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 Post subject: Updated Hickok 539 Calibration document
PostPosted: Dec Fri 16, 2011 6:22 pm 
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Hi,

With Daniel Schoo's approval, I've corrected, reformatted and updated his classic document on calibrating Hickok 539B/C tube testers - I have also included data on values need for 230VAC operation.

http://www.desmith.net/NMdS/Electronics ... ation.html

If you find any errors, please let me know.

Thanks


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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Dec Mon 19, 2011 1:18 am 
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Nice job. I have another 539C to go thru over the winter. I will use your update, even though I have previously had no issues with the original document(s).


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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Dec Wed 21, 2011 7:46 am 
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Location: Tucson, AZ
Nice review and integration of the information. A few notes on this testing procedure, more FYI for people using this procedure.
Not sure on the statement "Remove the tester from the case and set it up on spacers so that the front panel is facing up in the normal operating position" as the front panel is level, not facing up.

Under the leakage Section, it is important to first adjust the bias so that it reads 40V at maximum bias setting, as this effects the impedance readings. I could not get the impedance to read correctly until this was corrected, the impedance range is driven from the bias voltage.

Under "6 LEAKAGE RESISTANCE METER TEST", one can use a slightly different procedure in accordance with the Hickok 539 manual for checking impedance.

In order for the leakage test to read accurately, the bias meter must be calibrated first so that it reads 40V at its maximum value on the 0-50V range (see Section 10). Connect two leads to the Grid (black pin jack) and Plate (red pin jack). Rotate the SHORTS switch to position B. Short the two leads and the Leakage scale should read 0 ohms, if needed adjust the bias volts (0-50 range) until the meter is zeroed. Connect a 1M, 1/2W, 5% resistor between the two leads and rotate the SHORTS switch clockwise to position B. The main meter should be reading approximately 1M ohms on the resistance scale. Rotate the SHORTS switch back to the TUBE TEST position and disconnect the 1M resistor/leads.

Daniel Schoo's article in AudioXpress in 2007 "Calibration of the Hickok 539C Tester" adds to this procedure. It would be nice to reference or provide a hyperlink to this article in the calibration document, as it adds significantly to the process.

"http://www.circuitcellar.com/AAI/media/schoo2798.pdf" may need to copy and paste in browser to pull up the article.

An alternative for the 83 tube in the Hickok testers is to build a solid state replacement using two standard diodes 1-3A/600-1000V followed by two 5.6V 5W zener diodes (back to back with each diode) and two 10 ohm 2 watt resistors see diagram. This gives 150V (+/-0.5) on the plate when taken with a 1000 ohms per volt meter. Without the Zeners I was seeing 156-157V on the plate, doesn't have a significant effect on GM but does effect plate current. There are slight variations on voltage drop between different standard diodes, usually the higher the voltage/current, the higher the Vf voltage drop. I use 3 amp versions. Since the Hickok testers need to be balanced for plate to plate of the rectifier (or diode to diode) differences, try to match the diodes/zeners within 5% of the Vf. This arrangement provided similar operating voltages/tube test results to the 83 tube at various operating points that I tested. An alternate in all other applications is to use two HV rectifiers such as HV05-08 diodes which have a 6-8V forward voltage drop per diode (NO zeners are required, they would need to be much larger) and the two 10 ohm 2 watt resistors. The HV rectifiers do not work well as a SS 83 replacement in Hickok testers (although they will give 150V on the plate of the Hickok 539) because the Vf can vary up to 0.5V between rectifiers and they are difficult to get a matched pair at different operating currents. This is not an issue when the voltage is filtered.

Another helpful article/calibration tool is Joel Hatch’s “Transconductance Tube tester Standard” article in the February ’05 issue of AudioXpress. It is very simple to make this standard and sidesteps many of the issues around the usual "Hickok 6L6 standard tube" and it does not change between testers or with time. When building the Transconductance Tube Tester Test Standard, you can also add a 3 way switch to short R1 of the voltage divider to give a transconductance of reading of 3000, and either parallel R3/R4 (284 ohm) resistor with a 220 ohm resistor or switch R3/R4 to a 124 ohm resistor(s) for to get a GM of 6,000 with R1 shorted. So you get a solid state standard that gives a GM of 1,500, 3,000 and 6,000. It can be used to verify plate draw which is 11.1 ma with R3/R4 of 284ohm or 22.1 ma (+/-0.1) for R3/R4 of 124 ohm. I recommend keeping the bias at 0 volts when using Joel's "Transconductance Tube tester Standard”, as the IXYS 10M45S can overload with too high a bias setting (between 0-2.5V there is no change in the GM reading, and it is not affected by different plate voltages 100-250V). I also recommend using an external 10 ohm x 50W load resistor for the heater load. The accuracy of the standard was within 3% between validation testing and also between several calibrated Hickok tube testers. It did not work in my AVO testers. Although I have/use several other "calibration tubes" , they drift over time and need to be rechecked/validated periodically.


Attachments:
SS 83 with Zeners.jpg
SS 83 with Zeners.jpg [ 60.3 KiB | Viewed 3589 times ]
SS 83 with NO Zeners.jpg
SS 83 with NO Zeners.jpg [ 61.59 KiB | Viewed 3589 times ]
HV05 Rectifiers Specs.jpg
HV05 Rectifiers Specs.jpg [ 94.82 KiB | Viewed 3589 times ]
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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Dec Wed 21, 2011 3:32 pm 
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mksj wrote:

Daniel Schoo's article in AudioXpress in 2007 "Calibration of the Hickok 539C Tester" adds to this procedure. It would be nice to reference or provide a hyperlink to this article in the calibration document, as it adds significantly to the process.




Yes. That was something I was hoping would be incorporated into the document.


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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Dec Thu 22, 2011 7:29 pm 
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Thanks for the feedback - I was aware of the AudioXpress article and I appreciate the comments made - over the "holiday" (some chance!) period I'll try to integrate your comments into the main document.

Cheers


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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Dec Fri 23, 2011 1:28 pm 
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Your effort is appreciated. Adding the above would make it the only document one would need.


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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Dec Fri 23, 2011 3:32 pm 
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This is a great post and thanks to Nick , MKSJ and everyone who contributed. Daniel sure has made it easier to understand and calibrate Hickok testers by his articles on the subject. I am interested in the 6L6 calibration tube sub mentioned (Joel Hatch’s “Transconductance Tube tester Standard” article in the February ’05 issue of Audio Express). Is this article available online anywhere?


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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Dec Fri 23, 2011 10:09 pm 
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Not sure how to access back copies currently since AudioXpress was acquired by the Elektor Group, I do see back issues for sale on occasion. I use to subscribe so had the paper copy. Attached is an adaptation of the circuit diagram, I wanted to test a wider range of GM/MA values as shown. Fairly simple to make and only needs a small heat sink if not run for long periods, parts from Mouser Electronics. I mounted mine in an octal test base and used PVC tubing for a housing. Switch and jacks for external heater load resistor mounted on the top. Should work in most tube testers within the parameters noted. This calibration standard did not work in my AVO tube testers, probably because they use AC or 1/2 wave unfiltered DC on the plate. The 539B is shown with the calibrator at GM=1500 (0-3000 scale), but I suggest using the 0-6000 setting as the signal voltage is lower (0.5V). The readings are the same on either setting of the Function Switch. Let me know if you have any questions.

When calibrating the 539B/C, there are some helpful additions that I feel are important to consider. Once you have checked that all internal components meet specifications, consider adding a multiturn pot for R52 so the grid signal can be adjusted if your signal level is off. I added a switch to disconnect the grid signal (mounted by the function switch), which I often use to check that the GM meter reads 0 when testing tubes. This detects an imbalances or offsets in the tester/tube. I also added a Grid bias fuse bulb, as added to later Hickok testers. It has saved my grid pot from going up in smoke several times.
Mark


Attachments:
Transconductance Tube Tester Standard GM 1500, 3000 and 6000.jpg
Transconductance Tube Tester Standard GM 1500, 3000 and 6000.jpg [ 132.89 KiB | Viewed 3511 times ]
Transconductance Tube Tester Standard Hickok 539B GM1500.jpg
Transconductance Tube Tester Standard Hickok 539B GM1500.jpg [ 137.93 KiB | Viewed 3511 times ]
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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Apr Sun 27, 2014 9:32 pm 
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I am a seasoned technician & I have to ask about a connection to complete the filament connection. My guess is that it where the zener diodes meet the resisters to assimilate the Vf. The diagrams I've seen do not show any connections, so I'm a little confused.
Thanks,
Robb


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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Apr Mon 28, 2014 12:56 am 
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I do not have any circuit drawing programs, just MS Paint. The resistors zeners are joined at the intersections, see below. Without the zeners, you do not get the proper voltage drop. Diodes with resistors and no zeners did not work properly when I tried it. The SS 83 has been tried in multiple Hickok testers and seems to give results very similar to the stock configuration. The SS 5Y3 has been tried in several 539A/B/C models, but unclear how it would work in other Hickok tube testers.
Mark


Attachments:
Hickok SS Replacement 5Y3 and 83.jpg
Hickok SS Replacement 5Y3 and 83.jpg [ 103.74 KiB | Viewed 834 times ]
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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Jul Thu 31, 2014 12:42 am 
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I stumbled upon this thread after finding a youtube video where a guy describes using one of these solid state 83 replacements with his I-177-B. Before I get down to business of making one of these, how does using this (and possibly the 5y3 sub) affect line adjustement? My locale seems to have relatively high voltage, ~ 123V, and I was hoping that the lack of loading from the 83 tube on the transformer wouldn't cause voltage in the unit to rise too high, even if you can get the B+/screen voltages, etc, in line using the SS replacement. Has anyone else on the forum tried these on other hickok testers, such as TV-7, and I-177-B?

I suppose if it's hard to get the line adjustment correct, that one could use a varaic to drop the line level to the tube tester to keep it all within spec?

thanks for this info, I'm going to see about ordering parts and making a couple of these for my various testers and trying them out.

-jon

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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Jul Thu 31, 2014 2:12 am 
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mksj wrote:
The SS 83 has been tried in multiple Hickok testers and seems to give results very similar to the stock configuration.
There are two problems with the pair of 10-ohm resistors in the filament circuit:
1) Having the resistors in series with the tube output makes the internal voltage drop load-dependent.
That was not true for the 83, which has a constant 15-volt drop.

2) They will only draw 250mA from the 5v filament line, rather than 3 amps.
That significant reduction in transformer loading may result in other transformer voltages being high.

- Leigh

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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Jul Thu 31, 2014 2:50 am 
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at least in the hickok circuit, there isn't much difference re: voltage loading... at least not from what I saw in the youtube video from a guy who tried this setup. He claims to have checked tubes with both an 83 tube, and one of these SS rectifier setups, and his numbers were well within reason. It seems that keeping filament/bias voltages within range would be most important.

I was most concerned with how this affected line adjust, since that wasn't really covered here, nor in the youtube video I was looking at. hopefully someone with experience with one of these in an actual tester can chime in and let me know.

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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Jul Thu 31, 2014 2:08 pm 
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Line voltage here is 123V and has been since the 1960s. I got about the same Gm readings with an 83 and with 1N5399s. Yes you could use a Variac or (cheaper) a bucking transformer to reduce the amount dropped in the line-adjust rheostat. I don't remember which Hickoks I tested the substitute in.

I picked the 10 ohms as a compromise between voltage drop and power dissipation. Voltage drop of 0.25V is negligible.

I can't see any point in replacing the 5Y3. It's common, cheap, and will last forever in that service, and it provides some load on the transformer.


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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Jul Thu 31, 2014 4:43 pm 
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Hi Alan,

You mention 1n5399's, I don't have my notes with me, but those are the Zener diodes in the Substitution posted by mksj? Am i correct to assume that you also put 1n007's or equivalent diodes in the circuit too? I couldn't see putting a hight watt low ohm resistor in there to load the transformer like the filament does exactly the same extent as the 83 would if it was just going to make as much heat as an 83.

It seemed from my reading the last few days that heater voltage, up to a certain point will effect cathode emissions, and the bias point and grid signal will effect emmission much more than a few extra volts and the plate and screen will, since they essentially change together with varying loading on the transformer, and percent wise, a few volts here and there don't matter as much as a few volts difference on the bias circuit. That seemed to be Nolan Lee's argument against subbing SS devices for the 5Y3 in the hickock circuit, since it directly controls/effects the bias, and seems to play out in real world usage. If I mess with the line adjust while testing a particular tube, I'll get minor, but noticable variations in reading on the tester, but changing the bias pot even a little bit, and changes in reading are much more drastic. At some point I'll try the 5y3 sub also, just to know what it does differently in my testers.

-jon

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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Jul Thu 31, 2014 8:38 pm 
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The series 1N4000 - 1N4007 and 1N5392 - 1N5399 were equivalent. We used the 53 series where I worked so I got used to them.


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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Jul Thu 31, 2014 11:46 pm 
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out of curiosity, is there some reason why you would need a 1200V PIV diode to make up a 5y3 substitute for a hickock tester? The schematic above calls for them, but it seems overkill, there isn't anywhere near that voltage present in the various hickock testers as far as I know. I figured if I'm buying other stuff from mouser, I should probably get these and make a few solid state subs just to try them and see how they work. at worst I'm out a few bucks, and some time. and maybe it works well?

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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Aug Fri 01, 2014 2:25 am 
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No reason at all, except they cost about the same (and I already have lots of 5399s on hand).

I checked some of the lower-voltage numbers on the Tek curve tracer once, and they all had about the same prv, around 1600V as I recall. Back in the "good old days" diodes would be tested after manufacture and graded into the various categories, but now I'm pretty sure it's cheaper to make them all the same.


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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Aug Fri 01, 2014 2:36 am 
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Do a search on this forum and you will find many test results after going solid state, some tubes read higher, some lower.

Dave


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 Post subject: Re: Updated Hickok 539 Calibration document
PostPosted: Aug Fri 01, 2014 7:35 am 
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alan,

this is a totally different topic, but what tek curve tracer are you using to get 1600V PIV test? my 575 with the higher voltage 122C mod, will only go up to 400V as far as I know.

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