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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1.6.4 Warranty Note
It is important to have protection from the elements as common weather conditions can
reach beyond the capabilities of the coupler. Although the SG-230 coupler is fully
waterproof and was created to withstand normal weather conditions, warranty will be
voided if left exposed directly to extreme weather such as snow, rain, and ice or prolonged
sun exposure. Even in milder climates, direct and constant sunlight can exceed the safe
operating temperature and can shorten the lifespan of your coupler.
1.7 Remote Installations
The SG-231 is supplied with ten feet of standard RF cable. SGC has two standard
lengths of antenna extension cable available in the event you need to mount the cable
farther than ten feet from the transmitter. A 25-foot extension cable is available (SGC
Part Number 54-67) as is a 50-foot cable (SGC Part Number 54-68).
If you need to install the antenna coupler more than 50 feet from the transmitter site, up
to two extension cables may be used for a total of 75 or 100 feet. However, SGC does
not recommend installing the Smartuner more than 100 feet from the transmitter
because two losses must be considered.
• The first loss in long distance installations is normal attenuation of the radio
signal coming from the antenna to the radio via the coax. As you may be aware,
the longer the coaxial cable run, the higher the loss will be. The amount of loss
depends on frequency. At 2 MHz, the loss is approximately .5 dB, while at 30
MHz the loss in 100 feet of coaxial cable is over 2 dB. This means that a 100-watt
transmitter would actually deliver about 70 watts to the antenna after running
through 100 feet of coax at 30 MHz.
If you are seeking the utmost performance at 30 MHz and you cannot avoid a
run of 100 feet, or longer, we recommend using a larger low loss type of coax
such as RG-8 (foam dielectric) or Belden type 9943 coax. Both of these will
reduce attenuation to less than 1 dB per 100 feet. However, this heavier cable is
harder to work with and may be quite expensive.
• The second loss which must be considered involves the losses in the DC power
and reset control line. At any distance other than the 10-foot cable that is
supplied by SGC, we recommend that the DC voltage at the antenna coupler be
measured, because if the coupler voltage drops below 10 volts, the coupler may
not operate properly.
For this reason, if distances are great, SGC recommends that the input DC
voltage at the transmitter site be adjusted to provide for +12 to +14 volts at the
coupler site.
We do specifically advise against use of a different power supply than the one used to
power the radio because of the danger of creating ground loops which may cause
oscillation of the final amplifiers or other undesired side effects. If you decide to use a