[Elecraft] K2 near the sea: leave on or not?

David Cutter d.cutter at ntlworld.com
Wed Apr 18 13:05:22 EDT 2007 

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" <jackbrindle at earthlink.net>
To: "Elecraft Discussion List" <elecraft at mailman.qth.net>
Cc: <d.cutter at ntlworld.com>
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, <d.cutter at ntlworld.com>
<d.cutter at ntlworld.com> 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 <KG3V at ChesBayVA.com>
>> Date: 2007/04/17 Tue PM 03:34:29 BST
>> To: "Fred (FL)" <ncsailors at yahoo.com>
>> CC: elecraft at 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)" <ncsailors at yahoo.com>:
>>
>>> 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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>>
>>
>>
>>
>>
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- Jack Brindle, W6FB
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