BNC Cables and Adapters. - Page 1
Forum section: electronics / testgear

author: blewisjr
author_rank: Frequent Contributor
timestamp: April 02, 2013, 01:06:16 pm
content: I am looking to get a BNC cable and some adapters for my Rigol DS1102E. I want to run some tests for learning on my Korad PSU. So I have a few questions.1. When looking for a cable what length and ohm rating should I shoot for. I figure the shorter cable will give less noise so around 3 - 6ft. But would I want a 50Ohm or 70Ohm cable or both?2. What adapters should I be looking for and what brand makes a decent quality adapter? I was looking into BNC to Banana plug for the power supply test so I don't have to deal with running wires through a output jack to use the clip attachment for the probe and alligator clipping the - terminal. Seems a bit sketchy to do it that way. So other than the BNC to Banana what should I look for?

author: grego
author_rank: Frequent Contributor
timestamp: April 02, 2013, 05:30:49 pm
content: I'd like to know this too - interesting question. I've been digging around on my own but some experienced answers would be helpful.

author: plesa
author_rank: Frequent Contributor
timestamp: April 02, 2013, 06:08:48 pm
content: 1. for cables I can recomnend the Metrel PVC 1.5m cables with stackable banana (S2025) 15 EUR/pair.For coaxial I'm using Pomona BNC cables (50 Ohm only).2. Quite good BNC-Banana adapters are Fluke PM9801/PM9082, old version on the left.http://www.scopemeter.com/accessories/pm9081-pm9082.htmOuter shield is insulated which can be quite handy, but they are little bit expensive (40 EUR/2pcs).The protective sleeve is removable (only on older type), it is useful when you need to plug into some instruments.The new revision has nickel plated "-" terminal and gold plated "+" terminalAlso Pomona has a banana to BNC adaptorshttp://www.pewa.de/cgi-bin/cosmoshop/lshop.cgi?action=showdetail&wkid=1364925859-4311&ls=d&nc=1364925865-4354&rubnum=&artnum=PO72910&file=&gesamt_zeilen=0Tsuche--pomona%20BNChttp://www.pewa.de/cgi-bin/cosmoshop/lshop.cgi?action=showdetail&wkid=1364925859-4311&ls=d&nc=1364925865-4354&rubnum=&artnum=PO72911&file=&gesamt_zeilen=0Tsuche--pomona%20BNC

author: BravoV
author_rank: Super Contributor
timestamp: April 02, 2013, 06:37:20 pm
content: BNC to banana in m-f or f-m variations are plenty out there and relatively cheap especially those made in China, but good one are quite expensive like above plesa mentioned, it was originally made by Philips and then with Fluke when they working together on T&M products while ago, now Fluke has newer model.Have few of them in both combinations PM9081 & PM9082, quality made for sure and no metal parts exposed.For more pics, check my thread about them (Here), as above pic shows, it was designed that the sleeved banana can be turned into non sleeve version, especially for those older measurement devices that accept only non sleeve banana plugs.

author: Smokey
author_rank: Super Contributor
timestamp: April 02, 2013, 07:01:54 pm
content: You want to match the impedance of the cable/connector to whatever your equipment is. Most test equipment is 50ohm, so that's the stuff you probably want to stock. Also stay away from cheap solid conductor BNC cables. I'm not talking rigid cable, I'm talking cheap BNC-BNC that use solid conductor instead of stranded to save money. You end up bending general use BNC cables way too much to have solid conductors.Along with BNC-BNC cables and a lot of clip/banana/alligator leads, at least a couple of each BNC adapter is a really handy thing to have around the lab.1) BNC T connectors - you want a bunch of these. One almost always lives on my function generator output splitting the signal to a scope input and DUT. Most of them should be BNC male on the bottom and BNC female on the sides of the T, but you should have at least one of all configurations.2) BNC female to banana male. You use these all the time for meters. Get a bunch.3) BNC male to banana female (with binding posts). Useful for hooking banana cables to function gen or anything else that only has BNC female on it. Probably just a couple of these would do.4) BNC to SMA ... optional but coolNice to have if you ever need to adapt some RF stuff.5) Right angle BNC and BNC gender changers. I find myself just using Ts most of the time, but if you really wanted to keep the noise down, you probably want some of these too.6) 50ohm BNC terminators. Get a few of these, just be aware of the wattage rating.

author: grego
author_rank: Frequent Contributor
timestamp: April 02, 2013, 09:40:46 pm
content: Digikey just collected $200 from me for various Pomona connectors and cables. Wheeee!

author: larry42
author_rank: Regular Contributor
timestamp: April 03, 2013, 12:23:09 pm
content: Quote from: blewisjr on April 02, 2013, 01:06:16 pm1. For connections on scopes you can afford (e.g. <500MHz) , the loss of the BNC cable will be negligible. A couple of 3-6ft are nice lengths. Buy RG-223 type cable for the best quality, otherwise RG-58 (50Ohm) are fine. In general I buy pre-made cables, crimping your own reliability is not cheap.Only buy 50Ohm cable, the connectors for 75Ohm BNC look similar, but are not! May cause damage when mating.2. Pomona, Radiall & Amphenol are my choices. I don't bother with the Chinese crap. A bad connector will damage everything it connects to.(for microwave stuff I use Huber & Suhner, M/A COM and Rosenberger in addition to the above.)

author: ivan747
author_rank: Super Contributor
timestamp: April 03, 2013, 02:40:29 pm
content: My $2 adapter is attached.This and a BNC cable will do it. I am not sure why would you need 50 ohms termination. The termination will get hot.

author: ben_r_
author_rank: Frequent Contributor
timestamp: April 03, 2013, 05:08:07 pm
content: Quote from: grego on April 02, 2013, 09:40:46 pmHa, just dropped $130 on a bunch of Pomona stuff from Test Equipment Depot! I feel your pain!

author: Electro Fan
author_rank: Super Contributor
timestamp: June 10, 2013, 07:43:48 am
content: Silly question(s), but below are three products (Items #1, #2, and #3) that look strikingly similar in their photos. The Pomona product (Item #1) on Amazon says it is a Female BNC, the Fluke products on Amazon (Item #2) and on the Fluke site (Item #3) look the same but have different (Fluke) product numbers.Item #1:Pomona 1269 BNC (Female) to Double Stacking Banana Plugshttp://www.amazon.com/Pomona-Female-Double-Stacking-Banana/dp/B00270TQ6K/ref=pd_rhf_cr_s_cp_37_A8SBItem #2:Fluke BP881 BNC to Male Double Stacking Banana Plughttp://www.amazon.com/Fluke-BP881-Stacking-Nickel-Plated-Temperature/dp/B000VRECBK/ref=sr_1_1?s=industrial&ie=UTF8&qid=1370847975&sr=1-1&keywords=Fluke+BP881Item #3:BP880 BNC to Female Double Stacking Banana Plughttp://www.fluke.com/fluke/usen/accessories/automotive/bp880.htm?PID=55791Question 1: is the BNC end of this product (which looks the same in all 3 photos) considered a female or a male? (I'm betting it's a female.)Question 2: is it correct to assume that Fluke rightly calls this product a BP880 and Amazon incorrectly calls it a BP881, or is their some other explanation?Thanks, EFPS, for added confusion here is another (Item #4):Fluke BP880 BNC to Female Double Stacking Banana Plughttp://www.testequipmentdepot.com/fluke/accessorycharts/automotive/bp880.htm- photo definitely doesn't match the BP880 photo on the Fluke web sitePresumably Items 1 and 3 are correctly labeled and shown in their photos and Items 2 and 4 are confused?

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 10, 2013, 11:34:25 am
content: Quote from: ivan747 on April 03, 2013, 02:40:29 pmtermination is meant for higher frequency testing to ensure flat impedance respond as seen by the source, and hence probed by the scope. for low freq or the presence high powered DC component, termination might not be a good idea. bundled Hi-Z probe is better solution for your purpose.

author: madires
author_rank: Super Contributor
timestamp: June 10, 2013, 01:36:39 pm
content: Quote from: ivan747 on April 03, 2013, 02:40:29 pmThe 50 Ohms termination is required to match the impedance of the cable because the scope has a much higher one. Some scopes got a low impedance feature (switch between 50 Ohms and high input impedance). If the impedance doesn't match you'll get nice signal reflections. Of course the terminator has to cope with the signal power. Standard 50 Ohms terminators mostly got 2W. But all this applies only to high frequency signals.

author: robrenz
author_rank: Super Contributor
timestamp: June 10, 2013, 02:47:32 pm
content: What kind of tests are you planning to do on the power supply?

author: SLJ
author_rank: Frequent Contributor
timestamp: June 10, 2013, 09:27:40 pm
content: Quote from: ben_r_ on April 03, 2013, 05:08:07 pmI spent around $80 at Test Equipment Depot last month on new Pomona banana leads, mini grabbers, and connectors. I made up for it this month though as I bought a pile of used BNC cables sight unseen from someone on-line for $10 and found out they were nice new unused Pomonas when they arrived last week. I usually make my own BNCs as I have a 1,000 foot roll of Beldon stranded RG-58. Bought it at a HAM fest for $20. $20 well spent.

author: ben_r_
author_rank: Frequent Contributor
timestamp: June 10, 2013, 09:35:29 pm
content: Quote from: SLJ on June 10, 2013, 09:27:40 pmMAN! Wish I could find a steal like that! I think Im good for a while on cables, but if I found a deal like that Id be all over it!