Hi there, Bob. I'm wondering if I gave you bad information. I regularly use two different types of wire tracer - the 'fox and=20 hound' type tracer that follows an electric field and the=20 magnetic-type that use a pickup coil. I sort of use them=20 interchangeably, so I might have gotten it wrong when I suggested=20 that following the electric field should work for following an=20 underground cable. The reason I'm now thinking that is because I've always used my=20 Jumper Tracer (with ferrite pickup coil) or one of our units=20 (open-air wound coil) whenever I've had to follow a buried cable. The solution is simple - add a pickup coil to your high-gain=20 amplifier. That can be an air-wound coil a couple of inches in=20 diameter or even an old AM radio loopstick antenna. Now you have to drive some current into that underground wire -=20 either ground the far end of the wire or, if you have two conductors,=20 just short them together at the far end. You won't get anywhere near=20 as much detection range if the two conductors are together in the=20 same cable (or pipe) but you can still follow it from a couple of feet away= .. Put an AC ammeter on the output of the amplifier to ensure that you=20 don't wreck it from driving into too low a load impedance. You don't=20 need much current - an Amp or so is fine. Please let us know how you make out! dwayne At 05:25 PM 5/19/2013, Bob Blick wrote: >I put a warble tone out on a known buried wire today, using a copper >water pipe outside my house for ground. The water pipe doesn't go >underground except way on the other end of the house, so it was >sub-optimal. > >It worked great for the wire above ground, easily four feet away my >detector was clipping. > >But as soon as the wire went underground I got nothing, absolutely >nothing. The test wire is in a plastic conduit less than a foot below >ground. > >My setup used a warble tone on an MP3 player running into a >reasonably-capable integrated amplifier putting out about 25 VAC. For >the detector I had a telephone handset amplifier I modified for high >input impedance and a stiff wire probe about a foot long. > >The buried wire was a power cable, I also tried driving one conductor >signal hot and another signal ground. Not very mych range aboveground, >nothing below. > >I'll try again driving in a local ground stake. > >Bob > > >-- >http://www.fastmail.fm - The professional email service > >-- >http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >View/change your membership options at >http://mailman.mit.edu/mailman/listinfo/piclist --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .