Combined coax + multiconductor cable - Page 1
Forum section: electronics / projects

author: jmw
author_rank: Frequent Contributor
timestamp: February 13, 2023, 07:09:30 pm
content: Are there any off-the-shelf cables that have 50 Ω coax and multiconductor wire bundled together? For example: what's in an active probe cable where there are wires for carrying power to the tip and coax for sending signal back? I could not find anything browsing Digikey but I don't know if I'm searching for the right name.

author: coromonadalix
author_rank: Super Contributor
timestamp: February 13, 2023, 09:39:52 pm
content: I dont know, we ordered in the past custom made dual rg316 coax and 5 wires in one special cable ...........It is doable but the priceit costed us 90$ a cable of 1.5 meter

author: coppercone2
author_rank: Super Contributor
timestamp: February 14, 2023, 02:10:12 pm
content: because it was run through a extruder.

author: DC1MC
author_rank: Super Contributor
timestamp: February 14, 2023, 02:15:27 pm
content: https://www.primuscable.com/collections/bundled-cablehttps://compucableplususa.com/products/compucableplususa-best-bulk-multimedia-cable-in-wall-cable-multi-signal-access-cable-500-ft-type-1-cat-6-x-1-pc-rg-6-u-quad-shield-coaxial-cable-x-1-pchttps://simiacable.com/en/cctv-a-combined-cables/

author: jonpaul
author_rank: Super Contributor
timestamp: February 14, 2023, 02:21:04 pm
content: Mogami and other cable fab can make anything you need but a setup fee and MOQ.Easy to make a short cable with different conductors with large shrink tube or cable ties.Frequently seen in broadcast studiosJon

author: switchabl
author_rank: Frequent Contributor
timestamp: February 14, 2023, 05:35:02 pm
content: For small runs (or one-offs) where custom cables aren't an option, braided cable sleeves are also worth a look.

author: edavid
author_rank: Super Contributor
timestamp: February 14, 2023, 06:42:54 pm
content: Quote from: DC1MC on February 14, 2023, 02:15:27 pmThose all have 75ohm coax though.If OP can use that, VGA cable would also work.

author: SeanB
author_rank: Super Contributor
timestamp: February 14, 2023, 07:48:15 pm
content: How about HDMI cables, where you do have some screened pairs, and also a few other pairs of non screened cable, in an overall screened sheath. Just have to get the longest ones you can get, or best price per foot, and chop off the plugs, or even just use them as is.

author: edavid
author_rank: Super Contributor
timestamp: February 14, 2023, 08:02:44 pm
content: Quote from: SeanB on February 14, 2023, 07:48:15 pmHDMI cable is shielded twisted pair, not coax as OP requested.

author: jonpaul
author_rank: Super Contributor
timestamp: February 15, 2023, 12:20:51 am
content: use RG/174/U or similar small dia 50 Ohm for smaller and more flexible cable.High db/km attn but much easier to make multiconductor cables.https://www.l-com.com/Images/Downloadables/2D/RG174-100_2D.pdfJon

author: coppercone2
author_rank: Super Contributor
timestamp: February 15, 2023, 07:40:46 am
content: I wonder what would happen if you took a braided cable, and vacuum sealed it with silicone, so the silicone gets into the braid, then hung it up to dry. They have a long cure time, the excess should drip off.

author: Haenk
author_rank: Super Contributor
timestamp: February 15, 2023, 02:46:33 pm
content: May I suggest something like this:https://en.wikipedia.org/wiki/DB13W3Should be available at your vintage workstation dealer (commonly used on SUN and SGI back then), or maybe used on ebay.

author: edavid
author_rank: Super Contributor
timestamp: February 15, 2023, 03:56:12 pm
content: Quote from: Haenk on February 15, 2023, 02:46:33 pmThat has the same issue of the coax being 75ohm, so it doesn't really have an advantage over a VGA cable.

author: dmderev
author_rank: Contributor
timestamp: July 03, 2024, 07:02:45 pm
content: I was also looking for a solution for active probe and eventually I found three options:1. Do it yourself with a nylon braid (simple but a bit less flexible than I wanted - with micro coax cablehttps://www.aliexpress.us/item/2251832707700559.htmland wires inside). Using 36AWG teflon wires makes it thin overall.2. Do it yourself, but with thin wall silicon tubing as jacket (same coax cable, tubing with 0.5mm wall, 4mm id). I saw that there are heat shrink silicone tubing available now, but I did not try how flexible they are after shrinking.3. USB4 "coaxial" cable (it has 4 micro coaxial connectors and many wires, suitable for differential active probes). There are even "silicone" cables (https://www.aliexpress.us/item/3256805198860016.html) which, if you order as a single piece, will come at any length. Or you can order longest cable (not really good for USB4, but you can cut it in pieces).As far as I know, LeCroy and Tektronix were ordering their cables directly. I used to have Tek cable but it had only two conductors in addition to coax cable.In all these cases, the miniature teflon coax cables are suitable up to few GHz. The USB4 cables have more roll-off at >2-3Ghz. And high frequency active probes usually need 4+ wires for DC bias and controls.

author: dmderev
author_rank: Contributor
timestamp: July 03, 2024, 07:06:32 pm
content: One other option - use 75Ohm cable (like S-Video) and put a series 25 ohm on the scope end. You will get a bit more division ratio (1:3) but it will be properly terminated. You will need 75 Ohms at the output of your buffer amplifier to properly terminate. There are different quality S-Video cables, some can work up to ~500+MHz.

author: Phil1977
author_rank: Frequent Contributor
timestamp: July 03, 2024, 07:22:20 pm
content: Quote from: dmderev on July 03, 2024, 07:02:45 pmDo you have any information about impedance and attenuation values of these coaxes? Maybe even a datasheet?