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Topband: "white powder" on solder joints

To: "Topband" <>
Subject: Topband: "white powder" on solder joints
From: "dick-bingham" <>
Date: Tue, 19 Dec 2006 09:51:47 -0800
List-post: <>
Regarding ===>

Date: Tue, 19 Dec 2006 05:39:30 +0000
From: Nick Hall-Patch <>
Subject: Re: Topband: Soldering ground radials
Message-ID: <>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 07:23 17/12/2006, you wrote:

>Years ago I had a radial system soldered together using regular lead/tin
>acid core solder.  I had to re-solder the radials about once a month.
>Otherwise, the solder turned to a white powder, and the soldered 
>simply fell apart.

Does anyone know what this  is, and why soldered
connections seem prone to it in moist atmospheres?   I've just opened
up the transformer box for one of my Flag antennas, and although
there's a bleed hole in the box, there's likely always a bit of
moisture in there during our wet, cool Northwest winters.

All the soldered connections (rosin-core) in the box are covered in a
white powder after about a year outside, and in fact, so are the
tinned leads of capacitors.   Probably silver solder isn't an option
with the thin enamel wire leads from the matching transformer, so is
one stuck with resoldering connections every year?   With two 10 kw
local AM BCB transmitters  (directional at my backyard), producing
mixing products in bad solder joints is a concern.

best wishes,


The "white powder" may be the rosin-flux residue that has degraded to a
powederd state. Try rubbing it down with a swab soaked with solvent to
see if this is the case.

Hopefully, you will find an intact solder joint below the powder...

73 - Dick - w7wkr 

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