Where to get good quality test/jumper leads? - Page 1
Forum section: electronics / general

author: IanB
author_rank: Super Contributor
timestamp: July 28, 2018, 10:21:47 pm
content: What's the deal with the swiveling spring on some banana plugs? There's no solid mechanical contact, and therefore no solid electrical contact. How useless is that? Should I solder the end to stop it swiveling?In other leads the assembly or crimping is poor and they have woefully high resistance.Any sources of high quality leads?I'd like good crimping at the terminations, good quality plugs or crocodile clips, low resistance, multi-strand/flexible cable with decent wire inside, and so on.

author: tooki
author_rank: Super Contributor
timestamp: July 28, 2018, 10:28:19 pm
content: Pomona/Fluke, Caltest, Mueller, Probe Master, Hirschmann/SKS, Stäubli (in no order other than US vendors first).Nothing wrong with lantern tips (the "swiveling spring" as you call it), but it needs to be good quality. Any of the above are great.

author: nanofrog
author_rank: Super Contributor
timestamp: July 29, 2018, 01:29:18 am
content: I've mostly Probemaster. Better value and quality than Fluke/Pomona (quality slipped when Danaher took over).

author: tooki
author_rank: Super Contributor
timestamp: July 29, 2018, 01:08:43 pm
content: I’ll add that I build a lot of test leads myself.For some, I really like using the Stäubli SLS4-B banana plugs whose mating surfaces are simply rolled-up sheet metal. They’re very compact plugs, stack nicely, and they are compatible with EVERY other banana plug and jack, which isn’t 100% true of others*. (The reason they work well is that the male plug is shorter, so fits any jack without sticking out, but because of the thin construction, any other plug inserted into the stacking port can actually extendintothe plug itself, giving it nearly infinite depth while remaining compact. You can even, in a pinch, plug them inmale to maleto extend leads, still leaving the female stacking ports free!!) The guy at the local mom-and-pop electronics shop recommended them to me, saying that they actually have better contact than the lantern style.The downside to these, as well as the other Stäubli plugs with a compact housing (SLS410/425 series, which are similar but with various lantern style tips), is that the housings themselves aren’t super durable, and are absolutely not designed to be removed, so use them for cables you intend to keep. But the housings are replaceable if they break. (The housings come in 2 sizes for thinner and thicker wires, ensuring good strain relief.)Stäubli catalog:Test Accessories - Main catalogOn the other hand, for temporary cables, I love the Pomona 1825 (4897 for the gold version), which is a really nice screw-set plug which doesn’t require removing any insulating housing to get to the screw. The downside to these is that the female stacking jack is not very deep, so the longer European banana plugs don’t go in fully. Pomona makes nice things like double banana plugs, too, but I’ve yet to use them.Pomona catalog:Pomona_Electronics_Catalog_2016.pdfAs for test lead wire for these DIY cables, for some things I use ordinary wire, for others I use nice silicone test lead wire. Digi-Key carries a decent selection of Cal Test wire in various gauges (it’s made in France, dunno who the OEM is). For regular 18ga, the Pomona 6733 silicone test lead wire is quite nice and not that expensive, and has the double-layered insulation for safety. (So does Cal Test at most gauges.) The softest 18ga I’ve found is the Mueller Electric, but it’s a LOT more expensive. (The local mom-and-pop shop carries something similarly soft at similar high price, but I don’t know the brand.)*Historical practice is that most European banana plugs are 20mm long, while most American ones are 15mm long. Rarely, a short 15mm plug won’t reliably mate with a deeply recessed 20mm socket, whereas a 20mm plug in a 15mm socket may stick out, either leaving a potentially dangerous exposed section, or even failing to stay in, if the retaining section of the plug doesn’t have enough mating surface to engage.)

author: IanB
author_rank: Super Contributor
timestamp: July 29, 2018, 05:06:09 pm
content: Quote from: tooki on July 28, 2018, 10:28:19 pmSo tell me about these. The ones I have are free to swivel on the plug, and even after I insert the plug into the socket the plug can still wobble and swivel around, even though the fit into the socket is tight, and this leads to a poor and scratchy electrical connection.Should I understand that "high quality" banana plugs with lantern tips will not behave this way? Should they be fixed and not be free to swivel, or should they lock in place when the plug is inserted? My concern is that anything with a loose mechanical contact cannot make a good electrical contact. That is why we crimp, or use screws, or spring clips, to overcome contact resistance.

author: tooki
author_rank: Super Contributor
timestamp: July 29, 2018, 06:04:25 pm
content: Quote from: IanB on July 29, 2018, 05:06:09 pmYou're right in theory, but overthinking it in practice, I think. Are you actually experiencing these "poor and scratchy" connections, or is this a hypothetical worry?I know that people have reported bad, inconsistent connections withreally cheapchinesium lantern tip plugs from fleabay, and the consensus seems to be that they a) are too loose and b) have seriously bad plating causing awful resistance.Good lantern tips are snug even when not inserted. The plugs should rotate, but not loosely, both inserted and not.The "looseness" you mention… well remember that they're spring-loaded and have many contact points, so this ensures a good contact even with some play. NO style of banana plug has zero play, that's just not how these things work!! A connection can begoodwithout beingrigid. You mention spring clips — well that's essentially the same thing as lanterns. And don't forget how many products use non-fixed connections, from USB plugs to the slip rings on VCR heads to the rotary switch in your multimeter to the speaker output relays in your hifi amplifier. Wiggle a USB plug while it's plugged in. Does the signal fail? No.Contact resistance is real, but if you mitigate it through plating, overall contact area, self-cleaning properties, etc., it's just not an issue. Lantern tips provide great contact area and self-cleaning properties, and quality ones have good plating.I checked, and without exception, all of my name-brand test leads use lantern tips: Fluke, Keysight, Probe Master, vintage Oldaker, and vintage Philips. I tried measuring contact scratchiness with my K2015 meter, but thermal effects from handling the plugs to rotate them cause bigger differences than the rotation! (We're talking within a single mΩ on a meter with 0.1mΩ resolution.)In a nutshell, for any application where a banana plug is appropriateat all, a quality banana plug is going to perform well, whether it's a lantern style or any other type they offer. But it's probably telling that every single quality manufacturer uses the lantern style in their best products.

author: IanB
author_rank: Super Contributor
timestamp: July 29, 2018, 07:16:15 pm
content: Well, for example, I bought these not so long ago:https://www.amazon.com/gp/product/B01HB1G6DKI found that if I plug them into a DMM and clip them to a resistor to measure the resistance, the resistance reading jumps around if I touch the leads or plug. The reading is not stable or repeatable.These leads seem nicely constructed and solidly made, except they are unsatisfactory. I don't want to spend money on another brand only to find they are also unsatisfactory. So perhaps I will try a big name brand like Fluke, Pomona or Probe Master and see what happens.

author: tooki
author_rank: Super Contributor
timestamp: July 29, 2018, 07:21:32 pm
content: Oh dear, that should not be the case at all.What meter are you using? What probes did it come with?

author: IanB
author_rank: Super Contributor
timestamp: July 29, 2018, 07:46:07 pm
content: I have been trying to check out my 121GW, and had a suspicion that the test leads were upsetting my measurements. I have a BM869s for comparison. Readings seem more stable if I use various DMM test probes to make connections. When I have time I will try to make some more detailed observations to quantify the issue.

author: nctnico
author_rank: Super Contributor
timestamp: July 29, 2018, 09:02:39 pm
content: Quote from: IanB on July 28, 2018, 10:21:47 pmI have the stackable ones from Hirschmann with silicon rubber leads. No problems so far and every now and then I do run a lot of current through them.