fine coaxial cable with copper strands? - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: November 15, 2024, 11:06:46 pm
content: I like RG316DS but it has a steel core. It seems silly for some things like noise measurements to have steel there.I wanted something similar (alot thinner then RG400) but with copper strands. I noticed all the thin coaxial cable is steel stranded.What is the thinnest copper stranded coaxial cable they make? I had a look through the data sheets but all the thin ones are steel.It does not need to go to a high frequency.And good non 50 ohm options might be OK too.

author: shabaz
author_rank: Frequent Contributor
timestamp: November 15, 2024, 11:43:59 pm
content: There's RG-174 which is thin but not too thin to be awkward to work with (about 2.8 mm outer jacket diameter) has copper strands and braid, and is flexible. Not my favorite coax to use, but it's low-cost and handy to keep a small spool of it.I've found that occasionally, a semi-rigid coax is needed for extreme shielding if you're doing very low noise measurements. In that case, RG-402 could be considered, it is easy to work with using a craft knife, and is approx 3.6 mm diameter to the tin-soaked copper braid.Another nice way, if 50-ohm transmission line is not required, is to use microphone cable. Sometimes it has a braid as well as star-quad wiring internally. Mogami offers that. It is also useful for scenarios where star-quad wiring is not needed, because sometimes it is useful to have the extra conductors for power etc. Such cables are pricey though, but excellent.Yet another option is to consider Ethernet cable, especially the shielded variants, and some are industrial and have a foil screen as well as braid. They have 100-ohm impedance. Some are in a star quad arrangement, and others are in twisted pairs, either two pairs or four. All super useful. The industrial ethernet cables are annoyingly expensive, though, and not super flexible, and they are about 6 mm thick.I have some of these options here, so if you'd like a comparison photo or peek inside a stripped end of the cables, let me know.

author: tooki
author_rank: Super Contributor
timestamp: November 16, 2024, 12:18:43 am
content: Quote from: shabaz on November 15, 2024, 11:43:59 pmRG-174 uses copper coated steel.Not that I share OP’s concerns about this. Thin coax cables are for signals, not power, after all.

author: David Hess
author_rank: Super Contributor
timestamp: November 16, 2024, 01:35:59 am
content: Whether the stranded center conductor is copper plated steel or copper depends on the manufacturer.RG-178 has a stranded silver plated copper center conductor with Teflon dielectric that is even smaller diameter than RG-174.Quote from: shabaz on November 15, 2024, 11:43:59 pmI like using RG174 as a tough replacement for microphone cable.

author: coppercone2
author_rank: Super Contributor
timestamp: November 16, 2024, 01:56:09 am
content: I thought it was a spec on the cable. So if I look through various manufacturers I might find what i want? Like copper stranded 316DS?

author: David Hess
author_rank: Super Contributor
timestamp: November 16, 2024, 12:44:16 pm
content: Quote from: coppercone2 on November 16, 2024, 01:56:09 amIf it has a stranded center conductor, then yes. I think all of my RG316 has a silver plated copper center conductor.

author: mtwieg
author_rank: Frequent Contributor
timestamp: November 16, 2024, 02:53:54 pm
content: Back when I worked with high field MRI scanners, we had a spool of RG316DS made by Huber Suhner which used a stranded silver plated copper core. Very distinct lime-green jacket. I don't recall the part number, but I believe it was no longer being produced by the time I graduated. I'm certain there's some sort of replacement out there, as the need for such a thing certainly didn't disappear for MRI scanners.Quote from: David Hess on November 16, 2024, 12:44:16 pmAFAIK all RG316 has stranded inner conductor, but it's almost always CCS. Stranded doesn't mean it doesn't have steel in it.

author: coppercone2
author_rank: Super Contributor
timestamp: November 16, 2024, 05:57:28 pm
content: well, maybe not that thin, I think it might be a little weak. I need to find something in the middleI don't think I can accept lime green wire

author: tooki
author_rank: Super Contributor
timestamp: November 17, 2024, 05:05:56 am
content: Quote from: David Hess on November 16, 2024, 01:35:59 amIncorrect. RG-series coaxial cables are defined in military specifications, and they do not leave that up to the manufacturer’s discretion. (Although manufacturers sometimes make up their own derivative designs that don’t actually adhere to the standard, in which case they tack on some more letters.)The last version of that standard is attached below.It clearly states that the conductor is “seven strands of copper-covered steel wire”.

author: tooki
author_rank: Super Contributor
timestamp: November 17, 2024, 05:08:37 am
content: Quote from: David Hess on November 16, 2024, 12:44:16 pmThe RG316 standard specifies: “Seven strands of silver-coated, annealed-copper-covered, steel wire”.

author: tooki
author_rank: Super Contributor
timestamp: November 17, 2024, 05:10:34 am
content: Quote from: mtwieg on November 16, 2024, 02:53:54 pmWell, RG316DSis a derivative of RG316, not actually an example of RG316 itself. So in theory they could use a conductor wire that isn’t steel. But of course since the goal is to keep the performance as close as possible (just with better shielding in this case) they probably stick to the silver plated, copper covered steel.

author: shabaz
author_rank: Frequent Contributor
timestamp: November 17, 2024, 06:06:17 am
content: A project I was working on in my spare time.. it's an audio project, and I wanted low noise connections off-board.I'm using star-quad cable (copper conductors) with copper shield. I don't recall the source of it, but Mogami, and audio/broadcast industry suppliers will have variety of cables for mic/lavalier mic, etc use available, and nearly all will be copper. But the steel core in normal RF coax will be fine for signals too.

author: coppercone2
author_rank: Super Contributor
timestamp: November 17, 2024, 07:10:31 am
content: they have 316 with copper core but no DS but I can live with that

author: RadioNerd
author_rank: Regular Contributor
timestamp: November 17, 2024, 08:53:21 am
content: How about composite video / RCA cables?Better ones are constructed with a kind of coaxial arrangement. Not all are made equally though, as some are just two parallel wires inside the insulation. But I have seen both.

author: David Hess
author_rank: Super Contributor
timestamp: November 17, 2024, 06:42:30 pm
content: Quote from: RadioNerd on November 17, 2024, 08:53:21 amTwo parallel wires are self shielding like twisted pair, but not quite as good.

author: coppercone2
author_rank: Super Contributor
timestamp: November 17, 2024, 07:42:57 pm
content: I like braid

author: TimFox
author_rank: Super Contributor
timestamp: November 17, 2024, 07:48:14 pm
content: A typical spec for single-braid shielding is 94% coverage.Double-braid and continuous foil are close to 100%.

author: coppercone2
author_rank: Super Contributor
timestamp: November 17, 2024, 09:57:31 pm
content: In db, that is only 12dB of reduction though. Granted, not many dB come through a cable, but double braid is appealing for that reason-30dB would be 99.9

author: TimFox
author_rank: Super Contributor
timestamp: November 17, 2024, 10:04:06 pm
content: Of course, double braid is stiffer than single braid.I have seen small audio cables with much less braid coverage, presumably to increase flexibility.Foil shields are not very flexible.

author: coppercone2
author_rank: Super Contributor
timestamp: November 17, 2024, 10:24:14 pm
content: I noticed 316DS is OK. It does not seem to want to rip connectors off the PCB

author: ejeffrey
author_rank: Super Contributor
timestamp: November 17, 2024, 11:28:41 pm
content: Quote from: coppercone2 on November 17, 2024, 09:57:31 pm94% coverage does not mean 6% leakage, referring to it in dB makes no sense. Just like a screen room can be effective with just a copper mesh with much less than 94% coverage. The gaps are small compared to the wavelength and the insulation thickness so you get very strong suppression of coupling. Of course it's not zero, so especially if you have cables running together in a bundle double shielding can be important. But don't take the 94% as an electrical measurement.

author: coppercone2
author_rank: Super Contributor
timestamp: November 18, 2024, 12:14:36 am
content: what can you compare it to to get a electrical number? A twin lead?It says a single braid does like 55dB of attenuation and a braid and foil does 90dB. So 35dB difference from having 'full mechanical coverage'I wonder how much rejection a 50 ohm twin lead would have in the same test

author: David Hess
author_rank: Super Contributor
timestamp: November 18, 2024, 01:50:14 am
content: I like doubled shielded coax for patch cables that I use a lot, despite them being stiffer, because the double shielding makes the connector fastening much stronger.In applications like receiver testing, double shielding is mandatory because otherwise the test signal will leak around attenuators.

author: coppercone2
author_rank: Super Contributor
timestamp: November 18, 2024, 02:27:19 am
content: connectors ripping out is the number one reason I made alot of DS cables too, especially near rack mount equipment where you gotta get behind it and it gets difficult etcFor that the steel I think might be better, and all of that is very high frequency too. But I think it might be the wrong choice for some of these noise measurement low frequency things

author: shabaz
author_rank: Frequent Contributor
timestamp: November 18, 2024, 04:11:22 am
content: The off-the-shelf coax patch cables I use are RG-316DS too, but for some measurements even that isn't sufficient. I sometimes have enough noise from the environment that I cannot identify and/or is out of my control, and with modern 12-bit 'scopes, it's readily seen even with double-braid coax. I then resort to semi-rigid cable. Photo shows one of the cookie/biscuit tins I use, attached to RG-405 cable.The blue one in the photo is a ready-made RG-405 cable (these semi-rigid cables are often available with- and without outer jacket), but thicker RG-402 might be more convenient for lab use, and it's not as fragile. Plus RG-402 is easy to work with (easier than normal coax!), so I prefer DIY'ing my own cables with that coax (example is the white RG-402 cable in the photo, which I soldered up myself).

author: Smoky
author_rank: Frequent Contributor
timestamp: November 30, 2024, 01:09:58 am
content: I bought two SMA cables recently on close-out from Arrow for $4 each. They are stamped "SRC 316" on their jacket.It turns out that they have a copper core center conductor plated with silver. The shielding dB is 90 and I read in another brochure that it is its "minimum" rating.Compared to RG 316 and RG 316 DS (double shield), they can't hold a candle to it.I've found a seller on Ebay that is selling new SMA cables with it. I have no affiliation:https://www.ebay.com/itm/166717839266I've attached the entire page regarding the specs of SRC 316

author: Smoky
author_rank: Frequent Contributor
timestamp: November 30, 2024, 02:31:15 am
content: Last weekend I was searching Ebay for SRC 316 cable and an odd item popped-up. It was a cable made by a company named Sea-Tel.https://www.ebay.com/itm/185955692552Come to find out that this company used the SRC 316-TS cable to connect their satellite dishes to televisions on ships at sea.Anywho, this cable found its way onto Ebay 9 years later and so I bought it.I plan to cut it into 24" lengths for patch cables.Winchester Interconnect purchased SRC Cables and their line of cables are still produced. WireMasters in Tennessee is their sole distributor.I contacted them for a quote for the SRC 316-TS cable so I hope to hear back from them next week.If it's very expensive maybe a group-buy on EEVblog could happen

author: shabaz
author_rank: Frequent Contributor
timestamp: November 30, 2024, 04:29:17 am
content: I guess you're aware, but just in case, what potentially can make or break plans to self-assemble patch cords is:(a) any requirement for special tools to assemble the connectors (for instance, with SMA, this is often but not always the case and some of those tools are expensive)(b) whether the connectors are readily available (at a reasonable price) to suit the cable; a normal RG-316-suitable connector often won't accommodate RG-316DS cable, so the options are reduced.Once those considerations and time are factored in, it's harder to justify self-assembling patch cords since RG-316DS patch cables from reputable distributors might be available for a lower cost.Having said all that, I still self-assemble some cables (but try to use a ready-made one if I can, if it's going to work out cheaper).For example, I currently wish to self-assemble certain cables, and I have some of the tools I will need but not all, so I'll have to spend an additional $150-$200 to acquire those.

author: Smoky
author_rank: Frequent Contributor
timestamp: November 30, 2024, 06:33:09 am
content: Thanks for the reply Shabaz.I purchased 82 of these SV Microwave SMA connectors on clearance from Arrow.Their part number is M39012/55-3030 used with M17/152-00001 cable (RG-316DS/RD-316):Their build quality is impressive just by looking at the drawing. Can they be used with SRC 316-TS? I'm not sure until the SRC is cut to get its dimensions read from a caliper. My only hope is that the Aluminum Mylar Tape over the Teflon insulator will slip into the body of the connector because the outer crimp ring is not intended to be "crimped" it is to be soldered. Soldered through the braid and to the body of the connector. I'll scan the instructions that came with the connectors and post them.

author: Smoky
author_rank: Frequent Contributor
timestamp: November 30, 2024, 07:36:24 am
content: Here are the instructions that came with each M39012/55-3030 SMA connector:As you can see, everything is soldered. There is no crimping.The SRC 316-TS has the additional Al Mylar tape wrapped over the dielectric. I'm hoping to trim it back slightly from the edge of the Teflon so when it is inserted into the body it does not touch the center contact. That way the outer two braids can then be soldered through to the outer surface of the body without interference of the Al Mylar.Ultimately, the Mylar tape must slip into the body without having to be forced or it's a no-go with these fittings.No special tools required I don't think. I'll be using Kester 24-7150 Lead/Silver solder if all things fit.

author: shabaz
author_rank: Frequent Contributor
timestamp: November 30, 2024, 07:39:35 am
content: Nice, that's more than enough connectors to be totally worth it.SV Microwave connectors are very decent, and expensive!

author: Smoky
author_rank: Frequent Contributor
timestamp: November 30, 2024, 10:18:35 pm
content: I clipped a small section of the yellow SRC 316-TS cable from Sea-Tel to see its inner layers of shielding.A poof of dust formed in the air the moment I spread apart the outer layers of copper braid from the cable!The aluminum layer of the Mylar tape had corroded into powderSome areas you can see straight through to the dielectric. But in other areas you can see dense shiny aluminum.This cable was NOS but eight years old and I'm sure it started to decompose long before that. The package is dated 2016 and the cable and fittings look perfect and were in a sealed bag.I think I'll stick with RG-316 DS for now

author: coppercone2
author_rank: Super Contributor
timestamp: November 30, 2024, 11:40:12 pm
content: yeah I was never a fan of the foil cable, it seems to be shot as a magic bullet solution to like high frequency shielding, but its durability is poor for any engineering use that is not sealed in a nice house wall. Probobly with braid and foil, it stays pretty good, but pure foil is very weak.But that is to be expected with any martime technology, you might think you can get a good deal, but the ocean and sea makes sure its totally shot before you get itIts amazing how advanced materials that can basically last for a infinite amount of time get quickly destroyed by the sea. Stargate atlantis always made me think of that, the fact that walls of their ocean city are still a nice color after 10000 years lol, its more impressive then the actual stargate. I think you could make it from solid monel and it would look like shit within 10 years lolI basically heard a exorbitant amount of bad reviews for equipment that was purchased from decommissioned martime stuff, like radios etc. The weirdest corrosion damage and hardest repairs. Unless its in the greasy heart of a big old ship, protected by a constant mist of disgusting oil. Older submarines supposedly protected equipment nicely, because it was basically a grease pit, and its small and cramped enough that any kind of water leaks or puddles or whatever were aggressively prosecuted by endless cleaning details.

author: Smoky
author_rank: Frequent Contributor
timestamp: December 01, 2024, 03:44:24 am
content: I'm looking at this SRC 316-TS cable a little more closely. I took a small watercolor brush with alcohol and cleaned the surface of the Aluminum Mylar tape. The majority of the foil is still there and the green color is the layer of adhesive that bonds the foil to the Teflon. One must scrape down through the green layer to reach the white Teflon.I then grabbed my DMM and I'm getting good continuity on the foil even around the small voids of it.I wonder too as to how much dust is being created just by bending the cable? The silver braid rubbing the foil on every flex.Another thing too, I was able to slip the center conductor/Teflon dielectric/foil & adhesive combo into the bore of the SV Microwave SMA connector with a perfect snug-fit. Which is probably the best scenario for such a cable . The foil rubs the inside walls of the connector which is gold plated giving it a good connection.Maybe clean the glue/foil off of the end tip of the cable with a quick spin of a small sanding drum on a Dremel instead of scraping it to make a decent gap between the center contact and the foil?And it might be helpful to lightly wipe the inside bore of the connector or just the top of the aluminum foil with Deoxit Gx5 Gold before it's inserted to stem corrosion from dissimilar metals?Maybe I won't give up on this cable yetI hope WireMasters gets back to me. I'll bring up with them what I discovered.

author: coppercone2
author_rank: Super Contributor
timestamp: December 01, 2024, 04:10:03 am
content: I thought your supposed to strip the tape and make a joint on only the braid? I think I read that some where, that you are not supposed to crimp the foil, I assume it would get messed up and fracture .

author: Smoky
author_rank: Frequent Contributor
timestamp: December 01, 2024, 04:48:41 am
content: Imagine that the contact is already soldered to the center conductor and is now butted to the Teflon.There would be only a 1/8" band of white Teflon visible before the foil/green layer begins.When the cable is inserted into the connector the Al Mylar tape will be rubbing against the inner walls of the connector since it's a nice, snug fit.The 2 layers of braid would then be folded over the outside of the connector. The solder ring would then be slipped over the braid.Soldering would finish the job.

author: Smoky
author_rank: Frequent Contributor
timestamp: December 02, 2024, 03:43:18 pm
content: I just received a reply from Winchester, the makers of SRC 316-TS, about the decomposing of the Aluminum Mylar Tape layer."We guarantee our product for one year."I guess that settles it

author: coppercone2
author_rank: Super Contributor
timestamp: December 02, 2024, 09:51:58 pm
content: thats actually a substantial amount of time for things having to do with the ocean.They would totally get bank rupted by people getting returns from ships that went out into the tropic regions etc. Some ships sail in basically every temperature and it wrecks havok on most materials. I expect IRL this cable would be painted with 15 layers of paint too

author: Smoky
author_rank: Frequent Contributor
timestamp: December 02, 2024, 11:55:35 pm
content: Coppercone2, SRC's cable has nothing to do with the ocean or the seas.Sea Tel used SRC's cable products for parts in their satellite business.The cable is intended for many uses and is SRC's said "improvement" over RG-316 and RD-316.I would suggest that SRC, which is now owned by Winchester, put an expiration date on their cable because something is going on with it.Maybe when the jacket de-gasses it reacts with the aluminum layer of the Mylar tapebut surely something is going on inside of it over time, and in my case, it's not saltwater.I can cut open old hanks of RG-316 and it looks the same as the day it was made. You can't say that with SRC 316-TS.By the way, the seller on Ebay who sold me the cable refunded me in full. Thank you SatBBC

author: coppercone2
author_rank: Super Contributor
timestamp: December 03, 2024, 02:54:45 am
content: if it has sea in the name that means something about their customer base IMOif it was mostly space it would be space tel

author: Smoky
author_rank: Frequent Contributor
timestamp: December 06, 2024, 02:11:24 am
content: I got the quote from WireMasters and they want $2.80/ft for 500ft (minimum roll from SRC/Winchester), so around $1,500 for the SRC 316-TS.So I called SRC/Winchester in Santa Rosa, CA directly, twice, today and on Tuesday. You get sent to voicemail no matter what number you press to speak to someone.All the messages include some sort of statement "I'm working remotely so please leave a message."Today's call I left a message with the "Quality Assurance" guy.I pleaded my case about needing some short lengths and such and about my corrosion discoveries.Will I get a response? I doubt it