BNC cables -- buy ready-made or self-assemble? - Page 1
Forum section: electronics / general

author: rs20
author_rank: Super Contributor
timestamp: December 09, 2014, 12:17:42 pm
content: Hello,My home lab is lacking BNC cables. I need 50 ohm of course, I suppose I only need 1 GHz or so although 4 GHz seems so common that it seems like there's no point compromising here. And I want good quality, but I don't want to waste money on the lab equivalent of Monster cables. So much I want to know:-- Do people typically assemble their own BNC cable assemblies*, or just buy pre-made? I have no idea what standard practice is here. I'm not looking to be a hero, if special equipment or great skill/patience is required to make my ownproper performingcable, I'm out. This isn't digital after all, small screw-ups do cause issues.-- Buying online seems to be the way to go; what brands am I looking for? I've had a quick search through the forum, and I've seen Canare and Belden mentioned, but a quick look on their website only lists 75 ohm Video BNC assemblies, leaving me wondering if I'm missing something (for instance, people build their own in real life, hence this post).I just don't want to end up with some Wun Hong Lo BNC cable that has leaky shielding or something, nor spending $100 on something that performs no better thanthe $15 alternative. Any advice (/links to previous threads that I've missed) greatly appreciated.* BTW, when I say "BNC cable assembly", I mean a cable with a BNC connector on both ends. Not even sure if I'm getting terminology right here.

author: TSL
author_rank: Regular Contributor
timestamp: December 09, 2014, 12:35:15 pm
content: Hi,Personally I make my ownI bought connectors and crimp tools here...http://www.rfsupplier.com/and then bought lengths of top quality coax to make my cables, its actually quite easy and once you get the hang of it, quality repeatability is also easy.My first few I built I swept with an analyzer to make sure they were OK and consistent.If you're going to a Ghz or more and you want some flex in your patch cord then you should look at Flexiform 405 or RG405, its PTFE insulated and good to 20Ghz, handles 200W at 1Ghz!! and short lengths can be had for a reasonable price.RFsupplier will make up good patch cables if you want, to specific lengths, if you don't want to do it yourself.regardsTim

author: madires
author_rank: Super Contributor
timestamp: December 09, 2014, 12:36:13 pm
content: If you just need a few BNC RG58 cables I'd recommend to buy them. If you need some fancy coax cables or build antenna cables from time to time, a coax crimp tool isn't expensive.

author: Zucca
author_rank: Unknown
timestamp: December 09, 2014, 02:06:27 pm
content: Had the same questions a couple of months ago. I took the risk to buy stupid cheap ass RG58 cables from Ebay China.If they fail I will open a post.100Mhz for me are more than enough for my applications. So far for DC/low freq signals I can´t complain, I use the RG58 to shield low freq signals rather than to carry high freq stuff...You should self assemble and have patience and time for it, you will never regret a good DIY job.

author: nctnico
author_rank: Super Contributor
timestamp: December 09, 2014, 03:46:19 pm
content: I have given up on making my own BNC cables especially with the connectors you have to solder. Good BNC cables can be bought from Ebay for little money. These for example:http://www.ebay.com/itm/281032666015But don't try to use these over 1GHz. For that you'll need to look at SMA/SMB cables made fromRG223. These are more expensive though; count on $30 for a 1 meter cable from China.

author: rs20
author_rank: Super Contributor
timestamp: December 10, 2014, 11:06:26 am
content: Thanks everyone. So Iwasscared of making my own partially because I had bad memories of assembling my own 3.5mm audio cables which always ended in a flimsy, fragile cable, and b) RF magic. But having actually looked at how the three-piece BNC connectors work, it's wonderfully elegant-looking, there's little room for variation, and it seems like it's not nearly as much of a black art as I had imagined. The end result looks sweet too, again unlike those 3.5mm cables. So I'm definitely keen to build myself. Firstly, do these parts look sane?:--RG 58CU cable--BNC connector for RG58C/U--Crimp tool that matches the spec above--Magical coax stripping device that I'm suspicious ofThe thing that worries me is that the BNC connector schematic shows very specific lengths that the jacket, braid, insulator, and conductor should be cut to, but the coax stripping device only mentions the "depth" of cut being adjustable. Does depth mean how deep the cutter cuts into the material, or how far apart the cuts are along the length of the cable? How can the stripping tool page have no dimensions on it at all? Halp!

author: VK5RC
author_rank: Unknown
timestamp: December 10, 2014, 11:35:34 am
content: Make my own, I find it quite relaxing! Different lengths, male to female etc. I have not had any problems with homebrew BNC cables but one of my SMA cables passed the DC tests but f****ed up at 2GHz. that SMA cable did my head in for quite while until I twigged the cable was buggered. I kept thinking it was the DUT. I now RF test all my SMA cables after construction.

author: Muttley Snickers
author_rank: Unknown
timestamp: December 10, 2014, 12:00:54 pm
content: G'Day rs20,I can only speak from my own experience, exactly 30 years fitting coaxial connectors and not just as a hobby but as part of my profession, every type you can name and for the last 20 years literally hundreds of BNC's to RG-59 and to a lesser extent RG-58 for test and patch leads.I have a collection of coax strippers and a couple are adjustable for both length and depth, those that can't be adjusted for length I modify and put in shims to space the blades to the position that I require, the ones you posted have slots for the blade position so you need to play with these to find a happy medium or flip the blade which will change the cutting point. Be careful with your BNC selection to make sure they have a side entry hole in the centre pin if you intend to solder, this is an entry/escape point for the solder and apply the absolute minimum pre- solder to the centre pin, some crimp type generally don't have this vent and the centre pin hole may be of a different diameter for this style, you can re-use a solder type but a crimp you cant.My preference for both stranded and solid centre core cables is to solder unless I am 30 feet in the air hanging off a scaffold in which case I will use a crimp type RG-59 75 ohm BNC or if it's RG-6 cable I will crimp on an F-Type then use an F to BNC adapter, really depends on access to the device being installed. Initially you can prepare cables with a Stanley type knife and most times you still need the knife after using the strippers as the depth of cut does vary when doing quite a few, set a shy depth cut and tidy up with the knife.If your only making a dozen or so leads then a good box cutter knife is fine, use a ruler or you could make up a jig to give a guide for length once your satisfied with the fit. Also get some good boots /socks/ strain relief on the cables before the connectors as it gives a professional look and feel much better than shitty heat shrink.Alway's make your own if you can, and if you cant, try harder.Muttley

author: Muttley Snickers
author_rank: Unknown
timestamp: December 10, 2014, 12:07:46 pm
content: Sorry I forgot something,You cannot tell what the shield content is on a prefab cable until you cut it open and believe me I've seen some really nasty stuff down to around 20% shield.Muttley

author: GreyWoolfe
author_rank: Unknown
timestamp: December 10, 2014, 12:44:37 pm
content: Mutley says-Always make your own if you can, and if you cant, try harder.Can't agree more. I make all my own cables, from CATV to ethernet to BNC jumpers to terminating coax for ham radio antennas. it is very satisfying to roll your own. Expect to make a couple of mistakes in the beginning but perseverance will be rewarded. Since the lengths I use are typically custom to the application, I find it just easier to make my own, which is another advantage. I hate having extra cable rolled up behind something because premade was too long or having to use some type of barrel connector to join 2 cables together because they are too short.

author: G0HZU
author_rank: Super Contributor
timestamp: December 10, 2014, 09:19:50 pm
content: For short BNC cables eg up to a couple of metres I always buy good branded ready made BNC cables. eg Suhner, HP or Radiall.Probably the worst thing you can do is buy really cheap unbranded BNC cables. They are usually awful with poor quality cable and the connector quality is poor leading to unreliable performance.Next worse is to try and make your own using decent cable and cheap unbranded BNC connectors. It doesn't matter how good you are at making the cable, it will still be crap in terms of performance and reliability.If you buy decent branded BNC connectors and make your own using decent quality cable (and you know what you are doing) then that is the closest to getting the performance from a ready made top branded cable.