SG-231 MANUAL
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
© 11/00 SGC, Inc.
P.O. Box 3526, 98009 Fax: (425) 746-6384 Tel: (425) 746-6310
E-Mail: [email protected] Website: www.sgcworld.com
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10.0 Troubleshooting
Only a small number of installation mistakes can be made. These will fall into one of
several categories: ground fault, cable fault, and antenna fault. There is also a slight
chance of an electrical fault in the coupler.
When you are troubleshooting the SG-231 and you understand that there are three
variables, you should change each variable, in sequence, to determine where the
problem lies. If you change the ground, antenna, or supply voltage, you are bound to
change the performance of the coupler.
10.1 Ground Faults
Common ground faults include faulty counterpoise, indecisive ground, differing
resistance, improper bonding, and problems resulting from inaccurate assumptions.
Faulty counterpoise.
The most common problem encountered here is when an
installation has been made without a proper counterpoise. If the counterpoise is
electrically smaller than the antenna, the system may load “upside down”—where the
antenna acts as the counterpoise and the counterpoise radiates. When this condition
occurs, the operator may encounter “RF Bites” from touching metal objects connected to
the counterpoise.
Indecisive ground.
A second kind of ground fault occurs when the decision whether
the ground or the antenna should radiate is difficult. When this condition is
encountered (usually at a frequency where the counterpoise is near resonance), the
coupler may cycle repeatedly. This condition may be addressed as follows:
• You may give short bursts of CW and when the coupler stops in a tuned
condition, as indicated by the remote tuned LED, you may invoke the SmartLock
Pro Tune Lock function, thus forcing the coupler to retain correct settings.
• 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.