Budget 10V (etc.) Voltage References/Standards on the marketplaces out there

[guenthert]

It looks like the majority of these units use gold plated but brass body binding posts.

Cheers

Alex

Yes, they're (like the ones on Dave's uCurrent) ordinary Gold plated speaker terminals. Luckily thermocouple effects (normally) aren't that important at the 10V level and specified degree of accuracy.

   In case of fredchu's LT1021 reference it's worse though: plate and bottom of the nut are plastic; a wire must be threaded through the hole in the post to make more-or-less contact.  It's one of those 'what were they thinking' things.  

[Rax]

once I got Ian's PDVS2mini.

I missed this part at the first go around. I can't find much info on this - is this available? I see a review, but not much else beyond that, but still looking into it.

[Andreas]

https://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-2-mini-detail

[Rax]

   I got one of fredchu's (seller's name on eBay) LT1021 based 10V references [1] (meanwhile he also offers LM399 based ones) almost a year ago.  Works like a charm afaict.  Unfortunately a good chunk of my gear is still in storage, so I can't sensibly characterize it. 

   I like that it has screw/banana-plug combination terminals.  They are gold color (gold flashed?), not sure if they are truly low thermal EMF terminals though (there is no claim that they would be).  Oddly, the same kind is used for input and output (clearly marked though, albeit with sticky labels -- it's not meant to be used in decades like old -hp- gear).

   I also like that he publishes pictures of the internal construction.  Removes the mystery and temptation to open one up oneself (and potentially invalidating calibration).

EDIT:  with the recent addition of a 50+ y/o -hp- 735A DCV transfer standard, I'm now in a better position to evaluate the LT1021 based 10V voltage reference (fortunately I already had a DV211 "dekavider" KVD).  Still can't say much about long-term stability, but at least the short term stability / [absence of] noise was good enough to verify the power-on behavior (limit of hysteresis) of the -hp- 735A (see attached, the green line being the differential voltage between those sources).
 
[1]

guenthert - you seemed quite a bit more critical in your later post; have you reconsidered your initial take? I was just going back to reviewing these suggestions and fredchu's LM399 reference has just come into my radar...

[guenthert]

   I got one of fredchu's (seller's name on eBay) LT1021 based 10V references [1] (meanwhile he also offers LM399 based ones) almost a year ago.  Works like a charm afaict.  Unfortunately a good chunk of my gear is still in storage, so I can't sensibly characterize it. 

   I like that it has screw/banana-plug combination terminals.  They are gold color (gold flashed?), not sure if they are truly low thermal EMF terminals though (there is no claim that they would be).  Oddly, the same kind is used for input and output (clearly marked though, albeit with sticky labels -- it's not meant to be used in decades like old -hp- gear).

   I also like that he publishes pictures of the internal construction.  Removes the mystery and temptation to open one up oneself (and potentially invalidating calibration).

EDIT:  with the recent addition of a 50+ y/o -hp- 735A DCV transfer standard, I'm now in a better position to evaluate the LT1021 based 10V voltage reference (fortunately I already had a DV211 "dekavider" KVD).  Still can't say much about long-term stability, but at least the short term stability / [absence of] noise was good enough to verify the power-on behavior (limit of hysteresis) of the -hp- 735A (see attached, the green line being the differential voltage between those sources).
 
[1]

guenthert - you seemed quite a bit more critical in your later post; have you reconsidered your initial take? I was just going back to reviewing these suggestions and fredchu's LM399 reference has just come into my radar...

Not really.  The LT1021 based reference performs as claimed as far as I can tell.  I just wished better posts (on the output) would be used, but those would be driving up the cost.  That probably doesn't make any sense on a LT1021 based reference, but something to be considered for a LTZ1000  based one, perhaps also for a LM399 based one.

[Rax]

It seems that I may be heading into getting a 731B and a 510A (1kHz)...

A lot of members of this community seem to use these 731s for secondary (quasi-primary?....) bench references (I know they're not in the same league as the 732s!...). The 510A seems more like a bonus from that one transaction I am in the middle of.

When I'll recover (a few coins accruing in the hobby chest), I'm thinking I may get one of those fredchu's LM399 based references. I'm still not 100% sure I understand how one (731) stacks against the other (fredchu LM399).

[J-R]

Of the vintage Fluke stuff, perhaps also check out the 515A.  It has a fair amount of flexibility, relatively speaking. Having one adjusted and calibrated may not make a ton of sense due to the excessive amount of manual tweaking involved, so maybe combine it with a good, calibrated 6.5 digit or better DMM instead.

[branadic]

Multiple options are available, depending on how much gold you want to spend:

Guildline 4410 https://www.ebay.com/itm/295245155830
Harwell VR-5 https://www.ebay.com/itm/204178697194

If you buy one or more of the Harwell please provide some teardown images to the community.

-branadic-

[Rax]

Of the vintage Fluke stuff, perhaps also check out the 515A.  It has a fair amount of flexibility, relatively speaking. Having one adjusted and calibrated may not make a ton of sense due to the excessive amount of manual tweaking involved, so maybe combine it with a good, calibrated 6.5 digit or better DMM instead.

I would do the former anyhow (currently neck deep into an 8505A including all hardware and software calibration adjustments, in addition to full repair - the motherboard needed being replaced and other smaller issues) and already have the latter (freshly calibrated/adjusted/stickered 8502A).

Once the 8505A is fully working and adjusted (almost there), I'll then of course add 7.5 digit capabilities on my bench. Happy camper.

[MegaVolt]

https://www.ebay.com/itm/334432987035

[RoadDog]

$43 reference off eBay.

Reclaimed LM399 and LT1001. Claims all the other parts are new.

I figure I’ll watch it with my 34401. I imagine this should drift more than my aged meter although I’m not sure how much.

I’ll measure its load sensitivity and PSRR. Maybe mess with some capacitive loads and see what it does. Not sure of what kind of setup to do for measuring TC although I’d like to figure out a setup for that. Kind of new to this. Any tips for that or other things I should try to measure? Anything else to poke and prod at?

[Andreas]

My standard program for measurements would be:
- T.C.  within 25+/-15 deg C environment (perhaps a heater box in a car cooling box, or a proper refrigerator)
- Ratio T.C. between 7V and 10V output
- PSRR
- 1/f noise (0.1 .. 10 Hz Amplifier 10000 fold) with screening for popcorn noise
- optional wideband noise (10Hz-100kHz with AN83 amplifier)
- for LM399: sensitivity to tilting.
- unheated vs. heatet output voltage
- ageing drift
- optional EMI drift over 100kHz - 60 MHz

see also here: overview picture

https://www.eevblog.com/forum/metrology/adr1399-reference/msg4737989/#msg4737989

with best regards

Andreas

[deepfryed]

You can read more about adventures of "Awesome14 (Kaysert - Tom Kayser)" here:

Calibratory D-105 DC Precision Voltage Reference Standard
https://www.eevblog.com/forum/metrology/calibratory-d-105-dc-precision-voltage-reference-standard/
Search for the teardown EEVBLOG members have done on Awesome14 artwork - be careful

Best regards
ScoobyDoo

What have I ever done to you?... I had a perfectly good couple of hours this afternoon, and you've tricked me, and sucked me into this juicy, evil and... splendidly insane thread. How do I get my hours back?.... 

Oh dear, I stumbled upon this and my whole evening's been used up reading the thread which I haven't finished. I hope the poor fella got some help. He still seems to be selling it, though the price is over $1000aud now