Table of Contents
Advertisement
,.
R.F.
COAX
-~
MOUNTING~
SCREW
GAEPS-30071-O
Figure12.
Electrical and Mechanical Connections
Step 4.
Route and connect the solder lugs of the con-
trol cable as shown in Figure 12. Tie-wrap the control
cable to the coaxial cable, and attach the lug housing
with mounting screw.
3.6
COAXIAL CABLE
(Refer to Figure 13.)
Use type RG-58/U or RG-8/U, 50-ohm, coaxial
.
cable with the appropriate UHF connectors (PL-259) on
both ends to interface the RF OUTPUT from the radio
to the RF INPUT to the antenna tuner.
C~J':""
~/
3 CONOUC1aI
CASU:
CONtRO<.
CIN€
ro!MlNAl.S
\
,13(')
ANT T1JNE
I
'-AHTEHNA
TRITON
HF-SS8
RADIO
'--GOlD
WG
~
,w...
.rl
Tl961A OR
TlKZA
ANTENNA
T\JNER
He
_F
INPUT
\
~
OR RGlIV COAX
BEPS-3OO1'-0
GOlD
STRAP
Figure 13. Electrical Block Diagram
J
!
6
4.
GROUND SYSTEMS
(Refer to Figures 14 and 15.)
.
4.1
A common ground for the entire radio system
(radio, dc power supply, antenna tuner, etc.) is re-
quired for proper system performance. This type of
grounding is accomplished through the use of three inch
wide grounding straps terminating at the GROUND
LUG on the antenna tuner, which in turn is connected
to the antenna ground plane. When at all possible,
avoid multiple path ground connections. They result in
ground loops which may have high circulating currents.
On certain operating frequencies, ground loops cause
radio and/ or antenna tuner instability.
4.2
The ground strap to the antenna tuner must be
within a maximum of 5 feet of the tuner. If the
ground strap is long in terms of the operating frequency
wavelen'6th, it can actually present a high impedance to
the ground lug on the antenna tuner. As a result, the
antenna
tuner is electrically "floating"
above the
reference ground of the system.
4.3
An adequate system ground is usually easily ob-
tained on a metal hulled ship with a metal deck.
All communications equipment can be grounded to the
,metal structure of the ship at convenient places.
4.4
Wood and fiberglass vessels present more difficult
.
grounding problems. Large ground straps are re-
.
quired to electrically bond equipment together, and an
artificial ground plane must be created. Either of two
methods is used to achieve the required ground plane:
ground plates or screening. Ground plates or screening
is installed inside the hull of the craft so that good elec-
trical contact with the' water is made through the
capacitive effect of the hull (dielectric). At least 100
square feet of the area below the water line is recom-
mended. Figure 14 shows an example of a ground
system where a ground plate is placed on the inside of
the hull of the vessel.
4.5
An artificial ground plane can be further improved
with the addition of copper screening connected
through a ground strap to the base of the antenna tuner
and placed in the immediate vicinity of the antenna
tuner. The antenna tuner should also be grounded to
copper pipes, the metal water tank, and the engine to ex-
tend the ground system. The addition of 1/4 wavelength
radials extending from the ground lug of the antenna
tuner creates a further improvement in system per-
formance. Figure 15 shows a radial ground system.
.
Advertisement
Table of Contents
