I said this in another thread, but be warned about RCA cables. They are not built like normal coax. The reason some of them have such good feel/bend parameters is because they are non-braided. So you have a single layer of thin wires (somewhat circularly distributed) in the extruder along with your center wire. It seems to have a much better flexibility because of this, but poor shield coverage. If you make it with rg coax then this problem is eliminated of course, but you don't get what most people want RCA for, which is the great usability it has.
Would be interesting to see someone do tests on this sort of wire for shielding vs tight braid lab coax.
Indeed, spiral shielding is not as good as braided. (Though just being braided isn’t enough; it needs to be good, tight braiding).
However, I do not agree at all that spiral vs braided is in any way the primary factor in flexibility. The stranding of the center conductor is a big factor, but far more important are the materials of the dielectric (inner insulator) and jacket (outer insulator).
For example, if we look at RG-174 coax, it has a polyethylene dielectric and PVC jacket over a basic braided shield. The shallow angle of the braiding makes it not as flexible as others (more on this later), but above all, the PVC itself is THE difference. At work I have two reels of RG-174, one from Huber+Suhner (a super premium Swiss manufacturer), and one from Tasker (an Italian manufacturer). The one from Tasker is super stiff, while the Huber+Suhner is flexible and lovely. If I remove the jacket, they have practically identical flexibility, so it really is the stiff PVC jacket alone that makes the Tasker so stiff. The Huber+Suhner RG-174 is more flexible than most RCA audio cables.
I also have a box of Huber+Suhner double-shielded RG-316. It’s very similar to RG-174 in overall dimensions, but with PTFE dielectric and FEP jacket. Despite having
two braided shields, it is only the stiff FEP jacket that makes the cable stiff. If I strip off the jacket, it’s super flexible.
That cable uses very tight braids at close to 45 degree angles, which makes them very flexible.
Stäubli makes a variant of RG-58 that uses a silicone dielectric and jacket, and a finely stranded conductor. I finally got around to ordering some and it is absolutely lovely. By far the most flexible coaxial cable I’ve ever touched. The downsides are that it’s expensive, and that it’s 45 ohm instead of 50 ohm.
As an aside, I have made the observation that modern cables of all types seem to be largely significantly stiffer than older ones. I am often surprised at how soft, for example, the power cords on many old devices are. (I have a box full of old oscilloscope probes and it’s striking how much softer their cables are than any modern probes.) I don’t have any concrete explanation, but my suspicion is that it’s some combination of cost-cutting and of modern regulations about phthalate plasticizers, etc.
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