Hi Jack
You may well be right about the origination of "conformal coating" but it
was quickly taken up by other services who saw its benefits. I agree that
for MOST amateur situations it's probably over the top, but one of the
respondents to this thread has done it because he feels it necessary in his
situation.
David
G3UNA
----- Original Message -----
From: "Jack Brindle" <[EMAIL PROTECTED]>
To: "Elecraft Discussion List" <elecraft@mailman.qth.net>
Cc: <[EMAIL PROTECTED]>
Sent: Wednesday, April 18, 2007 3:49 PM
Subject: Re: [Elecraft] K2 near the sea: leave on or not?
Conformal coating is actually meant to solve a completely different
problem. Imagine an environment that regularly goes from high heat/
high humidity to very cold/dry conditions in just a few minutes. When
that happens, condensation is sure to happen. Conformal coating takes
care of this situation very nicely.
Oh, this situation happens thousands of times every day - it is the
environment for aircraft avionics...
To the original poster: Don't worry about it. It really isn't a
problem where you live. If you worry about this, you also need to
worry about the sand particles from the Sahara that are regularly
carried into South Florida on the tradewinds (and also effect
hurricane development).
On Apr 18, 2007, at 4:54 AM, <[EMAIL PROTECTED]>
<[EMAIL PROTECTED]> wrote:
In the old days we used to call it tropicallising, now it's called
conformal coating and refers to a material either sprayed, painted or
dipped onto the electrical parts. Conformal coating for military is very
expensive and time consuming involving inspection with a uv lamp to pick
up the uv die in the material, to descover imperfections and can be up to
3 layes thick.
If you don't keep you equipment in an air tight box, then leave it
switched on to slow down the deposition of salt products. I think this
works by keeping the interior warmer and thus higher air pressure to
prevent the ingress from the surroundings. Of course when you switch off
it cools and the pressure falls and drags in the cooler contaminating air
from the surroundings and that's when the damage starts. So, switch off
and immediately put into an air tight box. It all sounds a bit
excessive, but the other way is to coat everything with bare metal with a
suitable coating, like the one mentioned from another reply. The lacquer
and and varnish sprays that you hold 6" away are only partly effective
because tall components create shaddows and the spray doesn't get in
properly. They work on the solder side fairly well, but the cut off
component wires do not get a coating - it runs off. Genuine conformal
coating comes expensive, is thick and does not run. Last time I boug
ht some it was about £40 for 400mL (circa 1990) made by Dow Corning but
there are more types to choose from now. If you spray, use several
layers and get right in between the components; let it dry between
sprays. Take care that on some rf components you may get a small shift
in value upsetting your carefully trimmed filters etc.
David
G3UNA
From: Tom Zeltwanger <[EMAIL PROTECTED]>
Date: 2007/04/17 Tue PM 03:34:29 BST
To: "Fred (FL)" <[EMAIL PROTECTED]>
CC: elecraft@mailman.qth.net
Subject: Re: [Elecraft] K2 near the sea: leave on or not?
I operate from the shores of the Chesapeake Bay in Virginia. The water
there is
only moderately salty but corrosion is very rapid compared to my
experience
with inland QTHs. I was wondering if this would be a problem for my
equipment.
So far, no problem. I imagine anyone near the sea shores has this
problem.
73,
Tom KG3V
Quoting "Fred (FL)" <[EMAIL PROTECTED]>:
RUSTY Florida area?
I'm surprised to hear about corrosive salty-air
regions in Florida. Just never heard of it?
Our son lives on big island of Hawaii - near
Hilo. The salt water air type of corrosion, on
things like bicycles, etc. - is notorious in Hawaii.
Things there - not protected, don't last so long.
Islands of Hawaii - are in the trade winds region
of the Pacific - and I guess get their daily dose
of salty air, naturally. I'm not sure this is
the case on either coast of Florida. I'm probably
wrong tho. The big island, above city of Hilo -
gets a daily dose of natural rain, like 2 pm
every afternoon. Perhaps the rain there, has
some salinity.
For some reason I've not heard this about Florida.
We live 8 miles from the Gulf Coast of mid-western
Florida. I can't say I see anything around our home,
or in my garage, etc. - that has any appearance
of salt corrosion. Cars look exceptional - easy
to keep clean. No visible corrosion on anything
we have? No rust on tools, etc.
I wonder what the salinity is of the Florida
Atlantic ocean, vs the Hawaiian Pacific ocean
and the trade winds?
Fred,
N3CSY
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