- 10 -
Place a jumper across
L1MF
. Normally, jumpering any other positions will not be required for most
operations. Typically, the goal of reducing the array sensitivity
within the AM Broadcast Band is the only reason for adjusting the
jumpers in the Active units. If maximum AM Broadcast Band
reception is desired, or if the array is very far from strong AM
Broadcast signals, then no jumpers should be used. All eight active
elements in the array must have identical jumper settings.
Figure 6 - Active Element L1MF Jumper Locations
See the DX Engineering Active Receive Vertical Antenna user manual for more information about
additional peak response jumper settings.
Ground System
The
ARAV4
Active Elements work well with just a single copper ground rod placed as close as
possible to the mounting pipe. The mounting pipe can be used as the system ground if the pipe is an
adequate ground. It is recommended that a 3/4" or larger rigid copper water pipe, although
conventional copper coated steel rods may also work. Depending on soil conductivity, you can
expect better performance with multiple ground rods spaced a few feet apart. Increasing ground rod
depth beyond 5 ft rarely improves RF grounding because skin effect in the soil prevents current
from flowing deep in the soil. Avoid ground rods less than 5/8" OD. A good ground system
improves the array performance and enhances lightning survivability.
It is important that the
ground system is identical for each active antenna in the array.
You can test ground quality by listening to a steady local signal. Attach 15 ft of wire laid in a
straight line (away from the coaxial feedline) to the initial 4 ft to 6 ft ground rod. If you observe a
change in signal or noise level, you need to improve the ground. A second rod spaced a few feet
away from the first one may correct the problem or 10 to 12 ground radials, each 15 ft long, should
provide a sufficient ground system for most soil conditions.
Lightning Protection
While amateur radio installations rarely suffer damage from lightning, the best protection is to
disconnect electrical devices during storms. The key to lightning survival is to properly ground
feedlines and equipment and to maintain the integrity of shield connections. A proper installation
improves lightning protection and enhances weak signal receiving performance.
Consult lightning protection and station grounding information in the ARRL handbooks, or by
referring to the NEC (National Electric Code). The DX Engineering website also has technical and
product information “
Lightning Protection and Grounding
”. Use lightning surge protectors for the
coax feedline and control lines such as the
DXE-RLP-75FF
Lightning Protector, Receive 75Ω, DC
Pass, with F Connectors, for the array feedline at the station end single point ground.
Summary of Contents for DXE-RCA8C-SYS-4S
Page 31: ...31 NOTES...
