[TowerTalk] DIY conduit locator?

[Jeffrey Okamitsu]

Is the conduit metal or dielectric?  If it’s dielectric and there’s no conductor in it, depending on the diameter of the conduit you MAY be able to find it using a magnetic gradiometer to detect the small change in the earth’s field that is caused by the void in the earth caused by the conduit and the air inside it. It works better if the soil is laterite (has high iron content).  The method is used in mineralogy and works reasonably well.  You would have to build one, but it’s not a daunting task and there are designs that you can find on the internet.  You’d have to “calibrate” it to set the detection threshold.

The DoD, national security community, and the intel community have gradiometers and magnetometers (atomic magnetometers) that can detect even very deep voids (you can find the information in the public domain) - for example, for detecting a tunnel.

If the conduit is metal is conductive or if there is a wire in it a simple wire tracer might work.

The DoD has developed some very amazing low false alarm wire detectors used to find wires that are used in victim initiated or command wire IEDs without using the usual induction method (which is dangerous).  However, the best working methods and hardware are not public domain.  I will say it’s easy to detect “something” with a sensor that doesn’t use induction.  But detecting a real target versus clutter and false alarms is very hard.

73, Jeff
W3KL

> On Oct 28, 2020, at 11:11 AM, Grant Saviers <grants2 at pacbell.net> wrote:
> 
> Trying to find a design for a empty conduit tracer.  We've dug at a couple of places at the 501c3 where it was "supposed to go", NG.  Seems to me this is a simple widget for energizing a test wire in the conduit or some sort of mouse - LF or magnetic placed on the end of a snake.
> 
> Some googling hasn't found a design so hoping a towertalkian has a design or link to one that works.  This 2" conduit was installed some time ago at 24" depth but where it routes is now lost.
> 
> The commercial tracers are $3000.  My budget is more like $20.  The usual AM radio and dongle SDR's are available.
> 
> Also interested for when I need it to exactly locate my coax conduits before digging.
> 
> Grant KZ1W
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