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My CCW dual polarity H/V antenna, has never had condensation.
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Chris used a Hammond RP1060 with a
Hylec vent and wire glands of unknown manufacture. There is no obvious name on the exterior. [I'm looking at it right now, not quite willing to tear it apart until my new Hammond cases arrive.]
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The RP1060 has a tongue and grove case with a neoprene gasket.
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The Hylec vent has a special membrane,
Polyether sulphone PES, similar to Gortex in that it allows air to freely pass but blocks water. I suspect it has much smaller holes in the material and is even better at blocking water then Gortex.
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I received this antenna at least 3 years ago, maybe 4 or 5 and it was placed in service that weekend and endured a series of storms.
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I opened it after the storms passed, no trace of water, I then installed it "permanently. [I used "" because it's been moved 3 times]
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I opened the case after the first winter, in late March and there was no trace of water.
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Central Kentucky gets a lot more rain in winter then snow.?Here is a list of average monthly temperatures and precipitation
https://www.usclimatedata.com/climate/lexington/kentucky/united-states/usky1079
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As you can see, we receive ~45 inches of precipitation, most of that is in the form of rain.
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I neglected to open the unit for the next few years. I opened it prior to moving last year, August, and then again this spring, March.
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There has never been a trace of condensation.
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As I explained in the post that started this thread, my theory on moisture ingress suggests water doesn't seep in along well sealed seams but is sucked in as air laden with water vapor as the temperature drops and the volume of air inside the case decreases, the water vapor condenses and is trapped.
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[I'll admit I haven't used Charles' and Boyle's Law since university physics...so please bear with me,]
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https://chem.libretexts.org/Courses/University_of_California_Davis/UCD_Chem_002A/UCD_Chem_2A/Text/Unit_III%3A_Physical_Properties_of_Gases/06.03_Relationships_among_Pressure_Temperature_Volume_and_Amount#:~:text=Because%20PV%20is%20a%20constant,equation%20V%20%3D%20constant%2FP.
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V¡ØT [anyone up to calulus?]
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https://www.omnicalculator.com/physics/charles-law
"In the second problem, we heat an easily-stretched container. It's filled with nitrogen, which is a good approximation of an ideal gas. We can find that its initial volume is?0.03 ft??at room temperature,?295 K. Then we put it close to the heating source and leave it for a while. After a few minutes, its volume has increased to?0.062 ft?. With all of this data, can we estimate the temperature of our heater?"
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Let's reverse this, if the temperature is decreased, the volume of air will decrease from 0.062 ft? to 0.03ft?. [Air is mostly nitrogen and I don't feel like trying to calculate precise thermal expansion/contraction versus temperature for the mixture of gasses that compress out atmosphere.]
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Here is a practical example. Take an empty 2 liter sodapop bottle at room temperature.?Screw the top on tightly. Place in your refrigerator.
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Leave for an hour and then remove, notice how the sides have pulled in? The volume of air in the container has decreased as the result of cooling.
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In the world of electronic enclosures in the real world, do you think the decrease in air volume might not suck in air laden with moisture? And might not an alternative air vent that allows air and water vapor to move both ways might prevent air laden with moisture from condensing because it can escape just like if there were vent holes?
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I am not trying to argue, I will state as a fact the CCW dual polarity antenna with the Hammond case, wire glands, and Hylec vent doesn't have any water condensation after a typical year in central Kentucky. Or after several years in Central Kentucky.
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Also, a Carlon PVC case with a tongue and grove mating surface and the factory supplied flexible gasket (I believe it is neoprene, but I'm not sure), a wire gland and a quarter inch hole with Gortex repair tape on both sides has also never had condensation after a typical central Kentucky winter. This case protects a PA0RDT Mini-Whip antenna.
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I've been playing with active antennas since July 1979. Most were E-Field antennas. All of them experienced "water ingress" [Well except for the vacuum tube unit, it was warm to the touch at 10F and over heated in 50F weather] until the CCW.
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Based on my experience with that antenna I decided to try the Gortex tape for a friend who needed an antenna "now." It was late September, a series of t-storms was forecast the next day and I had a contract job which promised to be a nightmare for the next few months. The Hytec vent has a delay (really long delay) getting here from England, so I took a gamble with the Gortex repair tape. I was out of my preferred spray on conformal silicon coating, so the PCB went in 'naked.' I threw the whole thing together in few hours and half expected it to maybe last the winter but would probably need the PCB replaced come spring. That was 3 years ago.
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https://www.hylec-apl.com/datasheet/1047/JDAE12PA_SW-Datasheet.pdf
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Until proven otherwise, I'm sticking with my "lower air temperature means less air pressure, means sucking in air/moisture from the outside and trapping the moisture inside after it condenses."
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Now I'll agree if you do not properly seal any ports, you will have water "wick" in by capillary action.
https://en.wikipedia.org/wiki/Capillary_action
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Look up Capillary action on youtube. There were too many demonstrations for me to pick out the best one. Water will be "sucked in" narrow gaps, the narrower, the further the water will be 'sucked in' regardless of temperature.
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This is capillary action and demonstrates how any unsealed opening can allow water in regardless of air temperature, pressure differential, etc.
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One must properly seal all ports. I use wire glands with "O" rings on the base of the wire gland that mates with the case.
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I've used conformal silicon coating to protect, seal, the seams on PVC cases that don't have tongue and grove / flexible gaskets with the 1/4 hole with Gortex repair tape.
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I have a Geiger counter mounted in aluminum Budd case. [I only want to detect Gamma rays <cosmic rays for a random number project for a cousin of my wife>]. Given the unit operates with 400V, any water condensation would be "a really bad thing." The unit has a ~9V to 400V inverter, is powered via the coax, the clicks are amplified and fed back down the same coax with a Bias-T.
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The coax enters via a wire gland with "O" ring, and I sealed the seams with spray silicon conformal coating. The breathing vent is a Hylec vent.
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This unit has been in constant 7/365 operation for 15 months with no problems. Unless I open the unit, I can't be certain there hasn't been any water ingress, but, given the inverter board is mounted on two strips of double sided tape [non conductive PVC] on the bottom of the case, I have every reason to believe there has been no water ingress. And any condensation on the GM tube would stop detection.
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I accept holes in the bottom were the only way to control condensation in the past, I also accept that modern vents allow us to have better moisture control and keep insects out.
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Our hobby is fun but industry depends on reliable equipment, condensation would be a major problem for them. Somehow I can't see a major telecom outfit relying on a couple of holes to control condensation.
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I suspect Don Clement's use of Qingrong "Blue Breather Plug M12x1.5-10 Venting Screw In Vents for Solar GPS Tracker Box, Outdoor Lighting Prevent Condensation,5G Outdoor Telecom Enclosure" will work every bit as good as the more expensive (and damn near unobtainable) Hylec or Honeywell.
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The secret is in the membrane that allows air to pass but stops water. I suspect Honeywell and Qingrong [and many others] have developed/copied the membrane used by Hylec.
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Given the 'really bad stuff happening if there is water condensation in a high voltage PV array / control' I suspect Qingrong's products almost certainly work as advertised.
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I've ordered several and I'll see how they work. I'm still going to stick to the Hylec for critical applications until I get a better feel for the Honeywell and Qingrong.
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The stick on water barriers mentioned by Fred M. appear to be a bit more professional then my Gortex tape.
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