Based on type 84/6Z4. No longer in produc-tion.

4.8 7 prex loctal tubes

These tubes all have 6.3 volt AC/DC heaters.

7A4Medium-mu triode, loctal version of type 6J5,often numbered 7A4/XXL

7A5 Beam power pentode, loctal version of type6U6GT

7A6 Dual detector diode, similar to type 6H6 7A7 Remote-cuto pentode, loctal version of type6SK7

7A8 The only octode pentagrid converter producedin America by Sylvania, 1939. Used mostly inPhilco radios.

7AB7 Sharp-cuto pentode 7AD7 Power pentode 7AF7 Twin medium-mu triode 7AG7 Sharp-cuto pentode 7AH7 Remote-cuto pentode 7AJ7 Sharp-cuto pentode 7AK7 Sharp-cuto, dual control pentode for com-puter service. Perhaps the rst active device specif-ically designed for computer use.


7B4High-mu triode, loctal version of types 6F5 and6SF5

7B5 Power pentode, loctal version of types 6K6 and41

7B6 High-mu triode, dual detector diodes, loctalversion of type 75, similar to types 6AV6 and 6SQ7

7B7 Remote-cuto pentode 7B8 Pentagrid converter, loctal version of types 6A7and 6A8

7C4 High frequency diode 7C5 Beam power pentode, loctal version of type6V6

7C6 High-mu triode, dual detector diode 7C7 Sharp-cuto pentode 7E5Medium-mu high-frequency triode 7E6Medium-mu triode, dual detector diode, loctalversion of types 6R7 and 6SR7, electronically iden-tical to miniature type 6BF6.

7E7 Semi-remote-cuto pentode, dual detectordiode, similar to types 6B7 and 6B8

7F7 High-mu dual triode, loctal version of type6SL7-GT

7F8Medium-mu high-frequency triode, used as FMRF amplier and converter

7G7 Sharp-cuto pentode 7G8 Sharp-cuto twin tetrode 7H7 Semi-remote-cuto pentode 7J7 Triode-heptode converter, similar to type 6J8-G

7K7 High-mu triode, dual detector diode, similar totypes 6AT6 and 6Q7

7L7 Sharp-cuto pentode 7N7 Twin medium-mu triode, loctal version of type6SN7-GT

7Q7 Pentagrid converter, similar to type 6SA7 7R7 Remote-cuto pentode, dual detector diode 7S7 Triode-heptode converter 7T7 Sharp-cuto pentode 7V7 Sharp-cuto pentode 7W7 Sharp-cuto pentode

Note Types 7V7 and 7W7 are electronicallyidentical except for base connections of pins4, 5 and 7. On type 7V7, the suppressor grid(grid 3) is connected to pin 4, an internal shieldis connected to pin 5, and the cathode is con-nected to pin 7. On type 7W7, the suppres-sor grid and internal shield are connected topin 5, and the cathode is connected to pins 4and 7. All other pin connections are the same.If interchanging these tube types is necessary,conrm that pins 4 and 7 are connected at thesocket. (Pin 5 is usually connected to the chas-sis.)

7X6 Dual rectier diode 7X7 High-mu triode, dual detector diodes on sep-arate cathodes, used as FM discriminator and AFamplier, often numbered 7X7/XXFM

7Y4 Dual rectier diode 7Z4 Dual rectier diode

4.9 12 volt heater/lament tubes 12A5 Power pentode. UX7 base. Single-sectiontube with two side-by-side 6.3 volt heater-cathodestructures. Each is connected together to form (1)a 12.6 volt 300 mA heater for series heater strings,or (2) a 6.3 volt 600 mA heater for parallel heatercircuits. Mostly used in pre-war car radios.

12A7 Power pentode, rectier diode. Pentode sec-tion is similar to type 38. Diode has a low powerrating120 volt, 30 mA that limits the numberof tubes that can be tied to its B+ circuit. Usedin one-tube portable phonographs and a few two-and three-tube radios. Forerunner of such typesas 32L7-GT, 70L7-GT and 117L7-GT. UX7 basewith top cap. Not related to types 2A7 and 6A7.

12AB5 Beam Power Tube,[9]

12AE10 Beam Power Tube, Sharp Cuto Pentode[9]

12AL5 Dual diode (similar to 6AL5 except forheater)

12AT6 Dual diode/triode (Commonly replaced by12AV6 in consumer radios)

12AT7, ECC81, 6060, B309, M8162High-mu twintriode. Commonly used as R.F. amplier/mixer inVHF circuits.[9]

12AU7, ECC82, 6067, B329, M8136 Medium-mutwin triode. Two 6C4s in one envelope. Commonlyused in audio applications and television receivers

4.10 14 prex loctal tubes 27

12AV6 Twin diode/High-mu triode (see also:6AV6)

12AV7, 5965 Dual Triode. Medium-mu,Principally designed for VHF amplier/mixeroperation.[10]

12AX7, ECC83, 6057, B327, M8137 High-mutwin triode. Very similar to triode section of 6AV6.Commonly used in high-gain audio stages.[9]

12AY7 Dual Triode. Medium gain but low noise,intended for low-level/preamplier use.[9]

12AZ7Double Triode. Medium-mu, AFAmplier,or combined oscillator and mixer, 9-pin [11]

12B4A [9]

12BA6 Remote cuto pentode, 6BA6/EF93 with adierent heater

12BE6 Pentagrid converter, 6BE6/EK90 with adierent heater

12BH7 Dual Triode, Medium-mu, designed for usein equipment having series heater-string arrange-ment [12]

12BY7 Video Amplier Pentode 12DT6 Sharp cuto pentode 12DW7 Dissimilar triodes. One half 12AX7 value,other half 12AU7 value. (also known as 7247 orECC832)

12EG6 Pentagrid converter, both grids 1 and 3 aresharp-cuto, has 12.6 volt anode and screen gridvoltage, for use with audio equipment powered bya car battery

12FA6 Low-anode voltage, car radio version of12BE6 pentagrid converter

12FQ8 Common-cathode, dual split-anode triodefor use in musical instruments, frequency dividersand complex wave generators[13]

12FX8 Low-anode voltage, triode-heptode con-verter for car radios

12GA6 Similar to type 12FA6, but with lower con-version transconductance

12J5WGTHeater cathode type, mediummu triode,identical to 6J5WGT except heater characteristics

12K5 Tetrode, one of a few tubes that can functionwith low plate voltages (See Space charge)

12SA7 Pentagrid converter (Octal version of12BE6)

12SK7 Remote cuto Penode (Octal version of12BA6)

12SQ7Dual diode, triode (Octal version of 12AV6) 12U5G Tuning indicator identical to 6U5G exceptheater characteristics

12Z3 Half-wave rectier, UX4 base

4.10 14 prex loctal tubesThese tubes all have 12.6 volt AC/DC heaters

14A4 Medium-mu triode, loctal version of type12J5

14A5 Beam power pentode 14A7 Remote-cuto pentode, often numbered14A7/12B7

14AF7 Twin medium-mu triodes, often numbered14AF7/XXD

14B6 High-mu triode, dual detector diode, similarto types 12AV6 and 12SQ7

14B8 Pentagrid converter, loctal version of type12A8

14C5 Beam power pentode, loctal version of type12V6-GT

14C7 Sharp-cuto pentode 14E6Medium-mu triode, dual detector diode, loctalversion of 12SR7

14E7 Semi-remote-cuto pentode, dual detectordiode, similar to type 12C8

14F7 High-mu dual triode, loctal version of type12SL7-GT

14F8 Medium-mu high frequency triode, used asFM RF amplier and converter

14H7 Semi-remote-cuto pentode 14J7 Triode-heptode converter 14N7 Twin dual medium-mu triode, loctal versionof type 12SN7-GT

14Q7 Pentagrid converter, similar to type 12SA7 14R7 Remote-cuto pentode, dual detector diode 14S7 Triode-heptode converter 14W7 Sharp-cuto pentode 14X7 High-mu triode, dual detector diodes on sep-arate cathodes, used as FM discriminator and AFamplier

14Y4 Dual rectier diode


4.11 25 volt heater/lament tubes 25A6 Power pentode, octal version of type 43 25C5 Beam Power Pentode (Identical to the 50C5but with a 25 V 300 mA lament)

25F5 Beam Power Pentode (Identical to the 50C5,but with a 25 V 150mA lament, used in someAA5type radios using push-pull output)

25L6Beam-power pentode (Except for heater, elec-trically identical to type 50L6)

25Z5 Twin

Documents

List of Vacuum Tubes