Pearls of the Past (Only for the Voltaically Inclined)

[quantumvolt]

... I'm wondering if it was some kind of standard back then to build stuff in such a modular fashion?
...

It was. This super size base board from a very expensive HP gadget vandalized in Israel cost me USD 12  . If I live long enough it will be a Voltage Reference Nursery.

[mamalala]

... I'm wondering if it was some kind of standard back then to build stuff in such a modular fashion?
...

It was. This super size base board from a very expensive HP gadget vandalized in Israel cost me USD 12  . If I live long enough it will be a Voltage Reference Nursery.

I think i know which seller you got that from. Sells loads of stuff that looks like it has been pulled direcetly out of a war zone. After thesee things became the targets and have been hit, that is.

Wondering what the reasons are that nowdays you rarely (if at all) get such a nice modular unit design, apart from some bean counters wanting to save some bucks for connectors. My HP 5345A counter is also nicely modularized. Should make pictures of the insides of these two units. Marvels of engineering.

Greetings,

Chris

[sync]

I think the reason for the old stuff is simple. They need a lot of PCB area. One big PCB isn't enough. So using a back plane and lots of cards is a good solution and easy serviceable. Today all of this fits on a small PCB. No need for expensive connectors, more hand assembly and so on.

btw: quantumvolt, did you see this? https://www.eevblog.com/forum/testgear/fluke-732b-dc-standard-teardown/. DIY one would be hard.

[mamalala]

I think the reason for the old stuff is simple. They need a lot of PCB area. One big PCB isn't enough. So using a back plane and lots of cards is a good solution and easy serviceable. Today all of this fits on a small PCB. No need for expensive connectors, more hand assembly and so on.

btw: quantumvolt, did you see this? https://www.eevblog.com/forum/testgear/fluke-732b-dc-standard-teardown/. DIY one would be hard.

Fair enough. Not having seen much of the insides of modern high-spec equipment, i'm wondering if they go for (more or less) single board stuff there as well, since i can see certain benefits in a moduler design for such things. But then, maybe it's just me, simply liking such modular stuff.

Greetings,

Chris

[quantumvolt]

I think the reason for the old stuff is simple. They need a lot of PCB area. One big PCB isn't enough. So using a back plane and lots of cards is a good solution and easy serviceable. Today all of this fits on a small PCB. No need for expensive connectors, more hand assembly and so on.

btw: quantumvolt, did you see this? https://www.eevblog.com/forum/testgear/fluke-732b-dc-standard-teardown/. DIY one would be hard.

Yes, I've seen it. I even posted a link to a schematic there.

I have no aspirations at all of coming close to the real thing. But what I will make out of the two HP/Motorola diode+transistor devices will be comparable to the Krohn-Hite boxes based on 1N829 and a chopper amp. As I have the refs and a LTC2057 chopper amp, all I need to buy is 2 super stable resistors for a single 10 V output. The temp feedback circuitry for the last mV or so is tinkering and will be a project in itself.

I like to make experimental setups. I never finish anything. And I am not interested in owning real old quality measurement equipment - only studying the schematics. I guess I am in this for learning.

My 'scope' was a 10 dollar external USB sound card with level shifter and DC coupling. I almost fried my laptop with it. So for me the most important thing is to get a brand new hobby all round oscilloscope. Then I can  more than numbers.

But I like to look at other peoples old gear...

[quantumvolt]

JFYI - I sent a polite email to Agilent asking if there were someone who had knowledge about these refs. It is now beyond any doubt that they are HP parts (not Fluke).



http://www.pa.msu.edu/~edmunds/DVM_HP_3440a/hp_3440a_dvm_manual.pdf

They hardly answered any of my questions at all. Seemed totally uninterested (the author of the reply had been with HP/Agilent for 25 years and stated that it probably was a "heated reference" - WTF ... they didn't even check their archives? As is seen in my links here and in earlier posts it is open to anyone that searches for it that the part probably is a REFAMP diode+transistor from Mororola.

So much for HP Memory ...



http://www.hpmemory.org/timeline/dave_cochran/hpj_nov63.htm

[sync]

btw: In the 3440A manual the manufacture of QCR1 is General Electric and the GE part number is 4JX19A519. And look at this page: http://www.nsnlocator.com/nsndetail.cfm?NIIN=008522869&pn=1820-0001. There are alternative part numbers.

[quantumvolt]

Yes. Probably depends on the year (1963 is - just to say it - 50 years ago). Of course I checked in the manual that I took the photo from and linked to over - and the part QCR1 is not even in the parts list of the very same manual that uses it in the schematic (?). That is - AFAI can see.

But IMO that changes nothing. If you look at my first post here you will see a photo of the Motorola part. So that must have been used in a revision that I cannot find the manual for. That was one of the things I asked Agilent about.

And it still isn't a LMx99 or a LTZ1000 or any "heated reference".

EDIT: Where (in which manual- the one I link to?) do you find QCR1 in the parts list for the Ramp generator Assy? Please also give page. I can't find it.

[quantumvolt]

btw: In the 3440A manual the manufacture of QCR1 is General Electric and the GE part number is 4JX19A519. And look at this page: http://www.nsnlocator.com/nsndetail.cfm?NIIN=008522869&pn=1820-0001. There are alternative part numbers.

I looked at your link once more - it says: 1820-0001, 1820-0006, 48A51151C01, 4JX19A519, 4JX19A555, SCA11, SZA11.

The last one SZA11 is afaik a Motorola part. The Fluke REFAMP from Motorola is designated SZA263.

[sync]

Yes, I also think that SZA11 is a Motorola part number. Maybe your 1820-0001 is a SZA11.

EDIT: Where (in which manual- the one I link to?) do you find QCR1 in the parts list for the Ramp generator Assy? Please also give page. I can't find it.

In your linked manual. On page 7-9.

[quantumvolt]

Thank you very much. I must be blind. And also dumb to doubt the old manual. One of my ideas is that an instrument is only as good as the quality of its manual, and the old HP manuals are really serious, almost scientific documentation.

So I say "Sorry" to the authors of the manual for doubting their document   

[Galaxyrise]

Thanks. Anyone familiar with the rest of the large advanced analog ref schematic, and want to share their knowledge/skills in the form of pointing out what is absolutely necessary for a small DIY ref board with the transistor+diode part?

This thread has been great fun for me, hehe.  After reading the 732b teardown (which was wonderful), my next stop was the 732b User's Manual The "theory of operation" section was excellent.  Have you read it yet? I think it answers your question.

[echen1024]

Thank you very much for the beautiful nostalgic schematic.

"An LM399 is probably better"? Yes, sure.

[Edit all]
If I eat noodles for a month, I can buy a legion of LM399 today. The two devices I have found in the fleabay bush of Texas, USA are analog collectables. They are unnused original spare parts produced by Motorola and bought/packed by HP sometime in the 1960s/early70s. So we are talking about 40 years old RefAmps. In the mail list they are classified as 'unobtanium'.

I really like the schematic. It is built like a classic power supply with constant current through the temp compensated ref diode and a precision diff amp for gain. Typical HP quality "engineer" design. Could you please give a link to the manual.

---
[Notes for my next search  MHQ2221 MHQ2229   4JX19A519, 4JX19A555]

I am in Houston, TX. If you need a freight forwarding type of thing, let me know...

[quantumvolt]

Nice somebody find fun here - I hope there will be more. This thread will renew the never lived life of the two 40+ yo refs  . I look forward to getting them.

Even if I paid more than USD30 in shipping and postage for an envelope ("International Letter"), the USPS is not much faster than China Post. At least not to Thailand, that is. But I can wait 

   
Product & Tracking Information
Postal Product:

Features:

        International Letter

Date & Time
   
Status of Item
   
Location

November 8, 2013 , 6:39 am
   

Processed through USPS Sort Facility
   

CHICAGO, IL 60666

November 7, 2013
   

Depart USPS Sort Facility
   

COPPELL, TX 75099

November 6, 2013 , 8:56 pm
   

Processed through USPS Sort Facility
   

COPPELL, TX 75099

November 6, 2013 , 4:00 pm
   

Acceptance
   

GARLAND, TX 75042

November 6, 2013
   

Electronic Shipping Info Received

[Galaxyrise]

Have you got a rig to measure tempco vs current yet? That'll give you something to do while you wait

[quantumvolt]

Have you got a rig to measure tempco vs current yet? That'll give you something to do while you wait

No, I haven't. And I won't make one. Preparation takes imo much of the fun out of it. I will clear the path as I walk it.

My first rig will be a 7812 regulator, a metal film resistor + 100 ohm trim "current source", a 2 dollar fleabay digital thermometer and a Processing sketch that maps ppm-level (of course limited by my best measuring instrument Agilent 34401A which obviously is not good enough for this project). When I get to learn what I am up against, I will improve the setup step by step.

As everyone knows - the only way to "make" a Fluke box is to buy one ... 

[Galaxyrise]

You'll want some kind of "oven" too.  I've got a cheapie thing I built which is just some incandescent night lights in an outlet box with a dimmer.

[quantumvolt]

Well - they are here...

[quantumvolt]

It might take a week or two before they see any electrons  I need advice on a test circuit. I don't mean "use precision resistors" and so on - I mean the schematic and values/critical components. Oven, thermistors and other fancy stuff will have to wait. First goal is a reasonable circuit with a working and stable feedback.

My first attempt on making a simple oven-less hybrid from the two manuals:

http://www.ko4bb.com/Manuals/Fluke/Misc/732A_Users_Manual.pdf
pp. 111-14

http://www.ko4bb.com/Manuals/Fluke/Misc/732B_734A_Users_Manual.pdf
p. 60

Knowledgeable comments would be highly appreciated.

[Andreas]

Mhm,

is it really a genuine refamp? in a molded case and not hermetically metal can?

the SZA263 was in a metal can.

http://www.amplifier.cd/Test_Equipment/other/images/Fluke5442A_8_SZA263.jpg

The fluke handbook silk screen shows that the fluke refamp is smaller than a TO-99 case (probably TO-46)

With best regards

Andreas

[quantumvolt]

Mhm,

is it really a genuine refamp? in a molded case and not hermetically metal can?

the SZA263 was in a metal can.

http://www.amplifier.cd/Test_Equipment/other/images/Fluke5442A_8_SZA263.jpg

The fluke handbook silk screen shows that the fluke refamp is smaller than a TO-99 case (probably TO-46)

With best regards

Andreas

   I wrote in my 2nd post in this thread:


"
Well - I find little or no info about it, and it doesn't look exactly as I would have thought. But it is supposed to be an original HP part: 1820-0001 AMP, REFERENCE
"


So I have to leave your question as one of metaphysics and semantics. I do not have and have never seen a "genuine" REFAMP.

I have never claimed it is a Fluke part (although another poster suggested it was so)- I have repeatedly said it is claimed to be a HP part made by Motorola. If it has a SZA-name it would probably be SZA11 (se earlier post). It is - however - a "hybrid" of a transistor and a Zener diode (as is SZA263 and LTFLU-1).

You do not need a metal can or any special production technology parts for circuits that combine a transistor and a diode for making a net tempco close to zero. You can handpick discrete components and enclose them in thermally conductant chewing gum.

These parts - unless they are "fakes" (me thinks not - they were bought from one of the biggest American ebay dealers in used instruments - selling everything from original spare resistors to spectrum analyzers priced at multi-thousand dollars - all with good ebay feedback) were used in HP3440 and maybe -3450 from 1963 (HP3440). Anyone who feel compelled to do so, please check their "history"...

[quantumvolt]

Well - seek and you will find (at least if it is an HP instrument - the ultimate in documentation).


The original "AMPREF" (since the HP use of the transistor-diode from Motorola as a temp-compensated reference amplifier "REFAMP" is documented already in 1963, I now assume that FLUKE copied the idea from HP  ). The big, black, molded case AMPREF is clearly visible behind the two trim pots (black and blue below the metal 'bridge' with the text '... instrument is on').




The reference assembly board placement from the manual:





The AMPREF (QCR1A&B) placement on the reference assembly board - and the two trim pots (R60 and R51):






Source manual
http://www.pa.msu.edu/~edmunds/DVM_HP_3440a/hp_3440a_dvm_manual.pdf

Source picture (the whole instrument - top view)
http://www.hpmemory.org/pict/timeline/dave_cochran/hp3440a_top_hr.jpg

[Andreas]

Hello,

fine. that convinces me.

But since most semiconductors at that time were within hermetical (metal) packages, it explains that one could be easily in doubt.
Fine instrument with all those metal can semiconductors.


With best regards

Andreas