On 7/31/2010 3:01 PM, Adam Shirley WJ4X wrote:
> You might be better off not sealing the polyphasers to the box. Just
> make sure all the holes are on the bottom, and you'll have no problems.
>
>
I seal all conduit with the soft expandable foam where it enters the
buildings. This does NOT prevent the conduit from breathing.
I also have my grounded bulkheads on the "outside" of the entry point.
IOW the NEMA enclosures are mounted on the sides of the house and shop.
I have also used it at the tower end of the conduit as well. This
*helps* to keep the box at the tower dry, but it's not a cure all. In
direct sun those boxes get really hot, and pretty chilly at night
causing quite a pressure differential between day and night so that box
WILL breathe. Small holes and screens aid the natural breathing and
evaporation of the moisture, but if liquid water forms from condensation
it will most likely not flow out through small holes or screens due to
the meniscus properties, but it will evaporate in time and the air will
carry it out.
> Ya need a vent for moisture somewhere. The conduit from the shack will
> carry cold air/warm air to that box and make it sweat. I actually
> drilled a hole in the bottom of my box at the tower and installed a sink
> aerator screen to keep out bugs.
>
I assume you mean the aerator in the faucet? I had not thought of
those, but that might be a good approach for the Hy-Gain AV-640 matching
network as the stock vent in the bottom is large enough for mud dobbers
and paper wasps to enter.
http://www.rogerhalstead.com/ham_files/AV-640/AV640.htm
73
Roger (K8RI)
> 73!
> -Adam
> WJ4X
>
> On 7/31/2010 11:00 AM, jimlux wrote:
>
>
>> I was thinking silicone caulk to seal the the housing of the transient
>> suppressor to the box, not for the threads.. The idea being that you
>> drill a hole in the box and push the threaded part of the connector thru
>> the hole, with the housing of the suppressor snug up against the inside
>> wall of the box.
>>
>>
>> Cheaper and smaller than a bulkhead feedthrough and another cable inside
>> the box from feedthrough to suppressor.
>>
>> Of course, one could probably just use a piece of wire (not coax) to
>> connect the center pin of the feedthrough to the center pin of the
>> connector on the suppressor. The shield of the feedthrough is solidly
>> connected to the box, as is the housing of the suppressor, and the few
>> inches of wire probably wouldn't make much difference impedance wise, at
>> least for HF.
>>
>>
>>
>> You'd use whatever usual scheme you want for sealing the actual connector.
>>
>>
>>
>>
>>
>>
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