SMA end cap - Page 1
Forum section: electronics / rf-microwave

author: aylons
author_rank: Unknown
timestamp: September 03, 2018, 01:20:43 pm
content: Hi!I'm looking for somewhere I could buy a few hundred of silicon cover for SMA connectors like these:.A bit longer is better, and as this is for a company, I need a faster and bit more reputable supplier than an AliExpress seller.Ifound theseat McMaster-Carr, can anyone check if they will do the trick? Specially if this material material wil really get snug in the hexagonal SMA nut. The hardness should tell me this, but I'm not used to this scale and not so confident.

author: Lord of nothing
author_rank: Super Contributor
timestamp: September 03, 2018, 02:20:52 pm
content: https://www.ebay.de/itm/50pcs-Red-Plastic-Covers-Dust-Cap-For-RP-SMA-SMA-Female-RF-Connector-Adapter/290646804498?epid=1931333771&hash=item43abe64812:g:soMAAMXQdGJRy5oZhttps://www.ebay.de/itm/100pcs-Black-Plastic-Covers-Dust-Cap-for-RP-SMA-SMA-Female-Connector-RF-Adapter/300741385727?epid=1931989397&hash=item4605955dff:g:cYAAAOxy4RpRy5epthere are tonns off different on ebay.

author: coppercone2
author_rank: Super Contributor
timestamp: September 03, 2018, 03:01:11 pm
content: Get the ones that screw on if you can.

author: LukeW
author_rank: Frequent Contributor
timestamp: September 08, 2018, 03:08:07 am
content: It seems like one of those objects you find occasionally that is easy and cheap to buy on AliExpress, but impossible to buy anywhere else.You could try Amazon.I don't know how long they will take to ship.https://www.amazon.com/Plastic-Covers-Female-Connector-Adapter/dp/B00PRGR2OY

author: coppercone2
author_rank: Super Contributor
timestamp: September 09, 2018, 07:33:28 pm
content: don't you guys hate how you have all the exposed BNC and SMA and other threaded connectors in the lab? Why the hell is this always aftermarket item? I mean do people just expect that you have a excess of these things lying around? And the protector needs to have threads which are compatible with the grade of the connector used.I have a handful of caps I keep on my stuff but it would be nice if people supplied the metal ones. I mean come on, its not a complete product. Their sensitive to dust and shit... the rubber nipples suck. I never want to deal with prying them on and off.Banana plugs I live with but everything else just seems sloppy to leave uncovered. Also you can dent them. Maybe i should no longer put up with exposed banana plugs either.I am pretty sure those fucking nipples are meant to be put on exposed bolts. I only approve them on a exposed hose barb because there is no good way to protect a hose barb. Like your using mcmaster car bolt protection products for sensitive RF shit. I doubt it can do ESD damage but its so hodge podge. Good equipment has little ball chains that connect to protectors/open connectors for most things. Military equipment does it.The only problem I see with them being attached to the equipment, is that they can accumulate debris in them the port is being occupied. Lol, ideally you would have a tiny little compartment (like for fuses) that pops out so you can place the protector inside of the equipment. But thats never gonna happen, hell will freeze over before this is considered. It would need to be well engineered to be useful.. but for people that care so much they probobly have a little microfiber lined box that they store the connectors in, or whatever it is (suade?)Infact my spectrum analyzer looks like bobo the clown because I ran out of BNC protectors so you have a little fucking red nipple covering the BNC near two properly covered SMA connectors which look like eyes.If its some subassembly meant to be installed in something or a RF can meant to go inside of something I can kinda see it but its still fairly trashy. I think its some kind of ESD hazard maybe.As for their use on bolts, I think maybe its better to use correctly sized bolts, but I can appreciate the tiny bit of extra safety you get if a thread fails (however based on shock experiments its not much, it seems that when one yields the force is big enough to mess all of them up, and I don't really see the bolt failing before the nut does). It may make assembly a bit easier if you have a longer bolt if you don't have tools. I guess you can cut them to some minimum size that makes sense.I think I generally dislike this product. It also reminds me of a unpleasant to wear condom. I think it should be relegated to shipping bolts, in case you drop one on something hard. But no one protects bolts anyway, and to do it real proper you would ship them like ammunition lined up in little plastic containers.

author: aylons
author_rank: Unknown
timestamp: September 09, 2018, 08:29:14 pm
content: Hey folks,I generally agree that the metal ones are better for using in equipment. But this is not my intent - I want to cover tens of SMA cables that will be loose in the installation for further expansion (it is a big and complicated machine and passing the cables and installing them at the racks all at once will be much better). Using the metal threaded protection is cost prohibitive and an overkill.I'm not worried about the threads because it will cover the nut on a male SMA connector, not the thread on the female. In my experience, however, the rubber works better for cables and loose adapters, as it will protect the thread from impact up to the bottom of the thread, while the metal cover will only cover the beginning. I reserve the metal one for equipment-mounted connector, with the small chain attaching it to the chassis.The exception is off-the-shelf instruments, which usually do not have the anchor for the chain. In this case, I try to use a saver connector instead of connecting the cables directly to the equipment connector. Rarely used connectors are covered by either hard plastic caps or metal caps.

author: coppercone2
author_rank: Super Contributor
timestamp: September 09, 2018, 08:32:02 pm
content: i want a big oversized foam thing that screws onto stuff like VNA cables. I don't care how ridiclous it looks.

author: TheSteve
author_rank: Unknown
timestamp: September 10, 2018, 12:02:40 am
content: For precision connectors I wouldn't want metal caps, they will just accelerate thread wear.

author: aylons
author_rank: Unknown
timestamp: September 10, 2018, 12:27:23 am
content: Quote from: coppercone2 on September 09, 2018, 08:32:02 pmThis may be a good idea, as long as the foam does not leave residue in the thread or inside the connector. In this case, it would be terrible.Quote from: TheSteve on September 10, 2018, 12:02:40 amThat's why I use them only in rarely used connectors. Threading once in a blue moon with a quality cap will not deteriorate the thread. For often used connectors, a saver is a must.

author: coppercone2
author_rank: Super Contributor
timestamp: September 10, 2018, 01:14:04 am
content: i never tigthen them down real tight. I figured most o the ware happens because of the proper torque? just until you feel a bit of resistance. you can turn it a few times then you feel a bit of friction.the whole thing with RF connectors is really annoying because you can't really lubricate them, but your supposed to lubricate freaking metal. If their steel your coefficent of friction drops from 0.8 to 0.2. 4 times. And the oil acts like a dust trap, so unless their always covered you get a problem.Oh yea, think that gold plating is great? Gold has coefficent of friction of 2.5 on gold.Do they have soft plastic ones that actually screw on? rather then trying to yank off a bolt cap? Sometimes those stupid condoms require pliers to remove (particularly on BNC). plastic/aluminum might be worse too because if anything abrasive gets in it, its gonna embed and turn into a grinding stone, that can't be cleaned (like you make laps by putting diamond dust into aluminum by pressing it in with a few pounds of force). How the heck are you gonna remove an embedded particle in a plastic thread?Sliding those condoms on can maybe do the same thing, you can defiantly scratch things by dragging a dirty rag on them.In any case, I proclaim RF chassis connectors are all broken and they should have a secondary thread or lug to attach a cap to.Did anyone here ever do VNA experiments with various connectors with lubricant (PTFE or silicone preferred) on them? It's SO tempting. You would just need to throughly clean every time, and mechanically it would be better, but Microwave wise...I also suspect if its lubricated, and there is a grindy particle in there, it won't get stuck so easily even after doing its damage on softer connectors.I'm thinking about it too and it might be the case that a light grease film improves thermal conductivity because you won't have insulating air voids around the asparities that are making contact. It might make it more stable since you won't have them becoming as ductile due to spot heating potentially, this will change the mating resistance, so you wanna keep it the same rather then make it a bees dick better because it effects the calibration.

author: Howardlong
author_rank: Super Contributor
timestamp: September 10, 2018, 07:13:53 pm
content: Any good? I weighed them out at 400+ units. I usually throw them away, they're a PITA to remove when you're testing hundreds of units at a time.You can have them for nothing other than a virtual beer.

author: aylons
author_rank: Unknown
timestamp: September 10, 2018, 07:30:23 pm
content: Quote from: Howardlong on September 10, 2018, 07:13:53 pmWell, I can't pass such generosity, but I insist on paying shipping and a real beer. I'll DM you.