Specifications

SMARTUNER MANUAL 50
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
© Nov2000 SGC, Inc. P.O. Box 3526, 98009 Fax: [phone] Tel: [phone]
E-Mail: [e-mail] Web Site: www.sgcworld.com
• You may simply change the ground system so that it becomes larger than the
antenna at the problem frequency.
Differing resistance. The third kind of ground fault that we encounter occurs when a
ground system and an antenna have very different electrical resistance. This happens
when you install a very conductive copper antenna wire in an aircraft. When the
fuselage is used as a counterpoise, the aluminum must be much bigger than would a
copper ground because the internal resistance of aluminum is significantly higher than
copper.
By the way, this is why we don't like to use aluminum ground wires as radials. Just as
when aluminum is used in house wiring, several gauges larger are needed to carry the
same amount of current the same need applies here.
Improper bonding. The fourth kind of ground fault you may encounter occurs where
the ground is not properly bonded to the coupler. We go to considerable effort to make
sure the stainless steel ground stud is well connected to the coupler. In fact, we go so
far as to use large braid on the inside of the coupler.
Particularly in automobiles and aircraft, a single ground connection will not do. It is
mandatory that at least two ground bolt connections be used.
Inaccurate assumptions. The fifth situation to check for is what we call “dangerous
assumptions” about the ground system. When you bond from the antenna coupler to
copper or iron water pipes, you might make an assumption that the water pipes are a
good ground. But in many installations, copper pipes are used in the building but a
plastic main connects to the municipal system just outside the service entrance. So
much for a good ground.
11.2 Antenna Faults
The key to getting the most out of your SMARTUNER is to realize the antenna begins
right at the ceramic feed through insulator on the SMARTUNER case. In other words,
this is the feed point of your antenna system. Failing to install your coupler accordingly
will result in unsatisfactory operation. With this concept in mind, you can easily avoid
some of the common troubles with a properly planned installation.
Coaxial cable on output. Coax on the output is probably the single most commonly
asked question about the coupler and is the most misunderstood. Let us reiterate: The
SMARTUNER was not designed to feed a piece of coax.
Stray ground capacitance. Stray ground capacitance is the next largest cause of
malfunctioning installations. If you have a long lead wire from the coupler to a feed-
through (on a wall or bulkhead), you significantly increase your chance of problems.