For years i have been using a valve tester that i had developed in the past. The first tube testers were simple units designed for specific tubes to be used in the. Anyone who has a sizeable investment in vacuum tubes or vacuum tube hifi equipment owes it to themselves to have a good tube tester on hand to periodically check the tubes they are using. This is a common construction for small tubes such as the 12ax7 family or the 6sn7. All of the documentation and pcb design files for the vacuum tube analyzer vta are available for download at the end of this article. Importance of these three parameters differs for triodes and pentodes. Heres the inside story on the devices designed to gauge the vacuum tube s basic health part 1 checking for shorts and for noise by g. Mu voltage gain, gm transconductance and rp plate resistance are the three electrical characteristics that make up the overall electrical characteristics for a vacuum tube. All of these give an understanding of the performance of a particular triode vale or triode vacuum tube. An example of a top end laboratory tester is the new london instruments model 901a transconductance analyzer. Unlike tube testers that can only show simple characteristic such as transconductance at only one operating point, curve tracers show you all operating parameters across all operating conditions all at once. Harrison the vacuum tube delicate heart of most electronic equipment is understandably subject to many ills. Gm vs mu by mike mccarty most tube testers just check emission.
Vacuum tube preamplifier analysis and spice simulation. As the tube wears out, the transconductance decreases and the plate resistance increases. Vacuum tubes for the audiophile and vintage electronic parts for antique radio and ham radio. Sure, i do own a tube checker, but that apparatus mine is heathkit tc2p typically does no more than a simple cathode emission test on tubes, and a. Transadmittance or transfer admittance is the ac equivalent of transconductance. A common cathode vacuum tube preamplifier stage is analyzed and simulated. Ive noticed some confusion here and there on the net, so i thought id. A tube tester is an electronic instrument designed to test certain characteristics of vacuum tubes thermionic valves. A digital vacuum tube analyzer and curve tracer part one. We are the manufacturer and exclusive distributor of the at electron tube test system.
If the load default values page is selected then save values to memory eeprom is selected the unit will function quite well, the accuracy determined by the tolerance of the components used and firmware, this will normally produce better results than a calibrated tube tester produced during the heyday of vacuum tubes. El34 kt88 6l6 6ca7 6v6 5881 6550 kt66 kt100 kt120 vacuum tube tester amplifier bias current tool radio preamp ma version t1. Tubes should be tested in everything from vintage radios to contemporary guitar amplifiers, and its easy to put all of your valves through a tube checker. High stability and reliability, high precision and repeatability with all digital readouts. Maximatcher audio vacuum tube tester store and support. For repair work a simple test on a tube tester to find out if a particular tube is serviceable good or bad is sufficient. Power tube ratings plate current and transconductance. Of the vacuum tubes three operating characteristics dynamic plate resistance rp, transconductance gm and amplification factor mu two are explicit values and one is an implicit value. The number of electrons that reach the anode of a triode valve or vacuum tube under space charge limited conditions is primarily governed by the electrostatic field in the cathode grid region. A vacuum tube has three important electrical parameters to measure mu voltage gain, gm transconductance and rp plate resistance. If youre working with any kind of vacuum tube assembly, then youll need to have a tube tester on hand to make sure that all of your valves are working properly. Summing up, if you want a tester for occasional use for testing the tubes in your own equipment, you may no want to invest in the more expensive mutual conductance testers.
Many tube sellers now use the amplitrex at tube tester. A valve tester is an invaluable tool for those who wish to build and repair valve amplifiers. Most of the intelligence of the device resides in the software that runs on the pc. In electronics, a vacuum tube, electron tube in north america, tube, or thermionic valve or valve in british english is a device controlling electric current through a vacuum in a sealed container. Posts about transconductance tube tester written by jwk. The maximatcher is the only tester that allows you to directly compare full sets of output tubes at the same time. Selfexplanation panel, anyone can test a vacuum tube in seconds, no more steep learning curve. Mutual conductance or transconductance gm ratio of variation of plate current to variation of voltage on the control grid. Like the cylindrical structure, this lends itself readily to theoretical analysis. Four highly regulated dc power supplies are available. This is our new 2015 advance design, a tube tester with build in microprocessor control, automatic tube tester for beginner and professionals, you dont need to operate a very complicated vintage tube tester just to test out a simple tube, this unit can test both emissionma and dynamics transconductance us at the same time, it can also display both section of a dual triode testing result. Im in the early stages of brainstorming another project idea that will combine vacuum tubes with modern microelectronics in a useful and innovative way. Unlike those, you can use it to plot dc and ac characteristics. I really like the solid oak cabinet, and if it is in good shape, looks quite stunning.
How to use, calibrate, repair and upgrade vacuum tube testers. But, unlike the model tv11, the td55 will not test the early large pin tubes from the 1920s early 30s. Since this posting, i scored a relatively inexpensive hickok tester. Arizona tube supply audio and radio tubes for sale. Homepage for arizona tube supply vacuum tubes for sale. The simplest vacuum tube, the diode, contains only two elements. The revival of tube technology in guitar and audiophile amplifiers has also led to the renewed interest in vacuum tube testers and their ultimate purpose, testing and matching of audio tubes. These three parameters define the overall electrical characteristics of a vacuum tube. Introducing the new maximatcher ii, a fullfeatured vacuum tube test station that measures up to four tubes at a time. How to use, calibrate, repair and upgrade vacuum tube.
Its called analyzer to set it apart from tube testers which dont use constant dc supplies. Transconductance vacuum tube tester, model tv12, circa 1955 898209860. This article describes the functionality and features of the tube analyzer. Discussion in amps and cabs started by soulman77, dec 22, 20. For quite some time i have been looking at developing a design for a diy valve tube tester that is easy to build and uses readily available, low cost parts. Model 200 can check tubes for shorts and for quality by measuring transconductance of a tube on a rejectgood or on a microhmos scales. Old vintage valve testers are available online, but most of them provide only a crude gono. If you are concerned with testing a wide range of tubes, getting accurate readings, and want to accuratelycorrectly match power tubes then this is the tester for you. The tube analyzer has a usb port to connect it to a personal computer running windows, macos, linux, or freebsd. The model 901 transconductance analyzer is a direct reading vacuum tube transconductance meter capable of measuring transconductance under a wide range of dc operating conditions. Tube parameters electron tubes electronics textbook. Transconductance for transfer conductance, also infrequently called mutual conductance, is the electrical characteristic relating the current through the output of a device to the voltage across the input of a device. Tube testers evolved along with the vacuum tube to satisfy the demands of the time, and their evolution ended with the tube era.
The concept of a linear smallsignal ac model for the vacuum tube triode is presented and employed for circuit analysis. The dynamic or transconductance tester is far better than an emission tester and can be used to match tubes, whereas the emission tester cannot. I have some vintage vacuum tube testers for sale, and are listed here on this page. An inexpensive, easy to build diy valve tube tester for quite some time i have been looking at developing a design for a diy valve tube tester that is easy to build and uses readily available, low cost parts. However, like any test equipment, it must be used correctly manual mode with plenty of time for tubes to stabilize and the results must be reported correctly for the data to be meaningful. But no actual transconductance or other bench mark specs. Tube testers themselves arent very complicated devices the simple ones, are just a transformer wired to many different sockets and a meter to measure the. I looked at the rat tube tester and i dont think that is a project for me, at least not at the moment. The next group of tube tester advertising starts off with the superior tv12 above left.
Most of them do not measure transconductance or gm, but rather tube gain or mu. It is a very popular tester to find on ebay, and deservedly so. To many people, the most important characteristic of a vacuum tube is its amplification factor mu. Like many of you with a positive slant towards vacuum tubes, and in possession of a few hundred of these glow fets often from messrs. There is much confusion in the audiophile community about these factors as they affect tubes. The tv12 is a transconductance tester, unlike its equally common sibling, the emission tester tv11. It has both the short lamp testing method and the ability to use the gm meter. The upgraded matcher ii features a snazzy new carrying case, stronger power supply and stabilized measurement. All of these tubes have been tested for transconductance, shorts, gas, leakage and life.
Transconductance is defined here just the same as it is for fieldeffect transistors, another category of voltagecontrolled devices. Tubes should be tested in everything from vintage radios to contemporary guitar amplifiers, and it s easy to put all of your valves through a tube checker. The grid and the plate are flat, but the cathode is a small cylinder. A low cost, easy to build diy valvetube tester valve heaven.
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