Soldering leads in high and low current cables for calibration? - Page 1
Forum section: electronics / general

author: Zenwizard
author_rank: Regular Contributor
timestamp: December 30, 2023, 04:22:43 am
content: I I have a Valhalla Scientific 2500 on the bench with a pile of load resisters and an itchy adjustment tool. I have confirmed that they 2500 is out of range and needs to be adjusted but I need to make some wire leads to connect the 2500 to load resisters for the ranges.I have some nice heavy 12 gauge wire and some solid copper gold plated fork terminals that I can use for the binding post. Given that I am working with a current spread of 10 amps on the high end and 100uA on the low end I am wondering if I should solder the forks on or just pressure crimp them with the hex screws. My current though process is to tighten the allen screws and add a bit of solder to the exposed cup on the end of the wire getting the best of both worlds.But as this is used for calibration I am asking here. the 10 amp range is that hard one. I can use probe master leads for all the others if need be.Meter being used for aligning the 2500 is a Keithly DMM7510. Currently don't have access to a 3458AZen

author: alm
author_rank: Super Contributor
timestamp: December 30, 2023, 05:58:39 am
content: Generally crimping and soldering combines the worst of both worlds and be less reliable than either connection because a good crimp forms an airtight connection, while solder wants to get inside the crimp and deform plastically under pressure. I'm not familiar with crimp connectors that use hex screws, but if they form a solid crimp, I'd prefer to rely on crimping over soldering.

author: Zenwizard
author_rank: Regular Contributor
timestamp: December 30, 2023, 02:19:26 pm
content: These have screws that come down on top of the wire and will push it out on to the back side of the connector. They do not require a crimp tool so I am not sure how good of a gas tight connection they will make.Zen

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: December 31, 2023, 01:21:21 pm
content: Any metal to different metal connection can cause microvolt issues. It does generate some small volts. Different metal junctions generate different volts and this can be highly sensitive to ambient temperature. Metal to metal junctions are used for thermocouples and can generate more than microvolts.I don't know how accurate you need to be at microvolts. but even good Banana connections can cause problems. They are not solid copper and some are MUCH better than others,That is why there are so many people here looking for solid copper connectors.It is common practice to use good clean copper wire with pressure connectors and even clean the connection with alcohol to avoid any salt or oil from your fingers. You can also use a pencil eraser to clean your wires. A constant battle.Lots of good quality Banana are welded not soldered.Edit: file:///tmp/mozilla_mint0/p18-21-1.pdf

author: tooki
author_rank: Super Contributor
timestamp: January 04, 2024, 04:23:27 pm
content: Quote from: alm on December 30, 2023, 05:58:39 amGold-plated screw-mounted fork instantly makes me assume they’re using something made for audio, like the ones in the attached photos. Ignore that OP said anything about crimping, because it’s not.Quote from: Zenwizard on December 30, 2023, 02:19:26 pmIt’s simply a screw terminal, not a crimp. Crimping is an irreversible process. I suspect that, if torqued down enough, a screw terminal can make a gastight connection, especially if a ferrule is used to prevent strands from escaping. But I doubt that the screw threads in copper are strong enough to torque down that hard, I suspect they’d strip first.Quote from: Wallace Gasiewicz on December 31, 2023, 01:21:21 pmPlease upload the file; a local URL to a temporary file on your PC is useless.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: January 04, 2024, 07:17:06 pm
content: Maybe this will work, it's a chapter by a Fluke Engineer...I just wanted the chart but I guess I failed..Flukecal.comHTTPS://download.flukecal.com/pub/literature/p18-21.pdfOK I give up. Does not want to link.Also this: [size=78%]H:\Home\EnvRes Share\D8280\FIST\vol3-3\vol3-3.PDF (usbr.gov)

author: tooki
author_rank: Super Contributor
timestamp: January 04, 2024, 09:02:34 pm
content: Quote from: Wallace Gasiewicz on January 04, 2024, 07:17:06 pmThat’s because you borked the target address. The link text (which is just what you want the link to say, not the address it targets) says “HTTPS://…”, but the target URL says “http://HTTPS://” You can’t have both, the target URL needs to be just “https://…’Quote from: Wallace Gasiewicz on January 04, 2024, 07:17:06 pmWhy are you even attempting to insert local file URLs? Whether as link text or target URLs, they’re useless outside of your PC.Here’s working links. Try quoting this reply to see (in the text editor box) what the syntax is.Fluke Calibration Metreology 101: Watch Out for Those Thermoelectric Voltages!US Dept. of Interior Bureau of Reclamation: Electrical Connections for Power Circuits