Grounding; Mobile Station Grounding - Yaesu FT-891 Operating Manual

Grounding

The provision of an effective ground system is important in any successful communica-
tions station. A good ground system can contribute to station efficiency in a number of
ways:
r It can minimize the possibility of electrical shock to the operator.
r It can minimize RF currents flowing on the shield of the coaxial cable and the chassis of
the transceiver which may cause interference to nearby home entertainment devices
or laboratory test equipment.
r It can minimize the possibility of erratic transceiver operation caused by RF feedback
or improper current flow through logic devices.
An effective earth ground system may take several forms; for a more complete discus-
sion,see an appropriate RF engineering text. The information presented below is intend-
ed only as a guideline.
Inspect the ground system – inside the station as well as outside – on a regular basis so
as to ensure maximum performance and safety.

Mobile Station Grounding

Although satisfactory grounding in most installations will be achieved via the DC cable's
negative lead and the antenna system's coaxial cable shield, it is often recommended
that you provide a direct ground connection to the vehicle chassis at the mounting lo-
cation of the transceiver. Due to unexpected resonances which may naturally occur in
any location, improper communication system performance may result from insufficient
grounding. These symptoms may include:
r RF feedback (resulting in distortion on your transmitted signal);
r Unintended frequency change;
r Blinking or blanking of the frequency display;
r Noise pickup; and/or
r Loss of memory.
Note that these conditions may occur in any communications installation. The FT-891
includes extensive filtering designed to minimize the chance of such problems; howev-
er,random currents set up by insufficient RF grounding can nullify such filtering. Bonding
the FT-891 transceiver to the vehicle or vessel's ground system should clear up any such
difficulties.
Yaesu Musen does not recommend the use of "on glass" mobile antennas unless the
shield of the coaxial cable is securely grounded near the feedpoint of the antenna. Such
antennas frequently are responsible for the ground-related difficulties described above.
FT-891 Operating Manual
Application for FCC / IC
FCC ID: K6620651X50 / IC: 511B-20651X50
Installation
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