LDG RT-100 User manual

RT-100 OPERATIONS MANUAL MANUAL REV C
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LDG RT-100
100-Watt Remote
Automatic Tuner
LDG Electronics
1445 Parran Road
St. Leonard MD 20685-2903 USA
Phone: [phone]
Fax: [phone]
[e-mail]
www.ldgelectronics.com
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Table Of Contents
Introduction 2
Jumpstart, or “Real hams don’t read manuals!” 2
Specifications 2
An Important Word About Power Levels 2
Important Safety Warning 2
Getting to know your RT-100 2
Installation 2
Bias Tee Information 2
Operation 2
About LDG Tuners 2
A Word About Tuning Etiquette 2
Care and Maintenance 2
Technical Support 2
Two-Year Transferrable Warranty 2
Out Of Warranty Service 2
Returning Your Product For Service 2
Product Feedback 2
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INTRODUCTION
Congratulations on selecting the LDG RT-100 100-watt remote automatic tuner. The RT-100
provides full- and semi-automatic antenna tuning across the entire HF spectrum plus 6 meters, at
power levels up to 100 watts. It will tune dipoles, verticals, Yagis, or virtually any coax-fed
antenna. It will match an amazing range of antennas and impedances, far greater than many other
tuners you may have considered, including the internal tuners in many radios.
The RT-100 uses the same proven technology as other LDG tuners, but is engineered to be
installed outdoors near the antenna feedpoint, reducing potential SWR losses in the transmission
line. DC power is provided over the coax; no separate power cable is required. The RT-100
contains an internal “Bias Tee” circuit that separates RF and DC at the tuner.
The RT-100 is designed to be used with the optional RC-100 remote controller near the
operating position. It provides for on/off control, as well as automatic and semi-automatic tuning,
and contains a Bias Tee to inject DC onto the coax. The RC-100 is not required, but without it
you will need to provide a Bias Tee circuit near your transmitter or transceiver. Commercial
units are readily available, or you can easily homebrew one; circuit details are provided in this
manual.
LDG pioneered the automatic, wide-range switched-L tuner in 1995. From its laboratories
near the nation’s capital, LDG continues to define the state of the art in this field with innovative
automatic tuners and related products for every amateur need.
JUMPSTART, OR “REAL HAMS DON’T READ MANUALS!”
Ok, but at least read this one section before operating the RT-100 (this Jumpstart assumes
you have an optional RC-100 controller):
1. Turn off power to your radio.
2. Connect the antenna jack on the transceiver to the “Radio” jack on the optional RC-100.
3. Connect the “Tuner” jack of the optional RC-100 to the “Radio” jack on the RT-100 via a
suitable length of coax feedline.
4. Connect the antenna to the “Ant” jack on the RT-100.
5. Connect a source of 12VDC, 500mA to the Power jack on the optional RC-100.
6. Power up your radio and begin operating normally; the tuner will automatically initiate a
tuning cycle if there is an SWR mismatch.
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SPECIFICATIONS
•0.1 to 100 watts (peak) on SSB and CW, 30 watts on 100% duty-cycle modes.
•Latching relays for ultra-low power operation.
•2,000+ memories for near-instantaneous frequency and band changing.
•Requires 12VDC, 500mA, extracted from the coax feedline via built-in Bias Tee. DC
injection Bias Tee included in optional RC-100 controller, otherwise provided by user.
•1.8 to 54.0 MHz coverage.
•Tunes 4 to 800 ohm loads (16 to150 ohms on 6M), 16 to 3200 ohms with optional 4:1
Balun.
•For Dipoles, Verticals, Vees, Beams or any Coax Fed Antenna.
•Water-resistant case and rubber gaskets. Not immersible.
•Operating temperature range: 0ºF-110ºF (-18ºC - +43ºC)
•Optional external Balun allows tuning of random length, long wire or antennas fed with
ladder line.
•Optional RC-100 controller provides DC power injection, On/Off switch, and Tune button.
•Dimensions: 7.0”L x 5.5”W x 3.5”H.
•Weight: 1 lb. 0 oz.
AN IMPORTANT WORD ABOUT POWER LEVELS
The RT-100 is rated at 125 watts peak power input at most. Many ham transmitters and
transceivers, and virtually all amplifiers, are capable of transmitting well over 125 watts. Power
levels that significantly exceed specifications will definitely damage or destroy your RT-100. If
your tuner fails during overload, it could also damage your transmitter or transceiver. Be sure to
observe the specified power limitations.
IMPORTANT SAFETY WARNING
Never install antennas or transmission lines over or near power lines. You can be
seriously injured or instantly killed if any part of the antenna, support or transmission
line touches a power line. Always follow this antenna safety rule: the distance to the
nearest overhead power lines should be at least twice the length of the longest antenna,
transmission line or support dimension.
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GETTING TO KNOW YOUR RT-100
Your RT-100 is a quality, precision instrument that will give you many years of outstanding
service; take a few minutes to get to know it.
The RT-100 is designed to be installed at or near the antenna feedpoint. This reduces or
eliminates SWR losses in the coax transmission line, which can be significant under some
circumstances. The RT-100 is weatherproof and is intended to be installed outdoors. Tips on
outdoor installation appear later in this manual.
The RT-100 is powered over the coaxial cable that carries both RF energy and DC power; no
separate power cable is required. An internal “Bias Tee” circuit in the RT-100 separates RF from
DC power; this process is virtually lossless and has no effect on SWR. A second Bias Tee is
required at the transmitter end of the coax to inject DC power on to the coax. The RT-100 is
designed to be used with the optional RC-100 controller, which contains a Bias Tee to inject DC
power. It provides an Off/On power button, LED status indicator, and a Tune button which starts
an automatic tune cycle. If you do not use an RC-100, you must provide a Bias Tee to inject DC
power. They are available commercially, or you can easily “homebrew” one; details are provided
later in this manual.
The RT-100 provides 2,000 frequency memories. When tuning on or near a previously tuned
frequency, the RT-100 automatically uses “Memory Tune” to recall the previous tuning
parameters in a fraction of a second. If no memorized settings are available, the tuner
automatically runs a full tuning cycle, storing the parameters for memory recall on subsequent
tuning cycles on that frequency. In this manner, the RT-100 “learns” as you use it, adapting itself
to your favorite bands and frequencies. The RT-100’s latching relays hold the tuned
configuration indefinitely, even when DC power is removed. Tuning memories are stored in non-
volatile FLASH memory; they are retained indefinitely even when power is removed.
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RT-100 Connections
The RT-100 has three connectors:
•ANT SO-239: Output to the antenna. Connect the antenna feedpoint to this SO-239.
•Gnd (wingnut): Connect to an earth ground.
•Radio SO-239: RF and DC input. Connect to the feedline which comes from the transmitter or
transceiver via the optional RC-100 controller or other Bias Tee.
The tuner case is made of POLYLAC®, a flame-retardant ABS plastic.
Important Note: The transmission line between the Bias-Tee at the operating position (or the
RC-100 control unit) and the RT-100 tuner must never be grounded. Doing so would cause the
Bias-Tee to attempt to source 12 VDC directly to ground, damaging the unit. Never use coax
switches that ground unselected ports.
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INSTALLATION
The RT-100 tuner is designed for outdoor operation; it is water-resistant, but it is not water-
proof and must not be immersed. LDG strongly recommends using silicone coax sealing tape on
all outdoors coax connectors after installation to seal them. See Tips for Outdoor Installation
later in this manual for more on best amateur practice to ensure that your RT-100 will provide
reliable service outdoors.
The RT-100 is designed for use with coax-fed antennas. To use it with longwires or antennas
fed by ladder line, an external balun is required; the LDG RBA-4:1 is recommended.
Always turn your radio off before plugging or unplugging any external devices. The radio
may be damaged if cables are connected or disconnected while the power is on.
Secure the RT-100 to a Mast
Your RT-100 is designed to be mounted on a mast or other similar support; a clamp and
matching U-bolts are provided for this purpose. Remove the nuts and clamp from the U-bolt.
Place the U-bolt around the mast, then slide the clamp over the threaded ends of the U-bolt, so
that the flat edge of the clamp faces away from the mast. Insert the threaded ends of the U-bolt
through the back of the mounting bracket at the top of the RT-100. Thread the nuts back onto the
U-bolt, and snug them up. Tighten only as much as is required to keep the RT-100 from sliding
down the mast; do not over-tighten.
Although the U-bolt is electroplated to resist corrosion, you may wish to apply a thin layer of
grease to help prevent rust and aid in later removal. If you wish to use a larger U-bolt (to bolt the
tuner to a larger mast, or other support), refer the RT-100 mounting bracket dimensions for
sizing.
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Connect to Transceiver and Antenna
If upgrading an existing antenna, move the coax feedline from the antenna feedpoint to the
RADIO jack on the RT-100. Connect a 50-ohm coax jumper (as short as practical) from the RT-
100’s ANT jack to the antenna’s feed point.
Place a Bias Tee (RC-100 or other) convenient to the operating position. Connect the RT-
100‘s RADIO jack to the Bias Tee’s RF+DC jack via a suitable length of coax feedline; it can
be as long as necessary. This can be new coax for a new installation, or existing coax if you are
installing the RT-100 on your present antenna; simply move the existing coax from your
transmitter or transceiver’s Antenna jack to the RF+DC jack on the Bias Tee. Connect a 50-ohm
coax jumper (as short as practical) from the transmitter or transceiver’s Antenna jack to the Bias
Tee’s RF jack. For installation using the optional RC-100 controller, see the RC-100 user
manual.
Connect the Bias Tee to a source of 12VDC power capable of providing 500 mA. A
regulated power supply is recommended, but is not required.
The RT-100 has no SWR display. If your transmitter or transceiver does not have a built-in
SWR display, you may wish to put an external SWR meter between the output of the transmitter
or transceiver and the RF input of the Bias Tee:
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Tips for Outdoor Installation
The RT-100 is water-resistant, but it is not fully waterproof. The RT-100 should be mounted
on a mast with the mounting bracket facing upward, and the SO-239 jacks facing downward; do
not simply lay it on the ground. If necessary, pound a short mast into the ground near your
antenna and mount the RT-100 to it as shown on page 7. LDG strongly recommends grounding
the RT-100 tuner via the wingnut marked GND.
To prevent rain water from running down the coax and into the connectors, all connections
should be wrapped with coax sealing tape, such as Coax Seal™. Additionally, a drip loop should
be provided by coiling the coax and zip-tying it into a loop which hangs below the connectors.
The drip loop collects any water running along the coax, and makes it drip away from the tuner.
Also provide a drip loop where the coax enters the house, to prevent water from running along
the coax and into the house. Be sure the drip loop hangs below the coax entry point into the
house.
If you are using existing coax between the RT-100 and the indoor Bias Tee, inspect it
carefully for water damage. Best Amateur practice calls for cutting away one foot of coax for
each year the coax has been outdoors. If the coax was sealed with waterproof tape or other
material this may not be necessary.
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BIAS TEE INFORMATION
The LDG RT-100 incorporates a Bias Tee in the tuner itself, but a second Bias Tee is needed
at the transmitter end and is not included; you must supply one. The optional LDG RC-100 is an
ideal companion to the RT-100, and includes a built-in Bias Tee designed specifically for the
RT-100. However, you can easily “homebrew” your own Bias Tee from readily available
components.
Alternatively, ready-made Bias Tees are available from commercial suppliers, including the
SGC 54-70 DC Coaxial Line Isolator, the Array Solutions Bias Tee Master, and many others.
The Bias Tee must be rated for at least 1A current draw, and 1.8 to 54 MHz. For more
information on Bias Tee construction and theory, see the Wikipedia article “Bias Tee” at
http://en.wikipedia.org/wiki/Bias_tee, ARRL’s QST article in the January 2013 issue, Vol. 97,
Issue 1, p46, or the Array Solutions Bias Tee Master product review in the September 2009 issue
of QST.
A Bias Tee is a circuit which injects DC power onto the coax feedline, while isolating the DC
power from both the transmitter and the antenna; two are required, one at each end of the coax. A
sample schematic is shown below.
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