Acom 03AT Operating Manual

AUTOMATIC
ANTENNA TUNNING UNIT

AUTOMATIC
ANTENNA

TUNNING UNIT

OPERATING MANUALOPERATING MANUAL

ACOM 03AT

AUTOMATIC HF ANTENNA TUNING UNIT

OPERATING MANUAL

Table of contents

1. GENERAL INFORMATION.....................................................................................................................................2

1.1.

INTRODUCTION AND DESCRIPTION ...........................................................................................................................2

1-2.

OWNER ASSISTANCE ..............................................................................................................................................2

1-3.

EQUIPMENT SUPPLIED AND OPTIONS.......................................................................................................................2

1-4.

FEATURES..............................................................................................................................................................2

1-5.

SAFETY CONSIDERATIONS, EXPLICIT DEFINITIONS ...................................................................................................3

PRECAUTIONS:.............................................................................................................................................................3

2. INSTALLATION..........................................................................................................................................................4

2-1.

UNPACKING AND INITIAL INSPECTION.......................................................................................................................4

2-2.

LINE VOLTAGE .......................................................................................................................................................4

2-3.

REMOTE UNIT INSTALLATION ..................................................................................................................................4

3. POWER ON, RCU CONTROLS AND MENU .......................................................................................................11

4. OPERATION..........................................................................................................................................................12

4-1.

FUNCTION OPERATE AND AUTO TUNE PROCEDURE..........................................................................................12

4-2.

USING THE MEMORY .............................................................................................................................................14

4-3.

FUNCTION BYPASS.............................................................................................................................................15

4-4.

FUNCTION STATUS.............................................................................................................................................16

4-5.

FUNCTION SWR-CHK..........................................................................................................................................17

4-6.

USING STATUS AND SWR-CHK FUNCTIONS FOR RF PATH DIAGNOSTICS ............................................................17

5. MAINTENANCE ....................................................................................................................................................18

5-1.

CLEANING.........................................................................................................................................................18

5-2.

FUSES REPLACEMENT ...................................................................................................................................18

5-3.

ACOM 03AT MATCHING CIRCUIT SCHEMATIC DIAGRAM .......................................................................................20

5-4.

TROUBLESHOOTING..............................................................................................................................................23

6. SPECIFICATIONS.................................................................................................................................................24

6-1.

PARAMETERS ..................................................................................................................................................24

6-2.

FUNCTIONS.......................................................................................................................................................25

6-3.

STORAGE AND SHIPMENT..............................................................................................................................26

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1. GENERAL INFORMATION

1.1 Introduction and Description

This manual explains the installation, operation and maintenance of the ACOM 03AT Automatic HF Antenna Tuning
Unit.

The Automatic HF Antenna Tuning Unit (AATU) model ACOM 03AT is a complete and self-contained unit for
automatic matching of HF symmetrical-antenna impedance to an unbalanced 50Ω output, that covers a continuous

1.8 to 16MHz frequency range and will withstand 200 to 2500W input power depending on the antenna SWR used.
Input power up to 1000W is permissible in the whole frequency range when antenna SWR is 10:1 or better. For SWR
up to 50:1, matching is still possible but the frequency range and input power are restricted. AATU features a
Remote Control Unit (RCU) and can be controlled via an optical link, up to 50m long.

All indicators and controls are available via the RCU. All command input to the RCU is menu-driven.

1-2. Owner Assistance

If assistance is needed, you should contact your local dealer first. If you still have an issue you need to discuss with
one of ACOM’s specialists. The contact information is as follows: phone [phone], fax [phone],
e-mail [e-mail]

or by mail: Bul. Nikola Mushanov 151, 1330 Sofia, Bulgaria.

1-3. Equipment Supplied and Options

The ACOM 03AT AATU is shipped in a single cardboard carton. It contains three internal cartons:

- one internal carton, containing the remote AATU unit, the RCU, and installation accessories;

- a second internal carton containing the power supply cable, and

- a third internal carton with the optical control cable.

NOTE

A coaxial cable to the station is not included. It is normally a part of the antenna set.
Use type RG213 or equivalent.

Options:

- Unbalanced output with 50

Ω UHF(SO239A) connector;

- Serial control port for the ACOM2000A HF Linear Amplifier and for ACOM2000S Automatic Antenna Selector;

- PC control via RS232 or RS422 serial port.

1-4. Features

• Easy to operate. The only operator’s obligation is to apply CW power, while the matching process is fully
automatic.

• Nonvolatile memory for 99 different user’s tuning settings and selection of the power-on default.

• LCD comment display. All AATU status indications are explained via detailed text displayed on the dot-matrix,

back-lighted liquid crystal display (LCD) on the RCU.

• Less interference and improved electromagnetic compatibility during tuning. Retuning can be achieved in 8s (2-
3s typical) and at reduced RF power (10-100W).

• Guards your transmitter during the tuning process against excessive impedance mismatch via inserting a
powerful attenuator at the input, and removing it after that.

• The RF power is disabled during each commutation in order to save the vacuum RF-relay contacts, as well as to
keep the emitted spectrum as narrow as possible during the tuning process.

• Improves harmonic emission suppression of your transmitter since the matching circuit represents a low-pass
Pi-filter.

• Saves space on the operating desk. Since the AATU is controlled by the RCU only, the remote unit can be
located up to 50m from the operation position.

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• Remote matching – less losses in the feed line. The design of the main (remote) unit is foreseen for outdoor-
installation requirements. This permits you to locate it closely to the antenna feed-points, thus considerably
reducing the mismatched RF path length.

• Operates automatically without special signals from the transceiver – 10 to 100W CW is the only requirement to
perform automatic matching.

• Optical control link between RCU and remote AATU unit. This avoids erratic control in strong electromagnetic
fields, which is a typical case in the near field of HF antennas emitting 1-2kW.

• Continuous monitoring of the antenna voltage, temperature and power supply in the remote unit, and indication
on the RCU of any abnormal condition.

• Resource-estimate function (STATUS) giving the percentage of inductors and capacitors involved achieving a
match. This offers a possibility for monitoring the condition of the RF path, thus to forewarn possible problems.

• Safe power supply voltage for the remote unit (24VAC provided by the RCU).

• Features BYPASS function, where the effect of the inductors and capacitors on the impedance is excluded for

broadband operation (the balun transformer however still used) – you can use the antenna without a retune,
provided the antenna is broadband.

• When AATU is powered off, the BYPASS function is performed by default, too – you can use your antenna
without an AATU when the antenna features an acceptable SWR for any frequency segment.

• RF-path condition to the AATU can be checked using the functions “STATUS”, “BYPASS”, and “SWR-CHK” –
you can timely know about possible problems.

• Protection against atmospheric electricity via sphere spark gaps and a bleeder choke.

• Options: Unbalanced output with 50

Ω UHF (SO239A) connector; Control for the ACOM2000A HF Linear

Amplifier and for ACOM2000S Automatic Antenna Selector; PC control via RS232 or RS422 serial port;
Nonvolatile memory for user tunings.

1-5. Safety Considerations, Explicit Definitions

The ACOM 03AT Automatic HF Antenna Tuning Unit is a Safety Class I unit, i.e. the third grounding lead of its mains
cord, and the grounding studs on both units (the RCU and the remote unit), marked GND (GROUND), must be
connected to the station’s grounding system for safe operation. The AATU is designed to meet international safety
standards and complies with CE safety and electromagnetic compatibility requirements, as well as FCC regulations.

This operating manual contains information, precautions, indications for cautions and warnings which must be
followed by the user to ensure safe operation and to keep the ACOM 03AT in safe operating condition.

PRECAUTIONS:

The EXPLICIT DEFINITIONS described below apply to this operating manual:

W A R N I N G notes call attention to a procedure which, if not correctly performed, could result in personal injury,

fire hazard or electric shock.

C A U T I O N notes call attention to a procedure which, if not correctly performed, could result in equipment

damage, not only in the AATU.

N O T E notes call attention to a procedure which, if not correctly performed, could result in inconvenience only.

W A R N I N G HIGH VOLTAGE!

The AATU works with mains voltage 220-240VAC 50-60Hz and high DC voltage up
to 300VDC, which are LETHAL! Also, for your safety pull the AATU power plug out
of the mains wall outlet and WAIT AT LEAST 3 minutes EACH TIME BEFORE you
remove any cover!

4

W A R N I N G HIGH VOLTAGE!

Never allow anyone, ESPECIALLY CHILDREN, to push anything into holes in the
case – this will cause electric shock. NEVER TOUCH AN ANTENNA OR ANTENNA
INSULATORS during transmission – this may result in an electric shock or burn.
The RF voltage on the antenna insulators may exceed 5000V! NEVER EXPOSE the
RCU to rain, snow or any liquids. AVOID placing the RCU in excessively dusty
environments or in direct sunlight.

W A R N I N G

Do not undertake on your own repairs or changes in hardware or software of the
AATU in order not to endanger your or other’s health and life and not to damage the
AATU and the equipment connected with it, not covered by warranty. The
manufacturer is not liable for another’s actions and responsibility shall be assumed
by the doer.

C A U T I O N

To avoid damage (not covered under warranty) read the Installation – Section 2 of
this operating manual carefully. If you have any doubts about the installation,
operation or safeties of the AATU please consult your dealer.

2. INSTALLATION

2-1. Unpacking and Initial Inspection

C A U T I O N

Before you start any action on installing the AATU, thoroughly read this manual.
First, carefully inspect all cardboard cartons and their contents for physical damage.
If damage is noticed, notify your dealer immediately. Delay may infringe carrier’s
warranty conditions. Keep all packing for possible future transportation!

Take out the RCU, its mains power cable and the serial-control cables (option). Carefully check the RCU and the
cables for any possible shipping damage. Leave them оn the place where the RCU will be installed.

The remote (main) unit, together with the remaining installation accessories and both cartons with the 50m cables
are intended for installation at the antenna area. Take them out of their cartons separately and check carefully for
transportation injury. Return them back into their cartons after that in order to make it easy and safely to carry them
to the remote-unit installation place (for instance, at the antenna base).

2-2. Line Voltage

C A U T I O N

To avoid damage (not covered under warranty), check carefully if the voltage for
which the AATU is set corresponds to your mains nominal voltage.

Normally the AATU is supplied with Voltage Selector set for a nominal mains voltage of 230V. There might be
exceptions in cases of special delivery.

2-3. Remote Unit Installation

N O T E

Before you start any action on installing the remote unit, make a plan about how the
cables would be laid and where would they come through the wall on the premises
where the RCU will be installed. Have in mind that there is a connector installed on
the bottom end of the supply cable that needs a minimum of 22mm (7/8”) diameter

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hole. If you prefer a smaller hole, you should thread the whole cable length through
the wall, beginning from its bared end and leaving the connector in the room. In
such a case you would need only 8mm (5/16”) for this cable and another hole of
7mm (9/32”) diameter for the optic cable.

N O T E

The coaxial cable needed for a connection between the remote unit and the station
is not supplied but you should foresee its installation, too (unless it has been
installed previously). Normally you will need a 11mm (7/16”) diameter hole or 20mm
(25/32”) should you want to thread the cable with the PL-259 connectors installed.

W A R N I N G HIGH VOLTAGE!

To avoid disaster, the AATU installation and connection to the grounding and to the
antenna should be carried out only in serene quiet and sunny weather, when no risk
for thunders or atmospheric electricity activity exists. Not only a direct lightning hit
but also nearby strokes, as well as electricity induced by storm-clouds or a dusty
wind can cause voltages in either the antenna or the cables you are installing, that
are dangerous for life!

W A R N I N G HIGH VOLTAGE!

Do not begin installing the AATU before you have prepared a proper and safe
lightning grounding installation! Never use the AATU unless it is grounded to
guard you against lightning strokes! Do not use casual ground connections!

Installation of the remote unit must be accomplished in the order described below, before you connect the RCU and
the cables to your station.

a) Mount the AATU installation console to the antenna mast at a height at least 80cm (2.6 feet). This is needed in
order that winter snow cannot reach the height of the unit. Use both U-bolts M6 and the fixing screw M6x70mm
(supplied) – see fig.2-1,a,b & 2-2,f,g. Do not miss the fixing screw that avoids turning the unit around the mast.

b) Place the remote unit on the installed console and orient it with the hood head upward and the connectors
downward (see fig.2-1 and 2-2). You may need an assistant for the next operation.

C A U T I O N

When outdoors installed, the unit must be positioned with its hood head upward,
and with the connectors and the cable glands – vertically down. Never install the
remote AATU unit inclined to the vertical for outdoors usage in order to prevent it
from precipitation-water leaking into the unit as this may lead to damage, not
covered by warranty!

Settle carefully the unit onto the console and align its four installation blind holes (M6 threaded – see fig.2-4) to the
corresponding console holes.

An assistant may be needed at this point to hold the unit steady while you screw in the four screws М6х16mm (fig.2­1,c) loosely. Tighten them properly using a 5mm (0,2”) Allan key.

After having finished the above mount operations please check the strength and reliability of the installation.

6

Fig.2-1. Remote AATU unit on-mast installation and cables arrangement (bottom view).

c) Using a 5mm (0,2”) Allan key unscrew all 10 captive screws М6 located on the bottom panel of the unit (see fig.2­1,d). Pull the metal hood upwards carefully and remove it. Using a “Philips 1” screwdriver, unscrew all 12 М3х8mm
screws that hold the rear lid of the unit. Carefully slip it off in order to get access to the Printed Circuit Boards “Power
Supply” and “Control”. On the “Control” PCB find the two optic devices, marked U10 and U11 on the PCB, and
having knurled plastic nuts, permanently installed on their optic connectors (a split-socket type to tighten the optic­cable cores) - see fig.2-2,a & 2-3. The black-case device is the photo detector receiver while the white-case is the
optic emitter. For now, as the other cable end is still not connected, it is meaningless which core to which device
shall be connected. Identifying is easy on the second end at the first power on see S.2-4(c).

Fig.2-2. Remote unit connections

d) Unscrew the plastic cable-gland cap (marked “OPTOLINK CONTROL” on the bottom panel - fig.2-1,e & 2-2,e) and
thread it over the optic cable in such a direction as to be able to screw it onto the same cable gland later. Push the
bared optic cable end into the cable-gland hole and direct it to both optic-device apertures (fig.2-2,a-b & 2-3).

7

Fig.2-3 The “Control” PCB and optic devices in the remote AATU unit.

Push 2-3cm (one inch) more cable length into the cable gland (so that not to stretch the inside cable length after
having it connected to the optic devices (fig.2-2,a-b) and tighten the cable-gland cap using a wrench sized 22mm
(7/8”). Use only enough force while tightening in order that the cable be tight and could not slip out when pulled
occasionally (do not overdo it since a cable-gland destruction is likely).

C A U T I O N

The optic cable ends are supplied readily bared and prepared for installation.
Nevertheless, check on each cable end whether the external sheath has been
removed about 100mm (four inches), in order to move apart both fiber cores to both
optic devices. In addition, each fiber face must be cut as smooth as possible and in
a vertical section. Check whether the cut surface is clean of contamination and
lucid.

Should you need to bare the cable once more again, first peel off the external cable sheath about 10-12cm (four
inches) from the end. Be careful not to injure the cores under the sheath. Then cut small lengths (2-5mm, 0.1-0.2”) off
each core end in order to expose a clean and lucid surface of the transparent light-guiding plastic fiber. Use a clean,
sharp and smooth-surface knife. Keep track to make a precisely vertical section. The light loss and reflections
depend strongly on this operation quality. To improve the cut performance we recommend to pre-heat the knife blade
(to about 70-80 deg.C or 160-175F). Be careful not to contaminate the blade while heating and not to over-heat it.

Loose the split-socket-knurled nut of either optic device slightly (fig.2-3). Then push either core into the split socket,
shove the core against the stop, and tighten carefully its knurled nut by hand. Keep track that no foreign matter is
caught into the optic device aperture since this would obstruct the light beam.

Use only enough force while tightening in order that the cable be tight and could not slip out when pulled
occasionally (do not overdo in order not to damage the plastic case or the optic device). Repeat the same operation
with the second cable core and the other optic device. As mentioned above, identification of the channels transmit
and receive will be made at first power on – see S.2-4(c).

e) Unscrew the metal cable-gland cap (marked “24VAC/3A” on the bottom panel (see fig.2-1,f) and thread it over the
bared end of the four-core screened power-supply cable in such a direction as to be able to screw it onto the same
place later. Take out the plastic insert from the cable gland housing. Thread the insert over the cable end in such a
direction, that its split end be next to the metal cap, and the slender end – to the cable bared tag (see fig.2-4).

8

Fig.2-4 Power supply cable gland of the remote unit (bottom view).

Drag the detached (10-12mm or ½”)-piece of the cable sheath towards the cable end in order to loose the shielding
braid. Remove the cloth layer from the shield and carefully spread the braiding wires below it in a radial direction.
Move the plastic insert towards the bared area until the insert face reaches the split braiding. Then bend the
shielding wires back in order to lay them over the outside surface of the plastic insert (fig.2-5). Put them in order and
arrange carefully around the insert periphery.

Fig.2-5 Screening braid shaped before to push into the cable gland.

Holding the plastic insert fixed to the cable, push all four cable cores into the gland housing and direct them towards
the “Power Supply” PCB inside (fig.2-2,c-d). Use a small rotation around the insert axis in order to align its three
guides to the corresponding grooves in the metal housing, then carefully shove the insert into the gland body,
together with the shaped cable. Now, press the insert inwards in a manner that the back-folded braid touches the
metal-housing head closely, and while holding it in this position, screw in the metal cap against stop. Finally, tighten
the cap using a wrench size 20mm (25/32”). Use only enough force while tightening in order that the cable be tight
and could not slip out when pulled occasionally (do not overdo in order not to damage the gland thread).