10
Active Antenna Feedlines
Use 75 Ω coaxial cable from each
AVA2
Active Matching unit to the
DXE-RFS-3
. The four
feedlines from the
DXE-RFS-3
phasing unit to the
AVA2
Active Matching units can be any length
needed to accommodate the size of the array, but must all be the same length, velocity factor and
type. Note the orientation and numbering of the elements by using
Figure 2
.
Be sure the appropriate
vertical antenna element is connected to the proper ANT connector on the phasing unit. The default
(zero control voltage) forward direction is towards Element 1. Element 3 is the rear or null
direction.
Delay Lines
The
DXE-RFS-3
uses a time delay system, not a traditional phasing system. Delay line lengths are
dictated by array dimensions rather than operating frequency. This results in phase being correct for
a rearward null at any frequency. This system is especially effective when used with DX
Engineering
AVA2
Active Matching units. User-supplied passive elements can also provide
exceptional performance for single or dual band operation where high dynamic range is required.
The
DXE-RFS-SYS-3P
includes three sets of custom made delay lines. Made for array side spacing
of 70 feet, their electrical length is critical and careful measurements were made when
manufacturing these delay lines using high quality 75 Ω coaxial cable with a known Velocity Factor
(VF) which is a very important factor. To avoid performance degradation due to inconsistent
coaxial cable construction, all three of the delay line coaxial cable assemblies are manufactured
from the same spool.
Delay lines DLY1 and DLY2 are half the length of DLY3.
Delay line cables can be neatly coiled in a 1.5 ft diameter coil. Support the weight of the cables by
taping or securing them to the support pole or mast rather than allowing them to hang from the
connectors.
It is important to use 75 Ω feedline to the operating position from the
DXE-RFS-3
. Do not use
amplifiers, combiners, filters or splitters that are not optimized for 75 Ω systems.
Control and Power Connections
The
DXE-RFS-SYS-3P
system, with the
DXE-EC-4
Control Console, no other equipment is
needed for powering the
DXE-RFS-3
, the active elements or controlling the receive direction.
J12
is the 5-terminal connector plug on the panel of the
DXE-RFS-3
. It is labeled
G A B C G
.
The
DXE-RFS-3
uses a two part green connector and the top part can be removed by pulling it
straight off. This will allow easier wire replacement or servicing as needed. When pushing the
connector back in place, ensure you press straight inward.
