LDG AT-1000Pro User manual

1
LDG AT-1000Pro 1KW
Automatic Memory
Antenna Tuner
Manual Version 1.0
LDG Electronics
1445 Parran Road
St. Leonard, MD 20685
[phone]
[email protected]
www.ldgelectronics.com

2
LDG AT-1000Pro 1KW Automatic
Memory Antenna Tuner
Table of Contents
Introduction 3
IMPORTANT TUNER SAFETY WARNINGS 3
Jumpstart, or “Real hams don’t read manuals!” 4
Specifications 4
Operating Instructions 5
Getting to know your AT-1000Pro 5
Installation 7
Setup 7
Version Display: 7
Tune Memory Clear 8
Power-Up On/Off 8
Function Modes 8
Operation 9
Button Functions and LED Indications 9
Normal Operation 10
Memory Operation 10
Fine-tuning the tuner 11
Error Indications 11
A word about “roll-back” circuits 11
LED Error codes 12
Default Setting 12
Radio Interface 12
Theory of Operation 13
Some basic ideas about impedance 13
Transmitters, transmission lines, antennas and impedance 13
The LDG AT-1000Pro 14
The LDG AT-1000Pro 15
Care and Maintenance 17
Technical Support 17
Warranty and Service 17

3
Introduction
Congratulations on selecting the LDG AT-1000Pro tuner. The AT-1000Pro is an important
update of LDG’s flagship tuner, now providing fully automatic antenna tuning with memories for
high power amplifiers. The AT-1000Pro is intended for use with most tube or solid-state
amplifiers outputting up to 1,000 watts SSB. It will tune dipoles, verticals, Yagis or virtually any
coax-fed antenna.
LDG pioneered the automatic, wide-range switched-L tuner in 1995. From its laboratories near
our 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.
IMPORTANT TUNER SAFETY WARNINGS
Like all high power antenna tuners, your AT-1000Pro handles a great deal of RF energy. Very
large RF currents flow through the tuner, and very high RF voltages are sometimes present. Your
AT-1000Pro is designed to safely handle this RF energy within its specifications, with a
reasonable margin of safety. However, some amateur amplifiers are capable of outputting RF
levels in excess, sometimes far in excess, of the specified maximums. Operating significantly
above specifications will definitely damage or destroy your AT-1000Pro. Operating above
specifications can cause catastrophic failure of internal components; under extreme overload,
components could actually explode. You must observe the stated specifications of your AT-
1000Pro, just as you do with your amplifier or any conventional tuner operating at this power
level. Never operate your AT-1000Pro with the cover removed; lethal RF voltages may be
present during operation.
IMPORTANT ANTENNA 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 lon
g
est antenna
,
transmission line or su
pp
ort dimension.

4
Jumpstart, or “Real hams don’t read manuals!”
Ok, but at least read this one section before you transmit:
Safety Warning: Never operate your AT-1000Pro with the cover removed; lethal RF voltages
may be present during operation. Never exceed the rated specifications.
1. Connect your AT-1000Pro to a source of 11 – 15-volt DC power capable of supplying at
least 1 Amp. Press the Power button to turn on the tuner (Power LED will be on).
2. Connect your amplifier output to the AT-1000Pro input socket labeled “Transmitter” using
50-ohm coaxial cables. Connect the coax lead to your antenna to the AT-1000Pro output
socket labeled “Ant 1”.
3. Select Ant 1 (Ant 1 LED will be on). Select Auto mode to be off (Auto LED will be off).
4. Set your amplifier to “Standby” mode so it will NOT operate when you transmit.
5. Transmit a carrier from your exciter of about 30 watts CW, FM or AM.
6. Momentarily press the “Tune” button on your AT-1000Pro. An automatic tuning cycle will
begin, then stop. Check the meter to ensure an SWR of 2 or less before using your amplifier.
7. Turn your amplifier on; you’re ready to transmit.
Specifications
•Microprocessor controlled Switched L tuning network
•Two position antenna switch with 2000 3-D memories for each position
•Adjustable threshold for Auto mode
•Lighted cross needle meters
•Continuous coverage 1.8 to 54 MHz
•Power rating HF (1.8 to 30 MHz):
o1000 Watts Single Side Band
o750 Watts CW
o500 Watts Digital (RTTY, Packet, etc.)
•Power rating 6 meters: 250 Watts (any mode)
•Capacitor / Inductor fine tune controls
•Tuning time: 0.2 recall, 10 seconds average, 30 seconds max.
•Antenna impedance: 6 to 1000 Ohms (about 10:1 SWR, 3:1 on 6M)
•Dual meter scale 100/1000 watts
•Tuning power: 5 to 125 watts maximum
•Relay protection software prevents tuning:
oGreater than 125 watts in any load
oGreater than 75 watts into a 3:1 SWR load
•Soft touch buttons
•Includes 6 foot power cable, Icom and Yaesu interface, coax jumper (300 watt limit)
•Power requirements: 11 to 15 volts DC @ 1 Amp (user supplies power source)
•Enclosure sizes: 9.5W x 13D x 3.5H inches
•Weight: 5.2pounds

5
Operating Instructions
Getting to know your AT-1000Pro
Your AT-1000Pro is a quality, precision instrument that will give you many years of outstanding
service; take a few minutes to get to know it. On the front panel, there are eight pushbutton
switches:
•Power: turns your AT-1000Pro on and off
•Auto: toggles tuner between Auto and Semi-Auto tuning modes
•Tune: begins a tuning cycle, places the tuner in bypass mode
•Ant1: Toggles between the two antenna ports
•Manual capacity and inductance adjustments (rarely needed)
•Ind Up: adds inductance
•Ind Dn: subtracts inductance
•Cap Up: adds capacitance
•Cap Dn: subtracts capacitance
The Power switch does not turn the tuner completely off. It places it in a low-current “sleep”
mode. In the Off mode (Power LED is off), the tuner is in bypass, routing RF directly from your
amplifier to the antenna with no matching. On power-up, the tuner automatically restores the last
tuned setting.
Each pushbutton has a dedicated LED that indicates that function’s status. These LEDs are also
used to indicate other tuner conditions; see section on Button Functions and LED Indications.
In addition to the pushbuttons, there is a lighted cross-needle meter. This meter indicates forward
power up to 1,000 watts, reflected power up to 200 watts and SWR (see Theory of Operation,
below). Power readings are accurate to +/- 10% of full scale across the entire range.

6
Forward and reflected power are indicted on individual scales. SWR is read at the intersection of
the two needles, on the curved red scales across the center of the meter face. In the picture below,
the meter is indicating an SWR of 2.0.
On the back panel, there are six connections:
•Ant 1, standard SO-239 socket
•Ant 2, standard SO-239 socket
•Ground (wingnut)
•Transmitter, standard SO-239 socket)
•Radio interface jack (stereo 1/8” jack)
•DC power input (2.5 x 5.5 mm coaxial power connector, center pin positive)

7
Installation
Your AT-1000Pro is intended for indoor use only; it is not water-resistant. If you use it outdoors
(Field Day, for example) you must protect it from rain. Place your AT-1000Pro as near as
practical to your exciter (your transceiver or transmitter) and your amplifier, keeping free access
to the front panel controls. You should avoid placing other equipment on top of your AT-1000Pro
if possible.
Grounding will significantly improve the safety and performance of your tuner. Attach the ground
connection on the back panel to a suitable ground using heavy-gauge wire or metal braid. A
dedicated outside ground rod is best, but a nearby cold water pipe is sometimes satisfactory. The
ground connection on an AC outlet will not work satisfactory.
Connect the socket marked “Transmitter” on the back of your AT-1000Pro to your amplifier
output using high-quality 50-ohm coaxial cable and PL-259 plugs. Do not use crimp-on plugs for
this connection; only properly soldered plugs will be safe and provide satisfactory performance.
The coaxial cable should be rated for the maximum output of your amplifier. Keep the cable as
short as practical.
Attach your antenna lead-in coax to the desired antenna socket, either Ant 1 or Ant 2 on the rear
of the tuner with a soldered PL-259 plug. You can have two antennas connected at the same time
and switch between them using the front panel switch. Use cable rated for the maximum power
output of your amplifier. Your AT-1000Pro is intended for use with coax-fed (unbalanced)
antennas only. If you wish to use it with antennas fed with ladder-line, or with longwire antennas
you must provide a suitable balun to adapt your AT-1000Pro to the balanced load. LDG does not
presently sell a balun that handles 1,000 watts, but they are readily available from many ham
radio vendors.
Your AT-1000Pro requires 11 – 15 volts DC at 1 Amp. If your radio runs on 12 volts DC, you
can use the same power supply for your AT-1000Pro if it can provide the necessary 1 Amp
current; otherwise, you will need a separate power supply. We recommend a regulated supply be
used for satisfactory results. Connect the power supply to the DC power jack on the back of your
AT-1000Pro using the provided 2.5 x 5.5 mm coaxial power plug. Be sure to observe proper
polarity; the center pin and the red lead are positive.
Setup
There are three power-up options, selected by holding down one ore more buttons while applying
DC power (typically by plugging in the DC power connector).
Version Display:
Press and hold the Power button while applying DC power to the tuner. The upper three LEDs
(on Auto, C Up and L Up switches) will blink the version number. The left-hand LED will blink
the whole number, the middle LED the decimal point (one blink) and the right-hand LED the
fractional part of the version number. For example, if your tuner has Version 3.2 of the software,
the left-hand LED will blink three times, the center once and the right-hand LED twice: 3.2.
This is only an example; your tuner may have a different software version number.

8
Tune Memory Clear
Press and hold the Power and Tune button while applying DC power, then release the buttons.
This clears all tune memories, and is indicated by all the LEDs doing their version of the Finale
from Riverdance. Memory is clear when the dance ends.
Power-Up On/Off
Press and hold the Auto button while applying DC to turn on the Power-Up On option. In this
mode the tuner will automatically power up when DC is applied. Upper 3 LEDs (C Up and L Up)
will flash 3 times to confirm.
Hold the Ant 1 button while applying DC to set the Power-Up Off option. In this mode the tuner
will be off up when DC is applied. The lower 3 LEDs (C Dn and L Dn) will flash 3 times to
confirm.
Function Modes
Press the Power (Func) switch for 0.5 seconds to place the tuner in function mode. In this mode
you can set the SWR threshold for Automatic tuning, set the power meter scale range or manually
store tuning parameters.
All LEDs light to show Function mode has been entered until the Power (Func) button is
released. Once the Func Button is released, the three LEDs for Thresh, Scale and Store will be on.
While in function mode, pressing the Scale Ant 1 (Scale) button will toggle the meter between its
100 and 1000 watt scales. The meter will indicate the scale on the Forward power meter. It will
move to “10” for 100 watt scale and to “100” for 1000 watt scale. Press Power (Func) again to
save the setting.
Press the Auto (Thresh) button to set the SWR threshold at which a tuning cycle will begin when
in Auto mode. Each press of the button selects a higher SWR (1.5, 1.7, 2.0, 2.5, and 3.0), cycling
back to the beginning when you reach the end of the range. The selected SWR is shown on the
meter at the intersection of the two needles. Press Power (Func) again to save the setting.
Press Tune (Store) to manually store tuning parameters. Use this function to store manually
adjusted capacitor and inductor settings.
If no buttons are pressed within five seconds of entering Function mode, the tuner exits the
Function mode automatically.
Recap of function operation:
1) Press Func button for ½ second to enter Function mode.
2) Make selection
3) Press Func button again to exit Function mode.

9
Operation
Button Functions and LED Indications
Power: The Power button turns the tuner on and off. In the off state, the tuner is in bypass mode,
routing RF from your transmitter or amplifier directly to Ant 2 with no matching. No buttons,
except the Power button, will be active.
Pressing the Power button toggles the tuner between off and on states. When toggled to the on
state, the tuner resets to the last tuned setting (including antenna selection) before the previous
power-down. To turn the tuner off (that is, to put it in is low-power standby state), press and hold
the Power button for about 3 seconds. The LEDs will all light, then go out as the tuner powers
down.
Auto: The Auto button toggles the tuner between Automatic and Semi-automatic tuning. In Auto
mode, the tuner will begin a tuning cycle any time the SWR exceeds a threshold you set. In Semi-
automatic mode, the tuner will begin a tuning cycle only when you press the Tune button. The
Auto LED is on when the tuner is in Automatic mode.
Tune: The Tune button begins a semi-automatic tuning cycle, a memory tuning cycle, or places
the tuner in bypass mode. A momentary press (< 0.5 seconds) toggles the tuner between bypass
and its last tuned setting. The LED will blink once to confirm the change to bypass. Another short
press will restore the last tuned setting; the LED will blink three times.
A medium press (0.5 - 3 seconds) begins a memory tune; memories for the current frequency will
be scanned for a match. If stored parameters are not found, the tuner will automatically begin full
tuning cycle. The LED will come on after 0.5 seconds to indicate a memory tune. If the Tune
button is held longer than 3 seconds, the Tune LED will go off and a full tune will begin when the
Tune button is released.
Ant 1: Press the Ant 1 button to toggle between Ant 1 and Ant 2. The Ant 1 LED will be on for
Ant 1 and off for Ant 2. When you change antennas, the tuner references the last frequency used
on that antenna, and recalls tuning settings for that frequency, if any. When the tuner is off (or if
DC power is removed), the antenna selection defaults to the Ant 2 position.
Cap Up: The C Up button adds capacitance; holding the button down auto-repeats the add. The
LED blinks when you reach the upper capacitance limit.
Cap Dn: The C Dn button subtracts capacitance; holding the button down auto-repeats the
subtract. The LED blinks when you reach the lower capacitance limit.
Ind Up: The L Up button adds inductance; holding the button down auto-repeats the add. The
LED blinks when you reach the upper inductance limit.
Ind Dn: The L Dn button subtracts inductance; holding the button down auto-repeats the
subtract. The LED blinks when you reach the lower inductance limit.
Hi/Low Z: The Hi/Lo-Z relay can be manually selected to Hi by pressing the C Up and L Up
together. The two LEDs will light while the buttons are held. Pressing the C Dn and L Dn buttons
will set the relay to Lo. This setting is reset any time the tuner tunes.

10
Normal Operation
To prepare the tuner for use, press the “Power” button on the front panel. The red LED above the
button, and the meter lights come on, indicating that your AT-1000Pro has powered up. The tuner
resets to the last tuned setting (and Antenna selection) before the previous power-down.
Select the desired antenna by pressing the Ant 1 button. The LED is on when Ant 1 is selected,
and is off when Ant 2 is selected.
Set your amplifier to standby, so it will not operate when you transmit; tune with your exciter
only. Set your exciter to transmit up to 125 watts (with rollback), 30 watts max (without rollback;
see below), or on the frequency you plan to use. CW is usually the most convenient mode, but
you can also use RTTY, FM or an AM carrier.
While transmitting 5 – 125 watts, press and release the “Tune” button on the tuner front panel; an
automatic tuning cycle will begin. You will hear the relays in your AT-1000Pro operate as they
switch inductors and capacitors in and out seeking a match; they make a fairly loud buzzing
noise. You can observe the present reflected power and SWR on the meter during the tuning
process—but watch closely; it happens fast!
The tuning cycle will automatically end in a few seconds, with the meter indicating the final
achieved SWR, usually 1.5 or less. The Tune LED will blink five times, indicating a good tune
and a memory save. Check for an SWR of 2 or less. If the SWR is greater than 2, use the manual
adjustment buttons to adjust the SWR to level less than 2 (see “Fine-tuning the tuner”, below).
Unkey your exciter.
After tuning is completed, set your amplifier to operate, key your exciter and tune your amplifier
as usual (if needed). Good practice dictates tuning your amplifier into a 50-ohm dummy load
with a suitable power rating. You may tune your amplifier into the antenna through your AT-
1000Pro providing it has tuned the antenna to a low SWR, and also providing you do not exceed
the specified ratings of either your amplifier or your AT-1000Pro. Never press the Tune button
while transmitting more than 125 watts. Unkey when done; you are ready to transmit.
Memory Operation
At the end of each successful tuning cycle (SWR <1.5), the tuning parameters are stored in non-
volatile memory. For each antenna port, there are four banks of 2,000 memories, allowing you to
use an external 4-way antenna switch connected after the antenna jack. Each time a tuning cycle
is started, if a previous successful tune was performed on the given frequency, the stored
parameters for that frequency are quickly tried. If one of the stored parameters gives an SWR of
1.5 or less, the tuning cycle ends. If not, a full tuning cycle begins automatically, with the new
tuning parameters stored automatically upon successful completion of the cycle. The Tune LED
will blink five times, indicating a good tune and a memory save.
The memory storage and tuning process is completely automatic, with no impact on your
operation of the tuner. The effect is much faster overall tuning once the tuner has "learned" your
most common bands and frequencies. You will probably want to use memory tuning most of the
time.