User's Manual Part 2

Troubleshooting
G
ATEKEEPER SYSTEMS INC.
2007
CART CONTAINMENT MANUAL
Page 68
Using the multimeter to determine total antenna
Checking Antenna Resistance
Set the multimeter to the ohm scale and touch the two leads together. This gives you a baseline value, which
should be zero. If the value is not zero, calibrate the meter. If it is not possible to calibrate the meter to zero,
make sure to add the baseline value to any measured value you get when testing the antenna resistance.
14 AWG antenna used with Gatekeeper Systems antennas will have a resistance of approximately 2.2 ohms per
1,000 feet of antenna. The value for twisted pair antenna will be slightly higher.
1. Use the formula above to calculate the expected resistance. Write the number down.
2. Turn off the power to the CT. Do not use the
toggle switch, this de-energizes the board but
there is still power in the transmitter. If the
transmitter is hard wired (no cord), find the
circuit breaker and de-energize the breaker.
3. Remove the loop antenna from the terminal
block on the circuit board. Reading with the
antenna connected will give a false value.
4. Touch one of the meter probes to one end of
the antenna and one to the other end.
5. Record the reading and note whether the
reading is steady or fluctuating.
6. Compare the expected value and the actual
value. Use the table below to determine the
probable cause of the malfunction, then return
to the Main Troubleshooting Flow Chart and
continue the troubleshooting process.
Keep in mind that different multimeters have different sensitivities. Your results may not be exactly like
the examples.
Value Example Probable Cause
Close to expected 2.0 – 2.4 ohms for a 1000 foot
antenna.
Antenna is probably in good shape without
nicks, breaks or shorts.
0 0 There is a complete break in the antenna.
Much lower than expected 1 ohm for a 1000 foot antenna. This is usually due to a short in the twisted
pair leading from the CT to the antenna.
Much higher than expected 1 K-ohm for a 2,000 foot antenna This is frequently seen when a piece of
metal has been driven through the wire,
such as a sign pole or a metal spike for a
parking bumper.
Fluctuating Increases then decreases rapidly. This is caused by a capacitance in the
antenna, which means a non-insulated cable
bleeding to ground. This could be at a bad
splice or nick in the insulation that allows a
short into wet ground.