Introduction
3.1 VM-810/VM-850
This user handbook covers the use of the VM-810 and VM-850 cable and pipe location
systems.
The Vivax-Metrotech Model VM-810, Radio Frequency Line Tracers are excellent
instruments for tracing water and gas distribution lines, cables, inductive locating, and
blind searching. The high frequency signal of the VM-810 is able to jump insulators
and rubber gaskets often found in water and gas distribution systems. Since the
radio frequency travels easily through the soil, the VM-810 is an ideal instrument
for inductive locating. The floodlight quality of the RF signal will induce signal onto
conductors 8-10 ft. on either side of the transmitter making it an excellent instrument
for blind searches. The lower frequency VM-850 is particularly useful in congested
areas where it is essential to ensure as little bleed over to other conductors is
minimized. It is most often used for power, telecommunications, CATV, oil or gas
applications.
The VM-810/VM-850 transmitter generates a signal which is applied onto the pipe
or cable (conductor). The signal travels along the conductor, becoming weaker as it
gets farther away from the transmitter. The distance that the signal travels before it
becomes too weak to be detected depends on the method of connection, the type of
conductor surrounding soil, and depth of the conductor.
When positioned over the conductor, the receiver will detect the signal from the
conductor. The Receiver’s Left/Right Guidance System, field strength display, and
audio tone aid you in tracing. To display the depth of the conductor, you simply push a
button.
The Model VM-810/VM-850’s automatic impedance matching compensates for
differences in soil conditions, conductor size and material.
As with all electromagnetic locating systems, this unit is designed to locate metallic
conductors only. The word “conductor, pipe, or cable” refers to a metallic conductor
throughout this user handbook.
The VM-810 and VM-850 operate in a very similar way. The main differences are:
• VM-810 operating frequency is 83.0775 kHz
• VM-850 operating frequency is 9.82 kHz
• The VM-810 transmitter is powered from 6 x “D” cell alkaline batteries.
• The VM-850 transmitter is powered from internal rechargeable Lithium-ion
batteries. (Rechargeable batteries are used with the VM-850 transmitter as the
power drain from the lower frequency transmitter is much greater than that of the
VM-810)
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