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Introduction
The
DXE-VFCC
Vertical Feedline Current Choke kits are designed for use with coaxially fed, 50 Ω vertical
antennas such as the Hustler BTV series, the DX Engineering family of verticals and many others.
The advantages of using a VFCC:
Offers a substantially greater amount of isolation and current balance than coiled coaxial cable
All power goes to the antenna system improving efficiency
Prevents unwanted RFI by eliminating feedline current and radiation
Reduces noise or unwanted signals picked up by the feedline
Overcomes a less than optimal ground system
When quarter-wave vertical antennas are constructed over a good radial system, they have a feedpoint
impedance of about 36 Ω. When they are installed over an inadequate ground radial system there is a loss
introduced at the feed point that adds to the 36 Ω figure. This apparently improves the SWR but there is a
loss in the efficiency of the antenna. Transmitted and received signals suffer attenuation from this
inefficiency. Often, currents introduced on the feedline shield will cause unwanted transmit RFI and received
noise.
With a ground-mounted quarter-wave vertical, regardless of the radial situation, but especially with poor
radial systems, there is the need for a
DXE-VFCC-H05-A
Vertical Feedline Current Choke (VFCC) to keep
current off the feedline.
The VFCC kit comes in two power levels. The
DXE-VFCC-H05-A
rated at 2 kW continuous and the
DXE-
VFCC-H10-A
, rated at 5 kW continuous. Both kits include an insulated mounting plate used to mount the
choke to the base of the vertical and the necessary braid used to connect the choke to the vertical feed point
and ground system.
When a 1/4-wavelength vertical is mounted well above the ground and uses elevated radials, it is difficult to
keep current from traveling back to the operating position via the feedline. In this application, using an
additional feedline current choke like the
DX Engineering
DXE-FCC050-H05-A
installed outside of the
near field of the vertical will further reduce feedline currents.
Additional Items Required
Mounting Clamp
- Stainless Steel V-Clamp
DXE-SSVC-2P
, to mount the insulated plate to a 1" to 2" OD
(maximum) ground mounting pipe, usually the same one used to mount the vertical antenna.
Installation
Ground Mounted Vertical Antenna
The VFCC kit should be mounted to the same mounting pipe used to mount the vertical antenna.
The
standard 1-1/2" galvanized water pipe (with its 1.9" OD) is just fine for this application and can
usually be found at your local home building supply store.
It should be mounted horizontally as close to
the base of the vertical antenna as possible. If you are using a DX Engineering Tilt Base, sufficient clearance
is needed to ensure the antenna does not contact the VFCC when tilted. Proper orientation of the VFCC to
the Tilt Base also ensures good geometry of the feed connections during tilting.
