Download HICKOK B TRANSCONDUCTANCE TUBE TESTER service manual & repair info for electronics experts. Daniel Schoo produced a classic document on calibrating a Hickok B/C tube tester which was published in on AudioXpress. Hickok B/C Mutual Conductance Tube Tester – Checkout and Calibration. Version Use this procedure to test and calibrate the Hickok Model C mutual .
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Ohmmeter Circuit and Shorts Circuit. Low Voltage Source Circuit. The reasoning is this: This circuit does not directly measure the grid current, but converts it to a grid voltage change using a resistor and uses the tube under test amplification to convert this to a larger and more easily measured change in plate current. If you were to plot the tube book values for transconductance vs.
It just depends on how you choose to look at it. Whenever one makes a measurement, whether it is using a tube tester or just reading a tape measure, there will always be a limit to the accuracy involved and thus some associated error. Just setting the tester on an angled surface will often be enough to require re-adjustment of one or more of the meters.
I have experience in design and maintenance engineering and with analog and digital devices. This is a Hz. If not, adjust R15 to make them as identical as possible. In the circuits that they are typically used, their lower plate resistance makes them act more like an ideal voltage source in a voltage divider circuit than as a transconductance device which is how the tester is designed to evaluate them.
Also, a goodly number of them just happen to sell calibration tubes or calibration services or have calibration devices for ihckok.
Special Discussion of this circuit: However, if they are shorted it should be detected on the shorts testing. In the real world, I think that the best that one can do is correct each source of error as much as possible and remember that you simply have to live with the fact that there will always be some error left.
Any errors in the grid voltage signal is multiplied by the transconductance of the tube before it gets to the hicokk circuitry.
Accurate Calibration Of The Hickok 539B And Hickok 539C Tube Tester
hic,ok A curve tracer, by its nature, tests tubes at a variety of operating conditions, potentially including the plate currents and voltages that duplicate those of the desired application, whereas a tube tester generally only tests at one set of operating conditions, and usually at lower voltages than are used in many applications. Even without using the SS replacement, there is a tendency to have limited range of adjustment due to the fact that when this set was designed, the average line voltage in the U.
Built into the definition of transconductance is the assumption manul a tube behaves as a linear device. Note that the power supply for the op amp has to be separate and electrically isolated by a small transformer it can be quite small as this circuit draws practically no current. A bias voltage of about To get peak values, multiply by 3. When testing tubes hikok do not put much of a load on the tester power supplies, such as low power tubes designed for battery use, the line adjust control may not be able to bring the primary voltage down to the desired I very much doubt that the Hickok engineers were aware of this effect and it is quite possible that some of the original Hickok calibration tubes used to calibrate their testers 539n have been less than completely accurate to begin with because of this effect, 539g therefore, at least, for use with Hickok testers, were not really suitable as a calibration tubes in the first place!
In calibrating any linear device; therefore, a zero value and a slope, or gain value, determine a unique linear calibration. The hivkok accuracy of the set is directly proportional to this. The circuit inputs are symmetric and if the signal is symmetric, one half cycle charges the capacitor C3 by the same amount that the next half cycle discharges it so the net DC voltage the meter sees is 0 volts.
For example, suppose that there is 5 mv of error signal when the bias is set at -1 volt. A close second is to examine the manuql dynamic traces. They almost all interact, and badly. If the extra H.
Hickok B Tube Tester Instruction Manual & Tube Data | eBay
But only if Rload is quite small compared to Rcalibr. Or, alternately, and more to the point for this discussion, one point value and one slope value also uniquely determine a line.
This time, the meter should go up by 3 or 4 small divisions. Estimated on or before Wed. Before powering up the set, the physical zeroes of the meters should be checked and adjusted. The point is that the size of the offset error will also vary depending on the bias voltage being used for the measurement as well as the transconductance of the tube itself. I initially intended to leave this section out because it might sound egotistical.
hickkok It is nothing more than the classic inverting op amp voltage amplifier or you could use the non-inverting configuration instead if you wanted. One could use two separate windings or transformers in series with or in place of the existing two V windings to test at higher voltages and currents while keeping everything else the same.
Since the grid bias and screen grid supply is the same and is unregulated, if the DUT has a screen grid that pulls much current, the grid bias voltage is almost sure to increase when P4 is pressed.