Weatherproffing stainless steel antenna elements - Page 1
Forum section: electronics / rf-microwave

author: videobruce
author_rank: Frequent Contributor
timestamp: March 18, 2021, 10:56:42 pm
content: I just purchased a Nagoya NMO-200A dual band (mobile) vertical with the matching ground plane adapter for base station use. It's all stainless steel, but my concern are all the 'fittings, both the vertical and the horizontal elements are all 2 piece with set screws.What I am considering using is either "Noalox" (made by Ideal Industries) or Deoxit D5 (made by Caig Laboratories) on all the fittings & set screws. Both are 'anti-oxidants" and both are highly recommended for electrical/electronic connections especially the Deoxit D5.According to each container;the Noalox states "reduces galling & seizing, promotes good ground continuity". This is a spray. It's more for electronics and for model railroad nickel silver track.the Deoxit D5 states "removes oxidation, improves connections, seals & protects surfaces". This is a paste which is more for electrical connections 120/240 volt etc.What do you think, I don't like exposed connections, cables or otherwise in spite of them being SS.

author: bob91343
author_rank: Super Contributor
timestamp: March 18, 2021, 11:55:30 pm
content: I don't use either of those. My choice is molybdenum disulfide, available as 'Anti-Seize' or similar names. If I don't want to disassemble the joints frequently I will wrap with stuff called rubber tape, self vulcanizing. It's cheap enough and lasts forever in the outdoors. You may have to slice it off but so what.

author: coppercone2
author_rank: Super Contributor
timestamp: March 19, 2021, 03:59:24 am
content: moly-d is going to look like someone smeared tar on it, I do not recommend, very dirty stuff meant for well sealed gear boxes IMOWhat I do recommend is the deoxit bearing grease. They sell a caig brand grease that has deoxit in it, either plain grease or grease with particles (like thermal transfer compound, I think they have a moly-d bearing deoxit bearing grease also, but why? Moly-d is meant for high loads and low friction and thermal transfer I think, meaning its great inside of a gear box, but I don't think an antenna will benefit from these at all and it will just be extra messy. You will unscrew it and end up ruining a shirt, I personally hate dealing with black grease!The normal one is pretty transparant (like bacon lard) but it does have a bit of an aromaNoalox also sells a actual grease in a little tub.I feel like deoxit is not great for outdoor exposed applications, more like outlets and stuff with covers.It is D260 I think. Nice little tube and you can smear it on batteries and other stuff.Another very good corrosion inhibitor is the WD40 corrosion inhibitor, but it smells like naphtalene, pretty horrible stuff. I use that to maintain trash in severe environments.And NOALOX the kind you have is some stuff meant for aluminum, read the instructions, you are supposed to abbrade the aluminum and use it to prevent aluminum wiring fires, I would not use it for anything else. Having particles around stainless steel can make it worse maybe.. I would not add stuff you don't need there. If you just want it super clear then use crc silicone grease.https://caig.com/deoxit-grease-landing/

author: Ian.M
author_rank: Super Contributor
timestamp: March 19, 2021, 04:40:24 am
content: The trouble with many grades of stainless steel is it can suffer from severe crevice corrosion in the presence of moisture if you exclude oxygen from its surface. You therefore have to be *VERY* careful *NOT* to apply rubber self-amalgamating tape in such a way that it may trap moisture. In the presence of dirt and moisture, even an O ring or lip seal can exclude enough oxygen under it to cause pitting the size of cooked long-grain rice in under four months without movement.I strongly recommend using Lanocote grease, or pure anhydrous lanolin to pack all cavities in those joints, and I believe any sailor who does their own maintenance would agree. Lanocote is unfortunately brown and smells of wet sheep, but you can wipe off all the excess fairly easily. If you want a lower odor alternative that looks better, use pharmaceutical grade purified anhydrous lanolin.

author: videobruce
author_rank: Frequent Contributor
timestamp: March 19, 2021, 12:50:15 pm
content: I forgot that I have some NO-OX-ID "A Special" from Sanchem Inc. (outside of Chicago).It was highly recommended for model railroad track which I have and used it on to prevent oxidation of nickle silver rail (common problem). Thou, in that application it's applied, let sit, the wiped off.It is a thick 'grease' (brownish) which seems close to what coppercone2 recommended;https://www.sanchem.com/electrical-contact-lubricant.html

author: Ian.M
author_rank: Super Contributor
timestamp: March 19, 2021, 01:56:23 pm
content: Read this:https://www.w8ji.com/dielectric_grease_vs_conductive_grease.htmThen try to make some sense of Sanchem's somewhat schizophrenic marketing blurb for NO-OX-ID "A Special", which claims to be "conductive grease", yet they have paragraphs on the evils of metal particle loaded grease:Quote from: NO-OX-ID A-Special Electrical Grade.pdfHopefully it doesn't contain graphite, as that causes similar problems to metal particles.The problem with any conductive grease, when exposed to the weather is the risk of electrolytic corrosion due to dissimilar metals (or metal and carbon) in contact, if the grease fails to totally exclude moisture from the contact surface between the metal its on and the metal (or graphite) particles in the grease.Hopefully NO-OX-ID "A Special" is actually a dielectric grease and they are miscalling it "conductive grease" because a significant proportion of their customer base is so misinformed that they believe a dielectric grease will form an insulating film that prevents or worsens contact, and is so irrational that they cant be educated.Assuming it is a dielectric grease, it should be suitable for the application. . .

author: videobruce
author_rank: Frequent Contributor
timestamp: March 19, 2021, 05:42:06 pm
content: You are starting to rain on my parade.More reading..........

author: coppercone2
author_rank: Super Contributor
timestamp: March 19, 2021, 07:37:46 pm
content: dexoit says it too, it must depend on how good the thread and connector is. Some fucked up garbage screw terminal might benefit but smearing metal infused on a APC connector will not be good. I.e. if there is a piece of copper in the grease that wedges into a cavity under one of those pointy star washers on some metal you gouged up with a knife to get the rust off, I can see that making things better maybe.You need to keep in mind maybe not everything is nice slowly multiple grind finish, but stamped out on a machine running at ridiculous speeds where the stuff is jumping across some kind of assembly line, or the repair procedure is 'make it look shiny with yer blade before you put er back together' (well at least you won't have grits of sand in the area after?)I could see it maybe working on something like a car battery terminal too, they are severely mangled and abused and it seems like it would benefit electrically from bondo at times..I do have a miliohm meter, and it almost sounds fun to try to compare the greases. Any ideas? If someone makes a good experiment maybe I can buy one of those copper infused deoxit greases and compare to normal grease. You might need a microohm meter thoughand it might be like:apply grease with metal and have it be at a higher resistance until 3 months later someone drops a heavy toolbox filled with wrenches on the connector and its bent back into place with a screw driver and a brick.I think the problem is.. we are pretty clean and precise people with high parts standards. But its not economical for industry to be this way depending on where it is (some guys have big numbers but the net numbers are trash so everything is shaved for dollars in some industries, which explains why this grease exists).

author: TheMG
author_rank: Frequent Contributor
timestamp: March 19, 2021, 07:47:34 pm
content: I would just leave it alone.Make sure to use only the original hardware and fasteners (presumably they are also stainless steel). Dissimilar metals, generally speaking, are your enemy when it comes to corrosion.If you want, you can apply a light oil sparingly to the threads to help prevent galling (some grades of stainless steel can be more susceptible to this than others).It will be fine.

author: coppercone2
author_rank: Super Contributor
timestamp: March 19, 2021, 07:50:54 pm
content: oh right the best choice for this actually might be deoxitshield. That will protect against acid rain I think.I have it in the 'nail polish' bottle.https://caig.com/deoxit-shield-s-series/The specific claim is that it does things to prevent sulfur damage, which may be a concern if it is out in the rain and there is acid rain.I kind of want to see what a custom formulation of deoxit grease with extra deoxit shield active compound would be. I have a MHz monopole antenna that is pretty long with a screw on the bottom, I always wondered what the best way to connect it outdoors would be.If I recall the resistance of the shield deoxit is oh so slightly higher then the resistance of the normal deoxit when measured with a SMU, but over time it should win out, but I don't have the facilities or drives to do those tests. i trust it to be honest.. But I would want a pulse SMU or pulse microohm meter for measuring this, and the robrenz custom kelvin clips. I think as you imagining simulating acid rain is not too easy.I would need to be paid to evaluate this lol. boooring

author: cdev
author_rank: Super Contributor
timestamp: March 21, 2021, 10:15:14 pm
content: I would explore using lithium grease (no its not conductive, but I have gotten very low ohms readings using it with a roller inductor) I don't think its conductive) I had good luck with Genie brand which comes in small tubes for use with garage door bearings. their web site is geniecompany.comAfter it was recommended by hams I've used it it on an antenna tuner (one thats only used for receive) t worked great, resulting in a noticable improvement in the contacts. both a roller inductor and on my x-y table which is a semi-precision application. It's also an excellent lubricant on screw bearings (what its designed for) It made the adjustments for position on my x-y table vise feel as smooth as silk. Which is nice. I don't think it's waterproof but I would expect it to help preserve connection integrity at least a bit, by keeping a protective grease coating in where the metals meet. I wouldn't expect it to handleRF power but it has for others. (Hams using it up to the legal limit on antenna tuners swear by it.) Its also cheap.Quote from: bob91343 on March 18, 2021, 11:55:30 pmI love that kind of tape. If you pull it really tight, I'd expect it to make excellent waterproofing on RF coax terminations.Sometimes its called "self-amalgamating tape" or "self-fusing" tape.But RF loss may be significant in an RF situation if its put between conductors anywhere. . I don't know.Its good waterproofing but I wouldn't expect it to be low loss. It would keep stuff out of a antennas nooks and crannies.It does seem to make a good insulator. I'm attaching an info sheet. Its great stuff to have around because it really is durable and has good insulating properties..

author: coppercone2
author_rank: Super Contributor
timestamp: March 22, 2021, 04:01:58 am
content: yea if you are working with heavy gauge cables that stuff makes a great cover between the crimp and the rubber, and liquid electrical tape spray seems to stick to it well.I made 4/0 cables up for my resistance soldering/brazing unit, and I did this method for the cables after I soldered them with alot of high temp solder. I made sure the solder did not get into the insulation so there was some exposed copper but after you cover it up with scotch and liquid electrical tape (3 coats) it looks like almost a solid cable. Then you can put one more band of the scotch color on it if you want colors and then a small piece of clear heat shrink to put a color band on the cable.They have been around 1 year now and there is no peeling or anything and it looks pretty good, the only problem with the scotch silicone is that is is sticky, you need to coat it with something so it does not accumulate crud.It also seems to last forever, I had mine for 5 years before I found a use for it and it worked fine, unlike alot of tape products that fail. And it does not leave sticky crappy residue on things.Oh yeah, resistance brazing with silver solder would be I think the best possible way to water proof those things, I wonder if the plastic could survive.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: March 28, 2021, 07:12:10 am
content: I used to work in the mobile radio industry, pretty much all mobile antennas suffered from seized stainless rods. It was probably due to dissimilar metal to metal contact. The screws usually didn’t seize. The antennas didn’t “fail” electrically, but if suffering physical damage we would try taking parts from an old one, usually without much success.I would expect any high temperature waterproof grease to help. I have checked copper, aluminium and graphite loaded grease with a multi-meter. None are conductive, or at least not in the way we expect.