SGC SG-237 Operating Manual

SG-237 SMARTUNER™

INSTALLATION MANUAL

S G -23 7 S m ar t u n er ™ M an ual

SGC, 13737 S E 26th Street Bellevue, WA 98005 USA • Ph: 425-746-6310, Fx: 425-746-6384, Email : [e-mail]

www.sgcworld .com

SGC RESERVES THE RIGHT TO CHANGE SPECIF ICATIONS WITHOUT NOTICE

 Copyright SGC 2008

1

SG-237 Specifications

HF Frequency Range: 1.8-60 MHz
Power Input Range: 3-100 W (PEP)
40 W CW Max (40% duty cycle)
Input Impedance Range: 45-55 Ohms
VSWR (Typical): Less than 1.4:1
DC Input Requirement: +13.8 VDC (nominal)
Average Input Current: 300 mA
Initial Tune Time: Less than 2 sec. (typical)
Retune from Memory: Less than 10 msec. (typical)
Memory Bins: 170
Tuning Combinations: ½ Million
Antenna Length (>3.3 MHz): 8 feet (2.5 M) minimum
Antenna Length (<3.3 MHz): 28 (8.5 M) feet minimum
Installation: Any Position
Operating Temperature: -35 to +70 C (-31 to +158 F)
Case: Weatherproof ABS plastic with aluminum base
Cable: 9 foot shielded 4-conductor/RG-58 coax

(PL-259 connector)
Dimensions: 9”L x 7”W x 1.5”H (23L x 18W x 4H cm)
2 Lbs. (1 Kg)

1.0 The Coupler Basics

Congratulations on purchasing the most versatile and reliable HF coupler available on the market
today. Your SGC Smartuner™ is designed to give you dependable operation and the flexibility
to operate on any HF frequency without any extra ‘tuning’ effort on your part. Unlike a
traditional ‘tuner’ – there are no knobs or buttons to fiddle with. You simply install the unit, and
operate – the Smartuner does the rest! Once the unit is installed, it will automatically sense your
RF frequency and tune your antenna down to minimum SWR to maximize the efficiency of your
signal and squeeze the most out of every watt. A Smartuner doesn’t require any special interface
or balun and will work with any transceiver and any antenna within its specifications range.
Installation is simple too! Read on to get on the air quickly and easily.

There are three connections on the SG-237 case: (1) The coaxial RF cable and power cables
(bundled together) that will connect to your transceiver and power supply. (2) The antenna
output connection. (3) The RF ground connection. All that is necessary to begin using your
coupler is to supply power, hook up to antenna, ground, and transceiver – and transmit. The SG­237 does the rest.

S G - 2 3 7 S m ar t u n er ™ M an ual

SGC, 13737 S E 26th Street Bellevue, WA 98005 USA • Ph: 425-746-6310, Fx: 425-746-6384, Email : [e-mail]

www.sgcworld .com

SGC RESERVES THE RIGHT TO CHANGE SPECIF ICATIONS WITHOUT NOTICE

 Copyright SGC 2008

2

The SG-237 is supplied in a waterproof case, on a mounting plate with pre-drilled holes. It is
ideal for any mobile or base-station installation. RF and DC power is supplied to the unit
through the same bundled cable (9 feet supplied). The cable includes the RG-58 coax for the RF
connection to the transceiver, two wires for DC and ground, and two wires for optional
accessories. (See Section 5 for more details on the Smartlock™).

Wiring for the SG-237 is as follows:

RF Coax: To transceiver
Red Wire: DC Power
Black Wire: DC Ground
White Wire w/ Black Stripe: LED Indicator (Smartlock)
White Wire w/ Red Stripe: Tune Lock/Reset (Smartlock)

2.0 Coupler Placement

SGC always recommends placing the antenna coupler as close as possible to the base of the
antenna – regardless of whether it is an SGC coupler or another brand. All SGC couplers can be
operated with a coaxial cable output connection; but this is not our recommendation. Antenna
“tuners” which use coaxial cable connection are actually line trimmers and have a limited
adjustment range (25 to 800 ohms). This impedance limitation prevents high voltages and
current which may cause flashing or burning of the coaxial cable – not the coupler. Trimmers
are less expensive than actual antenna couplers and much more common. However, because of
the impedance range limitations, they cannot tune whip or end fed wire antennas. On the other

S G - 2 3 7 S m ar t u n er ™ M an ual

SGC, 13737 S E 26th Street Bellevue, WA 98005 USA • Ph: 425-746-6310, Fx: 425-746-6384, Email : [e-mail]

www.sgcworld .com

SGC RESERVES THE RIGHT TO CHANGE SPECIF ICATIONS WITHOUT NOTICE

 Copyright SGC 2008

3

hand, SGC antenna couplers are not limited in their impedance ranges and will tune all types of
antennas, including end fed wires and whips. For the most efficient operation possible, install
your SGC coupler as close to the feedpoint of your antenna as physical limitations allow. See
section 4.0 for examples of ideal configurations. More information, including details of several
real installations and technical notes can be found on our website.

3.0 Outdoor Installation

The SG-237 antenna coupler’s waterproof case is designed to withstand the environmental
conditions encountered aboard ship when mounted on weather decks. The internal construction
is designed to withstand the shock and vibration of marine service. Corrosion resistant hardware
and passive alloys are employed throughout. We do not recommend opening the case unless it is
necessary. For 99% of installations, the factory settings for jumpers will be correct.

The coupler must be installed in an area not directly exposed. Excessive weather or exposure to
heat and sunlight can shorten the life of the unit. Although the SG-237 built very solidly, it is
good installation practice to provide additional protection from the elements. SGC makes the
following recommendations:

3.1 Marine Mounting

The Smartuner should be located inside the house or under the aft lazaret on a sailboat.
On powerboats, the coupler may be mounted outside, but an additional protective housing
is recommended. The preferred installation if vertical is with the RF stud pointing
upward. The antenna connects to the bolt on the top. The SG-237 may be mounted in
any position, including inverted without any degradation of performance.

3.2 Desert and High Temperature Installations

The Smartuner may be used in very hot climates on a continuous basis if installed in a
manner that protects it from direct sunlight.

3.3 Additional Weather Protection Installations

To protect the unit from direct exposure to sunlight, and to prevent heavy build-up of ice,
we recommend installing the Smartuner under additional protective housing. If you are
mounting it on a tower or in an extremely hot or cold climate, a plastic wastebasket (such
as those made by Rubbermaid™) makes an excellent weather cover and costs only a few
dollars.

S G - 2 3 7 S m ar t u n er ™ M an ual

SGC, 13737 S E 26th Street Bellevue, WA 98005 USA • Ph: 425-746-6310, Fx: 425-746-6384, Email : [e-mail]

www.sgcworld .com

SGC RESERVES THE RIGHT TO CHANGE SPECIF ICATIONS WITHOUT NOTICE

 Copyright SGC 2008

4

4.0 Five Golden Rules of HF Installation

These rules apply to all types of stations, including base, mobile, airborne and marine. They are
very important for planning and installing your HF system, if you want to achieve good
communications.

1. Install transceiver as close to operation site and power supply system as possible
(whether an external power supply or battery system).

2. The antenna must be installed in an open space and as far as possible from your operating
point. Example: On a sailboat, use the backstay as the antenna, since it is the farthest
point away from the rest of the vessel.

3. The antenna coupler should be installed at the base/feedpoint of the antenna.

4. Always create your own ground with radial wire or copper straps. They will guarantee a
solid and proper ground system.

5. All cables – power supply, control or coaxial – must always be as short as possible and/or
necessary. An excess cable should be shortened to the proper length – never coiled.

Following these rules will minimize marginal installations and problem sources such as RF
feedback in the radio, power supply or cables and “hot” or RF burning microphones. If all five
of the above points are followed during the design and installation of your HF system, the
operator can expect top performance. Further information regarding applications, installation
and operation can be downloaded from our website at www.sgcworld.com. These publications
include:

• HF User’s Guide

• Go Mobile at 500 Watts

• Stealth Antennas

• Smartuner Antenna Coupler Manuals