N-connector panel mount assembly, but how? - Page 1
Forum section: electronics / rf-microwave

author: Neganur
author_rank: Unknown
timestamp: January 27, 2016, 11:03:53 pm
content: I'm used to connectors that are either crimped or soldered and sealed. This one however, has me puzzled.How is the shield supposed to be connected?I'm tempted to just throw it away and get one I can crimp/solder or an N-to-SMA panel mount connector.RF power is up to 10W.

author: Ian.M
author_rank: Super Contributor
timestamp: January 27, 2016, 11:14:35 pm
content: Is the frequency low enough that you can get away with solder tags under the fixing nuts at opposite corners?

author: Neganur
author_rank: Unknown
timestamp: January 27, 2016, 11:30:04 pm
content: It's some 50-500 MHz and I need to cover some 3-4 cm inside the enclosure.I think this connector is meant to be soldered directly to the PCB, so I'm probably better off looking for a different N-connector and some semi-rigid cable.

author: TheSteve
author_rank: Unknown
timestamp: January 27, 2016, 11:51:13 pm
content: I would think an eyelet from one of the mounting screws to the coax braid would work.

author: cdev
author_rank: Super Contributor
timestamp: January 28, 2016, 12:35:36 am
content: Old school and has that big problem with grounding. **Good point.**

author: Bud
author_rank: Super Contributor
timestamp: January 28, 2016, 12:56:32 am
content: There are hoods for them like this onehttp://www.digikey.ca/product-detail/en/83-765/ARF1167-ND/160102

author: vk6zgo
author_rank: Super Contributor
timestamp: January 28, 2016, 05:50:01 am
content: Quote from: Bud on January 28, 2016, 12:56:32 amTHe "N" connector is a standard panel mount unit.The hoods aren't meant for "N" connectors,but for SO 239 connectors to attempt a match between their non-specified impedance & 50 (or maybe 75)Ohm cable."N" connectorsare50 Ohm by design,so the hood may make things worse,rather than better.The normal way of making fairly critical VHF/UHF connections to panel mount "Ns" is to cut the coax to have the shortest possible centre conductor & braid pigtail,& solder the latter to the round body of the connector as close to the centre pin as you can get.500MHz sounds hellishly high in frequency,but,remember,a wavelength at that frequency is 600mm(roughly 2 feet in the King's measurements).The pigtail lengths are miniscule in comparison.That said,the "N" to SMA adaptor would look much nicer!

author: Bud
author_rank: Super Contributor
timestamp: January 28, 2016, 07:10:41 am
content: Quote from: vk6zgo on January 28, 2016, 05:50:01 amThis does not make sense. You can only match specified impedances.

author: vk6zgo
author_rank: Super Contributor
timestamp: January 28, 2016, 09:43:50 am
content: Quote from: Bud on January 28, 2016, 07:10:41 amNo,you can also match between measured or calculated impedances.S0239 impedances aren't specified,but they fairly obviously have some value of impedance.I don't know what it is!

author: ConKbot
author_rank: Super Contributor
timestamp: January 28, 2016, 08:55:19 pm
content: Those arent meant for coax. You can use solder tags and pigtails etc, but thats a hackjob. (for those firing up the keyboard with examples about what youve seen it in,no, I dont care what equipment youve seen it in or how much it cost, still a hackjob)You'd use one of those for something where just running a piece of wire from the center pin to your PCB, and using the metal case as the ground wont cause you problems. I.e. a HF radio, where your wavelength is in the 10's of meters, a 10cm jumper isnt gonna kill you.http://www.digikey.com/product-detail/en/082-5378-RFX/ARF1711-ND/2041837if you want it to go to RG-58/LMR-195 etc,http://www.digikey.com/product-detail/en/172129/ACX1143-ND/1011820for RG-174/LMR-100

author: jimmc
author_rank: Frequent Contributor
timestamp: January 28, 2016, 09:10:21 pm
content: 'Panel' connectors are for wires, use 'Bulkhead' connectors for Coax. (see ConKbot's post)Jim

author: Neganur
author_rank: Unknown
timestamp: January 28, 2016, 11:00:55 pm
content: Thanks for confirming that it's the wrong connector for what I am doing

author: vk6zgo
author_rank: Super Contributor
timestamp: January 29, 2016, 12:55:25 am
content: Quote from: ConKbot on January 28, 2016, 08:55:19 pmIwillfire up my keyboard--Yes,itisa hackjob ----ifyou have access to the nice connectors in your link,but for decades,such were the stuff of dreams for much of the Electronics Industry.Even though it is mechanically "messy",the method I described will work at 500MHz,& has been used with coax for many years.Obviously,the connectors you linked to are a neater & more secure way of doing the job,but blanket statements like yours can cause a lot of confusion amongst less experienced members.

author: AF6LJ
author_rank: Unknown
timestamp: January 29, 2016, 01:07:09 am
content: Quote from: jimmc on January 28, 2016, 09:10:21 pmThat's the way to do it.Open up any higher end piece of RF test equipment and you will see those connectors.sometimes they are SMA or K connector on one side N on the other.

author: _Andrew_
author_rank: Regular Contributor
timestamp: January 29, 2016, 01:11:08 am
content: How about these oneshttp://uk.rs-online.com/web/p/n-connectors/1120818/

author: AF6LJ
author_rank: Unknown
timestamp: January 29, 2016, 01:29:37 am
content: You might want something like this ...http://centricrf.com/adapters/n/n-to-n-bulkhead-flange/Or ...http://www.amphenolrf.com/242125.htmlThis is more like what is seen in the kind of test gear I have seen / owned / worked on.

author: SNGLinks
author_rank: Regular Contributor
timestamp: January 30, 2016, 11:13:08 am
content: Quote from: vk6zgo on January 28, 2016, 09:43:50 amThis is an investigation into the impedance of SO239/PL259 connectors.http://www.qsl.net/vk3jeg/pl259tst.htmlI think of them not as RF connectors but screened banana plugs!

author: Kalvin
author_rank: Super Contributor
timestamp: January 30, 2016, 12:34:14 pm
content: Something like these?N to SMA:http://i.ebayimg.com/images/g/6XIAAOxyIAZRrBSD/s-l1600.jpgN to BNC:http://i.ebayimg.com/images/g/Xu0AAMXQWlFRrBTg/s-l1600.jpgThere seems to be also N-type panel mount connectors with different kinds of pigtails.

author: AF6LJ
author_rank: Unknown
timestamp: January 30, 2016, 01:44:37 pm
content: Quote from: SNGLinks on January 30, 2016, 11:13:08 amThere is a lick of information in that study.What brand of connectors were used?Insulating material?Methods used to interface them to a cable, and cable type used?Let me also point out that in the real world an acceptable return loss for a mobile radio installation is ten DB. (2:1 VSWR more or less.)I have to call Bullshit on this study simply because of the gross omissions in important information.By the way..Based on my own tests using quality connectors and cable I have seen much better results using PL-259 / SO-239 combination.Would I use them in RF test equipment?NoApples and oranges comparison...

author: cdev
author_rank: Super Contributor
timestamp: January 30, 2016, 04:08:00 pm
content: There is a long kind of SMA that both grabs a PCB at its edge for soldering there and also lets one get a positive electrical connection on a metal case where the SMA passes through it. They are the SMAs that look abnormally long which bundle a pair of hex nuts and a lock washer with them.*Most* N's are 50 ohm connectors. They are thought of as 50 ohms.