At 02:58 PM 03/22/06, you wrote: >I have a shiny new Antennex FG1440 2 meter repeater antenna, and I >thought that before we install it on the tower, maybe I should put an >additional protective coating on over the fiberglass. Looking for >something that would not get brittle and crack off any time soon. Any >ideas? Urethane maybe? I once used some urethane designed as a >marine finish with great results, but I'm open to suggestions.. > >Thanks, >dave na6df
One local guy is using a double layer of white heat shrink. Went up about 3-4 months ago. Dunno how it's going to stand up to to summer sunlight / UV. The outside gelcoat is what gives fiberglass its watertight properties. Too many antennas have "died" after the fiberglass allowed rain water ingress. Be very careful that whatever you use is either clear or has a NON- METALLIC pigment, for example, many white paints get the color from titanium dioxide, a metal. Black is OK as the color comes from lampblack(carbon) and won't detune the antenna. (local urban legend comes to mind - a ham, never identified, uses white fiberglass boat paint on his short stationmaster antenna, then wonders where the signal went... finds out the white pigment is metallic... realizes that he just put a shielding coating on the radiating element and ended using the antenna as a very expensive plant stake) If you have a body shop in your area that specializes in fiberglass work (look under "Corvette" in the yellow pages) I'd start there. If you live in a maritime area, look for boat shops that specialize in fiberglass. A number of years ago a local ham took a super stationmaster that was shedding to a local body shop and they did a very good job of resurfacing it. He found the shop by an interesting method: one day he passed a late 1950s Corvette on the street and saw in his rear view mirror the 'vett pull into a fast food place. He drove around the block and pulled in, then walked into the place. A few minutes of talking to the 'vette owner and he had the name and location of a shop that did good fiberglass work. He just told the shop manager that final cosmetics were not as important as something that was as good as the original coating... or better. The antenna was 15 years old and it needed to last another 15. The manager promised to load the fiberglass outer coating up with lots of UV inhibitor. Despite the comments about cosmetics they did a beautiful job of resurfacing the radome, coating it and applying a nice clear gell coat to the antenna, which, as I understand it, is still in service. Personally, I would use what Celwave recommends even though it's about $150 a gallon. maybe more by now. This is a paint by Sherwin Williams, Polane Type "HS 2.8 Plus Polyurethane", along with the appropriate catalyst Any good paint store should be able to get this, or its equivalent for you. You can sometimes get quart samples for asking for them. If not, buy a quart (about $40). It will do two or three short antennas. But don't get the silver color... If that's out of your price range, a good grade of urethane marine paint will _probably_ work just fine. A "painters mitt" will help apply it evenly. Just wear old clothes and if you can get it, put the mitt on over a elbow or shoulder length rubber glove (talk to your vet to get one or two - and I'm talking horse and cow vet, not a dog and cat vet). And you want to do it with old (read "disposable afterwards") clothes on, and on a warm day which means that you want to do it fast enough to get that damn glove off and let your arm breathe... Better to have a helper or two to help you manhandle the antennas, and a homebrew cradle to support them from the ends only. No doubt that there are a few others around that need antennas coated - get enough paint to do all of them, split the cost between you guys and then they can be the helpers... Mike Perryman K5JMP made a comment on this list back in 2003... >If you use auto-body polyester resin, you will need to add a UV >inhibitor. If not, the surface will become very cloudy, and begin to chalk >within a month or two. In two years it will be just as before. >Even a gel-coat will begin to chalk fairly quickly if it is used without >the UV inhibitor. Also there are many different grades of polyester >resin... the grading affects flexibility / hardness... and cost!! >The auto-body grade is generally the bottom of the barrel, so to >speak. There are many reasons the that the correct paint is >expensive... first of all, it works. And will last for 10 yrs plus > >IMHO.. West Systems Epoxy would be the way to go. You can tint it >any color you want (being careful not use metallic pigment is a must!!). >Or, use their gel coat. You can also add a UV inhibitor for a few bucks >more. I have used this stuff many times in the past for with outstanding >results. It, however, costs more than the Polane. I used to work in a >"custom fiberglass shop" back when dino's roamed the earth. We produced >fiberglass/carbon fiber bodies for race cars. TOO much experience doing >"hand-layup" of 'glass!!! We found that the better quality stuff is just exactly >that.... Better Quality! > >One other thought.. If I were to re-gel my stationmaster antenna, I would >want it to last for many years. Our site requires a bonded rigger to >satisfy insurance purposes. I can't afford a couple a grand every two or >three years to hire the tower crew. In effect the proper paint will save >you money in the long run, and maybe prevent damage to the radome. Which was followed by a posting from Ralph Mowery KU4PT which included the following info, with a 1998 date. The area code may have changed, and Mr. Stadalman may no longer be there. >Antenna Painting Instructions > >The following is courtesy Celwave This is what I received when I asked > them for a recommendation of what to use in refinishing my 18 year > old PD455 > >>Celwave receives requests for advice about refinishing weathered antenna >>radomes or changing the radome color for aesthetic reasons. We do not >>take a position on any manufacturer's paint. However, Sherwin-Williams >>seems to make a product, which should be compatible with radomes and >>not interfere with the antenna's electrical performance. The following >>suggestions are not a substitute for detailed instructions and mix ratios >>provided by the paint manufacturer. >> >> >>RADOME MATERIAL (Standard Color) >> CELWAVE PRODUCT LINE >>1. Spun Epoxy Fiberglass (Blue) >> Penetrator Antennas (AxR, BxR Series) >> 2. Polyester Impregnated Fiberglass (White) >> Stationmaster Antennas (PDxx Omni Series.) >> 3. Polyester Impregnated Fiberglass (Grey) >> FR CELlite Panel Antennas (AP18, 19 Series) >> 4. ASA (Grey) >> FR CELlite Panel Antennas (AP90 Series) >> 5. AES/ABS (White or Grey) >> US Panel Antennas (Other APxx Models) >> 6. Gel Coated Fiberglass Tubing (White) >> Marine Antennas (Cel-1, 3 etc.) >> >>Notes: >> >> FOR RADOME MATERIAL USE THIS FINISH #1, #2, #3 >> Primer and Top Coat #4, #5 >> Primer may be required ---- >> >> (Top Coat retention may be tested with adhesive tape after >>paint dries) >> #6 Requires Pre-Treat (Acid Etch) to remove gloss, then Primer >>and Top Coat >> >>SHERWIN-WILLIAMS PRODUCTS: >> >> Etch P60G2 "Wash Primer" >> Primer D61H75 "Polane 2.8 Plus Spray Fil" >> Top Coat Polane Type "HS 2.8 Plus Polyurethane" >> >>SURFACE PREPARATION: >> >>Removal of surface contamination is normally accomplished by using an >>alcohol solvent, ethanol, propanol, isopropanol, or butanol. A ten percent >>solution of methyl ethyl ketone in water can also be used whenever >>stubborn oil or grease is encountered. >> >>APPLICATION PROCEDURES: >> >>Painting to be done indoors, as the uncured product is sensitive to >>moisture. Apply one coat of Polane 2.8 Plus Spray Fil D61H75 Primer. >>It is designed to fill and/or hide profile and surface imperfections on >>metal castings, structural foam, plastic and wood. Apply one coat of >>Polane HS 2.8 Plus Polyurethane Enamel Monochromatic Intermix >>Color System F63 Series. >> >>FOR FURTHER S-W PRODUCT INFORMATION CONTACT: >> >> Ralph Stadalman - Product Finishing Representative >> The Sherwin-Williams Company >> Chemical Coating Facility >> 3165 Tucker Road Bensalem, PA 19020 >> Voice = (215) 638-0104 >> Fax = (215) 638-1008 The current version of this same info is at <http://www.celwave.com/index.php?p=184&l=1&listName=applicationnotes&indexVal=1&sid=6400d322df365b7270dab831251e3b57> Mike WA6ILQ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
