Specifications

63
© 1998 SGC Inc
SG-235 Manual
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA 98005 USA
P.O. Box 3526, 98009 Fax: [phone] Tel: [phone] or 1-800-259 7331
E-mail: [e-mail] Web site: http://www.sgcworld.com
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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-235 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 volt-
age, you are bound to change the performance of the coupler.
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Common ground faults include faulty counterpoise, indecisive ground,
differing resistance, improper bonding, and problems resulting from
inaccurate assumptions.
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The most common problem encountered here is when
an installation has been made without a proper counterpoise. If the counter-
poise is electrically smaller than the antenna, the system may load Òupside
downÓÑwhere the antenna acts as the counterpoise and the counterpoise radi-
ates. When this condition occurs, the operator may encounter ÒRF BitesÓ from
touching metal objects connected to the counterpoise.
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A second kind of ground fault occurs when the decision
whether the ground or the antenna should radiate is difficult. When this con-
dition 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.
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The third kind of ground fault which 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 alu-
minum must be much bigger than would a copper ground because the inter-
nal resistance of aluminum is significantly higher than copper.