spring contact center pin on hardline connector good? - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: November 25, 2023, 03:48:29 am
content: I got these. I figured it would be solder but the center pin is actually a spring contact that attaches to the center pin of the coaxhttps://www.amphenolrf.com/901-9723.htmlI assume its good since amphenol sells it. but i really expected solder here.are these things good?

author: coppercone2
author_rank: Super Contributor
timestamp: November 25, 2023, 06:42:49 am
content: and I can see it being a explanation for some RF troubles. they expect you to file down the center pin of a coaxial connector. Now if this gets put on a buncha RF cans in a factory you can bet someone might make a mistake here. the rigid cable going open circuit seems to be a pretty common problem.or perhaps its the other way around where this won't crack like a solder joint, but having to file a tiny wire... i can see that going wrong! i happen to have a loupe that measures angle so hopefully it will be good enough. i wonder if the magnification is enough.

author: SeanB
author_rank: Super Contributor
timestamp: November 25, 2023, 11:02:56 am
content: You can bet though that Amphenol does sell a cable end preparation machine for these cables, which takes care of doing the work all for you, stripping the cable end, then cleaning off the outer to accept solder, and the inner to mate correctly. the hand method is for reword or repair, where you only have one or two per week to do, and thus can use hand tools, though I would say there are tools they sell for that as well. If you have ever used circular pin DIN military connectors, you get the hand tool to insert and extract with the service plug, but you can also have the manufacturer tools as well if you buy them, and also the proper crimp tools, or just solder them.for these the press fit, with the connector body soldered on, is a lot more reliable, as the solder does provide a seal, and thus the contact will not degrade long term, even with vibration, unlike a solder joint.

author: Professzore
author_rank: Contributor
timestamp: November 25, 2023, 05:12:08 pm
content: Hi,It depends on the purpose of use. I prefer solder on the centre pin and press-fit for the shielding for nearly all applications when the cable and the connector may be moved around at least once a year. Spring-loaded connections are for permanent setups with absolutely no movement (neither cable nor connector).In general, if you follow the instructions of both the cable and the connector manufacturer, and both are compatible with each other without any discrepancies, the whole setup will work within specs.The quality of the product will be great without question. I've never ever had any negative experiences with any of the Amphenol products. (On the other hand, I have had troubles with Hirschmann...)

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: November 25, 2023, 08:44:36 pm
content: I haven't used this particular type, though I have used an Amphenol type-N connector which requires you to solder a pin to the center conductor, solder the outer jacket to a ferrule, then thread the assembly onto the connector body. The pin makes contact with a spring-loaded socket. These are rated to 12 GHz, and were used in a benign environment (no vibration).As for filing the pin, when I assemble the more traditional semi-rigid connectors with the soldered center pin, I use an old Tyco SMA kit (59981-1), which comes with a jig (311396-1 cable-dressing fixture) that helps with filing the center pin. This is a piece of tool steel that has a sloped side and a countersunk hole through which one inserts the stripped cable. The center pin protrudes out just a tiny bit past the sloped side, and you use a file to taper the pin. Gives me good results every time. You may be able to make such a jig in the shop, it saves time when making multiple cables.What may be a bit harder to DIY is the trimmer tool included in the kit (312317-1). This has a small hole through which one inserts the stripped cable, which bottoms against a blade inside the tool. The blade scrapes off any residual copper dust or chips that may stick to the exposed dielectric on the cut face of the cable.

author: coppercone2
author_rank: Super Contributor
timestamp: November 25, 2023, 08:48:32 pm
content: I have a tiny OD countersink on a pen. Its a jewelers tool. I was hoping to use it. I heard they work but dull rather quickly. you can buy carbide ones. They are meant for wire artists / workers to deburr wire used for springs, rings, trinkets, etc. Very small....

author: coppercone2
author_rank: Super Contributor
timestamp: November 25, 2023, 08:53:04 pm
content: and yes, a semi rigid cable should be very little use I think, they don't like you bending them even. I guess it sounds like it is not appropriate for a RF probe that uses semi rigid cable, which this is not.

author: coppercone2
author_rank: Super Contributor
timestamp: December 10, 2023, 01:28:12 am
content: for stripping this stuff, I noticed I got something that works kinda OK without whatever the right tools are.Score with a brand fucking new pipe cutter then saw with a exacto blade. Poor blade life but you get a evenly cut segment without too much deformation around the end. But you need to pick at the teflon tape inside to cut that. ughthis stuff is frustrating. the 141 is much easier then 086

author: coppercone2
author_rank: Super Contributor
timestamp: December 10, 2023, 02:45:49 am
content: cable prep for these things is fucking awful. filing that little shit. big diamond file on a leatherman works, with a monaclei should have just spent a few dollars more and soldered this BS. then you can bend into shape you need, trim, and then solder, instead of having to know the exact lenght to get any semblance of process going here (getting it nice after its bent is hard)also its hard to get it in there LOL. I was tempted to add a dash of grease but IDK if its that fucking teflon tape shit in the cable I just left it dry save for a tiny bit of diluted flux on the coaxial cable exteriorbut on the positive, impedance is low. I have two more to make, so I will use a tiny bit of deoxit gold on the center pin to act as a lubricant, just a film of absolute minimum quantities. maybe that will make me like it more.Despite all looking identical, 1/4 cables took me 3 attempts to get the pin in the hole, I unbent it with plastic pliers when it went wrong. Luckily this is low frequency, I just liked the idea