Old cold solder joints

[Jim Simmons]

Ron,
Having had no experience with lead-free solder I can't testify as to its
aging properties; however, being about the same age as your Clough-Brengle
transmitter (70 years) And being in electronics about that long as a
maintenance technician, builder and always a student I can tell you that all
current carrying conductors will become brittle after a few years of
performing their assigned duties.  I believe this is because of the constant
movement and agitation of electrons within the conductor.  Copper wires and
connectors are especially prone to this condition.  Wires become brittle to
the point of where they will snap if moved and connections will corrode and
become more like semi-conductors than conductors.  The diode like action of
the connectors is a prime source of noise and radiation that will affect
everything around them because they act as mixers (heterodyne effect) to the
signals they carry. These symptoms vary from "It just ain't quite right" to
total failure and cause much pulling of the hair.  I would venture to guess
that about 80% of the problems with old equipment can be attributed to this.

The problems you mentioned are all in the high current portion of your
transmitter (plate and antenna circuits).  And seeing the pictures of the
damage it has suffered, it must have gotten quite a few sharp and sudden
jolts in its travels to your doorstep.  Therefore, it doesn't surprise me
that the wires and the solder joints have failed.

I know of no way to "age" solder joints, so it would seem to boil down to
whether you want the transmitter working with shiny joints or not working
with all the old corroded joints.  Personally, I would prefer it to be
restored to working condition.  Just be very careful when moving the wires
around while repairing it because they will be brittle.

73 Jim N5MSJ

-----Original Message-----
From: Boat Anchor Owners and Collectors List
[mailto:BOATANCHORS at LISTSERV.TEMPE.GOV] On Behalf Of Ron Lawrence KC4YOY
Sent: Sunday, November 13, 2005 3:09 PM
To: BOATANCHORS at LISTSERV.TEMPE.GOV
Subject: Old cold solder joints

I have a question about old solder joints.
I've heard the no lead free solder will not hold up
over the long term, but is it normal for old solder
joints to get cold as they age?
Working on the Clough-Brengle transmitter I've found
a lot of really cold (loose) solder joints, where the wire
that was soldered has just broken free of the solder.
If the solder joints were this cold when it was built
it could not have worked most of the loose joints are
in the antenna coils and the plate cap leads to the final
tubes. These look like original solder joints, they aren't
any shiner that any of the others in the transmitter.

Does anyone know what I can use to age new solder
joints? I really don't want to have a bunch of shiny
solder joints in this thing.

73, Ron
http://radioheaven.homestead.com/CB87project.html

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