Chinese Metrology accessories list

[gmac34]

Probably it would have be better to avoid fiddling with the zero calibration until had cleaned well the connectors (any contact cleaner and cotton swabs will do), made sure the front rear switch is clean and doesn’t cause a lot of resistance ( very common on old 34401a) and obtained a low emf short.
Luckily for you a low emf short is quite cheap. Get a piece of solid copper form a cat 5 wire and stick it in the front like I showed above in my Keithley 2000. Low mass and copper, it does not get any lower EMF than that.

[PascalNE]

My conclusion is that anything but semi-finished products (e.g. copper bars, rods and wire) will likely not serve low thermal EMF applications. Spade lugs are an exception, but anything with springs or threads on it will likely be alloy.

That's probably a good rule of thumb, although for convenience reasons I think people will always want products like banana plugs. Which is sort of why I made this thread to find the good genuine ones that don't cost $20 per binding post.
I am curious about the binding posts I'll receive tomorrow as the manufacturers have told me they are just copper not CuTe or CuBe maybe I'll ask redtony about how we gets the manufacturing done especially on binding posts which I imagine always need machining?

If I was more brave I'd probably swap out the recessed inputs on my ADCMT for binding posts but I don't want to mess up that shiny nice front panel.

[dietert1]

You could have a look at the Advantest R6581T thread. The binding post mod has been described there. Just one 3D printed part as mount for the binding posts.
I did that for each of our three R6581T meters and they do a standard deviation of about 20 nV for null measurements (100 mV range, 100 PLC, Autozero enabled). That is without any special shorting plug but just a piece of copper wire between the two binding posts.

Regards, Dieter

[PascalNE]

Thanks I’ll take a look. And now I think about it and there’s already binding post sized holes it really wouldn’t be too difficult unfortunately the ADCMT/Advantest 7461A is pretty badly documented even by the community I can’t even find any photos inside.  But I imagine just swapping binding posts wouldn’t be too bad.

[std]

Definitely, and banana plugs are a never ending frustration as oppose to the simplicity and flexibility of lug nuts. I'm lucky my ADCMT 7461A still has shiny copper tubes

Japanese guys usually did everything conscientiously. If the tubes are really shiny, it's not copper, but gold-plated copper, I think. Copper, as far as I've seen, stops shining over time and becomes dull.

but I don't know how long that'll last, I mean how long would it stay oxidation free in a humid environment?

Cover it with some kind of protection. Deoxit gold? But I haven't tried it at all because it's sold for audiophiles and costs fortune, a tiny tube of 30-50 bucks.

And why do companies  choose to use recessed inputs is it safety? cost? ease of use?

I read the revelations of HP manager, It is clear that they tried to make the product cheaper and even speed up its assembly. So the solutions chosen in it (I mean HP34401A) are not top-notch, but ordinary and really mass-market. There are a lot of signals about this inside, even high-voltage PCB layout mistakes (which actually cause problems). Thus, it has the most ordinary terminals, for ordinary engineering. And this is the right decision, I think. Although I agree with you that choosing normal test leads is a nightmare. But it is a nightmare for one simple reason - you have to buy them from Keysight for big money. When you buy from Keysight for big money, you have no problems at all. Also note, 34420A has a completely normal golden-plated special connector, it even comes with a bottle of Deoxite.

[PascalNE]

Hello, I have some good news my xianyu order finally arrived that I ordered with CSSbuy it took about 3 weeks in total (pretty slow)
What I ordered:
- 1 gold plated binding post $2.09(bbs.1ppm.cn/redtony) https://www.goofish.com/item? id=711428863560&categoryId=125958001
- 2 copper binding posts $1.67  (bbs.1ppm.cn/redtony) https://www.goofish.com/item?id=674240096284&categoryId=125958001
- 2 copper binding posts $2.73 (nimolv) https://www.goofish.com/item?id=720090510951

Final cost with CSSbuy to UK - ~£20 from a merchandise cost of £6.03  (this is why I want to start a store)

So what did I get?  A free gold plated binding post so now I have a pair instead of one and redtony have me an a couple of copper spade connectors and nimolv gave me 4.

First Impressions (not a review)
Both seem like pretty nice quality but the nimolv one is certainly a little bit more premium feeling, on the redtony ones I find the knob to be  a little small although I know he's made some bigger ones (if you look at page two and at the picture I sent of the big order you'll see) so that will sort out that issue.

In terms of the parts I think the redtony ones use a different finishing technique as they are much much shinier where as the nimolv ones are barely finished if at all and you can already see (very slight) oxidation.
It also seems like the nimolv ones use all copper parts where the redtony ones use (probably brass) but only where it doesn't matter at all like on the fastening nut.
On closer inspection it seems all the parts on redtonys ones are either copper or gold plated copper.
Another thing I noted was that for the lug nuts the nimolv ones were much softer (and more oxidated) where the redtony ones were definitely harder to deform but I don't know what this suggests.

All the products passed the magnet test which is good. After that I tried filing down a bit off everything and everything passed that as well and looked like nice orangey copper with no plating (except for the gold plating which also looked like copper underneath) So I think we know they are copper of some variety. Verifying the exact alloy is a more long term goal. But I don't see any reason why these can't be the 99.9% copper they say they are (although I'm not a metallurgy expert)

So in conclusion all looks good if you have any questions please ask. 

[PascalNE]

Had a go at crimping the spade connectors onto some wires so I have some thoughts to add.
The redtony ones (bbs.1ppm.cn) ones seem to be identical to 2 of the nimolv ones just with the different finishes. The nimolv ones being less shiny and more flexible. I think they were both 1mm thick which did test my £4 aliexpress crimpers and were pretty tricky to crimp onto smaller gauge wire we commonly use for test leads (they also have a larger thermal mass which would lead to longer settling time)

The other ones from nimolv I believe were 0.7mm thick and they were much easier to crimp as they also had a smaller "initial diameter"? (probably not the right term) So I am yet to try the 0.8mm ones from redtony but I'll get to soon.
For now I'd recommend these ones from nimolv (AKA xuanyi technology on alibaba) https://item.taobao.com/item.htm?id=652899496172  at £0.1 each they really aren't bad. EDIT: the nimolv ones certainly suffer from more oxidation so if humidity is high where you are I'd recommend the redtony ones.

Also I did notice there was bit of an inconsistency in how soft the nimolv ones were some of them were more flexible than others even of the same type I guess this is inconsistent finishing?

[gamalot]

I was just thinking where to post my question. It seems this topic to be suitable enough, if not I will remove the message.

I know what Thermal EMF is. So far I am trying to find banana plugs from China (Aliexpress). And then having bought several I have huge doubts. The question is - is this a gold coating at all? Is this "gold" at all, or some kind of fake?

We call these lantern type with secondary contact and made from beryllium copper which is inferior for thermal EMF.
The best of this type may be Fluke 5440A-700x that has 1.3uV/K EMF.

To avoid all these secondary tertiary contact and finger heating, here is what I use cheaply and effectively to replace regular banana jack.
4mm thick-wall Teflon tube or bamboo chopsticks.

Hi Lymex, what do you think about the use of lantern type banana plugs for Pomona 5291A low thermal EMF patch cord?

I am from Tieling, immigrated to Australia, and lived briefly in Dalian.

I was on the 38 forum until they closed and reopened. I no longer have a mobile phone number in China so I can't complete the forum certification. 

Later I spent my time on the Crystalradio forum, but now they are closed and I don’t know when they will reopen. 

I am so very happy to see you here again.

[zlymex]

...
Hi Lymex, what do you think about the use of lantern type banana plugs for Pomona 5291A low thermal EMF patch cord?
...

Hi gamalot,
I think they are compatible because I see no difference in construction and material.

For those two forums they are not closed but just invisible for visitors. However, I can register 38hot for you if your PM me with username and e-mail.

[PascalNE]

Hello,

A giant order has arrived from redtony I made on behalf of another forum member + a lot of gifts we agreed split. The forum member is generously letting me test all the items (non destructively) for a few days so I'll have reviews on everything.
There's 6 recessed binding post adapters
10 gold plated binding post
100 0.8mm copper spade connectors
50 0.8mm gold plated spade connectors
+ gifts
10 of all the different knobs/"hats"
0 ohm short
many other items

Unfortunately I have no time at all today to test anything as I have a very important exam but tomorrow afternoon I should get to start reviewing different items. 
The cost was also  much much lower than using CSSbuy.

[PascalNE]

Just a quick post about the different types of knobs (heads) that redtony makes.
From top down in the picture you can see.
1- Nimolv binding post for references
2- large glazed ceramic head with gold plated copper threads
3- large plastic head with gold plated copper threads
4- original small plastic head with copper/gold plated threads
5- small all ceramic head with ceramic threads (for high voltage applications?)

I definitely find these bigger ones to be less fiddly.
I also want to correct what I said in a previous post where I said I thought redtony's posts use gold plated brass fastening nuts these actually seem to be gold plated copper

[TERRA Operative]

I do like those larger ones on the left...

Do you plan to stock shielded multicore teflon insulated cable too? Silver coated is common, but bare copper is harder to find.

[PascalNE]

Yes, I think it's an ideal product for me to sell since it can be very annoying to buy in short lengths. I just have to buy a couple long reels and cut pieces out. I'd probably also sell some with connectors crimped on in whatever combination people want.

[PascalNE]

Added reviews for all the items I've tried to the first page also added whether or not they'll be stocked and in what quantity.
Also adding nv amplifier to my (long) list of summer break projects, for accurate thermal EMF testing. 

[PascalNE]

Looking for some better kelvin clips I saw these https://item.taobao.com/item.htm?id=540555760189  mentioned in this topic https://www.eevblog.com/forum/metrology/diy-low-emf-cable-and-connectors/200/  But I wondered If anyone knew of a source for high quality real copper clips that don't cost too much?
(I'll add them to the list if they are suitable)
Also does anyone know a reliable taoboa store for high quality cabling?

[std]

...

Btw, you can use "gold testing" probe that have been known for a long time. These methods are described when buying gold jewelry. Basically, this is a small drop of acids and other substances on the object. Or scrape the object on a test ceramic plate and then test with acid or another chemical.  I'm going to buy some chemicals and check crap from Aliexpress. I'm not talking about banana plugs, but more serious things, like Kelvin test probes. Although it's clear that you can choose a radical way - just not buy anything there.

[PascalNE]

I might get something like that to test the products I get.

My Aliexpress kelvin clips do manage to do 0.0000 ohm consistently but I spent months thinking my new ADCMT 7461A  was rubbish because I'd get different readings from my vishay resistors all the time and it would jump around +-30ppm

It was only when I soldered some wires onto my resistors and wired them directly I saw that it is perfectly stable.   (after an hour warm up)

[std]

...

I removed text above about Kelvin probes. I must continue my 4W measurements with 4W Kelvin test leads, because I just connected 4W zero/short plug, got good minimal readings with it, and then discovered that if nothing is connected at all (the bananas are pulled out on the 4-wire circuit), then I get those same "absolutely stable" 0.000,003 ohms...  WTF?... How can this be with Kelvin test probes in 4W conenction, with HI-HISense, LO-LOSense soldered. (They normally show infinity, i.e. OVL.D  OHM 4w).

[gmac34]

I have seen that behaviour on a couple 34401, my personal one included. I’m positive it’s normal, when you unplug the short whatever voltage was present on the sense input will stay there due to the very low leakage of the frontend. Readings with nothing connecting sense + and force + are meaningless any way

[TERRA Operative]

I've started collecting Yokogawa resistance standards recently.
I'm starting to need to get a few sets of kelvin interconnects sorted, spade lug to spade lug and spade lug to banana jack using shielded teflon insulated cable.

When will we be able to buy stuff?

[PascalNE]

When will we be able to buy stuff?

I do apologise for the wait. My exams finish next week  So after that I'll get started on working on it.
I guess my question to the community is do I start selling the traditional way (through the forum using paypal) or do I wait till my website is fully up and running to start selling stock?
Either way it shouldn't be more than a month (hopefully)

I'd also like find the very best parts to use in my wires so my tests for that are still ongoing (I'm going to be ordering some of the Staublis soon)

I'm also thinking of making a big order from redtony pre-emptively based on what people were interested in. I do think his spade connectors are the best (my nimolv ones are already oxidising) And definitely the normal binding posts and the ones for recessed inputs since I think they are both good

[TERRA Operative]

No rush, well, besides my own impatience...

I'm happy to buy directly via these forums/paypal to start with. I have no real preference there.

[tatel]

Also does anyone know a reliable taoboa store for high quality cabling?

Not taobao, not PTFE, but what about this one? @Alex Nikitin recommends it for most uses, it has four wires, so looks good to make kelvin wires?

https://www.eevblog.com/forum/buysellwanted/wtb(ukeu)-124-core-coppersilver-plate-ptfe-wire-for-measurement-leads/msg5917472/#msg5917472

[PascalNE]

Ordered a couple meters of the "Van Damme XKE MINIATURE Starquad Cable" as per Alex Nitkin's recommendation the key specs are XLPE insulation and a mix of pure copper and silver plated copper conductor it's also screened with copper 

I also bought some stuff from AliExpress to test making custom cables so I got some of the cheap PTFE wire which I'll test and some pure copper shielding jacket and also some PET cable sleeving.
I think this way I could have more flexibility to customise cables for what people want but we'll see how it compares to off the shelf solutions. I do have that very nice satellite grade PTFE wire that AVdG generously gave me so I can compare them to that.

I'm not an expert on this topic so let me know what would be good to test. 

[gmac34]

Regarding the ptfe stuff on AliExpress, I also bought some, but just as with copper and brass there is a” translation issue”. PTFE usually means FEP which I understand as being cheaper to produce (can be extruded)
There is a clear difference therms of maximum temperature it can handle, but still it’s at least 200c. It’s less clear how it compares in therms of leakage, volumetric resistance of FEP should be comparable to that of PTFE ( 10^18 ohm) so maybe it’s good enough.