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 Post subject: What is the difference between the Hickok 533 and 533A
PostPosted: Jan Fri 11, 2019 11:38 pm 
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Location: Madison, WI 53704 USA
I have a very nice Hickok 533 tube tester. It is calibrated and I have mechanicly cleaned all the button switch contacts. I just finished replacing the Noval and miniature 7 pin sockets with new ceramic sockets. I have been thinking of upgrading to a 539B or C. In my research I came across the 533A and just got to wondering what the difference is between the 533 and the 533A.


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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Jan Sat 12, 2019 2:16 am 
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Here are a few articles and comments I found. Without checking the schematics myself, they would appear to quite a bit different. It's for sure that if these are correct, they would not share a common tube chart.

http://antiqueradios.com/forums/viewtop ... f=8&t=2237

http://audiokarma.org/forums/index.php? ... es.355968/

The 533's lowest bias level is much higher than that of the 533A, too high, in fact, to test many tubes accurately. 12AX7's are among the tubes it over-biases. I'm sure people with 533's will argue that point, but the tube spec data will confirm it, if you're interested.

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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Jan Sat 12, 2019 3:17 pm 
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Barry H Bennett wrote:
It's for sure that if these are correct, they would not share a common tube chart.

They do not share a common tube chart. The 533 chart is also used for 532-533DM-534-534A-534B-600. The 533A chart is also used for 533DM (Series 600)-535-600A-605-605A. One major difference between the two is that the 533 uses a 1.4 milliamp 60 ohm meter movement and the 533A uses a 500 microamp 233 ohm meter movement.

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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Fri 20, 2020 1:50 am 
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Please forgive me - I'm new to the ARF, but not new by any stretch ;-) and after selling my Hickok 533A upon retirement, I've been regretting it ever since. Just bought a 533 but it's an odd one. It has the old-style 533 meter, which I understand is very different (and more accurate?) from the one in the 533A. It also has the bias fuse, and knobs like the A version. I hope we can post photos here. Anyone know how to tell the difference internally? Is it possible Hickok put an old meter and label on a (then) newer A version? I opened it up - it has the correct tubes, what appears to be original tweed-like insulation on all the wires, and the bias fuse wiring looks the same as all the other wires. All of the solder joints have some kid of red paint or seal on them. Any help, guidance, or advice (other than don't clean the switches with Deoxit!) would be appreciated.


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 Post subject:
PostPosted: Mar Fri 20, 2020 2:12 am 
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Well, you actually can clean the switches with Deoxit D5, but I'd avoid spraying the switches directly. Use a Q tip and apply directly to the contacts as much as possible.

I've of late been more or less spraying the entire switch with D5, exercising it a few times, then spraying it again with iso alcohol. Then air from a can. Then bake or heat gun. THEN a little D5 on a Q tip applied directly to the contacts. I've seen no ill effects from this as of yet. Tricky but important, keep any spray from getting all over everything else in the instrument.

As an experiment I used a little Deoxit D5-Fader on the mechanical parts of the interlocking switch. The D5-Fader version claims to leave a type lubricant film, but also non conductive, so if a little goes astray it shouldnt present a big issue.

Stay tuned. Or just clean with iso alcohol in the first place, then D5/Q tip on the contacts.

Hope that helps. Do a search of the forum ... there have been tons of other ideas, posts, and topics on switch cleaning. This one is just my current version.

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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Fri 20, 2020 1:02 pm 
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I had a 533 that I sold probably 50 years ago, then bought another about '05 or so when I got interested in old ham radios again.

Image

A number of years ago there were several of us ARF'ers who participated in an ad hoc study of how "our" testers compared. A pair of tubes were mailed from one of us to the next, and we each added our data. There was only one 539, and, I was the only 533 owner represented. The results are shown below.

Image

Image

Image

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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Fri 20, 2020 1:49 pm 
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I've got a 533 in "as bought" condition.... in other words, unknown. If you get stuck with yours by other means, I can pull mine out and get you any kind of measurements you may need. Might be an excuse for me to check the restoration / calibration of mine at the same time. Let me know.

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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Fri 20, 2020 2:13 pm 
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So were does the 534B fit into the designs ?


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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Fri 20, 2020 6:21 pm 
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Bluetrain1950 wrote:
So were does the 534B fit into the designs ?


Hey Bluetrain - please don't take offense, but how does the 534B fit between the 533 and the 533A? Just trying to keep this train (of thought) on track, that's all - thanks!

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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Fri 20, 2020 6:56 pm 
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i been told the 534B is the same as 533 or 533A except 534B has voltage , ohm , and amp meter . Anyone know if that is true ?


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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Mon 23, 2020 3:23 pm 
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[quote="Mikeinkcmo"]I had a 533 that I sold probably 50 years ago, then bought another about '05 or so when I got interested in old ham radios again.

Image

A number of years ago there were several of us ARF'ers who participated in an ad hoc study of how "our" testers compared. A pair of tubes were mailed from one of us to the next, and we each added our data. There was only one 539, and, I was the only 533 owner represented. The results are shown below. /quote

Thanks, Ken!

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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Mon 23, 2020 6:17 pm 
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My recollection, one major difference between the 533 and 533A was the grid signal voltage of 5V vs. 2.5V, the 800/800A were also 2.5V. The Hickok 1961 calibration document for the 533/533A only looks at the specs. for the plate, screen and bias voltages with no adjustments. Some discussion of calibration of the English potentiometer for a "calibrated" 6L6 and then tweaking the resistance spools (i.e. fudge factor for one this particular tube). All very rudimentary and primitive, not to mention the variation on voltage sag/adjustment under testing are very different between models.

Testing the same tube between different tube testers manufactures/models is pretty meaningless for multiple reasons as they were never meant to be used in this manner. In particular with Hickok tube testers the roll chart numbers good/bad just apply to that model and in almost all cases do not correlate with typical operating conditions. There are some series of models that share the same operating conditions and the same chart data (like the Hickok 533A-600A-605A). About the only useful bit of information from the comparison chart is readings within the same model, and that assumes that everything is operating according to spec. in a device that was made 50+ years ago. Calibration of most Hickok models is a bit of a misnomer, as in most models there is no adjustment or field calibration procedure. Other than checking the voltages and the 83/5Y3 that they are functioning reasonably well. The Gm chart comparison above seems to indicate that the same tube tester models kind of give similar readings, the data would have been more relevant if the actual operating voltages were also checked. A small deviation in the bias or signal voltage can have a significant change of Gm. Older models, the signal levels are way too high for smaller signal tubes.

I have done comparisons of a group of various tubes (small signal through 6L6/EL34) tested on a bench top rig with regulated power supplies, amplitrex, uTracer, AVO CT160's, 580A (modified) and 539B at the same operating conditions/voltages and for the most part they do compare within about 10%. This is measuring the actual operating voltages, the way the Gm is derived varies. The first four tube testers used the tube published data sheet recommended operating values and in some cases multiple points were measured to compare the operating Gm curve. The bench top rig, amplitrex, uTracer were quite close in readings, then the AVO CT160's (part of this is the method that the Gm is read off the non-linear dial), then the 539B (compared at the same measured operating voltages) and finally the 580A. The Hickok 580 series tube testers have some inherent faults in the design that have been described by others. I have mitigated some of these issues with a Gm 0 balance pot for each voltage tap, individual adjustment of all voltages, and ability to use both unfiltered and filtered bias supply. This does significantly improve the Gm correlation under the same operating parameters using standardized tubes and comparing results.

Since the vast majority of Hickok tube testers only look at the operating conditions of a tube at one fixed set of values (often far different than normal operating conditions), they are basically designed as a pass/fail tester not to compare tubes. Even low reading Gm tubes may operate fine in say a radio despite testing low in your tube tester.


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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Tue 24, 2020 2:04 am 
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Meaningless? I find that interesting since all testers had mho scales, and, the sample group was very random, all unknown background, and condition, yet resulted a std deviation average of 16%, and Hickoks as a group, were half that value.

Surprisingly close I'd say. Toss out the worst two, and data is getting pretty consistent.

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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Tue 24, 2020 5:53 am 
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Mikeinkcmo wrote:
Toss out the worst two, and data is getting pretty consistent.


Certainly close enough for government work, even the FAA. And I bet the data would be even closer if all the TTs were calibrated to Hickok specs, by the same person, with the same test equipment, with solid state power rectifiers (with matched sections).

John


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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Tue 24, 2020 11:46 pm 
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This is a good thread. I will say that most of the Hickok testers used a pulsating unfiltered DC for the Plate. screen and bias voltages, no filter caps were used. So you can't say tubes were tested at a fixed point, quite the contrary


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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Thu 26, 2020 9:06 pm 
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I just wanted to add something that covers most of the Hickok tube testers and something others might want to pursue. I did a simple DC conversion to a few of the 539C/B models. Using a single Electrolytic capacitor and 2-3 zener diodes to filter the PDC it eliminated balancing the screen/control grid, which is the most critical part of the calibration. It does increase the Gm somewhat, but the trade off is less variance between testers. For the Hickok's that never had balancing controls for the plate and screen The results could be even better than for the 539's and looking for a balanced 5Y3GT is not necessary. Its posted on our eccher.com website under VHSystems with a lot of other Mod's. All are word documents and free to download. I have the time, but not the energy to do more with this, but it might be something for others with time on their hands.


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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Mar Sat 28, 2020 10:49 pm 
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[quote="mksj"]My recollection, one major difference between the 533 and 533A was the grid signal voltage of 5V vs. 2.5V, the 800/800A were also 2.5V. The Hickok 1961 calibration document for the 533/533A only looks at the specs. for the plate, screen and bias voltages with no adjustments. Some discussion of calibration of the English potentiometer for a "calibrated" 6L6 and then tweaking the resistance spools (i.e. fudge factor for one this particular tube). All very rudimentary and primitive, not to mention the variation on voltage sag/adjustment under testing are very different between models.

Thanks, mksj! I am aware of the difference in grid screen voltages between the 533 and the 533A. What I'd like to know is this: how can I tell the difference by looking inside? Is there is an additional winding on the 533A transformer? That would be hard to tell, as there are so many of them. Or did Hickok simply make some modification to the 5v circuit to reduce the voltage to 2.5v? That would be much easier to spot. And if I could find a PDF of the 533A it would be helpful. The only ones I can find are .djvu files that I can't open.

Richard

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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Apr Wed 01, 2020 4:18 pm 
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So I've learned that Hickok added a voltage divider of some kind to the 533A, mounted on a phenolic board, and located either above/near the transformer, or behind the meter. This particular 533 has just such a board, mounted just above and to the inside of the transformer. On it are both 100 and 1800 ohm wire-wound resistors, as well as a strange-looking (string?) wound air core something. There's also a 1.2K (5 watt?) 10% resistor on the board. Might this be the voltage divider that provides the lower 2.5v grid signal level? Anyone?


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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Apr Wed 01, 2020 4:32 pm 
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KG9MM wrote:
I have a very nice Hickok 533 tube tester. It is calibrated and I have mechanicly cleaned all the button switch contacts. I just finished replacing the Noval and miniature 7 pin sockets with new ceramic sockets. I have been thinking of upgrading to a 539B or C. In my research I came across the 533A and just got to wondering what the difference is between the 533 and the 533A.


CQ, CQ - KJ6QVB calling KG9MM

QUESTION: Does your 533 have a phenolic board mounted near the transformer with a couple of wirewound resistors on it? I posted a photo of the one in my 533.

I'd also like to hear more about those replacement sockets. Where did you get them?

Richard


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 Post subject: Re: What is the difference between the Hickok 533 and 533A
PostPosted: Apr Wed 01, 2020 4:40 pm 
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richardbruce wrote:
Mikeinkcmo wrote:
I had a 533 that I sold probably 50 years ago, then bought another about '05 or so when I got interested in old ham radios again.

Image

A number of years ago there were several of us ARF'ers who participated in an ad hoc study of how "our" testers compared. A pair of tubes were mailed from one of us to the next, and we each added our data. There was only one 539, and, I was the only 533 owner represented. The results are shown below. /quote

Thanks, Ken!


Hey, Ken - here's the "533" I recently acquired. Note the bias fuse and the 533A-like switches. No little windows for the numbers like the 533.

Richard


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