USA CAl Club: Round 3 suggestions

[rhb]

Round 2 has been an interesting and educational process.  Many thanks to all who contributed especially cellularmitsosis, TiN and vindoline who did the serious heavy lifting to make it happen.

I'd like to raise some issues that seem to me obvious from my experience.

1) We need a precision voltage divider able to provide outputs on all the DMM ranges.

2) The PX reference needs more robust packaging.  TiN did an excellent job on the FX, but the PX is fragile in its present form.

3) A GPIB-USB interface combining the Tempduino and an RTC in a case so that people who do not already have a logging system can collect data more easily.

4) Test scripts portable to Windows and Linux for all the measurement options  which have been thoroughly tested.

5) We need more resistors so that all ranges are tested.

6) DC current, AC volts and current sources.

7) A transit temperature and humidity logger that records to an SD card.

Some of this I intend to do, some of it I know how in principle, but probably not to the level of quality needed. And some, all I know is it's needed for a full DMM cal.

Have Fun!
Reg

[hwj-d]

The original idea behind PX was to have a small, compact, easy to send ltz1000 reference. Not more. With it in mind someone have the ability to compare/verify his 5.5, maybe 6.5 dmm in the 10 voltage range. This was not, at first, as i understand, to test the ref itself in long sessions, to get the reliability and characteristic curve, except as a side effect. One should test its own dmm better as with this chinese ones. So someone take this test, and ship it to the next interested for same simple thing. Same with this resistors, see if your dmm out and how much. The star shipping methode gives the sender, in this case vindoline, the ability, to check the ref for next shipping. In my oppinion, the ref ist robust enough, for input voltages between 12V and 15V for same output voltage, and protected against polarity reversal. The output should be save for >= 10Mohm impendance and not shortcut protected. These are the only conditions.

In the course of time, however, further requirements arose from participants that the reference behavior of the measurement should be recorded, and without temperature and humidity sensor with timestamp this would not really make any sense. So Jason kindly sat down again and developed an additional kit.

To make long words short, now we are sitting in front of the px, and realize that it is not robust enough for all this, and compare it with tin's reference, which plays in a completely different league. Yes, that's right. But px wasn't meant to be that way in my opinion. Actually, this should also, in its own original compact form, as my suggestion, without all the fuss around, go on its own quick journey.

Ok, i'm not at once in the usa club for now, so consider this as a suggestion on my part, hold it simple.

 

[Tj138waterboy]

I would like to participate as well as a beginner I agree with both above posts. As a whole I would like the ability to get all voltage ranges as well as resistance ranges which is why im building up a 100v ref. Also from the pics I see the cal club ref looks to be the size you would expect for a basic vref but seems flimsy. Im not sure if this is to keep shipping price down or just what was available to house the unit. The bigger point I would agree on is that probably less than 50% of the eevblog members have better than 6.5 digit meters so the build/quality/accuracy could be more geared towards that kx vs px type. The star pattern shipping seemed to be a good idea to keep track of changes during the voyage but another method could be for the next round, ship to member longest distance first that has known good calibratee 7.5digit or higher gear to get first baseline readings then to nearest member or two that has questionable lesser digit equipment then back to you or another member along the list with good calibrated equipment 7.5digit or better leapfrogging all the while. Also do you have any sort of paypal or such for contributions? Any of you guys putting in this much effort could benefit from posting a link for donations to make this happen. As a side note would there be any issue with using 2-5ppm smd resistors for resistance only measurements more cost effective than getting all ranges of foil type.

[rhb]

The original intent was to fit the PX in a $3.50 USPS flat rate box.  It changed a bit when TiN added the FX.   Shipping is now $30/person vs the original $7/person.

If we had 3 PX references which were shippable for $3.50, then we could rotate them with the FX to people with 7.5 and 8.5 digit meters and send just a PX to people like me who only have 5.5 and 6.5 digit meters.

That would shorten the waiting time substantially and every 4th trip of the FX/PX would give us a comparison on each PX.

My ultimate goal is to be able to do a full cal of all my T&M gear with everything traceable to the group cal kit.  I've got lots of RF gear whereas other people just have meters and voltage references.  I could have bought a new 3458A for what I've spent on RF gear.  But then I wouldn't have the RF gear.   For my construction and repair projects the 34401A is quite adequate.

My hope is that we can fully test DMMs by the end of 2020 and RF gear to 3 GHz by the end of 2021.  That's an ambitious goal, but we have come a very long way in the last year.  I now have a very well equipped electronics bench in addition to a full machine shop.  What I don't yet have is enough of it organized to work efficiently.  I'm making progress, but if I just spent time organizing it I wouldn't have any play time.

To quote Lao Tsu, "A journey of a thousand miles begins with a single step."

[SilverSolder]

The simple PX-only suggestion seems a good idea. 

Of course, it is probably a "gateway drug" to more serious volt-nuttery... but it does potentially open the club to far more people. 

Before you can become a nanovolt-nut, you have to first be a microvolt-nut... and before that, a millivolt-nut! 

[Tj138waterboy]

Im looking at this in more of beginner, intermediate and advanced level transfers. Honestly i would probably consider the px an advanced level due to the ltz1000. Kind of comparing a resistor of s102 class tho vhp. Both would be accepted as good enough but the cost would make it less viable to just send a set of vhp class to just anyone that may not be as knowledgable on setup and measurements, "ie running too much current through it or mis-handling".  I like the semi instruction manual provided with the current round which does help with user error being less likely and would incorporate  it again even for the most basic task. As for your goal of keeping the shipping cost down I think under $15 would be more realistic goal to be able to include a complete kit that would include px ref somewhat in its current configuration, something like a hammond 1590a/b housing some s102 class resistors, a power supply, and a good set of test leads, so theres no variation of power supply used and users without lab supplies will not have to worry. Worst case I could seperating the kits to keep cost lower. Or not putting resistors in an enclosure but using 4 wire shorting blocks with resistor attached instead.

[rhb]

I was absolutely terrified handling the FX.  I've read numerous tales of woe from experienced people who blew a reference they had built, including cellularmitosis who blew the original LTZ1000 for the PX reference.

Conrad Hoffman wrote a series of articles on a DIY metrology lab which you can find on line.  It's a lot of work to match the resistors TCs, but the experience is valuable and the dollar cost is low.

I'd like to know what it would cost to make 3 PX references in sealed Hammond boxes.  The references are over $60 each at Digikey, but I gather there are cheaper sources.  I rather fear that the current PX reference will need repairs before it makes the rounds to everyone.

I'm not  interested in super accurate voltage references beyond reading about them.  I'm concerned with the practical task of keeping over a dozen pieces of T&M kit in cal.  Even if the cals were free, shipping on a lot of my gear would be $300 round trip.

And if you think metrology grade DC connectors are expensive, price RF connectors.  Mere basic bench RF connectors (e.g. APC-7 to N adapter for an 85046A S parameter set) cost over $130 each.  Once you go over 6 GHz the prices get eye watering.  A 1 mm 110 GHz RF connector is $1000 for just one!

But first things first.  Reducing the waiting time and covering more meter ranges and functions are more important.

[rhb]

I'd like to pose two questions:

Best way to extend the references to other ranges including things like the 3478A with its "3" leading digit scales?  Simple divider or divider and op amp?

Best way to produce a DC current source? Preferably multi-range, but anything is better than nothing.

It seems to me that those should be addressed before dealing with AC V & A.

Resistors seem fairly simple, more of them in a more robust package separate from the other references.

[CatalinaWOW]

I am a little confused.  RHBs post essentially suggests development of a portable cal lab.  One which is essentially plug and play (scripts set, instruments set, interfaces set).

While that is a laudable goal I question both the scope of the task and the purpose.  Starting with purpose.  The need for calibration really comes when delivering product to a specification or when comparing measurements.  Both of these requirements are only satisfied by full traceability back to an accepted reference standard.  While that kind of traceability could be achieved through this reference, it would require the heart of the star topology to do full evaluation of the kit each trip back, and also to maintain traceability (presumeably through paid calibrations) to reference standards.  That is a huge burden on whoever currently owns the middle.

I don't know the use cases for each member of the club, but I suspect that a significant majority of us are hobby users at various levels of intensity.  We seldom, if ever deliver product based on our measurements.  Sharing of data is more common, but often not dependent on high level calibration.  So for us this is volt nuttery in its purest form.  Something we absolutely don't need, but do for? Fun, curiosity, bragging rights....?

So now into the scope side of the issue. 

Having a canned cal lab sidesteps one of the pleasures of volt nuttery.  With prior apologies I will point to Conrad Hoffman.  I suspect that much of his pleasure has been derived from the development of his own tools.  There is a good deal of that in my own path.  Some coming winter will see me measuring many resistors as I assemble my own precision divider. 

The cost of shipping has already been mentioned, and as more capabilities are added it will only go up.  The chance of something horrible happening will remain fairly constant, but the pain of a lost package will grow as more and more is invested.  As proud as I am of the USPS, UPS and other services that give us one of the better delivery systems in the world accidents and errors do occur.

Rather than extend this rather rambling comment I will put a vote in for the simpler end of the scale.  If the club evolves to a portable cal lab, I will probably drop out, as it serves a function I don't need, takes away from the do it yourself element of the project and my membership would add risk to the club and to myself.

[rhb]

I'm interested in building RF gear and specialty lab gear.  It matters that if I set the output frequency and level of my 8648C that I know that the frequency is correct,  the output level is accurate and there are no major spurs.  By the same token if I measure an RF source or amplifier I've built I need to know that what I see on the spectrum analyzer is correct and not an artifact of some fault which has developed in the SA.

Even with new gear, it's important to verify performance.  With 20+ year old gear greater vigilance is needed.

If my T&M gear is not in spec I can waste a huge amount of time chasing down blind alleys.

Metrology is a much broader subject than voltage, resistance and time.  I'm much more interested in measuring plane surfaces to a fraction of an arc second than I am voltage to 1 ppm.  I have practical applications for the level accuracy.  I have no application for 1 ppm voltage accuracy.  So far as I can tell, people pursuing that are doing it just because they find the problem an interesting challenge.

There's no point in sending an RF cal kit to someone with no RF gear, so why would you do that?  I won't know until I have time to analyze the data, but I doubt that I have any need of an FX class reference.  Getting a PX for an annual check for $7 probably suits my needs a lot better than $30 to get an FX.

Volts, resistance and time are arbitrary.  You can set the value to anything you want.  What matters is that the interrelationships among different quantities are accurately maintained.  If your voltage, resistance and amperage measurements don't match ohms law closely enough for the work you  are doing you have a problem.

[Tj138waterboy]

I am a little confused.  RHBs post essentially suggests development of a portable cal lab.  One which is essentially plug and play (scripts set, instruments set, interfaces set).

While that is a laudable goal I question both the scope of the task and the purpose.  Starting with purpose.  The need for calibration really comes when delivering product to a specification or when comparing measurements.  Both of these requirements are only satisfied by full traceability back to an accepted reference standard.  While that kind of traceability could be achieved through this reference, it would require the heart of the star topology to do full evaluation of the kit each trip back, and also to maintain traceability (presumeably through paid calibrations) to reference standards.  That is a huge burden on whoever currently owns the middle.

I don't know the use cases for each member of the club, but I suspect that a significant majority of us are hobby users at various levels of intensity.  We seldom, if ever deliver product based on our measurements.  Sharing of data is more common, but often not dependent on high level calibration.  So for us this is volt nuttery in its purest form.  Something we absolutely don't need, but do for? Fun, curiosity, bragging rights....?

So now into the scope side of the issue. 

Having a canned cal lab sidesteps one of the pleasures of volt nuttery.  With prior apologies I will point to Conrad Hoffman.  I suspect that much of his pleasure has been derived from the development of his own tools.  There is a good deal of that in my own path.  Some coming winter will see me measuring many resistors as I assemble my own precision divider. 

The cost of shipping has already been mentioned, and as more capabilities are added it will only go up.  The chance of something horrible happening will remain fairly constant, but the pain of a lost package will grow as more and more is invested.  As proud as I am of the USPS, UPS and other services that give us one of the better delivery systems in the world accidents and errors do occur.

Rather than extend this rather rambling comment I will put a vote in for the simpler end of the scale.  If the club evolves to a portable cal lab, I will probably drop out, as it serves a function I don't need, takes away from the do it yourself element of the project and my membership would add risk to the club and to myself.

I don't think this would take away from diy'ers because im sure there are more starters that can't afford or have access to any better than a questionable ebay reference or resistor. Im all for Mr. Hoffmans methods for starters but as for me, all my equipment is more than 5 years out of cal which include 2 HP 3478a one of which came uncalibrated, Hp6111a, Hp54503a, and multiple refs on breadboard and arduinos. Yes any of us can tell arduino to output a specific frequency or measure a alkaline battery but unless there is some form of getting all equipment closely agreeing with a calibrated source then every project I start on I question if its even usable due to my equipment may be off by order of magnitude.

[tomato]

... unless there is some form of getting all equipment closely agreeing with a calibrated source then every project I start on I question if its even usable due to my equipment may be off by order of magnitude.

You need a calibrated source to tell if your equipment is off by an order of magnitude? 

[RandallMcRee]

. . .
My ultimate goal is to be able to do a full cal of all my T&M gear with everything traceable to the group cal kit.  I've got lots of RF gear whereas other people just have meters and voltage references.  I could have bought a new 3458A for what I've spent on RF gear.  But then I wouldn't have the RF gear.   For my construction and repair projects the 34401A is quite adequate.
. . .

(I, Randall, underlined several words for emphasis)

Well, CatalinaWow and I do not support your goal. I am not interested in RF gear. Sure, you can calibrate your 5/6.5 digit DC range using the cal kit but I am not sure how SA calibration suddenly became a US cal club concern.

I say *NO*. I say hell no.
The more complicated this becomes the less likely it is to succeed.

Yes, metrology is wide, but NO the US cal club is only DC volt-nuts. It seems to me that time-nuts are not part of this particular club. (I mean someone could have started such a club--but they did not and have not.) And RF nuts are not part of this either.

I find it fascinating to measure DC volts to great precision. I don't need to justify it to rhb or anyone else. If you don't care about it, don't join the club. Simple.

So, a long-winded way of saying lets keep things on the simple side.

Thanks,
Randall

[ArthurDent]

I also am very interested in frequency and actually have had a crystal standard that was running for over 35 years except for down time to replace batteries. However with fairly cheap GPSDOs anyone can have a very precise 10Mhz standard that can always give you traceable standard frequency far more accurate than you'll probably ever need. I have 2 antennas, 2 splitters, and multiple GPSDOs running 27/7 plus Rb and XTAL standards so I have frequency covered quite well.

That isn't true for voltage. To have a reliable voltage reference you really need to have your house standard, which will drift, checked against a higher standard on some schedule and the USA CAL Club fills that requirement nicely. I have bench meters like an HP 3457A and others that agree quite well but they haven't been checked in a long time and this club is a good way for me to check this stuff out at very little expense. My LTZ1000A standard has been aging for several months and the 10 VDC output seems to be quite stable. Once I compare my voltage standard against the traveling standard I can a have a little more confidence in my voltage readings and use it to calibrate some of my supplies shown in the photo.

Anyone who wants to have a wide range of voltages for their meter (which could be far different than my meter) could build a divider to suit their needs. Having a traveling divider that would fill everyone's needs would be costly and bulky. Keeping this simple is the way to go.   

[TiN]

I am in "nay-sayer" club on trying to make DIY calibrator. I tried that idea, (which resulted in KX ref design) but came to (in)sanity after seeing glimpse of the mountain sized iceberg of design and costs to make something capable verifying even just 6.5d meter. Also to make such unit fool-proof will make it big, heavy and expensive to ship.

 I think inception of CalClubs happen because there are number of people with LM399/LTZ refs and 3458As around who did not want to bear traceable calibration costs/don't have friendly lab nearby. Getting calibrated 10V/10kOhm standards by mail for traceability is all they wanted, thanks to ACAL .

Now from purpose point of view. Even if one magically builds a portable highperf calibrator with current, resistances , dividers and whatnot (not unreal, Mickle.T did that more than once, all alone) such calibrator will need traceable calibration by itself. You can take 10V DIY ref and do official calibration by decent lab. But getting accredited lab to do full calibration on wonderbox with DIY UI, protocol and unknown stability - well, tricky to say gently. I have built calibrator from commercial modules and bits, and even with that I am not comfortable shipping it to traceable cal lab. It will still take few more years before I am confident.

Price of accredited 6.5d meter calibration even with shipping is small (few hundred $) so those who need/want it just pay that and get their report for all functions/ranges.

Now , there is nothing wrong with idea of "portable" calibration lab for transfers between different labs, but it is much more limited and purpose exclusive club. Being part of one it's very expensive and time consuming, and paying $hundreds on shipping alone is not even worth mentioning. Also all members of such club must have similar capability and gear available, so our transfers can be evaluated for validity after each shipment/transfer. No need to say such level is for "lost case" volt/ohm-nuts and amount of participating members is less than amount of fingers on one hand. It is not what USA Cal Club here is about, in my non-member opinion

I'd like to note good idea from rhb as well - if one does not need FX reference, such member can ask not to ship FX , and get only PX/ohms ref? It is two cases now, so that can help to reduce shipping expense to half? So there would be two member lists, like "mild volt-nut case" and "severe volt-nut case"?

[hwj-d]

...
I'd like to note good idea from rhb as well - if one does not need FX reference, such member can ask not to ship FX , and get only PX/ohms ref? It is two cases now, so that can help to reduce shipping expense to half? So there would be two member lists, like "mild volt-nut case" and "severe volt-nut case"?

Oh, I for myself would have one of this FX too, lovingly.
And what would tell me that?
All my LTZ1000's have the same noise floor of >= 8 µV with >= 1.1x µV StdDev. And I'll bet my ass, that's the same with the FX. 
And everyone interested knows, why this is as it is.
No dmm gets better by the measured reference! 
 

[rhb]

For those who complain I am proposing feature creep, please read the start of the USA Cal Club: Round 2 thread.  Jason's intent was a $7 per round trip traveling voltage reference.  The current kit is much more capable, but it costs over 4x as much.

I am not a volt nut.  My concern is practical metrology to support my measurement requirements.  Those happen to be more comprehensive than many, possibly even most, of the people active in this section.  Metrology is a vast field which is central to *all* engineering and scientific effort.  I need dimensional metrology references in addition to electrical references.

Building a Fluke 5700A class calibrator is not what I am proposing, nor am I proposing a monolithic kit for calibrating everything anyone might have.  What I'm proposing is gradually expanding the range of calibrations that can be performed so that the club is useful to people who are interested in solving practical metrology problems, i.e. if I measure voltage, resistance and current for this voltage source and resistor, will all my measurements agree?  And how accurately?  The range of subtle issues which must be addressed to simply do that on a single DMM range is large.  Doing it on multiple ranges progressively grows in difficulty until even TiN gave up. Not because he could not do it, but because he could not do it to the level of accuracy he sought.

I am think there should be 3 PX references and two mailing lists, a PX & FX list and a PX only list.  Everyone participating will benefit from that in the form of shorter waiting times and better quality cals.  The cost to do that is pretty nominal and I'm quite happy to pick up part of the tab.

A voltage reference alone will not calibrate a DMM.  All it provides is a comparison against other voltage references.  It is a necessary, but not sufficient reference for my purposes.  It is all that matters to others.

Relative to RF calibrations, voltage calibrations are trivial.  Even low frequency  AC is vastly harder than DC.  Just go look at the specs for AC vs DC on any meter.

People who are only interested in voltage references only need access to a voltage reference and s limited range of resistance references.

People who want to calibrate a DMM for general work need more references.  People who want to calibrate LCR meters need more.  People who build radios need even more.  There is no point in sending a set of precision capacitance and inductance standards to someone whose sole LCR meter is a $20 ebay unit.  Any set of inductors, capacitors and resistors, suitably packaged for which good quality measurements are available is sufficient for them.  Someone with a 4284A/4285A set needs something rather better.  And if there is a base set of 3 low end references for those with only a $20 LCR meter which rotates around with the precision set to those with higher end meters,  then a lot of practical metrology problems are solved.

In summary, I'm proposing that if you just need a PX, you get that.  If you need an FX, get the FX/PX set and measure the PX as a service for the PX only people.  I am proposing that be extended to a best effort full DMM cal kit for those who want that and similar programs for other measurements up into RF.  The kits should meet the needs of the recipients who are paying for the shipping costs.  And one size does not fit all.

Have Fun!
Reg

[TiN]

Point was that to calibrate 6.5d meter you do need full fledged MFC. So I don't understand how 3 more PX references can help?   
Anyone can do full DCV calibration using existing Cal Club equipment. You build youself precision 1:10, 1:100 divider (or buy one from ebay) and null-meter and derive 100mV, 1V, 100V, 1kV from FX(PX)+divider combo, like most of calibration labs are doing. No need reinvent a wheel and trying to invent worse stability 100mV / 1V / 100V / 1kV reference  .

Maybe get practical and list what items/functions/stability specifications you think are needed.
RF, AC, temperature, dimensional, LC and whatnot (we can talk about gases/biomed/ionizing radiation too) seem to be outside of the USA Cal Club scope/desires?

Doing it on multiple ranges progressively grows in difficulty until even TiN gave up

Never! I just build more calibrators...

The kits should meet the needs of the recipients who are paying for the shipping costs.  And one size does not fit all.

Not really. Kit is a courtesy of members organized it, and it does not need to meet any needs or recipients, just because they pay $30 for shipping.
Participation in community club is not mandatory. If one does not see it useful, no reason to apply for it, just to complain about $30 shipping (which is cheap!).

[SilverSolder]

In summary, I'm proposing that if you just need a PX, you get that.  If you need an FX, get the FX/PX set and measure the PX as a service for the PX only people.  I am proposing that be extended to a best effort full DMM cal kit for those who want that and similar programs for other measurements up into RF.  The kits should meet the needs of the recipients who are paying for the shipping costs.  And one size does not fit all.

This sounds eminently sensible.

[maxwell3e10]

For me the interest is not necessarily in absolute calibration but in ability to play with very stable, low noise voltage sources to characterize the performance and quirks of various DMMs. In terms of additional elements to the calibration kit, a calibrated 10:1 and 100:1 divider might be good, its not too bulky or heavy.

[Conrad Hoffman]

Though I've built many volt-nut gadgets, my main interest is in getting my three Fluke 731B references as close to truth as possible. Even though I only have a couple 6.5 digit meters, I can compare my references to the traveling standard to far better, and also log the results. I break things down into "standards I can self-generate" and "standards I can't". That means I can get frequency from GPS or NIST WWVB stations , and I can create ratios to any degree needed (I also have a 752 to do the meters), but I can't generate my own volt or ohm. For me, the ideal kit would be the good voltage reference and, hopefully, a recently measured stable resistor. Anything else is a bonus I wouldn't refuse, if it doesn't delay things by too much.

[SilverSolder]

Even though I only have a couple 6.5 digit meters, I can compare my references to the traveling standard to far better, and also log the results.

It would be very interesting to know how you do that.  A stable and sensitive null meter springs to mind, but the two references being compared likely have different enough voltages that it is hard to see how you can null anything without some kind of accurate divider in the middle of it all?

[vindoline]

Shipping is now $30/person vs the original $7/person.

That is not true. The current kit fits perfectly in a USPS medium flat rate box. The cost is $14.35 for 2-Day priority mail anywhere in the US.

[vindoline]

I also think that there has been some confusion about the purpose or intent of the club. Perhaps it's because of our name "USA Cal Club." I don't think that the point has ever been to serve as a rotating calibration service. Frankly, if you need a calibrated meter you should have it calibrated by a professional lab. If you just want to check your 4.5 digit hand held DMM, eBay is full of "DMM check" style references which are fine.

What we have offered is the chance to use a stable, low-noise voltage reference that has been verified by multiple experienced members of the "volt-nut" community. In return, those that are able can verify the reference with their equipment and provide feedback and additional confidence in the reference. With TiN's very generous addition of the FX, we now also have a pretty darn good absolute 10V reference!

What do I use the PX and FX for? For one thing, I use them to check the stability and drift of my bench meters - an HP3456A, a Fluke 8506A, and a Keithley 196. The stability and tempco of the LTZ1000 refs is much better than the LM399's in my meters. Therefore, if I "log" the LTZ, I actually get an idea of how stable my meters are and what their Tc's are. OK, I also used the FX to "tweak" the 10V scale on my 3456A to exactly 10V. This will let me easily re-check the FX when it returns from each hop.

[Conrad Hoffman]

Even though I only have a couple 6.5 digit meters, I can compare my references to the traveling standard to far better, and also log the results.

It would be very interesting to know how you do that.  A stable and sensitive null meter springs to mind, but the two references being compared likely have different enough voltages that it is hard to see how you can null anything without some kind of accurate divider in the middle of it all?

Pretty easy- 845 null meter between the standards, with the output read by a moderately good meter with GPIB for data logging. Since I'm trimming my standards to match the reference, there's no big mismatch problem.