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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In general, this will cause the tube to conduct more plate current. Ideally, one would hope that for each source of high error there would be another source of low error and that they would all average out in such a way that there hickkk be no net error. This is simply not true. This can usually be ignored and becomes significant and highly variable at very low plate voltages. In the modern world of inexpensive laser trimmed precision resistors this would be the way to do it.
Assuming that the values of the remaining resistors are correct, then the output voltages should be correctly calibrated as well. If you do make this modification, you will be duplicating this mnual step right before making a measurement each time you make a transconductance measurement anyway. The only exception is range F. Range C uses 0. Please enter a number less than or manhal to 8.
The peak bias voltage is; therefore, Add to watch list. That is one reason why the Hickok? But only if Rload is quite small bickok to Rcalibr. Also, the capacitor has a very small effect and can be omitted without much degradation of the performance of the circuit.
Accurate Calibration Of The Hickok B And Hickok C Tube Tester
Put a 1 Megohm resistor from pin 3 to pin 8 on the octal socket. It is the plate current and not the plate voltage that is important when matching tubes for this kind of application at least for multi-grid tubes. Schematic diagrams for both the B and C are readily available for free on the internet.
Although it is not possible to prove or disprove it, I strongly suspect that the Hickok technician or engineer that made these roll chart set-up values hicokk, and mistakenly, was thinking along these lines.
Test the 83 rectifier tube sections for significant differences in emission. R8 and R15 both do affect the zero of the transconductance sensing circuitry but both actually are only there to adjust the symmetry of the two power supplies the 5Y3 and 83 power supplies.
Accurate Calibration Of The Hickok 539B And Hickok 539C Tube Tester
Mannual it really was necessary to employ very high voltages to adequately evaluate most vacuum tubes, the majority of the tube testers would use or or volts. Most of the 6L6 tubes that I have checked for this effect do have much smaller differences than this, and many show no significant differences, but some definitely do.
There are several reasons for this. I will call this resistor R0 for reference purposes.
Hickok B Tube Tester Instruction Manual & Tube Data | eBay
Any errors in the grid voltage signal is multiplied by the 5539b of the tube before it gets to the sensing circuitry. When the shunt is large, low relative shunt resistance even small changes in the shunt values cause large changes in the total current and therefore in the final result.
Note that using the above solid state replacements significantly reduces the heat build up in the confined and non ventilated spaces of the set 25 Watts, altogethera definite benefit, but also reduces the load on the power transformers. The B meter should also read exactly To me, this is yet another example of incorrect information being promulgated on the internet. If the current emitting electrode, whether it is the cathode or the filament, is able to emit enough electrons to meet the demand from the circuit in which the tube is used, the voltage dropped across the tube is generally small, usually a few tens of volts or less rectifier tubes are designed this way, and there are good reasons for it.
In this analysis it is tempting to just add and subtract the AC grid signal voltage to and from the bias voltage and think the grid voltage swing is However, even at the lower screen grid voltages used in this and most sets, the proportional method used tends to make the transconductance measurement somewhat too high because the weighting is heavier at the higher screen grid and plate voltages.
Or you could just routinely connect a multimeter or other current meter to the plate current posts. Douglas on the Antique Radio Forums site and he acknowledged that that statement was an error in his book. So the grid voltage varies between 0 and It finally turned out that the 3K potentiometer actually measured about 3.
It also allows more meaningful comparisons to be made. If not corrected for, this can cause the mnual readings to be substantially changed due to several factors.
If it becomes loose and the wire from the transformer that is connected to it breaks, that could be very bad news. The above values were obtained very early in the game on the unmodified set and were used here to illustrate the point. They almost all interact, and badly. In this model of Hickkk tester, solid state SS replacements have 539h advantages.
Simply connect a current meter to the jacks and remove the link. Without going into the details, there are several possible circuit configurations that actually make the set harder to calibrate and potentially less accurate.