Anders,

Actually, the problem is not the black cable, which is a polyurethane
jacket. The conductors themselves are made of "copperweld", which is an
alloy of (I believe) steel and copper. The wire is much stronger and
stiffer than normal copper wire.  Both materials are chosen so that
geophones can be used in the field handled by "juggies", folks not known
to be gentle with seismic hardware.  I watched a crew routinely toss
geophones over the side of a stake truck onto concrete in downtown Los
Angeles. A Sensor engineer once told me his geophones were designed to
be dropped 50 feet from a helicopter.

Geophone connectors are available, but the main problems they address
are dirt and moisture, along with the aforementioned ruggedness issue. 
You can buy them from OYO Geospace or the Sensor Division of Input
Output in Holland, but their distribution system is not geared to tiny
orders.

Anyway, because the wire is stiff, I would guess that flexing is
breaking your solder bond.  You need to use a connector with a rigid
cable clamp so flexing of the wire doesn't translate down to the solder
joint.  Alternately, you can probably open up the geophones and
substitute ordinary wire on that end.  Be sure and observe the subtle
polarity marks. For a quick and dirty solution, just splice some
standard copper wire onto the geophone cable using one of those
cylindrical wire splices.  Because the copper wire will flex, that will
relieve the stress on the joint. A crimp splice is more vibration
resistant than a solder splice.

Doug

aheerfor@...... wrote:
> 
> I am using some geophones to record strange ground vibrations which make a
> up a local hum phenomenon like the Taos Hum in the US.
> 
> The recordings point toward a  technical  origin at a depth of 100 meters,
> possibly secret tunnels.
> 
> But I have a practical problem: The stiff black geophone cabling is
> difficult to connect to my recording equipment. I have used XLR connectors,
> but when handling the cabling, the connectors sometimes break loose. The
> soldering is stressed, and it eventually breaks up. This is causing some
> failed recordings.
> 
> How do you most easily make reliable connections?
> 
> I have heard that geophones sometimes come with special connectors for
> seismic equipment, but I have never seen these connectors, and they may
> even be hard to find on the market. Perhaps these connectors are ideal; I
> don't know.
> 
> Any opinions?
> 
> Regards, Anders Heerfordt, Denmark
> 
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-- 
Doug Crice          web site http://www.georadar.com
GeoRadar Inc.             e-mail dcrice@............
19623 Via Escuela Drive           phone 408-867-3792
Saratoga, CA 95070 USA              fax 408-867-4900

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