Coax/BNC cables and how to use them with breadboards - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: April 22, 2020, 05:52:19 pm
content: Hi,I recently purchased awaveform generatorthat I currently using as a freq counter.The problem is that I never used coax cables (currently I hooked up one of my scope probes, in order to use it as a counter).So I'm a bit unsure on how to proceed.I usually crimp my cables (at the end it all costs less) but is it viable with coax? I read somewhere that it's not easy to do so… also, what is the best choice to hook up coax to a breadboard? Make a little breakout board or is there some adapter which I haven't found.If I missed something important please I'm all ears also all eyes for any resources you find online.Note: I'm EU based, if anyone is going to suggests shops or sth to buy.Thanks

author: Gyro
author_rank: Super Contributor
timestamp: April 22, 2020, 06:17:35 pm
content: Yes, you can certainly get crimp BNC coax connectors, and they are cheaper than normal solder and clamp ones. The crimp tools are relatively cheap too (particularly for non professional ones).For the breadboard end. the simplest solution is to terminate bare coax with a couple of pieces of solid core wire (resistor leads) suitable for the hole size of your breadboard (assuming that you mean a plug-in one). you can also get cheap coax leads with BNC on one end and clips on the other, you can clip these across a high value resistor (or a matched terminating resistor of 600 or 50R depending on the source and plug this into the breadboard.The solution is dependent on the frequencies you are using though. At low frequencies (say <2-5MHz), the above will do fine. For higher frequencies, at the point where plug-in breadboards are no longer suitable, you will probably need more permanent soldered connection to your 'breadboard' (PCB or copper clad 'Manhattan' style prototype) either soldering to pads, or fitting a matching BNC connector using a solder tag. At higher frequencies, the correct value terminating resistor becomes essential.

author: hexreader
author_rank: Frequent Contributor
timestamp: April 22, 2020, 06:20:20 pm
content: I assume that you mean solderless breadboard?Buy a ready-made BNC to BNC cable of twice the required length. Thin flexible cables are nicer to work with, and quality is unlikely to matter, since breadboard is lossy and frequency limited anyway.Cut the cable in half to make two leadsCut a black pin-to-pin cable in half - something flexible and suited to plugging in to your breadboard - solder a pig-tail to the coax braid (suitably stripped and twisted) - this will provide ground pig-tail for 2 leadsCut a suitably coloured pin-to-pin cable in half and solder to the co-ax centre conductor - cover with thin heat-shrink tube, ideally the same colour as the pig-tail.Cover the BNC end of the co-ax with matching heat-shrink for easy identificationCover the messy end of the coax with matching heat shrinkJob done - BNC to breadboard pins - colour coded and flexible. Good enough for low frequency work. No crimping required.I find this to be cheaper than crimping my own leads, especially allowing for a few failures, and is definitely more reliable.

author: t1d
author_rank: Super Contributor
timestamp: April 23, 2020, 10:15:15 am
content: Nice job, hexreader!Moriambar, there are coax cables fashioned similarly to hexreader's design, but they have alligator clips, instead of DuPont pins. Some have J-clips. You could just connect the coax to the breadboard wire with one of these types and they would be usable for other things, too. They cost a few dollars and they can be ordered on Ebay.I like the J-Clip type. I do not like the alligator type, because the insulation boot makes it difficult (nearly impossible, for old hands) to squeeze open the alligator jaws. The slipper boot causes your fingers to slip off of the alligator stems.

author: MarkF
author_rank: Super Contributor
timestamp: April 23, 2020, 12:30:51 pm
content: I bought this set:https://www.amazon.com/gp/product/B07FZV589P/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

author: Moriambar
author_rank: Unknown
timestamp: April 23, 2020, 12:31:56 pm
content: Quote from: MarkF on April 23, 2020, 12:30:51 pmthanks. unavailable in Italy, unfortunately

author: David Hess
author_rank: Super Contributor
timestamp: April 23, 2020, 01:12:35 pm
content: I do basically what hexreader described except that I have a collection of short flexible RG-178 pigtails to go between my thicker coaxial cables and whatever I am working on.