[Lowfer] Moisture in tuner box...

[lowfer@mailman.qth.net]

At 03:52 PM 11/03/2002 -0600, Ralph Hartwell wrote:
>Nothing in my climate (Louisiana) is watertight unless it is potted or
>welded shut.  I have given up on most anything else and now install most
>of my outside hardware with the bottom of the enclosure open to the air.
>etc, etc.

Ralph:
No one has mentioned the use of techniques used for keeping
microwave waveguides moisture free, which are not difficult
and can be applied to the tuner boxes.

Two methods are used.
1. Dry Air compressor with pressure switch.
2. Nitrogen tank with regulator.

Of course these do require some investment unless you
already have access to the parts.

The cheapest method is the Nitrogen tank/regulator.
Nitrogen containers can be rented from the local industrial
gas supplier for, say, anywhere from $30 to $60 depending
on size.  Regulators with pressure gauge can be rented or
purchased.

If you can seal the box with "O" rings or similar so that you
have virtually a leakproof container, and the Nitrogen pressure
set for a very minimum 1/2 lbs, you may get a year usage from
one container.   Of course, opening the box and resealing
will shorten the time, but also keep in mind that the cubic
inch volume of the box is nothing compared to a 200 to 300 foot run of
eliptical waveguide.  Theoretically you could get many years use
from one tank.
In the microwave business we often achieved a year or more
on one large tank feeding six or more waveguides.  If we didn't
achieve this, we looked for "big leaks."   Nothing is perfect,
however, and minor leakage will always be part of the territory.
(The more runs, hoses and couplings: the more chance for teeny leaks)

The plastic hose and couplings used to connect the tank to the
box can be as long as required for proper tank stowage.  Tanks
do not need to be inside the house.  They can be right under the
box as long as the regulator has a protective cover.

Just some ideas.........

73,

Perry       w8au