Fluke 332A voltage reference for free to good home

[VintageNut]

I have a Fluke 332A that is taking up space and not being used.

It was working when I last used it.

Free to a good home. You pay shipping or we arrange pickup/drop off. I live in the Carolinas area of the USA and I travel often so I can arrange drop off. 

[Kosmic]

PM sent.

Thanks

[Vgkid]

Drats, too slow. Good luck kosmic.

[SoundTech-LG]

What's a 332A worth these days??? Mine comes in handy once in a while. Rather large though.

[branadic]

Wow, what a nice touch. My honest respect to VintageNut and congrats to the new owner, you are a lucky one.

-branadic-

[RandallMcRee]

Since I could not get this reference I snagged another 731B off the -bay.

I'm hoping that this next one will be a female. My current one is male. I'm going to stick them in a closet over halloween night.

Should have three 731Bs in the morning.

That's my story and I'm sticking to it.

[branadic]

Since Fluke 731A are up to 44 years old, I wonder how stability has improved during their aging. They were specified with 30ppm/year, how did they end up by now? Any data on that?



-branadic-

[e61_phil]

The 731B at work doesn't perform very well. Comparable with a LM399 based 34401A not better.

Anyway, I think the specification was very conservative. The 732A is also not so great on paper and I don't think the very good stability came only with age.

[branadic]

Thanks, that's a first hint. I wonder why someone would pay 220 ... 400€ in the bay for such a unit if you can build a LTZ1000 reference for less. Okay, you need the time to age it, but on the paper it would perform much better out of the box. Do I miss something?

-branadic-

[Echo88]

The Fluke 731B can be calibrated by every calibration lab, while they wouldnt accept a selfbuilt LTZ1000-Box i presume. Also the 731B is fully characterised, battery buffered and overcurrent-protected AFAIK.
But i get your thought, i didnt bother to buy one either and still wait for a low-priced 732A which has better specs.

[e61_phil]

The cal lab we use calibrates nearly everything. Our compliance department has a lot of "test tools" which are self-made and under calibration.
The cal lab doesn't gurantee any specs, they only give some paper with measurement data they measured. But that's the same for other equipment.

If you build a proper LTZ1000 10V Ref, with housing, batterys and so on. It will cost more than 220€ I would assume.

[branadic]

If you build a proper LTZ1000 10V Ref, with housing, batterys and so on. It will cost more than 220€ I would assume

Thanks for your response. So it's just an ebay price and not representing the real worth. Well, the most professional LTZ design by now is the one by Andreas, incl. battery pack, charge control etc.. I have build 3 of them and they are less than 220€/ea, but you need some time to build it. It's not a product with series production in mind.
Even a 732A or B goes for quite a big bucks, if not bought broken.

-branadic-

[e61_phil]

I estimated the following BOM

LTZ1000 50€
LTZ1000 resistors OPamps... 50€
VHD200 7V -> 10V 70€
Housing 15€
Binding Posts 20€
Power Supply 10€ if it is cheap
battery 15$ ?

That is more than 220€ and I think I forgot some parts.

Are your boxes much cheaper than that?

[Conrad Hoffman]

I had a 332 and gave it away. It was great when it was the only reference I had, but took up too much space and was too heavy to lift. Hint- never connect one to anything that can supply current, like a battery. Smoke will follow.

Never seen a 732 in any condition that I can afford, and anything less than three references is insufficient.

I maintain three 731s and they do quite well, but be sure to service them. My long term success with batteries has been poor, so I replace the batteries with a bunch of capacitance in parallel with a zener, so it looks like a battery of the correct voltage. I don't find much change when power cycling a 731, so I don't worry about it if the power goes out. You can adjust the reference current a bit and achieve way better tempco performance than factory, if you have the patience to test it for a week or two.

[branadic]

I maintain three 731s and they do quite well, but be sure to service them.

So how do they perform in respect to longterm stability compared to the datasheet values after all this years of aging? Do you have any data on this?

-branadic-

[Conrad Hoffman]

I don't have any solid written long term data, but by periodic comparison with each other and with a completely different design reference and with a couple meters, they've only wandered maybe 3-5 ppm over the last decade. IMO, the need for service/periodic maintenance will get you before drift does.

[branadic]

Thanks. Wow, 3-5ppm/decade is at least a factor of 100 better to what they were specified.

-branadic-

[e61_phil]

My experience with the 731B at work is much worse. It is more 3-5ppm/year

[branadic]

My experience with the 731B at work is much worse. It is more 3-5ppm/year

Still a factor of 10 better then specified. This is not that bad at all given that it is only temperature compensated and not ovenized.

-branadic-

[Conrad Hoffman]

I probably have an unfair advantage. My 731s sit in a corner of my basement lab, which is dehumidified, rarely has breezes or disturbances and changes temperature fairly slowly. Line voltage is also very stable here, though not as reliable as some places. They've been on 24/7 since I got 'em. My boat anchor HP 3455A does almost as well once it warms up. My Analogic (Data Precision) 8200, though incredibly handy, does need the periodic tweak to keep it calibrated. I believe it uses an LM399 though.

[Kosmic]

I received a huge and heavy box today 

The Fluke 332A made the trip in one piece. I did a quick check and it's 7ppm off my local 10V!

Thanks again VintageNut for your generosity. Much appreciated 

[bitseeker]

Very cool. Congrats, Kosmic!

[stijena1973]

I have a 332A missing preregulator PCB  (187312 module i think)

 I will have to replicate it; could You help?