Specifications

SG-231 MANUAL
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Another key lesson here is that even if you have a low capacitance lead, a high
capacitance antenna will not work well. If you have a whip type antenna, mounted on
the back of a van, you will have a large portion of the antenna running right next to
grounded sheet metal. This causes a high loss to ground, one reason why we do not
recommend CB type whip antennas. The other reason is the base insulation in ball
mounts is inadequate for everything but extremely low power.
Long lead lines. If you have a Smartuner feeding a 9-foot antenna with a 1-foot feed
line located inside a hull or inside a vehicle, you have 10% of the antenna where it will
do you no good. If you have more than 5% of the antenna inside a grounded cabin, you
will begin to lose performance.
A good rule of thumb is that under one foot of feed line is a good installation, one to
two feet aren't very good installations, and over two feet means you are asking for
trouble.
“Odd reactance.” The next category of antenna fault is what we call the “odd reactance”
problem. Although the Smartuner is an exceptionally well-designed product, you may
from time to time find an antenna length that just won’t quite work right. Generally
this occurs when the Smartuner is having a tough time making up its mind about which
of two tuning solutions is better. If it is a very close call, you can have an antenna
which causes cycling and just won't stay locked.
The solution in such cases is to add or subtract a couple of feet of wire from the antenna.
This generally cures the problem.
As part of your check-out of an HF system, you should operate on all channels and
frequencies which you plan to use on a regular basis to insure the coupler and antenna
which you have provided work well.
Antenna insulators. Sporadic operation may be caused by poor antenna insulators. We
have seen on sailboats, for example, people trying to save money by expecting the
fiberglass hull to act as an insulator and not using a lower insulator. The hull is not a
good insulator and a thin layer of wet salt water will degrade the ground further.
Similarly, mobile HF users who rely on a poor quality ball-mount find these are
especially prone to arc over inside the ball mount where it is difficult to detect.
The point we are making here is simply this: you should have a leakage path of 2 inches
at all points on your antenna and especially in the area of the feed point: 10,000 to
30,000 volts of RF energy will not be adequately confined by inexpensive insulators.
10.3 Transmitter Faults
Some vexing problems don't relate directly to the antenna or the ground system but
may nonetheless cause difficulties. Here are two of the most common types:
Oscillation. The transmitter may have a tendency to oscillate. The general symptom is
that the coupler will work well with another radio but will not tune correctly when the