[Elecraft] Remoting KAT500 to base of antenna

Thu Jan 21 10:48:18 EST 2016

Gore-Tex might let moisture out, but it might let it in. Moisture migrates from the more humid side of the membrane to the less humid side. It is a pretty slow process.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Jan 20, 2016, at 11:39 PM, Ian White <gm3sek at ifwtech.co.uk> wrote:
> 
> 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:elecraft-bounces at mailman.qth.net] On Behalf Of
>> David Cutter
>> Sent: 21 January 2016 07:08
>> To: Lewis Phelps; Elecraft at mailman.qth.net
>> 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" <lew at n6lew.us>
>> To: <Elecraft at mailman.qth.net>
>> 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 <d.cutter at ntlworld.com>
>> 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"
> <kl7uw at acsalaska.net
>>>> <mailto:kl7uw at acsalaska.net>>
>>>> To: <Elecraft at mailman.qth.net <mailto:Elecraft at mailman.qth.net>>
>>>> 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:
>>>>>   dubususa at gmail.com
>>>>> 
>>>>> 
>> ______________________________________________________________
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>>>> 
>>>> 
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>>>> Message delivered to lew at n6lew.us <mailto:lew at n6lew.us>
>>> Lew Phelps N6LEW
>>> Pasadena, CA DM04wd
>>> Elecraft K3-10 / KXV144 / XV432
>>> Yaesu FT-7800
>>> Lew at N6LEW.US
>>> www.n6lew.us
>>> 
>>> Generalized Law of Entropy: Sooner or later, everything that has been
> put
>>> together will fall apart.
>>> 
>>> 
>>> 
>>> 
>>> 
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>> 
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> 
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