18
C) Shorted or opened conductors caused by water migration into a control line or a feedline.
Over 80% of all Receive Four Square (RFS) malfunctions have been caused by the above
system problems. A thorough inspection and subsequent testing of each control cable, RF
cable, and their respective connections, will uncover the cause of most RFS troubles. Here are a
few other causes for RFS malfunction:
D) One or more burned out Active Vertical Antenna units model AVA-2 or AVA-1, due to
lightning pulse or high power RF overload. One-half wavelength on the lowest frequency is the
minimum distance between the Active antennas and any transmit antennas. If that distance is
less and high power is used, then the Time Variable Sequence Unit, model
DXE-TVSU-1B
must be used to interrupt power to the
AVA-2
units.
E) Damaged
RFS-3
unit due to lightning. This has been reported only a couple of times and is not
very likely.
F) Active units that were damaged by animals. Once we received actives damaged by an animal
that relieved themselves on the antenna whips and AVA units, as if they were “trees”.
The above items are the most common failure points in the system that need to be checked.
If necessary, the following further troubleshooting procedure may assist in finding the malfunction.
Receive Four Square Control Troubleshooting Procedure
1) Test the
DXE-EC-4
BCD Control Console unit, which should be
connected only to the control lines of the Receive Four Square
System. When the
EC-4
is connected to the control cable, do all of
the selected switch position LEDs light normally?
2) When rotating the Control Console switch from position 1, 2, 3 and 4, if all
LEDs light normally, measure BCD output voltages. Normally, +12 for the EC-
4 is output on the green connector terminals located inside the unit.
Connections 1, 2 and 3, reference to the ground pin G as shown below.
The
selected position will supply the BCD logic voltage as shown in the chart below.
Forward Direction
EC-4 Switch
Position
BCD Terminal
EC-4 LED
Illuminated
1
2
3
Element 1 (Default)
1
0
0
1
# 1
Element 2
2
1
0
1
# 2
Element 3
3
0
1
1
# 3
Element 4
4
1
1
1
# 4
BCD Directional Control Matrix, “1” 12 Vdc (Default)
The numbered terminals of the 4-pin green connector correspond to the numbers in the table
above, with voltage measured as referenced to the G ground terminal.
