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BARRETT PRC-4090 TACTICAL HF SDR TRANSCEIVER - INSTALLATION
The ground (earth) system is a key part of the overall antenna system and con-
sequently the system operation. An inadequate ground (earth) system is the pri-
mary cause of poor performance and tuning problems. Unless a good ground
(earth) system (counterpoise) can be provided, there is little point in installing
the antenna. In areas of good ground (earth) conductivity (i.e. the terrain is
always damp), an effective ground (earth) can be made through a grounding
(earthing) rod. This should be a minimum 1.5 metres in length and should
be installed as close to the tuner as possible. A suitable grounding (earthing)
can be purchased from Barrett Communications (P/N BCA90056). Several rods
bonded together will improve the ground (earth) contact. In some cases metal
water pipes may be used as a ground (earth) providing:
• The water pipe is close to the tuner and the water pipe enters the ground
close to the tuner.
• There are no joints or couplings in the pipe that will increase the resist-
ance path to ground.
• The water pipe enters soil with good conductivity.
• A low resistance joint is made with the water pipe.
Frequently the ground (earth) conductivity will not be sufcient to provide a
satisfactory ground (earth) for the Barrett 4011 tuner. This will almost certainly
be the case in well drained sandy soils or on rock. In these cases, a counterpoise
must be used as a ground (earth) system. This will also be the case in rooftop
installations where no existing ground plate (such as metal roong) exists.
The number of radials required for an effective counterpoise depends on the soil
quality, dampness and other factors which affect the conductivity of the soil.
The more radials used, the better will be the performance of the antenna/ATU
combination especially at lower frequencies. This manual suggests a minimum
of 20 radials, but optimum performance at low frequencies is not guaranteed.
The radials of the counterpoise need only be of much thinner cable i.e. 5.48mm
2
(#1 #2 SWG) preferably copper wire. RG58 Coaxial cable may be used. At the
base of the antenna, the radials all couple together at a common well bonded
antenna ground (earth) point. The radials should be buried into the ground to
a minimum of 200 mm depth.
Note: To accomplish reliable ATU tunes at frequencies below 5 MHz, it is not uncom-
mon, with poor conductive soil conditions, to require up to 120 radials each of up
to 70 m length, requiring thousands of metres of cable and a lot of trenching. This
is impractical and is the reason we do NOT recommend Whip/ATU antenna for land
based systems.
Ground (Earth) System
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