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Re: [TowerTalk] Coax questions

To: Jim Brown <>
Subject: Re: [TowerTalk] Coax questions
From: jimlux <>
Date: Sat, 28 Aug 2010 16:11:14 -0700
List-post: <">>
Jim Brown wrote:
> On Sat, 28 Aug 2010 13:58:22 -0700, jimlux wrote:
>> Most rental yards have a cable locator.  It comes with a little box with 
>> a cliplead that puts a low frequency AC on the cable (or pipe) you're 
>> trying to find, and the locator that looks for the signal.  Used all the 
>> time with modern plastic gas pipes (typically with a wire wrapped around 
>> it to facilitate this process)
> It seems like it ought to be possible to improvise something that would do 
> the job. One thing that would probably work is to drive the cable shield 
> (end to end) with a 1kHz signal that is feeding an ordinary power amplifier 
> (like what's in your home stereo) and look for it with a magnetic coil 
> that's connected to a portable headphone amplifier. Two easy-to-use coils 
> are 1) a dynamic mic; 2) a de-gaussing coil. 
> Another possible test signal is a QRP transmitter running on 160M loading 
> the cable shield as a long wire, then look for it on a portable RX. Even a 
> signal generator might put out enough signal to be heard on a portable AM 
> radio. 
> 73, Jim K9YC  

the commercial units have a specially designed sense coil with a well 
defined null, so you can find exactly when the coil is over the pipe/wire


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