My thanks to the entire group for the excellent responses (mostly :^)
) on my problem. It was only yesterday that I finally had opportunity
to address it.

The RF on the fish line did not work.... just did not seem to couple
and radiate. However, a very very simple procedure ( one of you
mentioned this ) did work. I had my wife pull and push the fish tape
back and forth while I listened very closely for any sound of it thumping
against the end of the pvc at the far end. It worked. I did not
actually hear it hittingi the duct tape, but I did hear it as it moved
back and forth on the last sweep at the end. It was only about 8 inches
under the surface of the sand ( much less than I had thought ) and was
located farily easily.

You guys came up with a plethora of solutions which would have been fun
to try.... one of the reasons I posted the question to this group,
even though a bit off topic.

To answer one question, the PVC will only be used for electrical, not
antenna, so the 3/4" is quite sufficient for my needs.

Again, thanks to all. I won't forget some of these methods suggested.

Ed K7AAT

Ed wrote:
"The RF on the fish line did not work."

Problem is that loss is proportional to signal frequency through the
earth, A low audio tone is much more appropriate. With a low audio tone
on an insulated conductor buried in the earth with reference to a ground
rod or ground bed, the conductor can be traced for miles. I`ve traced
4-ft. diameter poorly insulated steel pipelines for 8 miles or more and
they were buried several feet down for protection.

Reception can use a relay coil to sense the audio signal which is fed to
an audio amplifier and earphones. The coil core points toward the
conductor.

From the angles made by the core on both sides of the conductor the
depth of its cover can be closely estimated.

Best regards, Richard Harrison, KB5WZI

On Mon, 20 Oct 2008 00:25:00 -0500, (Richard
Harrison) wrote:

With a low audio tone
on an insulated conductor buried in the earth with reference to a ground
rod or ground bed, the conductor can be traced for miles.

During WWI, Heinrich Barkhausen was working with army field telephones
that exhibited strange whistling sounds, unrelated to the war
communications. These sounds were the RF emissions of lightning in
the AF band. What is more interesting is that the mode of propagation
was along Earth's magnetic flux lines, and the scale of propagation
was hemispheric.

As a byproduct of this research, Barkhausen suggested subterranean
communication employing a widely separated pair of rods in the earth,
and driving them with audio frequency communications. Range was
reportedly a function of the distance between the rods. The receiver
used the same earth connection method.

This was the subject of a Popular Electronics article in the mid 60s.

Not reported in that journal, Beverage of antenna fame was working at
the same time trying to develop a reliable RF communication system for
sending orders to troops in the field in Europe, from the US. His
system was a ground level wire of several 10s of miles long, oriented
end-on towards Europe. Troops could hear the US broadcasts in the
field with unsophisticated equipment. However, transmissions back to
the US didn't fare as well. They were overwhelmed on receive by the
back side orientation of the long wire towards the Caribbean and its
summer electrical storms. Dr. Beverage solved that by extending the
wire in that direction too and with termination.

Those frequencies were easily 30 times, or more, higher than
Barkhausen's suggestion - hence the very looooooong wire.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
"These sounds were the RF emissions of lightning in the AF band."

Richard also noted whistling sounds in army field telephones. I`ve seen
these audio radiations called "whistlers".

My efforts were to locate buried pipelines by a more convenient method
than bouncing a metal pick off of them. Pipeline rights of way can be
wide and pipes are often not where one may think but may be at odd
distances from the center of the right of way.

Connecting a signal to the pipe is much more effective than bouncing
signals off the pipe or detuning a metal locator with the pipe. Another
pipe tracing method in use is a vehicle (pig) launched into the pipe.
The pig contains a pneumatic hammer which produces so much noise that
it is easily heard through all the ground covering the pipe. Effective,
but it is not cheap to launch and recover pigs.

I`ve found broken pipes at the bottom of the Brazos River in Texas and
around offshore platforms in the Gulf of Mexico.

My efforts began with the availability of cheap SCR`s. I placed them to
key the output of cathodic protection rectifiers at a low audio
frequency rate. It worked well.

For more portability, I constructed a complimentary symmetry bipolar
power transistor generator which incorporated a 400-cycle Variac. The
generator was adjusted to produce a 12-Hz switching rate which proved to
work well. Output of the Variac was adjusted to give maximum power tnto
the pipeline wherever it was used from the switched 12 V automobile
battery. Connections to the pipeline are readily available at the
cathodic protection test points at intervals of several miles all along
the pipe.

Best regards, Richard Harrison, KB5WZI

Problem is that loss is proportional to signal frequency through the
earth, A low audio tone is much more appropriate. With a low audio tone
on an insulated conductor buried in the earth with reference to a ground
rod or ground bed, the conductor can be traced for miles. I`ve traced
4-ft. diameter poorly insulated steel pipelines for 8 miles or more and
they were buried several feet down for protection.

Thats a suggestion that I would have liked to have tried. I have the
generator, and could have easily fabricated a "receiver". Oh well.
Another technique to add to the repertoire !

Ed K7AAT