Good SMA/BNC/connectors/adaptors that don't break the bank - Page 1
Forum section: electronics / testgear

author: hp3310a
author_rank: Regular Contributor
timestamp: March 31, 2025, 11:37:13 am
content: Hi,recently I became aware that my low cost SMA and BNC adapters are really not up to the task when dealing with high frequencies or fast edges.Someone mentioned Huber & Suhner gear and I found out that RS would sell it to me. Provided I win the lottery, a BNC to SMA adapter is €70 + tax (https://uk.rs-online.com/web/p/coaxial-adapters/0494896). That is insane.So I looked around and there are other brands at RS, and I was wondering if those are any good. For instance the SMA-BNC adapter from RS PRO is still €14+tax (https://uk.rs-online.com/web/p/coaxial-adapters/1123788). Not cheap but I don't need 100 so it would be OK.I need a couple of such adapters and some SMA T-connectors and straight couplings, nothing fancy.Is there a general rule where to buy that kind of thing and be reasonably sure that it's not complete garbage. I hope this is the right place to ask, it's about measuring, so....

author: shabaz
author_rank: Frequent Contributor
timestamp: March 31, 2025, 11:54:43 am
content: Funnily enough, the ones that you've linked (RS 112-3788, which are Telegartner adapters), are the exact ones I've been using, I have about half a dozen of them. Quite reasonably quality for general use (I use them for connecting cables to sig-gens and oscilloscopes, etc., because I mostly only have SMA cables, but a lot of typical general-purpose test-equipment uses BNC of course.The adapters have a knurled area to hold which makes it easy to finger-tighten the SMA connectors without the center contact spinning and wearing out (obviously, normally an SMA connector is tightened with a tool, but for connecting to 'scopes or sig-gens for my purposes I would not expect to do that; these (relatively in the space of things) low-cost adapters are not for critical use).

author: tszaboo
author_rank: Super Contributor
timestamp: March 31, 2025, 12:37:45 pm
content: Basically from what I understand, these adapters come in 3 different grades according to the manufacturers, 4 according to mine.- Metrology- Engineering- Production- QC failed ones sold online without specifications for cheapThe price difference comes down to machining tolerances, time, and quantity and production checks. If you tell us why you need the adapter, it's easier to select.

author: shabaz
author_rank: Frequent Contributor
timestamp: March 31, 2025, 12:58:49 pm
content: By the way, you mention SMA T-adapter, but they might be very rare (I have not checked) since it's unsual to split 50-ohm cables like that without an actual component performing power splitting instead (which you could DIY or buy off-the-shelf), although BNC T-adapters are very commonplace. I keep a few BNC T-adapters handy, I don't think I've spent a lot on those since they are very non-critical. I usually go for an RS part or from some other distributor.For straight couplings, for SMA, I have tended to just use Huber & Suhner parts, since such straight couplings are not very expensive for non-critical purposes anyway.For all these adapters, it's worth always avoiding AliExpress, because there's a good risk they will damage cables or equipment.

author: hp3310a
author_rank: Regular Contributor
timestamp: March 31, 2025, 02:08:58 pm
content: Quote from: tszaboo on March 31, 2025, 12:37:45 pmBasically to hook up the oscilloscope or other measurement device to a signal source, so in your list the top point.Quote from: shabaz on March 31, 2025, 12:58:49 pmThe T-adapters are not rare. Huber & Suhner give them away practically for free at €110 eachhttps://uk.rs-online.com/web/p/coaxial-adapters/2118931More budget minded version with probably not exactly the same performancehttps://uk.rs-online.com/web/p/coaxial-adapters/1225249Quote from: shabaz on March 31, 2025, 12:58:49 pmHuber & Suhner are €30+tax at RS,https://uk.rs-online.com/web/p/coaxial-adapters/7164744RS-PRO €6+tax,https://uk.rs-online.com/web/p/coaxial-adapters/2469406Telegartner €11+tax.https://uk.rs-online.com/web/p/coaxial-adapters/7123295Quote from: shabaz on March 31, 2025, 12:58:49 pmUnfortunately you are right, my existing adapters are from Amazon or Aliexpress and they are all bad, some less some more.

author: Grandchuck
author_rank: Super Contributor
timestamp: March 31, 2025, 03:18:04 pm
content: Unfortunately you are right, my existing adapters are from Amazon or Aliexpress and they are all bad, some less some more.About half of my Amazon purchases of things electronic have been returned. Bad place to shop, in my opinion.

author: joeqsmith
author_rank: Super Contributor
timestamp: March 31, 2025, 03:28:46 pm
content: I bought some really low cost Ts.https://www.eevblog.com/forum/rf-microwave/nanovna-custom-software/msg5665155/#msg5665155While it worked good enough for my experiment, the one I checked was out of tolerance.https://www.eevblog.com/forum/testgear/dont-buy-sma-cable-assemblies-from-centricrf/msg5756199/#msg5756199

author: bson
author_rank: Unknown
timestamp: April 01, 2025, 12:49:01 am
content: Mini-Circuits? They have a huge array of adapters, reasonably priced if they're good enough.E.g.https://www.minicircuits.com/WebStore/dashboard.html?model=SF-BM50%2BPicker:https://www.minicircuits.com/WebStore/adapters.html

author: bdunham7
author_rank: Super Contributor
timestamp: April 01, 2025, 01:19:37 am
content: Quote from: Grandchuck on March 31, 2025, 03:18:04 pmeBay is actually a lot better. There are some really good sellers on there and you also may find some high quality NOS or used stuff. I used to routinely search eBay for "Mini circuits" among other things. Prowling for an N-type DC block right now...

author: hp3310a
author_rank: Regular Contributor
timestamp: April 01, 2025, 10:11:20 am
content: Thanks for mentioning Mini Circuits, that brought me to Digikey were the same components are actually cheaper than at RS.