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Old 3rd Aug 2022, 12:59 pm   #1
ianbatty311
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Question Hickok 536 Valve Tester

Hi, folks,

I have a Hickok 536 on the bench to write up.

It's working, but I like to examine things thoroughly so no-one else has to "excavate" data.

The manual is pretty naff - no photos of the front pane, but worse, no description of what the ENGLISH (yes, really) switch position/control do.

As well, there's no proper component listing.

I can put up with their "less than ideal" circuit, but does anyone have a really *good* image of it?

Tip to new players, yes, the Octal socket really *does* swap pin 2 back to pin 1, and pin 7 on to pin 8, and the B7G (7-pin miniature) is also scrambled.

You may very well wonder why, I cannot possibly help (thanks to Francis Urquhart)

p.s. - my AVO talk will be on the HRSA website:

www.hrsa.org.au

or just go to youtube and look for AVO HRSA

cheers,

Ian.
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Old 3rd Aug 2022, 1:07 pm   #2
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Default Re: Hickok 536 Valve Tester

ENGLISH:

https://www.vintage-radio.net/forum/...d.php?t=181128

Lawrence.

Last edited by ms660; 3rd Aug 2022 at 1:36 pm.
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Old 5th Aug 2022, 10:10 am   #3
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Default Re: Hickok 536 Valve Tester

Attached are the Operating Instructions. On page 2 (page 5 of the pdf document) the "ENGLISH" function is described.
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Old 6th Aug 2022, 1:42 am   #4
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Default Re: Hickok 536 Valve Tester

Hello, Robert.

Thank you so much for the info, (as we used to say "just read the manual, OK?")

1. Do you know *why* it's called ENGLISH - is it just a slang term like "give it a bit of English"

2. Looking at it, English is similar to the AVO use of the (implied) Merit tests, where you set a nominal gm value and read the deflection into the green sector (hopefully!)

3. Thanks for the manual, it appears to be the same as on many websites, but the circuit diagram is a bit naff - do you know of anywhere that has a better image?

4. The 536 tests at an anode voltage of 150, screen 125 (my measurements), but these (especially the screen) will give low gm readings on tetrodes/pentodes - an EL34/6CA7 for example reads only around 50% of its specified 12 000 microsiemens. Do you know of any conversion table "Hickok bogey to Manufacturer value?"

Thanks heaps,

Ian Batty
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Old 6th Aug 2022, 6:41 am   #5
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Default Re: Hickok 536 Valve Tester

Hello Ian,

I don't know why it is called ENGLISH but if I had to guess I would choose your explanation under 2 (AVO Merit test).

I don't know where to find a better quality schematic. Through the years I gathered a lot of info on valve testers but this is the only manual/schematic I found on the Hickok 536. A link to the collection: https://drive.google.com/drive/folde...Z3tFoaZxcrU7F2

I don't know if a conversion table like you wish for exists. I can't recall ever seeing one.
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Old 6th Aug 2022, 8:53 am   #6
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Default Re: Hickok 536 Valve Tester

Hi, Robert,

Thanks for the reply - I have used an AVO CT160 to plot the plate characteristics of a 6SH7 and a 6SK7, and these conformed to the original RCA curves. My idea was that you could sort out "mystery pentodes" into sharp cutoff (6SH7 - 6AU6 family) and remote cutoff (6SK7 - 6BA6 family).

I'd like to put together a description of the Hickok, so I'll probably do some characteristic curves for a comparison with the AVO family.

I do note that the AVO allows me to test *at manufacturers' voltage/bias/current settings*, which the Hickok clearly cannot.

Annoying - it's an example of a consumer product where you just shut up, pay the money, and trust that their test results as recorded do characterise the valve properly.

Getting to love my AVO more each day...

Cheers,

Ian.
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Old 6th Aug 2022, 10:24 am   #7
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Default Re: Hickok 536 Valve Tester

Quote:
Originally Posted by ianbatty311 View Post
*why* it's called ENGLISH - is it just a slang term like "give it a bit of English"
It's no mystery, it's called ENGLISH because the part of the meter scale being referred to for the test has English words on it, those being the words REPLACE GOOD (etc)

Lawrence.
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Old 6th Aug 2022, 10:52 am   #8
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Default Re: Hickok 536 Valve Tester

Cleaned up the circuit diagram somewhat but there are still portions (one switch wafer) that looks ugly but that's due to the poor scan quality.
Attached Files
File Type: pdf Hickock 536 circuit diagram.pdf (2.22 MB, 66 views)
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Old 7th Aug 2022, 6:30 am   #9
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Default Re: Hickok 536 Valve Tester

Hi to Martin and Lawrence

Thanks for the updates and the diagram - it confirms that the octal, UX4~7 and the B7G socket wiring are scrambled
Why, I have no idea, but it does make things difficult for any repairers!


Martin, did I give you the YouTube links for the talk and questions sessions?

Video link
https://youtu.be/ITJE4f-oVfc
(theory)

Video link
https://youtu.be/wqQV-yFLUd8
(pt 2)

Video link
https://youtu.be/scEQgrcmZJg
(pt 3)

Cheers,

Ian.
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Old 7th Aug 2022, 5:14 pm   #10
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Default Re: Hickok 536 Valve Tester

Yes, I git the links, haven't had time to listen to them in full yet. I do however have a hard time to hear the questions in part 2 & 3 so if you could transcribe those in the Youtube comments it would help a lot!

I found the Hickok 539B circuit diagram to be a lot like the 536 so I've included one I found at Electrotanya here. There are some corrections and errors described quickly at the bottom of this diagram.
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Old 8th Aug 2022, 1:22 am   #11
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Default Re: Hickok 536 Valve Tester

Hi, Martin and everyone,

Thanks for the feedback.

I did transcribe the questions for Part 3, but not #2.

I'll go back and do #2 in the next few days.

Cheers,

Ian.
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Old 11th Aug 2022, 8:03 am   #12
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Default Re: Hickok 536 Valve Tester

Actually the term 'English" as used here in the U.S. is a very old term generally meaning:
"Put your back into it" , "Push harder," or similar. As in: If you can't get that bolt loose, give it some English".
AFAIK, it dates back into the 1800's or before. One seldom hears it used unless it's in a historical book. (Yeah, Us Yanks have some very odd terms here. Comes with the territory).
Many of my collection of Hickok tube testers do use the term 'English" for a specific control.
I am not sure why the engineers at Hickok decided to use that term. It IS confusing, even for us U.S. folks. Likely something they decided to call a control to avoid a patent issue.
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Old 12th Aug 2022, 2:28 am   #13
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Default Re: Hickok 536 Valve Tester

On the ENGLISH control.

It's used to set the meter sensitivity when testing diodes.

OK, so that allows the instrument to register a meter reading read off the REPLACE/GOOD scale, as opposed to the actual gm readings when testing triodes or anything with a control grid.

The control is marked as SHUNT on at least one later release/model.

I get all that, but why not mark it as something *meaningful*, like MERIT, DIODE, or some other useful word (you and probably think of alternatives).

Hickok have produced an instrument that (i) does not test any valve at manufacturer's specifications...

does my EL34 still work at around 100 mA anode current? - no idea on the Hickok

or what about my 6AS7 series regulator at 250 volts/125 mA - nah.

(ii) has confusingly swapped pins 1 and 2, and pins 7 and 8 on the octal socket (but not the loctal!), and scrambled the B7G (but not the B8G!)

(iii) does not annotate variable resistors on the circuit diagram.

To paraphrase Zaphod Beeblebrox "If there's a standard anywhere around here, I want it caught and shot".

I will be putting together an article for Silicon Chip to help rescue others from the Slough of Bamboozlement.

Cheers,

Ian.
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Old 12th Aug 2022, 6:28 am   #14
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Default Re: Hickok 536 Valve Tester

Wow, Ian, you walk close to line of "politeness " on this forum.
I don't think you have done anything wrong, but judging one of the iconic American valve testers honestly, might raise some eyebrows.

Cheers for now.

Joe
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Old 13th Aug 2022, 1:54 am   #15
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Default Re: Hickok 536 Valve Tester

The basic Hickok tube testers were never designed to test valves at book values, only to provide basic testing and give a go/no go testing. So a lot of compromises, but basically designed to be portables testers. The funny socket numbering is stated in the manual was to reduce the selector set-up to a minimum. It is also well known that the role charts often are model/vintage specific, and the Gm readings in some cases represent new valve readings, while other they represent minimum values. The Gm readings also are just relative and not book values, or for that matter interchangeable between different tube testers. So at the end of the day they tell you more if you have a bad valve and not much more. The Hickok 536 is one of their more primitive models.

Hickok did make some "Laboratory Grade" models like the 539B/C, RD1575 and the WE models, these do not have the funny pin numbering and allow you to set voltages as opposed to a scale for bias, but you are still limited to a plate voltage of 150V in normal mode. There are a number of limitations, but better than their consumer grade. They had later models like the 580A, which can test to plate voltages of 300V @100mA with a bias range 0 to -50V, but it is hampered by some design flaws which can give erroneous readings if comparing the test results to book values. Some of these can be corrected.

These Hickok's testers still do not compare to the AVO testers as far as accuracy when comparing to book values, but surprisingly if you test a valve at the same operating points as the Hickok they do compare reasonable well.

I have a Hickok 539B, 580A, two AVO CT160's as well as a few others. They have all been modified to include solid state diodes and other mods enhance their accuracy. I have compared tubes on these testers to a bench top power supply/digital meter setup, uTracer curve tracer and also Amplitrex tested valves. At the end of the day, I find the uTracer the most helpful looking at operating characteristics across a range voltages. My AVO's are nice but finicky, They all have additional digital readouts which help to get more accurate readings, but they collect dust in my closet these days.

Attached is the 539C schematic in a high res.with the noted corrections. Their available schematics often do not correlate with a production model, as there were always changes and adjustments made over time.
Attached Files
File Type: pdf Hickok 539C Schematic Full.pdf (736.5 KB, 21 views)
File Type: pdf Hickok 536 Manual.pdf (1.99 MB, 26 views)
File Type: pdf Hickok 580A Checking Bias Voltage.pdf (452.8 KB, 24 views)
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Old 13th Aug 2022, 2:30 am   #16
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Default Re: Hickok 536 Valve Tester

Hello to Joe and Mark,

Apologies if I have gone close to the Politeness boundary.

I guess I like to see equipment that is well-documented, easy to use and that conforms to industry norms.

My frustration with the Hickok - as I hope I've made clear - is its non-standard testing.

Can I be assured that a power valve will actually operate correctly at full demand - the 6AS7 regulator triode, with its maximum plate current of 125 mA is one example.

I know that some of my ham radio/audiophile mates have found the AVO testers inadequate (consider the VT4/211 "hundred-watter") and have had to do test bench setups with multiple power supplies to verify serviceability.

Those are niche applications, true, and as a restorer of domestic/low-power military equipment, I'm OK with the testing range of AVO testers. With them, I *can* test at full anode current (EL34/6CA7) and voltage, so I can be assured that a "good" test result is credible.

Yes, I get that the Hickok I'm criticising is essentially a "point-of-sale" instrument, meant for ease of use rather than any complete analysis such as I *can* do (up to 100 mA/400V) on an AVO.

So thank you, everyone who has replied. I do appreciate the extra information that you've pitched up.

My approach to documentation is to read *every* comment and then to judge just how to balance my Mister Picky demand for concision and accuracy against the real-world usability of the equipment.

I was once "advised" to make a textbook "interesting". My reply was that I didn't know how to do that - but I *would* make it useful and authoritative.

Funny thing - the students complimented me on how good it was

Thanks again, all.
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Old 13th Aug 2022, 2:30 am   #17
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Default Re: Hickok 536 Valve Tester

Thanks, Mark, for the explanations. I have been collecting data and "bits " to build my own. I will be publishing my design ( I DONT know how well it will work !! ) when I put it together.
It will be another "knob twiddlers delight " and wont have any computers involved. It will all be analogue except for the metering, so some valve driving experience will be required. It will also be uploaded to Tube Testers, Rob's google drive.

Cheers
Joe
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Old 13th Aug 2022, 2:39 am   #18
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Default Re: Hickok 536 Valve Tester

Thanks to Ian too for the reply!!. Note the time we logged in our answers!!.
I have an Avo MKII, but it has bugs. I think more than anything, is its age.
I have "rebuilt " it, I still find it clumbsy. It also has the sticky meter movement, and a half repaired multi value pot that looks hand rolled and made from three of four different guage resistance wires.
This was open circuit when I received it years ago. It does have the transformers that are supposedly nice, and I will sell them on to fund my design ( Im an age pensioner now ). They are in mint condition.

Your comment:
My approach to documentation is to read *every* comment and then to judge just how to balance my Mister Picky demand for concision and accuracy against the real-world usability of the equipment.

Is exactly the same as mine, so I have decided to make my own tester.
Mind you, I am of Polish descent, so it might use reverse Polish logic ( as opposed to notation ) to work. .

Joe
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Old 13th Aug 2022, 4:31 am   #19
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Default Re: Hickok 536 Valve Tester

Hello, Marc,

Thanks for the PDFs, but do you - or *anyone* have better version of the 536 manual.

It seems to be the only one - every website I've visited has this version - it's the one I call the Vignette, due to its loss of edge detail.

I did get an improved bitmap of the circuit via Martin Forsberg (thanks, Martin), but I cannot find a fair copy anywhere.

Thanks for the 539 cct, it is good enough to use in publication as is.

I do notice that the 539 has the correct correspondences between switch pin numbers and valve socket pin numbers.

I consider Hickok's scrambling of the 536 correspondences to be a folly, and I don't accept their reasoning that it makes the instrument easier to use. Given that indirectly-heated B7Gs almost universally use pins 3 and 4 for heater, and that very few octals don't use pins 2 and 7, *and* that the B9G socket is *not* scrambled..... nah.

(But I'm getting boring about this, so that's a <Ctrl> <C> from me

Cheers,

Ian.
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Old 13th Aug 2022, 5:27 am   #20
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Default Re: Hickok 536 Valve Tester

Unfortunately that is the only 536 manual I have seen, it is a very uncommon model. Many portions to the manual are similar to the Hickok 600 as well as others. My recollection is most of the Hickok's use their rearranged socket pin outs to selector mapping, only the latter models like the 539B/C, 580, 752, and the TV-2, 7, 10 etc. had regular mapping. The wanky pin numbering I find it terribly confusing. They assume one just follows the roll chart settings, but it can lead to mistakes, and like any documentation there are errors. I have most of the Hickok manuals, but there is a lot of information on this site: https://www.stevenjohnson.com/hickok/data.htm
Regards,
Mark
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File Type: pdf Hickok 600 manual clean.pdf (317.4 KB, 30 views)
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