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Author Topic: Protecting outdoor balun  (Read 872 times)
KC6QJZ
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« on: June 18, 2012, 10:37:48 PM »

I would appreciate any suggestions regarding protecting a balun that will be located at the base of a 4-BTV antenna. The antenna will be ground mounted and the antenna cable run will be in buried EPVC. The balun will be formed on a twelve inch length of six inch diameter PVC pipe. I would like to avoid having the balun laying on the ground exposed to the elements. I am considering burying a plastic tote with the balun placed inside. Waterproof the plastic box with silicone. This is a new situation for me and I will appreciate any thoughts. Thank you.
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ZL1DAS
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« Reply #1 on: June 19, 2012, 12:12:53 AM »

Hi, have a look at these links, maybe there is something useful for you:
http://blog.k6fi.me/2012/03/hustler-4-btv-update.html
http://blog.k6fi.me/2012/02/hustler-4-btv-dx-engineering-install.html
In general terms from my experience in burying things there is always a very high risk of water leaking in
regardless how well you seal the enclosures. If it has to go underground: triple seal the dry setup in suitable
containers and really splash the silicon everywhere, make sure the item has external drainage where it is to be buried so it cannot become waterlogged [dig a hole and fill it with gravel...]. I personally would always prefer to mount baluns above ground: for easy access and you can still waterproof everything properly but leave a little air hole open [1-2mm diameter is sufficient and you can put some glass wool on top to block insects from entering] at the bottom to let the condensation out, moisture will will come in one day whether you like it or not. 73
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W9WLS
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« Reply #2 on: June 20, 2012, 02:34:45 PM »

If it's a "CHOKE" type, you could always slide a larger diameter piece of PVC pipe over the outside of the coil's , make it a bit longer than the coil form and make a notch in each end for the coax toenter and leave , put a pvc cap on each end and then go nuts with the silicone.
don't forget a small "WEEP HOLE" in the lowest point of the bottom cap.
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KF5KGN
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« Reply #3 on: June 23, 2012, 11:11:17 PM »

Another problem with enclosures is condensation.     Above or below ground I like to place drierite or any hygroscopic substance.     I have had success using the packing material that looks like styrofoam but are shaped more like "Tater Tots".     I am told they are made from potato.     Testing is simple; place one in water and if it disolves or turns into a blob, you have the potato substance.
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ZL1DAS
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« Reply #4 on: June 24, 2012, 03:02:35 AM »

Hygroscopic substances are fine as long as they still can absorb and no new moisture enters. Once they are depleted they form a corrosive soup. The most used substance is desiccated silica-gel. For a balun you need a ...condensation equalisation hole... or you might be lost long-term....


« Last Edit: June 24, 2012, 03:37:51 AM by ZL1DAS » Logged
W9WLS
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« Reply #5 on: June 24, 2012, 03:42:15 AM »

Hygroscopic substances are fine as long as they still can absorb and no new moisture enters. Once they are depleted they form a corrosive soup. The most used substance is desiccated silica-gel. For a balun you need a ...condensation equalisation hole... or you might be lost long-term....




WEEP HOLE
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ZL1DAS
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« Reply #6 on: June 25, 2012, 01:34:13 AM »

Thats right!!  This technical term regarding condensation was my invention and I had my bout of laughter while typing it.  It is hilarious what you can come up with [and get away with sometimes .. but not in this case!!]...  I am reading scientific articles all the time [most are job-related and boring] and obviously I cant resist at times of inattention to sound important. [Another example would be a: ... Delayed Primarily Coriolis Force Determined Amplified Hydrodynamic Rotational Pseudo-Vortex...  or just in short and therefore in more colloquial language a ...DPCFDAHRPV... certainly very useful to describe the directional swirl occurring when flushing your toilet, depending on which part of the hemisphere you reside. The closer you get towards the Equator the slower it gets, then it comes to a standstill and then it starts again in the other direction. It is supposed to be the fastest at the poles in opposite directions depending where you are: N or S, but all toilets are permanently frozen there, so we are still waiting for proper evaluation of this amazing theory. [Look at Wikipedia for the basic facts.]...I have also deliberately made a simple mistake in my describing explanations. Who finds it first? Price: A bottle of good wine if you pick it up yourself at my QTH in ZL1.... [quote from Wikipedia (abridged): the idea that toilets and bathtubs drain differently in the Northern and Southern Hemispheres has been popularized by several television programs, including The Simpsons  and The X-Files. Several science broadcasts and publications, including at least one college-level physics textbook, have also stated this.].... All up to you now to win this bottle of wine... Cheers...
« Last Edit: June 25, 2012, 03:22:57 AM by ZL1DAS » Logged
KF5KGN
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« Reply #7 on: June 27, 2012, 01:07:41 AM »

Darned Bernard, I never knew potato soup was corrosive.     I have about a gallon of drierite which is basically a hygroscopic substance that can be heated, dried and reused.     Preventive maintenance is my focus.     Some of my equipment aboard ship had weep holes and I understand there are many in Poland; Polish Leprechauns...wee Poles, hahaha.     I like your term Bernard, you must work for the government,  Roll Eyes
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ZL1DAS
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« Reply #8 on: June 27, 2012, 03:18:21 AM »

I would rather go on the benefit than ever work for the government  ......  Smiley
« Last Edit: June 30, 2012, 05:32:44 AM by ZL1DAS » Logged
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