LDG AT-600Pro Operation Manual

AT-600PRO OPERATIONS MANUAL MANUAL REV A

LDG AT-600Pro
600W Automatic

Antenna Tuner

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LDG Electronics

1445 Parran Road

St. Leonard MD 20685-2903 USA

Phone: [phone]

Fax: [phone]

[e-mail]

www.ldgelectronics.com

Table Of Contents

Introduction 3
Jumpstart, or “Real hams don’t read manuals!” 3
Specifications 4
An Important Word About Power Levels 4
Important Safety Warning 4
Getting to know your AT-600Pro 5

Front Panel: 5
Back Panel: 6

Installation 7
BASIC Operation 10

Using the Front Panel Buttons 10
User Configuration Options 10
Transmitting and Receiving 13

Tuning 14

Basic Tuning Operation 14
Manual Memory Tune 14
Manual Full Tune 15
Bypass Mode 16
Error Indication 16

Advanced Operation 18

Manual Inductor/Capacitor Adjustments 18
High/Low Relay Adjustment 18
Manual Memory Store 18
Status Check 19

Application Notes 20

Mobile Operation 20
Internally Generated RF Noise 20
MARS/CAP Coverage 20

Theory of Operation 21

Some basic ideas about impedance 21
Transmitters, transmission lines, antennas, and impedance 21

The LDG AT-600Pro 23
Quick Reference 24
A Word About Tuning Etiquette 24
Care and Maintenance 25
Technical Support 25
Two-Year Transferrable Warranty 25
Out Of Warranty Service 25
Returning Your Product For Service 26
Product Feedback 26

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INTRODUCTION

LDG pioneered the automatic, wide-range switched-L tuner in 1995. From its laboratories in
St. Leonard, Maryland, LDG continues to define the state of the art in this field with innovative
automatic tuners and related products for every amateur need.

Congratulations on selecting the LDG Electronics AT-600Pro 600-watt automatic tuner. The
AT-600Pro provides fully- and semi-automatic antenna tuning across the entire HF spectrum
plus 6 meters, at power levels up to 600 watts (250W on 6m). 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 some tuners you may have considered, including the built-in tuners
on many transceivers.

The AT-600Pro is designed to handle 600 watts of output power, and is ideal for use with
small outboard linear amplifiers rated up to 600 watts, or even newer high power transceivers.

JUMPSTART, OR “REAL HAMS DON’T READ MANUALS!”

Ok, but at least read this one section before operating the AT-600Pro:

Connect a 50-ohm coax jumper cable from the antenna jack on your amplifier to the TX jack on the

back of the AT-600Pro.

Connect your antenna’s 50-ohm coax feedline to the ANT 1 jack on the rear of the AT-600Pro.
Connect the supplied DC coax cable to the jack marked 12 VDC. Connect this cable to a DC source

between 11 and 16 volts DC, 500 mA. The jack center tip is positive.

Power up the transceiver, and select the desired operating frequency and mode.
Bypass the amplifier.

1

Begin transmitting, any mode

.

When the tuning cycle completes, activate the amplifier, and you’re ready to operate!

1 In SSB mode, simply speak into the microphone while transmitting. Tuning may be performed at up to 125 watts of input power, provided that the transceiver
employs a “roll-back” circuit to protect it from high SWR. For transceivers without roll-back circuits, power should be limited to 25 watts when tuning, to avoid
damage to the transmitter or tuner.

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SPECIFICATIONS

1.0 to 600 watt power range (SSB and CW), 250W on 6M.
Silver-teflon SO-239 connectors.
Over 4,000 memories for instantaneous band changing.
Built-in 2-port antenna switch, with 2,000 memories each.
Tuning time 0.2 to 15 seconds full tune, 0.2 seconds memory tune.

1.8 to 54.0 MHz coverage. Built-in frequency sensor.
Tunes 6 to 1,000 ohm loads (16 to 150 on 6m), 6 to 4,000 ohms with optional 4:1 balun.
LED bargraph displays power level, SWR, and status.
Antenna Indicator LEDs show the currently selected antenna.
User-selectable operating parameters: Auto/Semi, 125/12.5 watt scale, and more.
Optional radio interface cables available.
Power requirements: 11 to 16 VDC @ 1A max. 7mA when idle.
Dimensions: 10.5” x 8.5” x 2.8”Weight 3 pounds.

AN IMPORTANT WORD ABOUT POWER LEVELS

The AT-600Pro is rated at 700 watts maximum power input at most. Many amplifiers output
well over 700 watts. Power levels that significantly exceed specifications will definitely damage
or destroy your AT-600Pro. If the tuner fails during overload, it could also damage your
transmitter, amplifier, 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 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 power line
should be at least twice the length of the longest antenna, transmission line, or support
dimension.

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GETTING TO KNOW YOUR AT-600PRO

Your AT-600Pro is a quality, precision instrument that will give you many years of
outstanding service; take a few minutes to get to know it.

Front Panel:

The front panel of the AT-600Pro features eight pushbuttons, two LED bargraph scales, and
two indicator LEDs:

Power: Turns the unit on or off.
Func: Activates secondary function of other buttons.
Ant: Selects the active antenna port.
C Up: Manually increase capacitance.
C Dn: Manually decrease capacitance.
L Up: Manually increase inductance.
L Dn: Manually decrease inductance.
Tune: Initiates memory or full tuning cycle. Momentary push places tuner in bypass.
PWR Meter: Bargraph display indicates forward power in 0-60 and 0-600 watt ranges.
SWR Meter: Bargraph display indicates SWR during tuning or transmission.
Bypass LED: Lights when the tuner is in pass-thru mode.
ANT 2 LED: Lights when Antenna 2 is selected. Off when Antenna 1 is selected.

Each of the pushbuttons has the primary function listed above when pushed. Additionally,
pressing the FUNC button before pressing any other button will activate that button’s secondary

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function.

The power button on the AT-600Pro actually places the tuner in bypass and enters a low­power sleep mode, rather than turning the unit fully off. Press the Power button for 3 seconds to
turn off, or momentarily to turn on.

Back Panel:

The rear panel of the AT-600Pro has six jacks.

Ant 1: Connect a 50 ohm antenna coax feedline to this SO-239 connector.
Ant 2: Connect a second 50 ohm antenna coax feedline to this SO-239 connector.
Gnd (wing nut): Connect to the antenna system ground.
Tx: Connect a 50 ohm jumper coax from this jack to the ANT jack on the rear of the transceiver.
Radio: Connect the optional IC-PAC Icom radio interface cable or optional Yaesu interface

cable to a supported ICOM or Yaesu radio.

Power: Connect the supplied DC coaxial power cable to this connector, and connect to a source

of 11-16 VDC @ 1A. Center pin is positive.

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Installation

The AT-600Pro is intended for indoor use only; it is not water-resistant. If you use it
outdoors, (Hilltopping expedition, for example) you must protect it from rain. The AT-600Pro is
designed for use with coax-fed antennas. If use with longwires or ladder-line-fed antennas is
desired, an external balun rated to 600 watts is required.

Place the AT-600Pro in a convenient location near the transceiver and amplifier. Always turn
your radio and amplifier off before plugging or unplugging anything. The radio may be damaged
if cables are connected or disconnected while the power is on.

Connect the HF antenna jack on the amplifier to the TX jack on the back of the AT-600Pro,
using a 50 ohm coax cable rated 600 watts or higher.

Connect a 50-ohm antenna feedline coax to the ANT 1 jack on the back of the AT-600Pro,
and optionally connect a second antenna feedline to the ANT 2 jack.

The AT-600Pro is designed to interface directly with many popular ICOM and Yaesu
transceivers, enabling one button tuning. In the case of ICOM radios, the optional interface cable
also powers the tuner.

For ICOM radios supporting the AH-3 or AH-4 external tuner, connect the 4-pin Molex
connector of the optional ICOM interface cable to the radio’s Tuner port. Then connect the 1/8”
stereo plug on the other end of the ICOM interface cable to the jack marked Radio on the rear of
the AT-600Pro. Connect the coaxial DC power plug of the ICOM interface cable to the 12 VDC
Power jack.

For Yaesu FT-857 and FT-897, use the optional Y-ACC cable and plug the red end marked
Radio into the transceiver’s ACC port. Plug the black end of the Y-ACC cable into the jack
marked Radio on the rear of the AT-600Pro.

Unless the AT-600Pro is being powered by the ICOM radio interface cable as above, you’ll
also need to plug in the supplied DC coaxial power cable. This cable has a 2.5x5.5mm coaxial
plug on the end. Plug the coaxial plug into the 12 VDC Power jack on the rear of the AT-
600Pro, and connect the other end to a DC power source between 11 and 16 volts DC, capable of
supplying up to 500 mA.

Grounding the AT-600Pro tuner will enhance its performance and safety. LDG recommends
that you connect your tuner to a suitable ground. A common ground rod connected to buried
radials is ideal, but a single ground rod can provide a serviceable ground. LDG strongly
recommends the use of a properly installed, high quality lightning arrestor on all antenna cables.

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