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Keeping moisture out of 9913 type coax?
Just wonder what other's might do to keep moisture from getting into the semi-hollow 9913 type low loss coax. It would seem inevitiable with changes in temperature and pressure that moist air would eventually work its way into the coax and then condense. I had a fellow ham that took the precaution of pressurizing this type of coax to maintain positive pressure and keep out outside air. Seemed like a lot of effort but maybe it is necessary. I have tried to seal the ends of the coax with silicone sealant but I am not really sure that this has been effective in the long term. What do others do? What has been your experience? Dave - K8RSP (to reply to me directly remove NOSPAM from above address) |
As with all of my external cable connections (excluding mobile
installs), I use good quality plugs that physically screw together. The when I am finished, I use self amalgamating tape (costs about $20 Aust per roll) which provides a weatherproof seal around the connection - have cut the tape off plugs which I have done ten or more years previously to find them as dry as the day I put them together. On top of the self amalgamating tape, I use the normal electrical tape to give the birds something to peck at before they reach the self amalgamating tape (bloody cockies can be ferocious with antennas and coaxial cable here). I believe that the only way that coax is going to become water effected is if it directly exposed to water (i.e. rain), and once you have put the connector on the end of the cable, screwed it into the antenna and taped it up, the chances of water getting into it are very remote (bar the outer layer being cracked, cut or abraded). In my opinion, pressurising the cable is not something that is needed for the average hobbyist. Matt Dave Woolf wrote in message ... Just wonder what other's might do to keep moisture from getting into the semi-hollow 9913 type low loss coax. It would seem inevitiable with changes in temperature and pressure that moist air would eventually work its way into the coax and then condense. I had a fellow ham that took the precaution of pressurizing this type of coax to maintain positive pressure and keep out outside air. Seemed like a lot of effort but maybe it is necessary. I have tried to seal the ends of the coax with silicone sealant but I am not really sure that this has been effective in the long term. What do others do? What has been your experience? Dave - K8RSP (to reply to me directly remove NOSPAM from above address) |
On Wed, 31 Dec 2003 16:08:10 +1100, "Matt"
wrote: As with all of my external cable connections (excluding mobile installs), I use good quality plugs that physically screw together. The when I am finished, I use self amalgamating tape (costs about $20 Aust per roll) which provides a weatherproof seal around the connection - have cut the tape off plugs which I have done ten or more years previously to find them as dry as the day I put them together. On top of the self amalgamating tape, I use the normal electrical tape to give the birds something to peck at before they reach the self amalgamating tape (bloody cockies can be ferocious with antennas and coaxial cable here). I believe that the only way that coax is going to become water effected is if it directly exposed to water (i.e. rain), and once you have put the connector on the end of the cable, screwed it into the antenna and taped it up, the chances of water getting into it are very remote (bar the outer layer being cracked, cut or abraded). In my opinion, pressurising the cable is not something that is needed for the average hobbyist. It only took one lightening strike to change my mind about waterproofing 9913. I used coax seal and taped over that. The tower took a hit that removed every single bit of tape and coax seal from up there. I found the coax seal on the ground. It looked like some one had cut down one side and peeled it off. Then cut it so it looked like one of those pieces of expanded metal. It even removed the silver plating from the connectors. 15 minutes after the lightening strike I had water running out of my 2-meter rig. I ordered 1500 feet of LMR 400 right soon after. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair?) www.rogerhalstead.com Matt Dave Woolf wrote in message ... Just wonder what other's might do to keep moisture from getting into the semi-hollow 9913 type low loss coax. It would seem inevitiable with changes in temperature and pressure that moist air would eventually work its way into the coax and then condense. I had a fellow ham that took the precaution of pressurizing this type of coax to maintain positive pressure and keep out outside air. Seemed like a lot of effort but maybe it is necessary. I have tried to seal the ends of the coax with silicone sealant but I am not really sure that this has been effective in the long term. What do others do? What has been your experience? Dave - K8RSP (to reply to me directly remove NOSPAM from above address) |
Nasty, but unusual - in 20 years of playing with radios, I have not had
the problem that you have mentioned, but then again, I guess that I don't have a huge lightening rod of a tower that you do (bloody nice BTW). For the average user, the procedures I have mentioned will suffice 99.99% of the time (looks anxiously up into the sky to check for lighteningg). Matt Roger Halstead wrote in message ... On Wed, 31 Dec 2003 16:08:10 +1100, "Matt" wrote: As with all of my external cable connections (excluding mobile installs), I use good quality plugs that physically screw together. The when I am finished, I use self amalgamating tape (costs about $20 Aust per roll) which provides a weatherproof seal around the connection - have cut the tape off plugs which I have done ten or more years previously to find them as dry as the day I put them together. On top of the self amalgamating tape, I use the normal electrical tape to give the birds something to peck at before they reach the self amalgamating tape (bloody cockies can be ferocious with antennas and coaxial cable here). I believe that the only way that coax is going to become water effected is if it directly exposed to water (i.e. rain), and once you have put the connector on the end of the cable, screwed it into the antenna and taped it up, the chances of water getting into it are very remote (bar the outer layer being cracked, cut or abraded). In my opinion, pressurising the cable is not something that is needed for the average hobbyist. It only took one lightening strike to change my mind about waterproofing 9913. I used coax seal and taped over that. The tower took a hit that removed every single bit of tape and coax seal from up there. I found the coax seal on the ground. It looked like some one had cut down one side and peeled it off. Then cut it so it looked like one of those pieces of expanded metal. It even removed the silver plating from the connectors. 15 minutes after the lightening strike I had water running out of my 2-meter rig. I ordered 1500 feet of LMR 400 right soon after. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair?) www.rogerhalstead.com Matt Dave Woolf wrote in message ... Just wonder what other's might do to keep moisture from getting into the semi-hollow 9913 type low loss coax. It would seem inevitiable with changes in temperature and pressure that moist air would eventually work its way into the coax and then condense. I had a fellow ham that took the precaution of pressurizing this type of coax to maintain positive pressure and keep out outside air. Seemed like a lot of effort but maybe it is necessary. I have tried to seal the ends of the coax with silicone sealant but I am not really sure that this has been effective in the long term. What do others do? What has been your experience? Dave - K8RSP (to reply to me directly remove NOSPAM from above address) |
Dave Woolf wrote:
I had a fellow ham that took the precaution of pressurizing this type of coax to maintain positive pressure and keep out outside air. Seemed like a lot of effort but maybe it is necessary. Just out of curiosity: how exactly did he do this? 73 .... WA7AA -- Anti-spam measu look me up on qrz.com if you need to reply directly |
On Wed, 31 Dec 2003 17:44:21 +1100, "Matt"
wrote: Nasty, but unusual - in 20 years of playing with radios, I have not had the problem that you have mentioned, but then again, I guess that I don't have a huge lightening rod of a tower that you do (bloody nice BTW). For the average user, the procedures I have mentioned will suffice 99.99% of the time (looks anxiously up into the sky to check for lighteningg). The hit was on the old tower, but that still put the base of the repeater antenna at 90 feet, so the top would have been close to 112 feet. It hasn't been up in years. The surprising thing is the bolt took out the 7/8" Heliax about 30 feet down from the top of the tower. I did lose the front end out of one solid state 2-meter rig, but that was it. Everything else was still working including the one with the water running out. The current tower and even the old were getting hit about three times a year, but there hasn't been any damage in a while. My neighbor was looking across his back yard this past summer when the top took a direct hit. It apparently really impressed him. Now the neighbors really believe me when I tell them it's the neighborhood lightening rod:-)). OTOH I was out by the end of the driveway talking to the neighbor across the road with a storm in the distance. A strong bolt hit the power pole about 30 feet from us. We both decided we needed to be some where else... Quickly. Currently my biggest concern from lightening is the computer network. It's a 130 foot run to the shop and 25 feet in the other direction to my wife's computer. The pone line comes in underground, but it doesn't take much induced current to cost many dollars. So far, I haven't had any problems with the satellite dishes and feeds, but I have lost the antenna mounted preamp to the top UHF TV antenna. Course that may have been due to 2-meters instead of lightening.:-)) Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair?) www.rogerhalstead.com Matt Roger Halstead wrote in message .. . On Wed, 31 Dec 2003 16:08:10 +1100, "Matt" wrote: As with all of my external cable connections (excluding mobile installs), I use good quality plugs that physically screw together. The when I am finished, I use self amalgamating tape (costs about $20 Aust per roll) which provides a weatherproof seal around the connection - have cut the tape off plugs which I have done ten or more years previously to find them as dry as the day I put them together. On top of the self amalgamating tape, I use the normal electrical tape to give the birds something to peck at before they reach the self amalgamating tape (bloody cockies can be ferocious with antennas and coaxial cable here). I believe that the only way that coax is going to become water effected is if it directly exposed to water (i.e. rain), and once you have put the connector on the end of the cable, screwed it into the antenna and taped it up, the chances of water getting into it are very remote (bar the outer layer being cracked, cut or abraded). In my opinion, pressurising the cable is not something that is needed for the average hobbyist. It only took one lightening strike to change my mind about waterproofing 9913. I used coax seal and taped over that. The tower took a hit that removed every single bit of tape and coax seal from up there. I found the coax seal on the ground. It looked like some one had cut down one side and peeled it off. Then cut it so it looked like one of those pieces of expanded metal. It even removed the silver plating from the connectors. 15 minutes after the lightening strike I had water running out of my 2-meter rig. I ordered 1500 feet of LMR 400 right soon after. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair?) www.rogerhalstead.com Matt Dave Woolf wrote in message ... Just wonder what other's might do to keep moisture from getting into the semi-hollow 9913 type low loss coax. It would seem inevitiable with changes in temperature and pressure that moist air would eventually work its way into the coax and then condense. I had a fellow ham that took the precaution of pressurizing this type of coax to maintain positive pressure and keep out outside air. Seemed like a lot of effort but maybe it is necessary. I have tried to seal the ends of the coax with silicone sealant but I am not really sure that this has been effective in the long term. What do others do? What has been your experience? Dave - K8RSP (to reply to me directly remove NOSPAM from above address) |
On Wed, 31 Dec 2003 07:11:34 GMT, Zoran Brlecic
wrote: Dave Woolf wrote: I had a fellow ham that took the precaution of pressurizing this type of coax to maintain positive pressure and keep out outside air. Seemed like a lot of effort but maybe it is necessary. Just out of curiosity: how exactly did he do this? I'd go the commercial way and just purge it with a slight positive pressure. With 9913 you can seal the ends and use a small plastic tube in through the side. Flood the bottom connector to seal it (just the opposite of normal) then work a small hole through the jacket, braid, and into the inner tube. You can build a tap sorta like they use for a gas line, or water line, but smaller. You can also put a tap on the side of the coax connector. As far as I know you'd have to make your own as I've not seen any for the PL259s or N connectors although they may be available. The only coax I've ever seen purged was commercial hard line. (It looks like copper water pipe) They actually had a tap soldered on the side of the line with a flow meter connected. It was a very low flow and on a 900 foot run that was gasketed. They replaced it with what appeared to be 4" Heliax. (How'd you like to lift 900 feet of that?) You hook up a tank of N2, only run a few inches of water pressure and use a small flow meter to regulate the flow. Typically you'd purge the thing and then flood the top as well. you will still get a small flow. If the coax seal loses integrity the flow will increase. Lot of work and about $20 to $30 for N2 every few months. It's almost impossible to keep something like 9913 completely sealed. Even the PL259s and N connectors will leak through some. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair?) www.rogerhalstead.com 73 .... WA7AA |
Damn lightning - there should be a law against it g. I saw your tower
raising epic on one of your webpages, and was very impressed with it - would love that at my QTH, but am currently renting, and as I move around very frequently with work (10 times in the last 13 years), a tower would need to be very portable, and the hassles of doing something like your setup every 18 months or so would really **** me off. Currently I use a variety of wire antennas, and a number of poles to get the verticals at about the 25 foot level. Certainly no powerhouse, but able to get to pretty much wherever I want to (within reason of course). Matt Roger Halstead wrote in message ... On Wed, 31 Dec 2003 17:44:21 +1100, "Matt" wrote: Nasty, but unusual - in 20 years of playing with radios, I have not had the problem that you have mentioned, but then again, I guess that I don't have a huge lightening rod of a tower that you do (bloody nice BTW). For the average user, the procedures I have mentioned will suffice 99.99% of the time (looks anxiously up into the sky to check for lighteningg). The hit was on the old tower, but that still put the base of the repeater antenna at 90 feet, so the top would have been close to 112 feet. It hasn't been up in years. The surprising thing is the bolt took out the 7/8" Heliax about 30 feet down from the top of the tower. I did lose the front end out of one solid state 2-meter rig, but that was it. Everything else was still working including the one with the water running out. The current tower and even the old were getting hit about three times a year, but there hasn't been any damage in a while. My neighbor was looking across his back yard this past summer when the top took a direct hit. It apparently really impressed him. Now the neighbors really believe me when I tell them it's the neighborhood lightening rod:-)). OTOH I was out by the end of the driveway talking to the neighbor across the road with a storm in the distance. A strong bolt hit the power pole about 30 feet from us. We both decided we needed to be some where else... Quickly. Currently my biggest concern from lightening is the computer network. It's a 130 foot run to the shop and 25 feet in the other direction to my wife's computer. The pone line comes in underground, but it doesn't take much induced current to cost many dollars. So far, I haven't had any problems with the satellite dishes and feeds, but I have lost the antenna mounted preamp to the top UHF TV antenna. Course that may have been due to 2-meters instead of lightening.:-)) Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair?) www.rogerhalstead.com Matt Roger Halstead wrote in message .. . On Wed, 31 Dec 2003 16:08:10 +1100, "Matt" wrote: As with all of my external cable connections (excluding mobile installs), I use good quality plugs that physically screw together. The when I am finished, I use self amalgamating tape (costs about $20 Aust per roll) which provides a weatherproof seal around the connection - have cut the tape off plugs which I have done ten or more years previously to find them as dry as the day I put them together. On top of the self amalgamating tape, I use the normal electrical tape to give the birds something to peck at before they reach the self amalgamating tape (bloody cockies can be ferocious with antennas and coaxial cable here). I believe that the only way that coax is going to become water effected is if it directly exposed to water (i.e. rain), and once you have put the connector on the end of the cable, screwed it into the antenna and taped it up, the chances of water getting into it are very remote (bar the outer layer being cracked, cut or abraded). In my opinion, pressurising the cable is not something that is needed for the average hobbyist. It only took one lightening strike to change my mind about waterproofing 9913. I used coax seal and taped over that. The tower took a hit that removed every single bit of tape and coax seal from up there. I found the coax seal on the ground. It looked like some one had cut down one side and peeled it off. Then cut it so it looked like one of those pieces of expanded metal. It even removed the silver plating from the connectors. 15 minutes after the lightening strike I had water running out of my 2-meter rig. I ordered 1500 feet of LMR 400 right soon after. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair?) www.rogerhalstead.com Matt Dave Woolf wrote in message ... Just wonder what other's might do to keep moisture from getting into the semi-hollow 9913 type low loss coax. It would seem inevitiable with changes in temperature and pressure that moist air would eventually work its way into the coax and then condense. I had a fellow ham that took the precaution of pressurizing this type of coax to maintain positive pressure and keep out outside air. Seemed like a lot of effort but maybe it is necessary. I have tried to seal the ends of the coax with silicone sealant but I am not really sure that this has been effective in the long term. What do others do? What has been your experience? Dave - K8RSP (to reply to me directly remove NOSPAM from above address) |
On Wed, 31 Dec 2003 02:51:26 +0000, Dave Woolf wrote:
Just wonder what other's might do to keep moisture from getting into the semi-hollow 9913 type low loss coax. It would seem inevitiable with changes in temperature and pressure that moist air would eventually work its way into the coax and then condense. I had a fellow ham that took the precaution of pressurizing this type of coax to maintain positive pressure and keep out outside air. Seemed like a lot of effort but maybe it is necessary. I have tried to seal the ends of the coax with silicone sealant but I am not really sure that this has been effective in the long term. What do others do? What has been your experience? Dave - K8RSP (to reply to me directly remove NOSPAM from above address) Butyl rubber based self amalgamating tape, Electrical Tape, Top Coat, I use a coat of UV Stabilized clear Spray paint Tape: http://www.surplussales.com/Antennas/Antennas-7.html Over the years I have cleaned up a lot of messes where they connectors were not sealed properly. I have taken apart my connections to replace Damaged antennas and the connections are dry as a bone. after 10 years of more in the air. IMHO: Take a close look at Times Microwave cables, I think it's a better products than the equivalent Beldon. Ron |
"Ron" wrote in message ... On Wed, 31 Dec 2003 02:51:26 +0000, Dave Woolf wrote: Just wonder what other's might do to keep moisture from getting into the semi-hollow 9913 type low loss coax. It would seem inevitiable with changes in temperature and pressure that moist air would eventually work its way into the coax and then condense. I'd think it makes sense to seal the top, but let the connectors at the bottom breath, that would alleviate moisture ladden air from being drawn in at the top. Especially during rain storms! Another idea would be having the top sealed, and the bottom allowed to breathe through a plastic jar of desiccant. Pete |
On the antenna end, go up with the coax. Then any water that gets in will
come out the same end, instead of in the shack. I friend of mine did have puddle under his rig from water flowing out of 9913. No, he did not take a lightning hit. I don't use 9913 outdoors. Also, I think the flexible 9913 is not hollow. Tam/WB2TT "Dave Woolf" wrote in message ... Just wonder what other's might do to keep moisture from getting into the semi-hollow 9913 type low loss coax. It would seem inevitiable with changes in temperature and pressure that moist air would eventually work its way into the coax and then condense. I had a fellow ham that took the precaution of pressurizing this type of coax to maintain positive pressure and keep out outside air. Seemed like a lot of effort but maybe it is necessary. I have tried to seal the ends of the coax with silicone sealant but I am not really sure that this has been effective in the long term. What do others do? What has been your experience? Dave - K8RSP (to reply to me directly remove NOSPAM from above address) |
the only way that I have heard of sealing 9913 is to install a gas to form
pressure inside the coax. This way water will not get in either by leaking nto or condensation which is the main way it gets in... Randy ARS: WB4UNA Randy Chavis 247 Goff Court West Columbia S.C. 29172 |
Uncle Peter wrote:
"Ron" wrote in message . .. On Wed, 31 Dec 2003 02:51:26 +0000, Dave Woolf wrote: Just wonder what other's might do to keep moisture from getting into the semi-hollow 9913 type low loss coax. It would seem inevitiable with changes in temperature and pressure that moist air would eventually work its way into the coax and then condense. I'd think it makes sense to seal the top, but let the connectors at the bottom breath, that would alleviate moisture ladden air from being drawn in at the top. Especially during rain storms! That will certainly help. Another idea would be having the top sealed, and the bottom allowed to breathe through a plastic jar of desiccant. Unfortunately the desiccant doesn't last, because it absorbs moisture from the air in the shack. However, you can easily regenerate silica gel by baking it in a moderate oven for a few hours. Even better is "active" pressurization - keeping a positive pressure inside the line at all times. A very simple, low-cost method is to use a small fish-tank aerating pump in the shack, with the far end of the line sealed (exactly as Pete recommends) so there is *no* through flow. The positive pressure is very effective at keeping moisture out. In the shack, the air is connected by soldering a small brass tube through the side of a normal coax plug. PL259/SO239 connectors will leak, so you have to tape over them; most types of N connectors are already well sealed. Positive pressure is even more useful if you have a sealed box at the far end of the line, containing preamplifiers, relays etc. In the long term it keeps outdoor electronics in far better condition than the alternative method using a vent hole in the box, which exposes everything inside the box to atmospheric moisture. To make sure the air pressure gets through into the box, you may need to drill small holes through the insulators of some in-line connectors. Only small holes are needed because there's very little flow. For a deluxe job, pressurize the system with dry air, by connecting the pump through a tube of silica gel desiccant (regenerated every few months as above). I can't remember who first suggested this method, but I'd like to thank him! It worked very well indeed for me, for more than 10 years. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) Editor, 'The VHF/UHF DX Book' http://www.ifwtech.co.uk/g3sek |
On Thu, 1 Jan 2004 13:14:54 -0500, "Tarmo Tammaru"
wrote: On the antenna end, go up with the coax. Then any water that gets in will come out the same end, instead of in the shack. I friend of mine did have puddle under his rig from water flowing out of 9913. No, he did not take a lightning hit. I don't use 9913 outdoors. Also, I think the flexible 9913 is not hollow. I forgot "drip loops". All of mine come off the antenna with the exceptions of the wire dipoles, and curve upward. Then they are taped to the mast. I would have thought it would have kept the water out, but in the case of the lightening strike I had water coming out of the rig. course it could have blown out the coax farther down. It did just that with the 7/8" Heliax. (bout 30 feet down from the top). Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com Tam/WB2TT "Dave Woolf" wrote in message ... Just wonder what other's might do to keep moisture from getting into the semi-hollow 9913 type low loss coax. It would seem inevitiable with changes in temperature and pressure that moist air would eventually work its way into the coax and then condense. I had a fellow ham that took the precaution of pressurizing this type of coax to maintain positive pressure and keep out outside air. Seemed like a lot of effort but maybe it is necessary. I have tried to seal the ends of the coax with silicone sealant but I am not really sure that this has been effective in the long term. What do others do? What has been your experience? Dave - K8RSP (to reply to me directly remove NOSPAM from above address) |
Ron wrote: On Wed, 31 Dec 2003 02:51:26 +0000, Dave Woolf wrote: snipped IMHO: Take a close look at Times Microwave cables, I think it's a better products than the equivalent Beldon. Ron I agree. Not to sound like an ad for Times Microwave but IMHO the stuff is great and well worth the additional cost. I first started using it for S band and above. Today, it's the only type I got installed anywhere. Mike KG4RRH |
On Sat, 03 Jan 2004 17:00:25 -0500, Stilz wrote:
Ron wrote: On Wed, 31 Dec 2003 02:51:26 +0000, Dave Woolf wrote: snipped IMHO: Take a close look at Times Microwave cables, I think it's a better products than the equivalent Beldon. Ron I agree. Not to sound like an ad for Times Microwave but IMHO the stuff is great and well worth the additional cost. I first started using it Additional cost? It's been pretty much a few cents below 9913 most of the time. :-)) (admittedly I have purchased any in a couple of years, got enough to last for a while) And it takes the same connectors. for S band and above. Today, it's the only type I got installed anywhere. I pulled out well over a 1000 feet of 9913 after the lightening strike and ordered 1500 feet of LMR-400. I gave most of the 9913 to local club members. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com Mike KG4RRH |
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