Cheap N to SMA RF adapters, any good ? - Page 1
Forum section: electronics / testgear

author: uski
author_rank: Frequent Contributor
timestamp: October 11, 2015, 01:26:18 am
content: Hi,Just a quick question.. does anyone know if the price premium for a "good" N to SMA adapter is worth it ?For example the Minicircuits NM-SF50+ is $22 USD, but similar adapters can be found on eBay or Aliexpress from China for as low as $2 each :http://www.aliexpress.com/item/N-Type-Male-Plug-to-SMA-Female-Jack-Straight-Copper-RF-Coaxial-Adapter-Connector/32226832772.html(if link is dead, see attached screenshot)So, are these adapters any good ? Did anyone test them ? Can we expect a really bad impedance mismatch or insertion loss issues ?Thanks

author: Bud
author_rank: Super Contributor
timestamp: October 11, 2015, 01:38:52 am
content: If you intend to use them with industrial quality test equipment I'd say better invest in quality connectors/adapters. These Aliexpress ones may have incorrect/poor sizing of mating pins that may damage your equipment. They are ok when used with each other as through away or for prototyping, just do not mix them with quality connectors.

author: TheSteve
author_rank: Unknown
timestamp: October 11, 2015, 01:41:18 am
content: The good quality ones are generally worth the money unless they are stupid money. The cheapies have crap cut threads, poor tolerances and do cause very small impedance bumps. I have good ones and cheap ones, there certainly is a difference.btw, check out how much a replacement N connector is for your spectrum/network analyzer should it get damaged - prepare to fall over.

author: AF6LJ
author_rank: Unknown
timestamp: October 11, 2015, 01:48:54 am
content: Quote from: TheSteve on October 11, 2015, 01:41:18 amAgreed you really should stay away from the low end connectors.

author: uski
author_rank: Frequent Contributor
timestamp: October 11, 2015, 01:57:45 am
content: Thanks guysI thought about the electrical things but not about the mechanical things...

author: TheSteve
author_rank: Unknown
timestamp: October 11, 2015, 02:35:50 am
content: btw, 22 bucks for a minicircuits is very reasonable compared to an Agilent etc.Try checking out the prices of calibration grade open/short/load's.

author: AF6LJ
author_rank: Unknown
timestamp: October 11, 2015, 02:58:50 am
content: Quote from: TheSteve on October 11, 2015, 02:35:50 amWhich is why I cringe every time I see an inexperienced tech spin an N connector when he is attaching a cable.

author: uski
author_rank: Frequent Contributor
timestamp: October 11, 2015, 04:07:57 am
content: Quote from: AF6LJ on October 11, 2015, 02:58:50 amPossibly inexperienced tech here; what do you mean ?(I think I see what you mean, but I'm not sure - so I prefer to ask than risking staying dumb)

author: TheSteve
author_rank: Unknown
timestamp: October 11, 2015, 04:22:23 am
content: Quote from: uski on October 11, 2015, 04:07:57 amWhen you mate the connections you don't want the center of the N connector rotating, only the outer portion that you screw on should be turned. You want the center pin to push into the mating socket without it turning. So if you are attaching an N to SMA adapter when you tighten the last turn or two hold the SMA portion so only the outer threaded shield is turning, the SMA portion should not be turned which keeps the pin from spinning when it makes contact.PS - if you want to get all proper/fancy when you connect a calibration load etc you are supposed to use a torque wrench!

author: codeboy2k
author_rank: Super Contributor
timestamp: October 11, 2015, 07:00:39 am
content: Shahriar of The Signal Path has a good tutorial of various microwave components including connectors here.http://thesignalpath.com/blogs/2013/07/29/tutorial-on-microwave-and-mm-wave-components-and-modules/While he doesn't specifically talk about not-rotating the N connector, he does show how to properly connect a 1.85 mm connector without rotating it, why you should not rotate it, and how to use a torque wrench to tighten it.The video is chock full of microwave goodness, a good watch all the way to the end. Thanks, Shahriar!

author: uski
author_rank: Frequent Contributor
timestamp: October 11, 2015, 08:03:11 am
content: Quote from: codeboy2k on October 11, 2015, 07:00:39 amThanks for the link. I watched the bit about connector mating.However I always wonder... do people have time to watch these videos ? Even the eevblog videos are really long. If you consider all the interesting youtube channels, it's just impossible to watch everything. Sometimes interesting content is buried into long videos making it difficult to find (see, I would never have found that video by looking for it). Most of the time, I find that the content of the videos could fit in much shorter videos if they were edited properly and care was taken for the author to speak "to the point"... not necessarily the case here but a 1 hour long video is, hmm, long... and unless you already know the author, you're unlikely to find that video and watch it. Too bad. Glad you provided the link.

author: tggzzz
author_rank: Super Contributor
timestamp: October 11, 2015, 08:40:49 am
content: Quote from: uski on October 11, 2015, 08:03:11 amPrecisely.Videos are rude in the sense that they'minimise the author's time, but maximise the readers' time (note the differing placement of the apostrophe)are often narcissisticcould usually be replaced by textcannot be searcheddifficult to skip through fluff to find a worthwhile bitAs Voltaire(?) wrote a couple of centuries ago: "sorry this letter is so long, I didn't have time to make it shorter".

author: AF6LJ
author_rank: Unknown
timestamp: October 11, 2015, 12:50:26 pm
content: Quote from: TheSteve on October 11, 2015, 04:22:23 amRight OnAnd perhaps with the exception of F connectors you don't want to spin the main body of any RF connector as it can damage the center pin of the mating connector.A good habit to break, if one finds oneself spinning connectors.

author: nctnico
author_rank: Super Contributor
timestamp: October 11, 2015, 01:04:46 pm
content: IMHO it also depends on how often you use your RF gear. I have the cheap Ebay N to SMA adapters. I use my RF gear only a few times per year and I usually leave the adapters on when I store the equipment. What helps with that is standarising on a certain type of connectors (SMA, BNC or N). If you are really worried about wearing the connector on your RF gear the best option is to use a so called pin-saver (male to female adapter) which endures the many mating cycles.

author: uski
author_rank: Frequent Contributor
timestamp: October 11, 2015, 01:57:37 pm
content: Quote from: tggzzz on October 11, 2015, 08:40:49 amThank you so much, I feel less lonely in my hate of long (15mn+) and non searcheable multi-subject videosuski

author: AF6LJ
author_rank: Unknown
timestamp: October 11, 2015, 03:19:41 pm
content: Quote from: tggzzz on October 11, 2015, 08:40:49 amKeep in mind; Knowledge comes at a price, your time.The people who produce these videos put much more time in them those of us who watch them, and consider the years or decades of experience that back up what you watch.If we don't invest the time we don't get the knowledge.

author: tggzzz
author_rank: Super Contributor
timestamp: October 11, 2015, 04:37:37 pm
content: Quote from: AF6LJ on October 11, 2015, 03:19:41 pmWhile partly true, that completely misses the points.One person spends 10 hours making a 1 hour video. 100 people spend an hour watching it; that's a 10:1 ratio against your point.There is a limited amount of my life left, and I have to carefully decide how to spend it. I will spend a minute or so determining whether something (book, magazine, blog, video) is worth examining in detail. There is no way I am going to spend an hour of my (remaining) life determining whether a person I've never heard of has anything to say that I don't already know.Because mostly they don't.When I (and maybe you) were young information was difficult to get. There weren't many books on whatever topic, the local libraries' stock was soon exhausted, and it was a 3 week latency before books arrived from other libraries. Consequence: we devouredanyinformation available to glean the maximum possible from it.Nowadays the situation is completely reversedandthe key skills are effect search terms and quickly deciding the 99% we willignore.Think of it as "the elevator pitch" in everyday life.

author: AF6LJ
author_rank: Unknown
timestamp: October 11, 2015, 04:49:28 pm
content: Quote from: tggzzz on October 11, 2015, 04:37:37 pmWhile the amount of information at our fingertips has increased so has the amount of misinformation.The Internet has been accurately characterized as the largest source of misinformation the planet has ever seen; So you do have to choose your sources of information more carefully.I am into the last quarter of my life, I always have time to spend on learning , as I did in the last life I shall do in the next life.

author: nctnico
author_rank: Super Contributor
timestamp: October 11, 2015, 05:00:09 pm
content: Still I agree about watching videos. I watch very few technical videos because they are long winded and the interesting part is not easy to find. I like stories with pictures better because they are easier to make and highlight the key / interesting points.

author: tggzzz
author_rank: Super Contributor
timestamp: October 11, 2015, 05:15:07 pm
content: Quote from: AF6LJ on October 11, 2015, 04:49:28 pmSo, which would you do? Spend 3600s of your remaining life watching video on the off-chance it would be well spent, or spend 30/60s speed reading to find the stuff that reallyisvaluable to you?If an author wants my attention, they have to demonstrate their stuff is worth it.

author: tggzzz
author_rank: Super Contributor
timestamp: October 11, 2015, 05:16:27 pm
content: Quote from: nctnico on October 11, 2015, 05:00:09 pmJust so.And google can't help me - whereas it does help me with text.

author: Howardlong
author_rank: Super Contributor
timestamp: October 11, 2015, 05:30:53 pm
content: I think it depends when you watch videos. I tend to watch them during otherwise largely null time, such a during a commute (if downloadable, I wish more were) or when I'm stuffing envelopes or other largely mundane and mindless repetitive tasks associated with being a one-man-band. Sicking serial number labels on enclosures, boxing up products or sorting out one's expenses are the kinds of tasks that come to mind.

author: G0HZU
author_rank: Super Contributor
timestamp: October 11, 2015, 05:36:49 pm
content: I suspect that quite a few regular viewers of EE based videoblogs will happily watch >1hr videos in the same way lots of people will happily watch TV for several hours a day.Sure, the amount of useful info may be sparse in some of these videos but I think some people watch them for relaxation or for background noise and anything they learn is a bonus

author: nctnico
author_rank: Super Contributor
timestamp: October 11, 2015, 06:11:40 pm
content: To be honest I rather watch Game of Thrones than Dave taking an oscilloscope apart

author: tggzzz
author_rank: Super Contributor
timestamp: October 11, 2015, 06:46:50 pm
content: Quote from: nctnico on October 11, 2015, 06:11:40 pmSince I have that specific type of scope, I'll disagree!"A foolish consistency is the hobgoblin of a little mind"? Not really, because the surrounding metadata (i.e. comments) highlighted the relevance to me. Indeed, one of the comments (the need to fondle the delay line) was directly and immediately relevant to me; delightful.

author: AF6LJ
author_rank: Unknown
timestamp: October 11, 2015, 08:44:47 pm
content: Quote from: nctnico on October 11, 2015, 06:11:40 pmI would have to disagree, Television in the US is ruined by all the psychological warfare during commercial breaks. Add to that in my opinion less than ten percent of the television shows are worth watching.Television sucks deeply.

author: nctnico
author_rank: Super Contributor
timestamp: October 11, 2015, 09:25:12 pm
content: Commercial breaks? I download everything I want so see and watch it on my computer! I don't mind paying for the commercials through the products I buy so the televisions shows can be made but I rather not watch the commercials.

author: AF6LJ
author_rank: Unknown
timestamp: October 11, 2015, 09:36:25 pm
content: Quote from: nctnico on October 11, 2015, 09:25:12 pmI doubt we have the same types of commercials.Lets see do you have;The big munitions manufacturers buying commercial time on news shows in order to maintain editorial control and censoring the news through that editorial control.Big drug companies selling prescription drugs telling you to ask your doctor about a given drug.Drugs that have fatal side effects.Charities that show abused animals, then pleading for your money while sending only ten percent of gross income to actually help animals.Chemical companies pushing GM crops....I could go on....why bother you get the idea.Television in the US is a cesspit.

author: Berni
author_rank: Super Contributor
timestamp: October 11, 2015, 10:01:51 pm
content: I don't mind long videos since i usually do something else while watching youtube.That way i simply don't listen to the parts that are not interesting and pay attention when there is something good. If i realize the part is interesting half way trough then i simply drag the timeline back a bit and re watch the part i ignored before.

author: nctnico
author_rank: Super Contributor
timestamp: October 11, 2015, 10:08:23 pm
content: Quote from: AF6LJ on October 11, 2015, 09:36:25 pmI have no idea what the commercials are like nowadays. As I wrote: I download everything; in downloaded TV shows the commercials are already cut away.Edit: drats... how did we got this far off topic?I did find these $2 N male to female pin savers:http://www.ebay.com/itm/1pce-Adapter-N-plug-male-to-N-female-jack-RF-connector-straight-M-F-/271217075650

author: Rupunzell
author_rank: Frequent Contributor
timestamp: October 12, 2015, 01:16:06 am
content: Good microwave connectors, adapters are inherently expensive due to the exacting precision required.Best ones come from companies like Wiltron, Agilent, Maury Microwave, Amphenol RF and other well established manufactures.If the connectors involved are not made to the industry specification and tolerances, the resulting connector damage can be serious. Poor connectors and adapters often have poor RF performance on top of that.Even used name brand connectors and adapters can be damaged which could result in equally serious problems. Check, measure the connectors to verify the pin depth is correct, shell inner and outer diameter is correct, threads are in good condition as all these and other details matter. Once the connectors and adapters are of a known good condition, take care of them, joint them properly and do not abuse them.BerniceQuote from: uski on October 11, 2015, 01:26:18 am