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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Now, at this point the tubes may be closely enough matched for most applications, but if even closer matching is desired, further matching can be based on having transconductance values as close to the same for the matched tubes as possible hicjok the hickokk plate current. It is anything but a fixed constant value. Of course, a vendor can just include copies of the curves for his tubes and let the buyer try to figure out what they mean with respect to the buyers intended application.
Accurate Calibration Of The Hickok 539B And Hickok 539C Tube Tester
Estimated on or before Wed. It just has to be able to display V peak voltage at Hz. Mqnual has been noted that the B schematic contains errors in the bias meter circuitry. Now both are connected to pin 1 and thus to each other, i.
Skip to main content. I have been selling on eBay since – buy with confidence! Much of the analysis above has been about the transconductance features of hicklk tester. The other two requirements are that the junction of R17 2. In calibrating any linear device; therefore, a zero value and a slope, or gain value, determine a unique linear calibration.
Hickok B Tube Tester Instruction Manual & Tube Data | eBay
Change the physical orientation of the tester and hence of the metersand you will usually have to change this adjustment also. Hickok clearly made some important and poorly or undocumented changes during the production run. This is available at multiple sites on the internet and his comments on this topic seem to me, anyway to be quite reasonable.
The point here is that, in my opinion, it is a waste of time and money and effort to even use a calibration tube when a better, less expensive, and more accurate alternative is readily available.
In fact, this method could be used to accurately calibrate just about any tester, but it would be a bit cumbersome and inconvenient. These roll chart values were poorly chosen by Hickok. Sometimes, if a switch is left in the wrong position from the previous step, it could make a difference.
In other words, the plate hic,ok is determined by the grid-to-cathode voltage and is assumed to be independent of the plate voltage that is an hkckok, but frequently overlooked assumption.
If there is any detectable heater-cathode leakage, it is usually negligible when the filament is positive with respect to the cathode, but not when the filament is negative with respect to the cathode. The one possible exception is that the AC voltmeter used for checking the grid bias voltage must be at least as accurate as the overall tester accuracy desired, but this should not be a major hurdle.
Accurate Calibration Of The Hickok B And Hickok C Tube Tester
Note that these changes do also affect the emissions measuring circuits and may require a small change in this circuit including adding a resistor. Generally speaking, tubes pentodes, especially are considered to be best most usefully approximated as transconductance devices. 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.
In this circuit it is important that the alternating peaks be at least reasonably symmetric. Refer to eBay Return policy for more details. Thus the situation I have shown would be the situation if R8 was adjusted using the calibration tube. In some circuits, having a tube with adequate transconductance is not the only characteristic necessary for acceptable performance e.
If the tube was actually completely linear at these operating conditions, then the transconductance values would be identical. Most likely your set is going to be slightly different from mine, so some of the information here may be incorrect for your set!
This modification has a possibly significant unintended consequence. As has already been mamual, there is another way actually more than oneand in addition, more accurate!
This is not included in any of the usual calibrations procedures, and it is probable that the original Hickok engineers never even suspected that there was a problem, but if you want to be able to test higher current tubes while retaining good accuracy, you should make this simple modification. Special Discussion of this circuit: The item you’ve selected was not added to your cart.
This should be very close to the reading taken in the usual way at a grid bias hkckok about half way in between the two bias voltages that were used in the measurement. Note that the correction is made at whatever the value of the transconductance of the calibration tube that is used happens to be, and will be slightly different from one calibration tube to another, even if the mnual of each calibration tube happened to be known perfectly and with no error.