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Common ground faults include faulty counterpoise, indecisive ground,
d i f f e r i n g r e s i s t a n c e , i m p r o p e r b o n d i n g , a n d p r o b l e m s r e s u l t i n g f r o m
inaccurate assumptions.
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e .. 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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d .. 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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e .. 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.
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.
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g .. The fourth kind of ground fault you may encounter
occurs where the ground is not properly bonded to the coupler. We go to con-
siderable effort to make sure the stainless steel ground stud is well connected
to the coupler.
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA 98005 USA
P.O. Box 3526, 98009 Fax: 425-746-6384 Tel: 425- 746-6310 or 1-800-259 7331
E-mail: [email protected] Web site: http://www.sgcworld.com
© 1998 SGC Inc
SG-230 Manual