laying in a ground system is the best time to track down annoying noise
sources. Not only will you get much better voice communications, but
Weatherfax, Navtex and Loran reception will improve as well if they are also
tied into the ground system.
Particular attention should be paid to any device which uses an electric motor.
This means to turn on the water pressure pump, bilge pump, hot water forced
air heater fans, refrigeration and autopilot motors. A few small capacitors to
ground (.01 microfarads at 100 VDC) can resolve many issues. Bypassing of the
vessel's alternator is also a good idea.
6
6..3
3..3
3
B
Ba
as
se
e S
Stta
attiio
on
n G
Gr
ro
ou
un
nd
ds
s
In areas of high ground conductivity, an effective ground can be made
through a grounding rod. The rod should be approximately 3 meters in length
and should be installed as close as possible to the tuner. It may be necessary to
use several ground rods bonded together to improve the ground contact. Water
pipes are sometimes recommended as grounds and may be used provided plastic
pipe is not buried as part of the system and the following conditions are met:
a)
The water pipe is close to the tuner.
b)
The water pipe enters the ground very close to the tuner bonding point.
c )
There are no joints or couplings in the pipe that will increase the
resistance path to ground.
d)
The water pipe enters soil with good conductivity.
e)
A low resistance contact is made to the water pipe.
E
E a
a r
r tt h
h r
r e
e q
q u
u ii r
r ii n
n g
g a
a c
c o
o u
u n
n tt e
e r
r p
p o
o ii s
s e
e .. Frequently the ground conductivity will
not suffice to provide satisfactory operation of the coupler - almost certainly
the case with well drained sandy, rocky or loamy soils. Therefore, a counter-
poise (artificial ground) must be used as the ground system.
R
R o
o o
o ff tt o
o p
p ii n
n s
s tt a
a ll ll a
a tt ii o
o n
n r
r e
e q
q u
u ii r
r ii n
n g
g a
a c
c o
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u n
n tt e
e r
r p
p o
o ii s
s e
e .. In a rooftop installa-
tion where there is no existing ground plane, the ideal ground would be con-
ducting surface extending several wavelengths in all directions around the
antenna. On a rooftop, this situation may be approximated by placing a screen
of chicken mesh, copper hardware cloth or similar material over the roof of
the building. More frequently, a counterpoise system of radial wires must be
used. SGC recommends the use of at least 8-12 radials bonded together in the
center. If the antenna is at ground level, the radials should be buried a few
inches below the surface.
39
© 1998 SGC Inc
SG-230 Manual
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA 98005 USA
P.O. Box 3526, 98009 Fax: 425-746-6384 Tel: 425- 746-6310 or 1-800-259 7331
E-mail: [email protected] Web site: http://www.sgcworld.com