Gopher(s) ate buried Radio Dog Fence - several thousand feet - need scientific method to locate bre

[davefr]

I installed a 2-3 acre section of undergound electronic Radio Dog
Fence several years ago. On those several acres are several thousand
gophers.

Today one of those thousand gophers ate one of those thousand feet of
wire and I'm getting the fault alarm.

The radio fence manual is rediculous. It says to start at the half
way point and patch back to the control unit and keep doing it until
the broken section is located. That would take me several years and
several thousand feet of patch cords. Beside that I can't pinpoint
the flags (gophers ate those too!)

I want a scientific method of pinpointing the break however I don't
want to invest $1000's in a TDR (time domain reflectometer).

I do have some old signal generators and I heard there's an AM radio
method.

Anyone have any tips at locating the break. The dog doesn't really
need it anymore but I want to preserve it for future generations.

TIA

 

[Mark]

interesting question

is the wire a single insulated conductor or is it some kind of shielded
or multiconductor cable?

do you have acess to both ends and the break is in the middle of the
loop someplace?


i guess you could connect an AM signal gen to eac h end and follow it
with a portable AM radio

Mark

 

[Doug Miller]

I installed a 2-3 acre section of undergound electronic Radio Dog
Fence several years ago. On those several acres are several thousand
gophers.

Today one of those thousand gophers ate one of those thousand feet of
wire and I'm getting the fault alarm. [...]
I do have some old signal generators and I heard there's an AM radio
method.

Yep. Works great, too. Tune a portable AM radio to the very bottom end of the
band, and turn the volume all the way up. Hold the radio close to the ground,
and move it back and forth in the area where you think the wire is. When
you're over the wire, you'll hear a marked change in the noise on the radio.
Once you've found the wire in this manner, keep following it. When you *don't*
hear that distinctive sound any more, that's where the break is -- or at least
close to it. Go back to where you last heard the distinctive sound (probably
won't be more than six feet away) and dig up the wire (typically buried only a
few inches deep). Follow it until you find the break. If the other end isn't
readily evident within a short distance of the break, you can trace it in the
same manner.

 

[Dean Hoffman]

I installed a 2-3 acre section of undergound electronic Radio Dog
Fence several years ago. On those several acres are several thousand
gophers.

Today one of those thousand gophers ate one of those thousand feet of
wire and I'm getting the fault alarm.

The radio fence manual is rediculous. It says to start at the half
way point and patch back to the control unit and keep doing it until
the broken section is located. That would take me several years and
several thousand feet of patch cords. Beside that I can't pinpoint
the flags (gophers ate those too!)

I want a scientific method of pinpointing the break however I don't
want to invest $1000's in a TDR (time domain reflectometer).

I do have some old signal generators and I heard there's an AM radio
method.

Anyone have any tips at locating the break. The dog doesn't really
need it anymore but I want to preserve it for future generations.

TIA

I've never tried this so don't know if it will work.
The AM radio method is to hook one of the spark plug wires from a
running engine to the underground wire. The portable AM radio is
supposed to get more static as one gets closer to the break.

Dean

 

[Toller]

I recently had the same problem, though I only had 800' of wire. My
instructions told how to put a little coil across the leads, which created a
beat pattern. You could then use a radio to listen for it.

It worked, but was a real pita. I got various strong and weak signals all
over the place. Of course, in my case I didn't have broken wire; apparently
some insulation had worn off and the signal was shorting into the ground,
leading to a circuit too weak for the receiver. Maybe with a real break it
would work better.

 

[Doug Miller]

interesting question

is the wire a single insulated conductor or is it some kind of shielded
or multiconductor cable?

All the electronic dog fences I've ever seen use a single insulated conductor.

do you have acess to both ends and the break is in the middle of the
loop someplace?

Obviously he has access to both ends -- they're connected to the control unit.

i guess you could connect an AM signal gen to eac h end and follow it
with a portable AM radio

He already has an AM signal generator connected to each end -- the control
unit. All he needs is a radio, as I described in another post.

 

[[email protected]]

Your FIRST step should be to join the Varmint Hunters Association, and
open your place up to them, for a little clean-up.

It's OPEN SEASON for varmints, you'll recall.

 

[Elmo]

I installed a 2-3 acre section of undergound electronic Radio Dog
Fence several years ago. On those several acres are several thousand
gophers.

Today one of those thousand gophers ate one of those thousand feet of
wire and I'm getting the fault alarm.

The radio fence manual is rediculous. It says to start at the half
way point and patch back to the control unit and keep doing it until
the broken section is located. That would take me several years and
several thousand feet of patch cords. Beside that I can't pinpoint
the flags (gophers ate those too!)

I want a scientific method of pinpointing the break however I don't
want to invest $1000's in a TDR (time domain reflectometer).

I do have some old signal generators and I heard there's an AM radio
method.

Anyone have any tips at locating the break. The dog doesn't really
need it anymore but I want to preserve it for future generations.

TIA

Our Invisible Fence has occasionally had a break. Here's how we locate it.
Take one of the collar units off the dog.
Hold it (by the collar) at about dog height.
Walk to where the fence is.
If it chirps then you have signal there so move to a different location.
If it doesn't chirp then you're in the right area so move to a different location.
Repeat until you have two spots with chirps and a space between with no chirp.
Your break will probably be in between the two.

 

[Dan Espen]

I installed a 2-3 acre section of undergound electronic Radio Dog
Fence several years ago. On those several acres are several thousand
gophers.

Today one of those thousand gophers ate one of those thousand feet of
wire and I'm getting the fault alarm.

The radio fence manual is rediculous. It says to start at the half
way point and patch back to the control unit and keep doing it until
the broken section is located. That would take me several years and
several thousand feet of patch cords.

If you have 1 mile of wire, it would take an average of 5 tries to
isolate the break within 5 feet, a maximum of 11 tries.

Beside that I can't pinpoint
the flags (gophers ate those too!)

Time for plan B.

 

[Bill Janssen]

If you have 1 mile of wire, it would take an average of 5 tries to
isolate the break within 5 feet, a maximum of 11 tries.




Time for plan B.

If the wire is not broken but was a short to ground You can use a
resistance bridge
arrangement to locate the ground.

The two ends of the loop tie to two ends of a potentiometer, Put one or
two volts to the
two end connections of the loop and measure from the wiper and ground.
Adjust
the potentiometer for minimum voltage. Then the ratio of the two parts
of the pot.
is the same as the two parts of the loop.

Bill K7NOM

 

[Pop]

:I installed a 2-3 acre section of undergound electronic Radio
Dog
: Fence several years ago. On those several acres are several
thousand
: gophers.
:
: Today one of those thousand gophers ate one of those thousand
feet of
: wire and I'm getting the fault alarm.
:
: The radio fence manual is rediculous. It says to start at the
half
: way point and patch back to the control unit and keep doing it
until
: the broken section is located. That would take me several years
and
: several thousand feet of patch cords. Beside that I can't
pinpoint
: the flags (gophers ate those too!)

Well, that's actually pretty standard advice in that manual, and
actually does work well. It's called the "rule of halves".
If you start with 1,000 ft of wire for example and use the rule:
-- you get 500' the break could be in.
-- then 250'
-- 125'
-- 62'
-- 31'
-- 15'
-- 8'
-- 4'
-- 2'
-- 1'
-- 6"
but you'll find the break at about the 8' point because you can
eliminate the parts of the wiring not in the ground easily.

To estimate where the wire is buried, a cheap portable AM radio
will usually suffice. It may not do a lot to locate where the
break is because most wires are transformer driven and the
voltage will exist on both sides of the break, but it can locate
where the wire is buried reasonably well.

If you used the metal flag poles, you might locate the buried
portions of them with a cheap metal detector if you know they're
actually still there and not just mowed/dragged away.
If you have access to a "good" metal detector, it might locate
the actual wire too, depending on how deep it's buried.

Once the wire's located, you could also use the "shorting across
the break" trick to locate the break too, using the rule of
halves and the dog's receiver to tell when it starts working
again.
Short 500' and if Rx works, it's in that 500', else it's in
the other 500'. Then 125' and so on.

An afternoon would surely take care of this for the size field
you have once the wire is located.

The worst case scenario is that there are more than one break in
the wire. Only the rule of halves and looping back to the Tx
would work in that case. Had any heavy equipment or serious
ground movement in there lately?

HTH,

Pop

 

[Mike Berger]

This should work of course, but it would be best to capture
the gopher responsible and make him show you where he committed
his crime.

 

[Pop]

: davefr wrote:
: > I installed a 2-3 acre section of undergound electronic
Radio Dog
: > Fence several years ago. On those several acres are several
thousand
: > gophers.
: >
: > Today one of those thousand gophers ate one of those thousand
feet of
: > wire and I'm getting the fault alarm.
: >
: > The radio fence manual is rediculous. It says to start at
the half
: > way point and patch back to the control unit and keep doing
it until
: > the broken section is located. That would take me several
years and
: > several thousand feet of patch cords. Beside that I can't
pinpoint
: > the flags (gophers ate those too!)
: >
: > I want a scientific method of pinpointing the break however I
don't
: > want to invest $1000's in a TDR (time domain reflectometer).
: >
: > I do have some old signal generators and I heard there's an
AM radio
: > method.
: >
: > Anyone have any tips at locating the break. The dog doesn't
really
: > need it anymore but I want to preserve it for future
generations.
: >
: > TIA
: Our Invisible Fence has occasionally had a break. Here's how
we locate it.
: Take one of the collar units off the dog.
: Hold it (by the collar) at about dog height.
: Walk to where the fence is.
: If it chirps then you have signal there so move to a different
location.
: If it doesn't chirp then you're in the right area so move to a
different location.
: Repeat until you have two spots with chirps and a space between
with no chirp.
: Your break will probably be in between the two.

That's sure worth a try, but it didn't work for me.
Without current flow, the Rx wouldn't pick up anything anywhere
except right up at the Tx. I had a literal break though; maybe
it works for a short ckt to gnd; was that what you found?

Pop

 

[Elmo]

: davefr wrote:
: > I installed a 2-3 acre section of undergound electronic
Radio Dog
: > Fence several years ago. On those several acres are several
thousand
: > gophers.
: >
: > Today one of those thousand gophers ate one of those thousand
feet of
: > wire and I'm getting the fault alarm.
: >
: > The radio fence manual is rediculous. It says to start at
the half
: > way point and patch back to the control unit and keep doing
it until
: > the broken section is located. That would take me several
years and
: > several thousand feet of patch cords. Beside that I can't
pinpoint
: > the flags (gophers ate those too!)
: >
: > I want a scientific method of pinpointing the break however I
don't
: > want to invest $1000's in a TDR (time domain reflectometer).
: >
: > I do have some old signal generators and I heard there's an
AM radio
: > method.
: >
: > Anyone have any tips at locating the break. The dog doesn't
really
: > need it anymore but I want to preserve it for future
generations.
: >
: > TIA
: Our Invisible Fence has occasionally had a break. Here's how
we locate it.
: Take one of the collar units off the dog.
: Hold it (by the collar) at about dog height.
: Walk to where the fence is.
: If it chirps then you have signal there so move to a different
location.
: If it doesn't chirp then you're in the right area so move to a
different location.
: Repeat until you have two spots with chirps and a space between
with no chirp.
: Your break will probably be in between the two.

That's sure worth a try, but it didn't work for me.
Without current flow, the Rx wouldn't pick up anything anywhere
except right up at the Tx. I had a literal break though; maybe
it works for a short ckt to gnd; was that what you found?

Pop

Nope, it was a clean break (made it myself with a shovel that I just stuck in
the ground while doing something else at least 2 feet away from the fence
location). But there was another case where that did not find the break and we
ended up getting our Invisible Fence Man to materialize with his magic equipment
that did more. I don't recall what the problem was -- that was 2 houses ago.

 

[Doug Miller]

If you have 1 mile of wire, it would take an average of 5 tries to
isolate the break within 5 feet, a maximum of 11 tries.

Nonsense. Maximum is indeed 11, but the average is TEN, not five.

 

[[email protected]]

This should work of course, but it would be best to capture
the gopher responsible and make him show you where he committed
his crime.

.........and sue the little bugger for damages.

 

[Neon John]

You don't need a TDR. A simple underground wire tracer will do. This
thing puts a low level RF signal on the line. You track it with a
receiver. Maybe you can rent one or perhaps find someone with the
phone or power company to come out and search.

I have a very old, antique cable locator made by Western Electric. It
consists of little more than a vibrator type induction coil. It feeds
several hundred volts into the wire. The receiver is nothing more
than several tens of thousands of wire wound into a coil and attached
to a set of headphones. The phones register a clicking sound, louder
the closer it gets to the wire. This is something you could make at
home.

Now the question arises, what are you going to do about the gophers
before the next time.

John

 

[davefr]

Thanks for the replies.

At first I tried an AM radio but barely heard the signal caused by
the fence. Part of the problem was that there was a radio station
broadcasting at about the same frequency as the fence.

Next I tried an old signal generator and connected the RF Output leads
to each end of the wire loop. I tuned the radio and signal generator
to about 600 khz where there wasn't any radio station.

I taped the radio to a yardstick. It turns out the radio had the be
aligned perpendicular to the underground wire to get the signal.

It was easy. I just walked the fence line until the output dropped
off. Then I went past it until I re-intercepted the signal again.
That distance was only a few feet. Within inches of the center point
in the null area was a fresh gopher hole and that's where the fence
was eaten.

 

[willshak]

This should work of course, but it would be best to capture
the gopher responsible and make him show you where he committed
his crime.

Rub his nose on the broken wire?
Or, put collars on all the gophers and put them outside the perimeter,
so they won't come back onto the property.

 

[Art Schwartz]

Rent-A-Coyote...