The key point about a semi-permeable vent is that it blocks liquid water (and insects) from getting into the enclosure, but *always* allows water vapor to escape. As David points out, plain mesh won't do that under all conditions.
In the UK, an equivalent to the Gore-Tex engineered vents is available from Farnell for about £5 ($7.50). Part numbers 2308394 (black) or 2308395 (grey). CPC normally has them a little cheaper (part numbers EN83188 or EN83189) but they are currently out of stock. Compared with the value of the KAT500 inside the enclosure, a properly engineered semi-permeable vent is a very good investment. 73 from Ian GM3SEK >-----Original Message----- >From: Elecraft [mailto:[email protected]] On Behalf Of >David Cutter >Sent: 21 January 2016 07:08 >To: Lewis Phelps; [email protected] >Subject: Re: [Elecraft] Remoting KAT500 to base of antenna > >Yes, but the weight of water eventually pushes it through - it's cheap but >not perfect. If you use a 20mm fitting as I did back then, water accumulates >inside until a large droplet forms then exits. The Gortex is better but more >$ £. > >David, G3UNA > > >----- Original Message ----- >From: "Lewis Phelps" <[email protected]> >To: <[email protected]> >Sent: Wednesday, January 20, 2016 8:03 PM >Subject: Re: [Elecraft] Remoting KAT500 to base of antenna > > >> But might not this re-introduce the surface tension problem? >> >> Lew N6LEW >> >> >>> On Jan 20, 2016, at 10:18 AM, David Cutter <[email protected]> >wrote: >>> >>> From my work in the food industry (if memory serves), critter invasion is >>> prevented with 0.64mm square nylon netting. This is common in the >>> dress-making industry. (I think it can also be found as a stainless >>> steel gauze). This can be glued over a breather (drip) hole in the base. >>> >>> David >>> G3UNA >>> >>> >>> ----- Original Message ----- From: "Edward R Cole" <[email protected] >>> <mailto:[email protected]>> >>> To: <[email protected] <mailto:[email protected]>> >>> Sent: Wednesday, January 20, 2016 8:29 AM >>> Subject: Re: [Elecraft] Remoting KAT500 to base of antenna >>> >>> >>>> Fred, >>>> >>>> Your high desert climate will probably produce less condensation than >my >>>> sub-arctic/maritime environ. What I do for enclosures is to not seal >>>> them airtight but provide good drain openings which air can exchange. >>>> Of course the shelter is made to repel direct rain/snow. >>>> >>>> I suspected that my TR relays were "freezing up" at lower temps making >>>> the action delayed so I used some big aluminum Dale resistor strapped >>>> onto the relays to add direct heat by conduction. I happen to have 28v >>>> equipment so used 28v thru the resistors to produce heat within their >>>> wattage rating (used 40w resistors at both relays). Of course this also >>>> provided some heating of the ambient air of the enclosure which helped >>>> keep moisture from forming even in 90% humidity of the fall. It rains >>>> 8-days with one day off from August to October when temps finally >drop >>>> below freezing and rain becomes snow. You don't have anything near >>>> that. >>>> >>>> One thing I have noticed about drain holes in some equipment is they >are >>>> too small to allow water to drop free due to surface tension and in my >>>> environ that results in the weep holes freezing tight. I drill them out >>>> to 1/4 inch. Of course if you are prone to insect/archnid invasion that >>>> is problematic. >>>> >>>> PS: I lived five years in the high Mojave Desert so know all about >>>> "critters of the desert" (never stick your hand into a confined space >>>> before kicking it to see what crawls out or "rattles"! >>>> >>>> 73, Ed - KL7UW >>>> ------------------------------------------ >>>> >>>> 3. Reno/Sparks is a high desert [4,500'] directly adjacent to the >>>> Carson Range and Sierra Nevada [really big mountains]. Winter temps >go >>>> down into single digits, it does snow/rain. Should I do anything to >>>> prevent condensation in the weatherproof box [light bulb, drain hole, >>>> ???]. >>>> >>>> 73, >>>> >>>> Fred K6DGW >>>> - Northern California Contest Club >>>> - CU in the Cal QSO Party 1-2 Oct 2016 >>>> - www.cqp.org >>>> >>>> >>>> 73, Ed - KL7UW >>>> http://www.kl7uw.com >>>> "Kits made by KL7UW" >>>> Dubus Mag business: >>>> [email protected] >>>> >>>> >______________________________________________________________ >>>> Elecraft mailing list >>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>>> Help: http://mailman.qth.net/mmfaq.htm >>>> Post: mailto:[email protected] >>>> >>>> This list hosted by: http://www.qsl.net >>>> Please help support this email list: http://www.qsl.net/donate.html >>>> Message delivered to [email protected] >>>> <mailto:[email protected]> >>> >>> >______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> <http://mailman.qth.net/mailman/listinfo/elecraft> >>> Help: http://mailman.qth.net/mmfaq.htm ><http://mailman.qth.net/mmfaq.htm> >>> Post: mailto:[email protected] ><mailto:[email protected]> >>> >>> This list hosted by: http://www.qsl.net <http://www.qsl.net/> >>> Please help support this email list: http://www.qsl.net/donate.html >>> <http://www.qsl.net/donate.html> >>> Message delivered to [email protected] <mailto:[email protected]> >> Lew Phelps N6LEW >> Pasadena, CA DM04wd >> Elecraft K3-10 / KXV144 / XV432 >> Yaesu FT-7800 >> [email protected] >> www.n6lew.us >> >> Generalized Law of Entropy: Sooner or later, everything that has been put >> together will fall apart. >> >> >> >> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] > >______________________________________________________________ >Elecraft mailing list >Home: http://mailman.qth.net/mailman/listinfo/elecraft >Help: http://mailman.qth.net/mmfaq.htm >Post: mailto:[email protected] > >This list hosted by: http://www.qsl.net >Please help support this email list: http://www.qsl.net/donate.html >Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
