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duplexers, antennas, repeaters
In article ,
Jeff Liebermann wrote: Sorta. I have problems securely attaching connectors to RG-213/u. Unlike the rigid and semi-rigid cables, crimp type connectors are problematic. In addition, much of the RG-213/u floating around is NOT silver plated, but bare copper. That will corrode, and form diodes. Yeah, you have to make sure you're getting the "good stuff", with silver-plated copper braid... and then (I think) solder, rather than crimp. Interesting. I always hear people bragging about LMR. Are we using the term "Heliax" generically? Is semi-flex no good too, (It's all aluminum and brass metallically isn't it?) A picture is worth 1000 words: Heliax: http://www.google.com/search?tbm=isch&q=heliax LMR type coax: http://www.google.com/search?tbm=isch&q=LMR+coax I've never heard of semi-flex. Perhaps you mean semi-rigid coax, which includes aluminum outer jacket coax as used in the CATV industry? The coax is fine, but where it transitions to a brass or silver plated connector, there's a problem. In general, it's a bad idea for reducing PIM (although I use CATV coax because I'm cheap). See http://www.isoconnector.com/cableassemblies.html - "semi-rigid" and "semi-flex" are different constructions. Cramolin is now DeOxit and has been reformulated. Well, sorta and sorta not. Cramolin is still made by the original (German) manufacturer, but isn't easily acquired in the U.S. DeOxIt is made by Caig, who used to import Cramolin but are now making a similar product themselves. It's a total disaster on RF connectors because it contains oleic acid, which is great for removing oxides from electrical contacts, but equally good at rotting off the plating from connectors over long time periods. The reformulated DeOxit allegedly contains a different anti-oxidant, which allegedly has the same effect. My recollection is that the instructions which came with Cramolin said that you should clean the remains of the "red" Cramolin (the oxide remover) off of the contacts after de-oxidizing. They made another "blue" product which was intended to provide some residual anti-re-tarnishing protection... I think it was based on palm oil. When I use Cramolin (I still have a bit of the concentrate) or DeOxIt on contacts, I follow it with a final cleaning using isopropyl or denatured alcohol (or acetone if I'm feeling really thorough), to remove the remains of the anti-oxidant. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
duplexers, antennas, repeaters
On Sun, 11 Sep 2011 17:29:04 +0000 (UTC), "Geoffrey S. Mendelson"
wrote: Jeff Liebermann wrote: Cramolin is now DeOxit and has been reformulated. http://store.caig.com/s.nl/sc.2/.f It's a total disaster on RF connectors because it contains oleic acid, which is great for removing oxides from electrical contacts, but equally good at rotting off the plating from connectors over long time periods. The reformulated DeOxit allegedly contains a different anti-oxidant, which allegedly has the same effect. Cramolin is still alive and well. It was and still is made in Germany, DeOxit is made in the US, Caig used to be the US distributor of Cramolin products, but went their own way, with a different formula. Got it. All I can find it DeOxit in California. More detail: http://siber-sonic.com/electronics/caig.html I'm not sure which one is the one that you call "a total disaster", but AFIK neither is to be used for anything except cleaning. Caig sells solutions (pardon the pun) for use on connectors. Different stuff. Most of it is just grease to keep the connectors from oxidizing. The total disaster was what I found on a tower where someone had used Cramolin to clean an assortment of 7/16 DIN and N connectors. The 7/16 DIN connectors were stainless. They turned black and had a rough pitted surface. The N-connectors were silver on brass. The silver was intact, but would flake off in small pieces, exposing the underlying brass, which rapidly turned dark green. Everything had to be replaced. I don't recall how long it took to get to this point but I think it was at least 2-3 years. If you Google for corrosion characteristics of oleic acid, you'll find that it attacks steels, but is compatible with copper. Not true. Pure oleic is compatible, but add some water and the stuff becomes corrosive. Oleic acid is a major component (70%?) of peanut oil. You could probably use peanut oil mixed with some organic solvent in place of Cramolin. (No, I haven't tried it). I have them because I can only buy DeOxit in small tubes off of eBay and still get it shipped here, and that was the only way I could get fader lube, but I have never used them. Don't go looking it up and show me auctions of just fader lube, after I ordered the sets, which did not show I up, I commented to the vendor that I wanted just the fader lube and now they list it. They also replaced the missing packages. I mix many of my own chemicals. Most of the tuner lube type stuff is fairly simple. Organic solvent, ionic solvent (water soluble), oxide remover, and some oil: http://store.caig.com/s.nl/sc.2/category.293/.f -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
duplexers, antennas, repeaters
Jeff Liebermann wrote:
Got it. All I can find it DeOxit in California. More detail: http://siber-sonic.com/electronics/caig.html I believe on of the reasons that Caig stopped carrying it was that it is too corrosive to put on an airplane and they wanted something UPS/FEDEX would carry. Different stuff. Most of it is just grease to keep the connectors from oxidizing. The total disaster was what I found on a tower where someone had used Cramolin to clean an assortment of 7/16 DIN and N connectors. The 7/16 DIN connectors were stainless. They turned black and had a rough pitted surface. The N-connectors were silver on brass. The silver was intact, but would flake off in small pieces, exposing the underlying brass, which rapidly turned dark green. Everything had to be replaced. I don't recall how long it took to get to this point but I think it was at least 2-3 years. Ok, good thing I only use it to clean contacts and that's a drop on the end of a q-tip or toothpick. I mix many of my own chemicals. Most of the tuner lube type stuff is fairly simple. Organic solvent, ionic solvent (water soluble), oxide remover, and some oil: http://store.caig.com/s.nl/sc.2/category.293/.f For me those days have passed. Between space limitations, lack of working area, inability to order those chemicals, etc, I'm going to have to make do with little tubes sent airmail. Luckily I don't need much and have all I need for a long time. :-) Geoff. -- Geoffrey S. Mendelson N3OWJ/4X1GM Making your enemy reliant on software you support is the best revenge. |
duplexers, antennas, repeaters
"Dave Platt" wrote in message ... snip When I use Cramolin (I still have a bit of the concentrate) or DeOxIt on contacts, I follow it with a final cleaning using isopropyl or denatured alcohol (or acetone if I'm feeling really thorough), to remove the remains of the anti-oxidant. Isn't there any concern for plastic deterioration from the acetone? When I read what you wrote, I cringed, having seen acetone's effect on (some) plastics. Keeping a few four-leaf clovers on the bench? 73, Sal |
duplexers, antennas, repeaters
On Sun, 11 Sep 2011 18:39:04 +0000 (UTC), "Geoffrey S. Mendelson"
wrote: I believe on of the reasons that Caig stopped carrying it was that it is too corrosive to put on an airplane and they wanted something UPS/FEDEX would carry. Duh... They carry peanut oil, which is 75% oleic acid, but won't carry Cramolin, which is 5% oleic acid. I just checked the 49 CFR list at: http://www.ups.com/content/us/en/resources/ship/hazardous/download/chemical.html and Oleic acid isn't listed. The MSDS sheet shows slightly flamable, but otherwise safe. My guess(tm) is the business relationship fell apart and that the UPS/Fedex story isn't true. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
duplexers, antennas, repeaters
On 10 Sep 2011 18:27:58 GMT, dave wrote:
Cell sites are a different animal . We were talking about 2-way, point-to-point, VHF/UHF broadcast type sites. Perhaps you didn't notice but several of the examples of PIM and rotten coax induced intermod were for non-cellular systems. The problems are much the same with any service type. If you have moderate TX power, magnetic materials in the connectors, and sensitive receivers, PIM might be a concern. Also, it may not be obvious unless you've worked on a cell site, but the state-o-de-art in radio is currently defined by cellular. The current generation of cellular radios, pre-distorting power amps, tower mounted amps, cryogenic front ends, steerable antennas, channel loading, codecs, and environmental protections, are far superior to what I've seen in commercial radio, and light years ahead of the 3rd hand garbage commonly found in ham repeaters. Yes, cellular is different, but it's also quite superior. If the cellular people think they have a PIM problem, it's probably quite real. Unfortunately, cellular can't always get everything right: http://802.11junk.com/jeffl/SCCARC-talk-2010-06-18/Burning-Towers.htm http://www.cellsiteanalysis.net/cell_site_analysis_images/Cell_Site_Mast_Loaded.jpg YouTube is pretty intense. Duz that mean that you still haven't watched the video clip? -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
duplexers, antennas, repeaters
When I use Cramolin (I still have a bit of the concentrate) or DeOxIt
on contacts, I follow it with a final cleaning using isopropyl or denatured alcohol (or acetone if I'm feeling really thorough), to remove the remains of the anti-oxidant. Isn't there any concern for plastic deterioration from the acetone? When I read what you wrote, I cringed, having seen acetone's effect on (some) plastics. Keeping a few four-leaf clovers on the bench? It depends on what sort of thing I'm cleaning. You're correct... I don't use acetone on anything plastic. Depending on the plastic, either an alcohol, or a light petroleum solvent (Stoddard solvent, naptha, etc.) is a safer "wash". -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
duplexers, antennas, repeaters
In article ,
Jeff Liebermann wrote: When I use Cramolin (I still have a bit of the concentrate) or DeOxIt on contacts, I follow it with a final cleaning using isopropyl or denatured alcohol (or acetone if I'm feeling really thorough), to remove the remains of the anti-oxidant. I use 409 cleaner, which has a pH of about 11, or ammonia window cleaner, both of which should neutralize the acid. Acetone will make a mess of anything plastic and really is overkill. True - it's for metals-only applications. For open frame relays, I sometime use electroless silver to replate the contacts. Is that Cool-Amp (powder), or some form of liquid electroless silver? I've made up (and use) a homebrew substitute for Cool-Amp - silver chloride and salt, finely ground, and then rubbed in firmly. Makes a nice, solderable surface for DIY PC boards. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
duplexers, antennas, repeaters
On Sun, 11 Sep 2011 16:57:02 -0700, (Dave Platt)
wrote: For open frame relays, I sometime use electroless silver to replate the contacts. Is that Cool-Amp (powder), or some form of liquid electroless silver? http://www.cool-amp.com/cool_amp.html That's silver chloride and calcium carbonate powder. $25/oz. Ouch. I've used Cool-Amp immersion plating (it's not really electroless). It works well for PCB and contact plating. You might find this of interest: http://yarchive.net/electr/pc_board_silver_plating.html What I have is: http://www.transene.com/ag.html I think (not sure) it's a silver nitrate, ammonia, sodium hydroxide, and who knows what else mix. One catch is that it has to be applied warm, which is somewhat of a challenge. I'm sure easier to use stuff exists, but I didn't pay much for the 1 oz bottle which seems to be lasting forever. When I run out in about 10 years, I'll look at alternatives. Mo http://www.finishing.com/faqs/silverathome.shtml I've made up (and use) a homebrew substitute for Cool-Amp - silver chloride and salt, finely ground, and then rubbed in firmly. Makes a nice, solderable surface for DIY PC boards. Nice, but don't use salt. Use calcium carbonate instead. Salt (sodium chloride) might precipitate the silver out at silver chloride. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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