Some thoughts on cases for exterior loop antenna amplifiers. This equally applies to any electronics in exterior service.
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The top of the line cases are polycarbonate, Hammond probably manufactures the best as a mix of price, function, availability. Durable like they are designed for combat.
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Look up "Hammond Water-Tight ABS & Polycarbonate Enclosures"
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I've never been able to locate polycarbonate wire glands but black Nylon is probably as durable and UV resistant and readily available on Amazon.
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For controlled ventilation, the "Hylec vent" is probably the gold standard. This vent allows air flow but blocks humidity. This is what Cross Country Wireless used in my dual polarity horizontal and vertical active dipole. Sadly they come from England and have insanely long delivery times.
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Honeywell makes one that might be as good, I'll let you know in a year or so.
https://www.digikey.com/en/products/detail/amphenol-ltw/VENT-PS1NBK-N8001/7898283
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I built a PA0RDT mini-whip for a friend on a tight budget. I drilled a 1/4" hole in the bottom and used Gortex repair tape on the inside and outside. It's been in service for 2 years now and given we've had temperatures ranging from 98F to -10F, over a foot of water, 2 feet of snow (spread out over 2 winters), I suspect the crude Gortext double seal works just fine. However I still do not trust it for anything serious. Given how inexpensive the Honeywell vents are, I'll spring for one and replace the Gortex.
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Hammond polycarbonate cases are the ultimate and priced accordingly.
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PVC cases are much more affordable.
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I use Carlon electrical utility boxes for less serious projects. These feature a neoprene gasket that provides a reasonably good seal and stainless steel screws.
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I've found Carlon cases to be suitable for many exterior projects and for cases for interior projects. The walls are reasonably thick, the cases reasonably strong, and, the price several years ago was very reasonable
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[I ended up with oodles when an electrician friend hung up his tools.]?
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A catalog is available at
https://carlonsales.com/electrical.php
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Lowe's used to carry these but appear to have shifted to Cantex. Cantex is similar but uses zinc plated screws, which are guarantied to rust here in Kentucky. I have no experience with the quality of the weather seal in the Contex units.
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The Carlon utility box is just starting to show some wear from the weather.
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Our POTS (Plain Old Telephone System) landline NID/DSL filter is in a PVC box. It's sheltered from direct sunlight being on the north side of our home. The phone company supplied the box and internal frame and NID, I added a DSL filter and Cat 5 wiring in the fading dream Windscream, er sorry, Windstream will extend DSL out to where we are and I can give up a Consumer Cellular phone based WiFi hotspot.
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Oddly enough the local electrical inspector approved Cat 5 wiring from the Windstream NID to inside our home with no comments about "You need transient protectors." I guess the Tii belcore lightning transient in the NID qualifies.
https://tiitech.com/wp-content/uploads/datasheets/surge-arresters/356.pdf
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They meet UL 497 and Telcordia GR-1361 Core protection requirements.
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They also installed a NID case more suited to an 8 dwelling apartment building, too bad I can't legally do anything with the spare space. The installation tech allowed me to install the DSL filter. Nice of her.
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The GTE PVC box at my parents home was at least 40 years old when we sold the home and still in good shape and it was on the south east side of the house and received hours of direct sunlight.
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So PVC might be OK for extended service.
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I'll continue to use PVC for casual projects but for my CCW dual polarity H/V antenna and my N4CY loop amps, I'll go with the Hammon polycarbonate cases even though the PVC cases I've used for the N4CY looks have held up nicely.
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OK a bit of theory here. I suspect we have water ingress because the changing temperature, cooler, sucks in moisture laden air, by having a vent that allows air but blocks all humidity, we don't get condensation. A life time ago when I went for long hikes in the rain, a standard vinyl raincoat made you feel like vegetables getting steamed, I was amazed at my first Gortex raincoat, no steaming of the hiker. I've often wondered of an experiment to verify this theory. I sort of accept the Gortex tape as sort of proof.
YMMV
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