Only a few types are still used today, mainly in high-power, high-frequency applications. Receiving tubes have heaters or filaments intended for direct battery operation, parallel operation off a dedicated winding on a supply transformer, or series string operation on transformer-less sets. High-power RF power tubes are directly heated; the heater voltage must be much smaller than the signal voltage on the grid and is therefore in the In some valve part number series, the voltage class of the heater is given in the part number, and a similar valve might be available with several different heater voltage ratings.
The system assigned numbers with the base form "1A21", and is therefore also referred to as the "1A21 system". Often designations that differed only in their initial numerals would be identical except for heater characteristics. For examples see below. A four-digit system was maintained by the EIA for special industrial, military and professional vacuum and gas-filled tubes, and all sorts of other devices requiring to be sealed off against the external atmosphere.
Some manufacturers preceded the EIA number with a manufacturer's code:. Media related to Eimac vacuum tubes at Wikimedia Commons. This system is very descriptive of what type of device triode, diode, pentode etc. Like the North American system the first symbol describes the heater voltage, in this case, a Roman letter rather than a number. Further Roman letters, up to three, describe the device followed by one to four numerals assigned in a semi-chronological order of type development within number ranges assigned to different base types.
If two devices share the same type designation other than the first letter e. ECL82, PCL82, UCL82 they will usually be identical except for heater specifications; however there are exceptions, particularly with output types for example, both the PL84 and UL84 differ significantly from the EL84 in certain major characteristics, although they have the same pinout and similar power rating.
However, device numbers do not reveal any similarity between different type families; e. Pro Electron maintained a subset of the M-P system after their establishment in , with only the first letters E , P for the heater, only the second letters A , B , C , D , E , F , H , K , L , M , Y , Z for the type, and issuing only three-digit numbers starting with 1 , 2 , 3 , 5 , 8 , 9 for the base. They were usually special-quality versions of standard types.
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While the E80F pentode was a high quality development of the EF80, they were not pin-compatible and could not be interchanged without rewiring the socket the E80F is commonly sought after as a high quality replacement for the similar EF86 type in guitar amplifiers. The letters "CC" indicated the two triodes and the "F", the single pentode inside these types. A few special-quality tubes did not have a standard equivalent, e. The E91H is a special heptode with a passivated third grid designed to reduce secondary emission; this device was used as a "gate", allowing or blocking pulses applied to the first, control grid by changing the voltage on the third grid, in early computer circuits similar in function to the U.
Many of these types had gold-plated base pins and special heater configurations inside the nickel cathode tube designed to reduce hum pickup from the A. Note that elevating the cathode voltage above the average heater voltage, which in well-designed equipment was supplied from a transformer with an earthed center-tapped secondary, was less detrimental to the oxide insulation between heater and cathode than lowering the cathode voltage below the heater voltage, helping to prevent pyrometallurgical electrolytic chemical reactions where the oxide touched the nickel cathode that could form conductive aluminium tungstate and which could ultimately develop into a heater-cathode short-circuit.
Better, often dual, getters were implemented to maintain a better vacuum, and more-rigid electrode supports introduced to reduce microphonics and improve vibration and shock resistance. The mica spacers used in "SQ" and "PQ" types did not possess sharp protrusions which could flake off and become loose inside the bulb, possibly lodging between the grids and thus changing the characteristics of the device.
Later special-quality tubes had not base and function swapped but were assigned a 4-digit number,  such as ECC or ED, the first digit of which again denoting the base:. In use since at least , this system was maintained by Pro Electron after their establishment in The first letter or letter pair, in the case of a dual-system device indicates the general type:.
The following letter indicates the filament or cathode type, or the fill gas or other construction detail. The coding for vacuum devices differs between Philips and other Continental European manufacturers on the one hand and its Mullard subsidiary on the other. The following letter indicates the photocathode type:. The first incarnation of La Compagnie des Lampes produced the TM tube since and defined one of the first French systems;   not to be confused with Compagnie des Lampes , "French Mazda", see below.
First number: Heater or filament rating .
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This system consists of one or more letters followed by a sequentially assigned number . The British GEC — Marconi—Osram designation from the s uses one or two letter s followed by two numerals and sometimes by a second letter identifying different versions of a particular type. Note: K inkless T etrode beam power tubes are listed under other letter tubes - KT. Media related to Marconi vacuum tubes at Wikimedia Commons.
Older Mullard tubes were mostly designated PM , followed by a number containing the filament voltage. Many later tubes were designated one to three semi-intuitive letters, followed by a number containing the heater voltage. This was phased out after when Mullard adopted the Mullard—Philips scheme. Examples: . Media related to Mullard vacuum tubes at Wikimedia Commons. The system consisted of one letter followed by 3 or 4 digits.
It was phased out after when Philips adopted the Mullard—Philips scheme.
Examples: . Media related to Philips vacuum tubes at Wikimedia Commons. Media related to Philips gas discharge tubes at Wikimedia Commons. First number: Type .https://wrespencondpal.ml
List of vacuum tubes - Wikipedia
Valvo de , it was a major German electronic components manufacturer from to ; a Philips subsidiary since , Valvo was one of the predecessors of NXP Semiconductors. The system consisted of one or two letters followed by 3 or 4 digits. It was phased out after when Valvo adopted the Mullard—Philips scheme. First letter s : Type . Media related to Valvo vacuum tubes at Wikimedia Commons. Media related to Valvo gas discharge tubes at Wikimedia Commons.
Media related to Lamina vacuum tubes at Wikimedia Commons. Media related to Lamina gas discharge tubes at Wikimedia Commons. Rundfunk- und Fernmelde-Technik de , sv was the brand of a group of telecommunications manufacturers in the German Democratic Republic. The designation consists of a group of three letters and a group of three or four digits. Next letter s : Type, subset of the Mullard—Philips system.
Next letter s : Type, subset of the Mullard—Philips scheme. Media related to Tesla vacuum tubes at Wikimedia Commons. Media related to Tesla gas discharge tubes at Wikimedia Commons. The Tungsram system was composed of a maximum of three letters and three or four digits. Media related to Tungsram vacuum tubes at Wikimedia Commons. Vacuum tubes produced in the former Soviet Union and in present-day Russia are designated in Cyrillic. Some confusion has been created in transliterating these designations to Latin. The first system was introduced in It consisted of one or two letters designating system type and, optionally, type of cathode , a hyphen, then a sequentially assigned number with up to 3 digits.
Petersburg, Russia. Examples: . The first element is a number specifying filament voltage. The second element is a Cyrillic letter specifying the type of device. The third element is a sequentially assigned number that distinguishes between different devices of the same type.
The fourth element denotes the type of envelope.
An optional fifth element consists of a hyphen followed by one or more characters to designate special characteristics of the tube. This usually implies construction differences, not just selection from regular quality production. There is another designation system for professional tubes such as transmitter ones.
The first element designates function. The same precautions regarding shielding, coupling between input and output circuits, and proper R-F bypassing must be observed, as described under Class-C Telegraphy Operation. Due to the widely varying nature of the load imposed on the power supplies by SSSC operation, it is essential that particular attention be given to obtaining good regulation in these supplies.
The bias supply especially. Under conditions of zero speech signal, the operating bias is adjusted so as to give a plate dissipation of 50 watts at the desired plate and screen voltages. Due to the intermittent nature of voice, the average plate dissipation will rise only slightly under full speech modulation to approximately 65 watts. At the same time, however, the peak speech power output of over watts is obtained. The audio oscillator should be capable of delivering a sine wave output of a frequency of around to cycles so that the frequency will be somewhere near the middle of the pass-band of the audio system.
Since successful operation of the class-B stage depends an good linearity and the capability of delivering full power at highest audio levels, the final tuning should be made under conditions simulating peak modulation conditions. If a continuous sine wave from the audio oscillator is used for tuning purposes, the average power at full modulation would be about five times that of speech under similar conditions of single. One method of lowering the duty cycle of the audio oscillator to closer approximate speech conditions would be to modulate the oscillator with a low frequency.
List of vacuum tubes
Cut the audio output to zero. Apply volts of bias to the 4.
Apply the operating plate voltage fallowed by the operating screen voltage. Reduce bias voltage to obtain 50 watts of stand-by plate dissipation. Increase audio gain, checking the oscilloscope pattern for linearity as in the case of the exciter, and adjust for optimum antenna coupling. Readjust exciter unit for single side band operation. Disconnect test signal and connect microphone. Adjust the audio gain so that the voice peaks give the same deflection on the oscilloscope screen as was obtained from the test signal peaks. After the audio oscillator is disconnected and step 8 completed at half voltages, the full voltages can then be applied and the stand-by plate dissipation adjusted for 50 watts.
It is essential that the microphone cable be well shielded and grounded to avoid R-F feedback that might not occur when the lower impedance audio oscillator is used as an audio source. Typical operational data are given for SSSC in the first part of this data sheet.