ACOM 04AT
Remote Automatic
Antenna Tuner and Switch
User's Manual
Installation, Operation
and Maintenance
OUTSTANDING HF POWER PRODUCTS
May 2021
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 2 of 72 | S e c t i o n ABOUT DOCUMENTATION
May 2021
This manual is for electronic distribution mainly.
If you have it on paper and you no longer need it, please, recycle it!
The latest versions of our User's Manuals are available at
www.acom-bg.com
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n ABOUT DOCUMENTATION | Page 3 of 72
ABOUT DOCUMENTATION
All ACOM documentation (including manuals, brochures, specifications, descriptions, presentations, video
materials, etc.) are based on the latest available information at the time of creation of our documents.
As we always strive to constantly improve and update our products, ALL PRODUCTS, PRODUCT
SPECIFICATIONS AND DATA ARE SUBJECT TO CHANGE. ACOM reserves the right to make changes and
improvements at any time without further notice or obligation to notify any person or organization of such
revisions or changes, made in order to improve the reliability, function, quality and design, and/or
performance of the ACOM products and services.
Further, this User's Manual is provided AS IS and ACOM shall not be liable for possible errors contained
herein.
This manual supersedes all previous editions, which thereby become invalid.
The cover images used in the manual are illustrative only.
We are continuously striving to improve our documentation, but nobody is perfect.
And our documentation is not an exception of this rule.
Have you found any errors or would you like to suggest changes in our documentation?
Please help us by sending your suggestions to the following e-mail address:
documentation@acom-bg.com
The latest versions of our User's Manuals are available at
www.acom-bg.com
We highly recommend you to use this manual in electronic form as PDF-file instead of printed version. The
PDF-file is easy to read on any computer, tablet, smart phone or other similar device. In the PDF file you will
find the necessary information very fast due to context-oriented links (marked in orange) inside the file,
including context-linked Table of Content.
To open PDF-files you can use any free PDF viewer, for example:
- Adobe Acrobat Reader DC (https://get.adobe.com/reader);
- Foxit Reader (https://www.foxitsoftware.com/pdf-reader);
- Your web browser. Web browsers like Google Chrome, Firefox and Safari all have integrated PDF
readers.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 4 of 72 | S e c t i o n ABOUT DOCUMENTATION
May 2021
Title of Documentation
ACOM 04AT Remote Automatic Antenna Tuner and Switch
User's Manual
Installation, Operation and Maintenance
Type of Documentation
User's Manual
Purpose of Documentation
This manual explains Installation, Operation and Maintenance of the
ACOM 04AT Remote Automatic Antenna Tuner and Switch.
Record of Revisions
Description
Release Date
Notes
ACOM 04AT User's Manual
-
First edition
ACOM 04AT User's Manual
-
Second edition
ACOM 04AT User's Manual
25.04.2018
Third edition
ACOM 04AT User's Manual
21.05.2021
Fourth edition, R01
Validity
The specified data is for product description purposes only and may not be
deemed to be guaranteed unless expressly confirmed in the contract. All
rights are reserved with respect to the content of this manual and the
availability of the product.
Copyrights
© 2021 ACOM Ltd.
Copying this document, giving it to others and the use or communication
of the contents thereof without express authority, are forbidden.
Offenders will be held liable for infringement of any intellectual property
of ACOM Ltd. and all damages which may rise as a result.
Published by
ACOM Ltd.
Bulgaria | Bozhurishte 2227
Sofia-Bozhurishte Economic Zone | 6 Valeri Petrov Str.
GPS coordinates: 42.748616о | 23.209801о
Web: www.acom-bg.com
E-mail: documentation@acom-bg.com
Note
This manual has been printed on chlorine-free bleached paper.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n ABOUT DOCUMENTATION | Page 5 of 72
Contents
ABOUT DOCUMENTATION ................................................................................................................................ 3
1. GENERAL INFORMATION ........................................................................................................................... 9
1.1. Introduction and Description .......................................................................................................... 9
1.2. Owner Assistance .......................................................................................................................... 10
1.3. Equipment Supplied ...................................................................................................................... 10
1.4. Features ......................................................................................................................................... 11
1.5. Safety Considerations, Explicit Definitions .................................................................................... 13
1.5.1. Lightning protection when the tuner is installed in a building ........................................ 16
1.5.2. Lightning protection when the tuner is installed outdoor .............................................. 17
1.5.3. Electric Safety Precautions .............................................................................................. 18
1.5.4. General Safety Precautions ............................................................................................. 18
2. INSTALLATION .......................................................................................................................................... 19
2.1. Unpacking and Initial Inspection ................................................................................................... 20
2.2. Power Supply Voltage ................................................................................................................... 20
2.3. Installation and Connection for Indoor Operation ........................................................................ 21
2.4. Installation and Connection for Outdoor Operation ..................................................................... 23
2.4.1. If the wall mounting option is chosen ............................................................................. 24
2.4.2. If the mast mounting option is chosen ............................................................................ 26
2.5. Grounding, Additional Information ............................................................................................... 29
2.5.1. Lightning Protection Grounding ...................................................................................... 29
2.5.2. Grounding for Protection from Electric Shock................................................................. 29
2.5.3. Radio Frequency Grounding or Counterpoise ................................................................. 29
2.6. Connecting RF Cables, Additional Information ............................................................................. 29
3. GETTING STARTED ................................................................................................................................... 31
3.1. Turning ON and OFF ...................................................................................................................... 31
3.2. Indication, controls and menus ..................................................................................................... 32
3.2.1. Tuner Information Area on the Amplifier Screen ............................................................ 32
3.2.2. Segment UP/DWN buttons (Second Function - BAND) ................................................... 33
3.2.3. TUNE button (Second Function - BYPASS) ....................................................................... 33
3.2.4. АNT Button (Change of Antennas) .................................................................................. 34
3.2.5. Tuner Related Menus ...................................................................................................... 34
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 6 of 72 | S e c t i o n ABOUT DOCUMENTATION
May 2021
4. STARTING UP AND MAIN FUNCTIONS ..................................................................................................... 35
4.1. What is tuning type / Rate (Selectivity Degree, Sharpness).......................................................... 35
4.1.1. SHARP .............................................................................................................................. 36
4.1.2. REGULAR .......................................................................................................................... 36
4.1.3. WIDE ................................................................................................................................ 36
4.1.4. FIXED ................................................................................................................................ 36
4.2. Tuner Assignment and Unassignment .......................................................................................... 37
4.3. Tuning Modes: FULL, QUICK and BYPASS ...................................................................................... 37
4.4. Quick Tuning and Non-Volatile Memory ....................................................................................... 37
Organization and use of the tuning settings memory ............................................................................. 38
4.5. Operation in BYPASS Mode ........................................................................................................... 39
4.6. Changing Frequencies and Antennas ............................................................................................ 39
4.7. Specific of Operation in TRANSMISSION Mode ............................................................................ 40
4.8. Power Reduction at Overload ....................................................................................................... 40
5. BASIC FULL TUNING CYCLE ...................................................................................................................... 41
5.1. What a Full Tuning Cycle Does ...................................................................................................... 41
5.2. Operator Actions for a Full Tuning Cycle ....................................................................................... 42
5.2.1. Full Tuning for Transceivers with CAT ............................................................................. 42
5.2.2. Full Tuning for Transceivers without CAT Capability ....................................................... 42
6. ADVANCED FUNCTIONS AND OPTIONS ................................................................................................... 44
6.1. ANTENNA ASSIGNMENT Menu ..................................................................................................... 44
6.1.1. Antenna Assignments by Bands ...................................................................................... 44
6.1.2. Setting the Tuning type / Rate (Sharpness, Selectivity), (S, R, W, F) ............................... 44
6.1.3. Editing Antenna Names ................................................................................................... 45
6.2. Maintenance Functions - ATU SERVICE Menu .............................................................................. 45
6.2.1. ATU Individual Data ......................................................................................................... 45
6.2.2. ATU Status ....................................................................................................................... 45
6.2.3. Deletion of Individual or Group of Stored Tuning settings .............................................. 45
6.2.4. Erasing the Whole NON-Volatile Memory ....................................................................... 46
6.2.5. Checking the Resource Used for the Current Tuning ...................................................... 46
6.2.6. Dumping the NON-Volatile Memory in a File on a PC ..................................................... 46
6.2.7. Restoring (Loading) the NON-Volatile Memory from a File - Memory Load from File ... 48
6.2.8. Aging and Refreshing of Settings ..................................................................................... 49
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n ABOUT DOCUMENTATION | Page 7 of 72
6.3. Overview of TUNING SETTINGS and Resources Used ................................................................... 50
6.4. Measurements in the Tuner - ATU MEASURE Menu .................................................................... 51
6.4.1. Voltage and Current at the Antenna Output ................................................................... 52
6.4.2. Reflected Power, Forward Power and SWR at Antenna Output ..................................... 52
6.4.3. Power Supply Voltage and Temperature in the Tuner Unit ............................................ 52
6.4.4. Tuner Working Hours....................................................................................................... 52
7. MAINTENANCE ........................................................................................................................................ 53
7.1. Cleaning ......................................................................................................................................... 53
7.2. Fuse Replacement ......................................................................................................................... 53
7.3. Block Diagram and Principle of Operation .................................................................................... 55
7.4. Troubleshooting - Monitoring the Antenna-feeder Path Status ................................................... 59
8. SPECIFICATIONS ....................................................................................................................................... 61
8.1. Parameters .................................................................................................................................... 61
8.1.1. Operating Frequency Range ............................................................................................ 61
8.1.2. Minimum Range of the Matched Impedances (at Each of the Four Antenna Outputs) . 61
8.1.3. Maximum Allowed Input Power ...................................................................................... 61
8.1.4. RF Input Characteristics ................................................................................................... 61
8.1.5. Antenna Outputs Characteristics, Antenna 1 to Antenna 4 ............................................ 62
8.1.6. Full Tuning Duration (Basic Cycle) ................................................................................... 62
8.1.7. Input Signal Needed to Prepare User Tuning Settings .................................................... 62
8.1.8. Power Supply ................................................................................................................... 62
8.1.9. Remote Control ............................................................................................................... 62
8.1.10. Maximum Length of the Input Coaxial Cable .................................................................. 62
8.1.11. Size & Weight (operating, excluding fastening elements and connected cables) .......... 62
8.1.12. Operating Environment ................................................................................................... 63
8.2. Functions ....................................................................................................................................... 63
8.2.1. Process of Matching of Antenna Impedance ................................................................... 63
8.2.2. Modes of Tuning .............................................................................................................. 63
8.2.3. Memory for the User Tune Settings ................................................................................ 63
8.2.4. Types of Antenna Selectivity / Bandwidth ....................................................................... 63
8.2.5. Bypass and Use ATU Modes ............................................................................................ 63
8.2.6. Overview of Tuning Settings ............................................................................................ 64
8.2.7. Evaluation of the Resource Used ..................................................................................... 64
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 8 of 72 | S e c t i o n ABOUT DOCUMENTATION
May 2021
8.2.8. Backing Up the NON-Volatile Memory ............................................................................ 64
8.2.9. Cable Required from the Radio Station ........................................................................... 64
8.2.10. Protection Mechanisms ................................................................................................... 64
8.3. Storage and Shipment ................................................................................................................... 65
8.3.1. Storage Environment ....................................................................................................... 65
8.3.2. Shipping Size and Weight ................................................................................................ 65
8.3.3. Transportation ................................................................................................................. 65
8.3.4. Returning to the Service Provider ................................................................................... 65
8.4. Information on Disposing and Recycling of Old Electrical and Electronic Equipment .................. 66
APPENDIX 1 | Lightning Protection ................................................................................................................. 67
NOTES .............................................................................................................................................................. 70
Figures
Figure 2-1 ACOM 04AT tuner .......................................................................................................................... 19
Figure 2-2 Desk installation bracket ................................................................................................................ 21
Figure 2-3 Securing the tuner to a desk .......................................................................................................... 22
Figure 2-4 Tuner rear view with connectors ................................................................................................... 22
Figure 2-5 Wall installation bracket ................................................................................................................. 25
Figure 2-6 Tuner installed on a wall ................................................................................................................ 25
Figure 2-7 Mast installation bracket ................................................................................................................ 26
Figure 2-8 Securing the tuner to a mast .......................................................................................................... 27
Figure 2-9 Accessories ..................................................................................................................................... 28
Figure 3-1 Amplifier screen with tuner installed ............................................................................................. 32
Figure 6-1 ACOM Terminal S screenshot ......................................................................................................... 46
Figure 7-1 Tuner Block Diagram ...................................................................................................................... 56
Figure 8-1 Packaging cardboard box ............................................................................................................... 65
Tables
Table 1-1 Package contents ............................................................................................................................. 10
Table 2-1 Accessories list ................................................................................................................................. 28
Table 8-1 Maximum input power of the tuner as function of the antenna SWR............................................ 61
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n GENERAL INFORMATION | Page 9 of 72
1. GENERAL INFORMATION
Congratulations on purchasing one of the finest antenna tuners in the world today.
ACOM is pleased that you have chosen one of our products, and we will endeavor to provide you with the
information and support you need to enjoy your purchase for many years.
We urge you to read all of the following materials before you embark on operating your new antenna tuner.
1.1. Introduction and Description
This manual explains:
• Installation
• Operation and
• Maintenance
of the ACOM 04AT remote automatic antenna tuner for HF + 6 m with integrated four-way antenna switch.
The ACOM 04AT tuner is specifically designed and developed to work exclusively with the ACOM series of
solid state (transistor) amplifiers, e.g., ACOM 700S or ACOM 1200S.
It automatically selects one of four available antenna outputs (as assigned in bands by the operator) and
matches the impedance of the chosen antenna output by transforming it to 50 Ohm with SWR below 1.5:1
at the tuner input (typically below 1.3), providing an optimum load impedance for the amplifier.
Any necessary readjustments are swift, following the frequency changes and antenna selections.
The tuner matches all load impedances presenting a SWR below 3:1, regardless of phase angle, in a
continuous frequency range of 1.8-30 MHz and 50-54 MHz. In many cases, the tuner will match loads with
higher SWR (up to 10:1) as well, however a reduction in power may be necessary if the protective functions
of the tuner activate due to high values of SWR, current, voltage, forward or reflected power at the antenna
output.
Provided the SWR of the feedline/antenna system is up to 3:1, the tuner can handle input power levels up to
1200 W (PEP, mean or continuous carrier), regardless of the operating communication mode. For
feedline/antenna system SWRs between 3:1 and 10:1, the maximum permissible power at the tuner input is
gradually reduced down to 200 W at SWR=10:1 (see Table 8-1 Maximum input power of the tuner as function of
the antenna SWR), allowing for operation within tuner component specifications.
The tuner can be installed both in the shack and in a remote location, e.g., in a separate room, in a sheltered
location outdoors or even out in the open, close to the antennas, so that any feedlines from the unit to the
antennas, working in mismatched conditions, are kept as short as practically possible to avoid unnecessary
losses.
Generally, a remote installation of the tuner is preferable to a local one, because it reduces RF losses in most
of the feedline's length. Thanks to the built-in automatic antenna switch, a significant reduction in both
installation effort and required cable length can be achieved (up to three times the feedline length with four
antennas and in-shack tuner installation).
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 10 of 72 | S e c t i o n GENERAL INFORMATION
May 2021
A single cable connects the tuner to the radio station - the main coaxial feedline, which is often already preinstalled. Tuner power supply, control and RF signals are combined on the feedline, easing remote
installation, lowering costs and uncluttering the shack.
Provided a low loss hi-quality cable is used (e.g., RG213), the distance between the tuner and the shack can
be up to 100 m (330 ft). However, the length of the cable should be kept at minimum to avoid any
unnecessary losses, which exist in any cable even in matched conditions.
The wide operating temperature range of the tuner (-40 to +65 °C), the single cable to the shack, and the
included accessories - all make for an easy outdoor installation.
However, if you have a choice of installation locations, you should always prefer one that is sheltered from
the elements. It will prolong the operational life of the tuner and reduce material wear.
Regardless the choice of installation location, the operator is able to control and monitor the tuner's work
via the amplifier front panel using simplified and intuitive menus in the original style of the ACOM transistor
amplifier series.
1.2. Owner Assistance
If assistance is needed, you should contact your local dealer first. If necessary, your dealer will contact ACOM
for additional guidance.
If you still have an issue you need to discuss with one of ACOM's specialists, the contact information is as
follows:
ACOM Ltd.
E-mail: support@acom-bg.com
Bulgaria | Bozhurishte 2227
Sofia-Bozhurishte Economic Zone | 6 Valeri Petrov Str.
GPS coordinates: 42.748616о | 23.209801о
1.3. Equipment Supplied
The ACOM 04AT antenna tuner is shipped as package, consisting of:
Table 1-1 Package contents
Nr.
PACKAGE CONTENTS
Pcs.
1
Antenna tuner ACOM 04AT (unit only)
1 2 Weather Protection Hood ACOM 04-WP
1
3
Installation accessories set ACOM 04-DT (for desk mounting)
1
4
Installation accessories set ACOM 04-WM (for wall mounting)
1 5 Installation accessories set ACOM 04-MM (for mast mounting)
1
6
Fuse replacement set
2
7
User's Manual
1
Table 1-1 Package contents
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n GENERAL INFORMATION | Page 11 of 72
1.4. Features
• Easy set-up of user tuning presets
For a CAT transceiver a single press of the TUNE button on the amplifier front panel is all you need.
• Transparent (invisible) operation
After setting up the user presets (auto tune) for the frequency segments and antennas, the operator will
not be involved with tuner operation.
• Three kinds of frequency segments, according to antenna bandwidth
The operator can choose according to the nature of each of the four antennas (narrow band - Sharp,
normal - Regular, and broad band - Wide).
• Capability of operation at fixed frequencies (Fixed)
• Non-volatile memory
Non-volatile memory for user presets (auto tune), independent for the four antennas, the three types
of segment width, and more than 1000 random fixed frequencies for each antenna.
• User presets
The user presets are automatically loaded, following frequency and antenna selection changes.
• Export (backup) of preset memory
Backup of preset memory to a computer file, import of previously made backup files from a computer
to the tuner memory.
• Helpful information
Information about the setting age, and alerts for settings that reach a certain age, defined by the
operator in 4 possible age levels.
• Power supply and control to the tuner
Power supply and control to the tuner, as well as status return from the tuner are facilitated over the
coaxial cable between the amplifier and tuner, no need for additional cables or special control signals
from the transceiver (the availability of CAT control from the transceiver will give further advantages to
the setup).
• Improved electromagnetic compatibility
Full tuning can be completed within 5 seconds (typically 2-3 seconds), at 25 W at the tuner input and
less than 6 W at the antenna output; quick tuning (from nonvolatile-memory presets) is completed in
less than 0.05 seconds with zero emitted signals.
• Input SWR during full tuning cycles
Input SWR during full tuning cycles - below 2:1, preventing activation of transceiver PA protection.
• Input SWR after completing a tuning cycle
Input SWR after completing a tuning cycle - below 1.5:1 (typically below 1.3:1).
• Relays with gold-plated contacts
Relays with gold-plated contacts for excellent receive characteristics.
• Relay switching
Relay switching will only take place when no RF current is flowing, preventing contact arcing critical for
preventing contact oxidation, surface melting and material transfer (otherwise resulting in poor
receiving performance) and to avoid any unwanted widening of the spectrum of signals, emitted during
the tuning cycle.
• Air-core coils and high-quality ceramic capacitors
Air-core coils (no magnetic materials) and high-quality NP0 (C0G) ceramic capacitors usage throughout
the matching circuit.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 12 of 72 | S e c t i o n GENERAL INFORMATION
May 2021
• Harmonic suppression
Improves harmonic suppression - the matching network is a low-pass L filter.
• Saves space on the operating position
ACOM 04AT can be located up to 100 m (330 ft) away from the shack.
• Remote installation
Allows remote installation, including outdoors, close to the antenna feed point, minimizing losses.
• Integrated antenna switch
Integrated four-way antenna switch - less coaxial cable, shorter unmatched sections, less losses.
• Automatically and manually antenna switching
Antennas can be automatically and manually switched from the amplifier front panel. The last used
antenna selection is memorized.
• Customized antennas names and types
Indication and editing of names and types of antennas in editable freeform.
• Protection mechanisms
Various protection mechanisms, including: antenna overvoltage, antenna overcurrent, excessive power
during operation and tuning, extreme temperatures and power supply voltages, as well as relay hotswitching.
• Safe power supply
Safe power supply voltage (26 VDC).
• BYPASS mode
BYPASS mode - all components of the matching network are excluded, allowing direct operation of
broadband antennas.
• SERVICE menu
This menu allowing analysis of the tuner status and review of the used resource of coils and capacitors
for all memorized and current tuning presets.
• Lightning arrestor and bleeder resistor
Integrated lightning arrestor and bleeder resistor for protection against static discharges; automatic
grounding of antennas on powering down.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n GENERAL INFORMATION | Page 13 of 72
1.5. Safety Considerations, Explicit Definitions
The ACOM 04AT is designed to meet international safety standards and complies with CE safety and
electromagnetic compatibility requirements, as well as FCC regulations.
This User's Manual contains information, warnings (signal words Danger, Warning, Caution and Notice) and
instructions, related to hazards, that should be followed by the user in order to ensure safe operation and to
keep the tuner in a safe working condition at all times.
The EXPLICIT DEFINITIONS described below apply to this User's Manual:
DANGER
These notes call attention to a procedure or instructions which, if not correctly performed,
will result in serious personal injuries and even death.
WARNING
These notes call attention to a procedure or instructions which, if not correctly performed,
could result in serious personal injuries and even death.
CAUTION
These notes call attention to a procedure or instructions which, if not correctly performed,
could result in minor or moderate personal injuries.
NOTICE
These notes call attention to a procedure or instructions which, if not correctly performed,
could result in property damage or equipment damage not exclusively to the tuner but
also to connected equipment.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 14 of 72 | S e c t i o n GENERAL INFORMATION
May 2021
Information notes described below apply to this User's Manual:
These notes highlight operating procedures or practices that may improve equipment
reliability and/or personnel performance, or to emphasize a concept.
ORANGE TEXT as LINKS
marks all internal links in the document between Sections, Figures, Tables, etc. for your
convenience.
The safety instructions contained in this User's Manual feature specific signal words
(Danger, Warning, Caution or Notice) and, where required, a safety alert symbol, in
accordance with actual standards ISO 3864 or ANSI Z535.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n GENERAL INFORMATION | Page 15 of 72
PRECAUTIONS:
DANGER
For details about lightning protection see APPENDIX 1 | Lightning Protection at the end of
this manual.
DANGER
For safe tuner operation, the tuner's grounding terminal labeled GROUND should be
connected according to the applicable standards and local regulations for electric safety,
fire safety and lightning protection, in all cases the radio station is equipped with outdoor
antenna/s!
DANGER
Never run cables into the radio station directly from outside (through a wall or window),
whether from antennas, tuners, groundings, telephone or network lines, etc. The cables
should first pass through the foundation of the building where they should be secured in
a way that is standard for your region (observe the recommendations stated in APPENDIX
1 | Lightning Protection at the end of this manual, if no other data is available), in order to
avoid conduction of a lightning strike with all resulting consequences - death, injury, fire,
equipment damage, destruction, etc. (see Point 8) in Appendix 1).
DANGER
Regardless of the recommendations herein, it is your responsibility to consult a
professional electrician for advice on installing your grounding system, and to refer to,
together with the electrician, the applicable standards and local regulations for electric
safety, fire safety and lightning protection, in all cases the radio station is equipped with
outdoor antenna/s, in order to ensure that your installation complies with all applicable
requirements. The applicable standards and local regulations shall prevail if there is a
difference in the requirements, and if they contain more or stricter requirements than the
minimum for installation stated in APPENDIX 1 | Lightning Protection.
NEVER underestimate the danger of lightning!
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 16 of 72 | S e c t i o n GENERAL INFORMATION
May 2021
1.5.1. Lightning protection when the tuner is installed in a building
DANGER
For details about lightning protection see APPENDIX 1 | Lightning Protection at the end of
this manual.
a) The tuner's terminal labeled GROUND should be connected through a low-impedance
connection with a cross section of no less than 20 sq. mm (preferably flat-shaped and solid band or plate, rather than with a flexible multistrand cable), to the main grounding plate of
the radio station (see Point 9) in Appendix 1).
b) The antennas should be connected by coaxial cables buried in the ground (when coming in
from the field) or securely attached to the wall of the building (when coming down from the
roof), all along the route from the antennas to the foundation of the building where, before
entering, are discharged from the lightning charges in a safe way - directly into the ground. For
this purpose, the braids of the coaxial cables should be securely grounded by a low-impedance
connection to the main grounding plate of the building (see Point 8) in Appendix 1).
c) From a low point close to the foundation of the building, before going up to the radio station,
the wires of the antenna cables should be equipped with pulse overvoltage limiters (surge
arresters), the grounding terminals of which should be connected through a low-impedance
connection to the main grounding plate of the building (see Point 8) in Appendix 1).
DANGER
When installing the tuner in the shack, do not connect antenna cables to the tuner if they
are entering the building directly, without being grounded through a low-impedance
connection to the main grounding plate of the building! Properly grounded antennas shall
be guided to the shack from the inside and from below, from the foundation of the
building and its main grounding plate rather than directly from outside! (see Point 8) in
Appendix 1).
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n GENERAL INFORMATION | Page 17 of 72
1.5.2. Lightning protection when the tuner is installed outdoor
DANGER
For details about lightning protection see APPENDIX 1 | Lightning Protection at the end of
this manual.
When installed on a roof or in the field, the tuner and antennas, if not provided with a separate lightning
protection, should be within the protection range of an existing lightning protection system.
Checking the efficiency range of a lightning rod is performed using the method known as "rolling sphere".
If the tuner and/or the antennas are not protected by an existing lightning protection system, the system
should be extended, its range of action should be increased or a new lightning protection system should be
built, with a sufficient range of action and in compliance with all requirements of the local standards and
regulations for electric safety, fire safety, and lightning protection.
a) The tuner's terminal labeled GROUND should be connected through a low-impedance
connection (preferably flat-shaped) with a solid cross section of no less than 20 sq. mm to the
closest (at a distance less than 6m) main conductor from an existing grounding system for
lightning protection, and where there is no such system, to a purpose-built individual
low-impedance grounding system for lightning protection, driven or buried directly in the
ground and in compliance with all requirements of the local standards and regulations for
electric safety, fire safety, and lightning protection (see Point 7) in Appendix 1).
b) The braids of the antenna coax cables should be connected through a low-impedance
connection (preferably flat-shaped) with a solid cross section of no less than 20 sq. mm to the
same grounding system for lightning protection, to which the tuner is connected, but with
independent connections, i.e., the connections of the coaxial braids to the grounding system
for lightning protection should not be broken in case the tuner is temporarily removed (e.g., for
maintenance).
c) Before the antenna cables are laid to the tuner, they should be equipped with pulse
overvoltage limiters (surge arresters), the grounding terminals of which should be connected
in the same manner as the braids in section b) above.
d) The feed line between the shack and a remotely located tuner should be coaxial cable buried
in the ground (when coming from the field) or securely attached to the wall of the building
(when coming down from the roof), all along the route from the antennas to the foundation
of the building. At the foundation, the braid of this cable should be securely grounded at
ground level and just before entering the building, through a low-impedance connection
(preferably flat-shaped) with solid section of no less than 20 sq. mm to the main grounding
plate of the building (see Point 8) in Appendix 1).
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 18 of 72 | S e c t i o n GENERAL INFORMATION
May 2021
e) At the place of entering the building, before going further to the radio station, the feedline
between the amplifier and tuner input should be equipped with a pulse overvoltage limiter
(surge arrester), the grounding terminal of which should be connected through a
low-impedance connection to the main grounding plate of the building (see Point 8) in
Appendix 1).
1.5.3. Electric Safety Precautions
WARNING
The electronics inside the tuner operate under high direct-current voltage up to 200 V,
which is fatal! Never allow anyone, especially children, to insert any object into box holes
- this may cause electric shock. Disconnect all cables from the tuner and every time wait
at least 1 minute before opening it!
WARNING
RF voltage at antenna feed point and elements may exceed several thousand volts!
Never touch the antenna or antenna isolators during transmission and tuning - this may
cause deep RF burns as well as indirect traumas, such as falling!
1.5.4. General Safety Precautions
WARNING
Do not undertake on your own repairs or changes in hardware or software of the tuner in
order not to endanger your or other's health and life and not to damage the tuner 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.
DANGER
To avoid damage (not covered under warranty) read the Section 2 INSTALLATION of this
User's Manual carefully. If you have any doubts about the installation, operation or safety
of the tuner, please consult your dealer.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n INSTALLATION | Page 19 of 72
2. INSTALLATION
The tuner can be installed at a fixed site (in a room), under a shelter or outdoors - with a special set of
installation accessories for desks, walls or masts (see Section 1.3 Equipment Supplied).
CAUTION
Never operate the tuner with its cover removed! Touching the components inside the
tuner while transmitting may result in RF burns and injury.
Mount/place the tuner so that the antenna terminals are not accessible during operation.
Do not mount the tuner in a position that will put it under water at any time.
Do not mount the tuner in a place that will allow sprinklers or water hoses to spray the
weather seals or connectors.
NOTICE
Do not try to additional weather sealing to the tuner. It should be installed in an airy
location in order to cool down during operation and to dry up after rain or morning dew!
Figure 2-1 ACOM 04AT tuner
Figure 2-1 ACOM 04AT tuner
with ACOM 04-WP weather protection cover removed, and without installation accessories
6
2
5
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 20 of 72 | S e c t i o n INSTALLATION
May 2021
Your new ACOM 04AT is shipped with the protective cover mounted. Regardless of which mounting option
will be chosen (desk, wall or mast), in order to mount the selected bracket, the weather protection cover
must be removed (see Figure 2-1 ACOM 04AT tuner, Pos. (2)).
The cover (Pos. 2) is fixed to the tuner body (Pos. 3) with 5 mounting brackets (Pos. 4). Place the tuner on a
flat leveled surface with connectors facing down. Unscrew the 5 bolts (Pos. 1) and carefully lift the weather
protection cover off the tuner body. If the tuner will be desk mounted, the weather cover (Pos. 2) and
mounting brackets (Pos. 4) should be safely stored.
The mounting brackets (Pos. 4) are removed by placing the tuner with the connectors facing up and
unscrewing the 10 bolts (Pos. 5), holding the brackets. If the tuner will be mast or wall mounted, the weather
protective cover (Pos. 2) will be reassembled after mounting the selected mast or wall bracket.
2.1. Unpacking and Initial Inspection
Before you install your antenna tuner, thoroughly read this manual.
First, carefully inspect the cardboard cartons and its contents for physical damage. ACOM
ships antenna tuners in highly protected containers, but it cannot assure that
mistreatment by shippers will not occur. If damage is evident, notify your dealer
immediately. Delay may void the carrier's warranty.
Remove all contents from the cartons and inspect the tuner chassis and all installation accessories for any
missing items according to the order. If you notice anything missing, immediately notify your ACOM dealer.
Delay may void the carrier's warranty.
Store safely the unused accessories.
Keep all packing materials for possible future antenna tuner shipment (see Section 8.3.4 Returning to the
Service Provider).
2.2. Power Supply Voltage
The tuner is powered by direct-current voltage +26 VDC +10/-15%, supplied through the coaxial cable from
the ACOM amplifier RF output to the RF input of the tuner, labeled 50Ω RF +26 VDC POWER & CONTROL.
NOTICE
In order to avoid any damage (not covered by the warranty), never connect the input jack
of the tuner, labeled 50Ω RF +26 VDC POWER & CONTROL to any power source except
the output of an amplifier from the ACOM transistor series.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n INSTALLATION | Page 21 of 72
2.3. Installation and Connection for Indoor Operation
For installation and connection for remote/outdoor operation see Section 2.4 Installation
and Connection for Outdoor Operation.
If the desk mounting option is chosen, the tuner is placed on the desk with the connectors facing to the back,
rubber feet facing down and secured in place with the provided desk bracket (see Figure 2-2 Desk installation
bracket). The decorative black anodized aluminum faceplate provides an aesthetic look, matching any
high-end ham radio setup.
Figure 2-2 Desk installation bracket
Figure 2-2 Desk installation bracket
Please, see Figure 2-2 Desk installation bracket).
The desk bracket (Pos. 2) is secured to the tuner body (Pos. 1) via 4 flat-head bolts (Pos. 3).
Be sure to place the provided metal spacer plate (Pos. 4) between the bracket and the tuner body. The bracket
is finished off with black polymer paint, reducing the possibility of accidental scratching of the desk surface.
After mounting and securing the tuner to the desk, the only contact surfaces are the rubber feet and rubber
protector of the bracket bolt, ensuring scratch-free desk surface.
4
2
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 22 of 72 | S e c t i o n INSTALLATION
May 2021
Figure 2-3 Securing the tuner to a desk
Figure 2-3 Securing the tuner to a desk
After securing the tuner body (Pos. 1) on the desk (Pos. 2) by fastening the bracket bolt (Pos. 4), the bracket (Pos.
3) remains hidden from sight (see Figure 2-3 Securing the tuner to a desk). This ensures both a tidy workspace and
the necessary stability of the tuner body together with up to 5 heavy coaxial cables connected to the back side.
DANGER
For INDOOR tuner operation, the grounding terminal of the tuner labeled GROUND and
the antenna feeders should be connected as described in Section 1.5.1 Lightning protection
when the tuner is installed in a building.
Figure 2-4 Tuner rear view with connectors
Figure 2-4 Tuner rear view with connectors
7
1
3
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n INSTALLATION | Page 23 of 72
Check if the antenna cables and grounding system of your radio station are installed as described in Section
1.5.1 Lightning protection when the tuner is installed in a building. Next, connect the grounding terminal (Pos. 5)
of the tuner labeled GROUND (see Figure 2-3 Securing the tuner to a desk and Figure 2-4 Tuner rear view with
connectors) to the main grounding plate of the radio station (see Point 9) in Appendix 1).
After connecting the grounding terminal, connect the antenna feeders (up to 4 coaxial cables) to the
respective connectors (Pos. 6) ANTENNA 1 through ANTENNA 4 on the tuner (see Figure 2-3 Securing the tuner
to a desk and Figure 2-4 Tuner rear view with connectors).
Without powering up the amplifier, use a coaxial cable to connect the tuner input (Pos. 7) labeled 50Ω RF
+26 VDC POWER & CONTROL (see Figure 2-3 Securing the tuner to a desk and Figure 2-4 Tuner rear view with
connectors) to the ACOM transistor amplifiers output labeled RF OUTPUT.
2.4. Installation and Connection for Outdoor Operation
The wall and tower mounting brackets, provided with your tuner, allow the tuner to be remotely mounted,
reducing losses, installation costs and installation complexity. This option should always be preferred if
applicable. Remote operation drastically reduces feedline losses, resulting from operating a mismatched
coaxial line, leaving only the inherent losses of the cable, operated in a source-feedline-load matched mode.
For installation and connection for indoor operation see Section 2.3 Installation and
Connection for Indoor Operation.
Before commencing tuner installation, carefully consider and map out the way the coaxial
cables run from the amplifier to the tuner and from the tuner to the antennas, as well as
the manner in which they will enter the shack.
DANGER
To prevent accidents, tuner installation and connection to the grounding and antennas
should only be carried out in clear, quiet and sunny weather, when there is no danger of
lightning and static discharges.
Life threatening voltages and electrostatic charges may occur in the antenna and the
cables you install, both as a result of a direct lightning strike or by induction after a
lightning strike on adjacent objects, and may also be statically induced by charged clouds
or energized by dust storms!
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 24 of 72 | S e c t i o n INSTALLATION
May 2021
DANGER
Do not commence tuner installation if you don't have a secure lightning protection
grounding system as per Section 1.5.2 Lightning protection when the tuner is installed
outdoor.
Do not use grounding systems that are nоt built to regulations - this may lead to fire, gas
explosion, other incidents or death, including that of other persons. Never use the tuner,
unless it is properly grounded!
At first, lay out the cables along the route to the radio station and antennas, and protect them from
mechanical damage, in case they move in the wind, snow or ice. When the end of the cable is inserted in the
foundation of the building, take precautions to seal against wetting the connecting terminals, main grounding
plate of the building (see Point 8) in Appendix 1) or other connections thereof. As a minimum, leave a
sufficient U-shaped slack before cable insertion to facilitate water drip off.
At the selected location install an appropriate set of installation accessories (ACOM 04-WM for walls or ACOM
04-MM for masts), as described hereafter. Do not install the protection cover at this point.
The tuner should be mounted strictly horizontally, with the connectors facing downwards and at a height of
no less than 1 m above base level (ground or roof).
The installation height above the base is essential in order to install cables with a sufficient U-shaped slack
under the tuner bottom level, so that any rain, dew and other precipitation or sprays reflected from base will
not wet the tuner and will safely drip off.
Also, in the case of heavy snowfall, the snow will not reach the tuner connectors.
2.4.1. If the wall mounting option is chosen
Please, see Figure 2-5 Wall installation bracket.
The protective cover (Pos. 1) is removed by unscrewing the five bolts (Pos. 2). The five cover holding brackets
(Pos. 7) are left in place, attached to the tuner body. Using the provided in the mounting kit four flat-head
bolts (Pos. 5), the wall bracket (Pos. 4) is secured to the tuner body (Pos. 3) and then the protective cover
(Pos. 1) is secured back in place with the five bolts (Pos. 2).
Please, see Figure 2-6 Tuner installed on a wall.
The whole assembly (Pos. 1 & 2) is then secured to a wall with 6 bolts (Pos. 3) with the weather protective
cover facing up. Although the weather protective cover (Pos. 1) provides the necessary shielding from the
elements, whenever it's possible, the tuner should be mounted under a shed. This way maximum protection
and minimum material wear both from water and sunlight and heat will be provided, extending the tuner's
operational lifespan. When installing the system outdoors always select a location, free from any possible
loose cables or other objects that might fall on or hit the tuner assembly.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n INSTALLATION | Page 25 of 72
Figure 2-5 Wall installation bracket
Figure 2-5 Wall installation bracket
Figure 2-6 Tuner installed on a wall
Figure 2-6 Tuner installed on a wall
2
1
1 5 4 6 7
3
2
3
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 26 of 72 | S e c t i o n INSTALLATION
May 2021
2.4.2. If the mast mounting option is chosen
Please, see Figure 2-7 Mast installation bracket and Figure 2-8 Securing the tuner to a mast.
The weather protective cover (Pos. 1) is removed by unscrewing the five bolts (Pos. 2). The five cover holding
brackets (Pos. 6) are left in place, attached to the tuner body. Using the provided in the mounting kit four
flat-head bolts (Pos. 4), the mast bracket (Pos. 3) is secured to the tuner body and then the weather
protective cover (Pos. 1) is secured back in place with the five bolts (Pos. 2).
Thread the three hose clamps (Pos. 5), provided with the mounting kit, through their respective rectangle
opening pairs in the mast bracket (Pos. 3).
Figure 2-7 Mast installation bracket
Figure 2-7 Mast installation bracket
The whole assembly (see Figure 2-8 Securing the tuner to a mast, Pos. 1 & 2) is then secured to the mast with
the connectors facing down using three hose clamps (Pos. 3). Always secure any loose cables, guy wires or
any other object that might fall on or hit the tuner assembly.
Both mast and wall brackets have mounting holes for securing cables with the provided cable clamps (Pos. 3
in the Table 2-1 Accessories list). The cable clamps are mounted with bolts (Pos. 11) and a combination of 2
washers (Pos. 10 and 13).
3
5 4 1
6
2
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n INSTALLATION | Page 27 of 72
Finally, slip the Weather Protection Cover ACOM 04-WP over the tuner (see Figure 2-5 Wall installation bracket,
Figure 2-6 Tuner installed on a wall, Figure 2-7 Mast installation bracket, and Figure 2-8 Securing the tuner to a mast),
(Pos. 1) - directing it with the protruding part (marked with ACOM) up. Place it over the provided four carrying
pins protruding from the tuner chassis. Carefully align the protection hood until the pins fit into the respective
holes. The cover will go down a bit and will rest on the five carrying plates in the tuner base.
Check whether all walls of the protection hood are equidistant from the tuner chassis and whether their
bottom edges are parallel.
Use the provided fixing elements in the installation kit to fix the protection hood securely in place. Loosely
screw all nuts and screws at first, then fasten them tightly.
Figure 2-8 Securing the tuner to a mast
Figure 2-8 Securing the tuner to a mast
NOTICE
When mounting in the open, never install the tuner in a slanted position neither with
protection hood down, to avoid contaminating the inside of the assembly, and to prevent
precipitation from seeping into it. This may cause damage that is not covered by the
warranty!
2
3
1
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 28 of 72 | S e c t i o n INSTALLATION
May 2021
DANGER
For remote/outdoor tuner operation, the grounding terminal of the tuner marked
GROUND, and the antenna feeders should be connected as described in Section 1.5.2
Lightning protection when the tuner is installed outdoor.
DANGER
After completing the tuner installation, attaching, and connecting the cables, check the
reliability of all fixtures and fasten again, if necessary. Apply mineral jelly or another
suitable lubricant to the connectors, grounding terminal, and assembling nuts and screws
to prevent jamming/clinching or damage to the threads in a future disassembly.
Table 2-1 Accessories list
Nr.
ACCESSORIES LIST
Pcs.
1
Mast bracket
1 2 Desk bracket
1 3 Cable clamps
5 4 Desk bracket bolt
1 5 Desk bracket bolt threaded pad
1 6 Hose clamp - small
3 7 Desk bracket spacer plate
1
8
Wall bracket
1
9
Hose clamp - large
3
10
Washer (DIN6798-A4.3-A2) - mounting Pos. 1, 8 and 3 (together with 13)
10
11
Bolt (DIN7985-M4x10-A2) - mounting Pos. 1, 8 and 3 (together with 13)
10
12
Flat-head bolt (DIN965-M4x12-A2)
4
13
Washer (DIN9021-M4-A2) - mounting Pos. 3 (together with 10 and 11)
5
Table 2-1 Accessories list
Figure 2-9 Accessories
Figure 2-9 Accessories
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n INSTALLATION | Page 29 of 72
2.5. Grounding, Additional Information
Ground the tuner and install the cables from the antennas and from the tuner obeying safety requirements
in Section 1.5 Safety Considerations, Explicit Definitions. You need to distinguish between different kinds of
grounding according to its function!
2.5.1. Lightning Protection Grounding
See the instructions provided in Section 1.5 Safety Considerations, Explicit Definitions and in APPENDIX 1 |
Lightning Protection. This kind of grounding is used for lightning protection of people, buildings and
equipment, but does not protect you from voltages or currents with mains frequency or emitted/induced RF
signals.
2.5.2. Grounding for Protection from Electric Shock
This grounding (or neutralizing in some cases) is used for protection from electric shock from currents with
mains frequency. It will not protect you from a possible lightning or emitted/induced RF signals.
To ensure that your installation complies with the requirements consult a qualified electrician to find out if
simultaneous grounding and neutralizing, according to the recommendations of Section 1.5 Safety
Considerations, Explicit Definitions, is allowed by the applicable standards and local regulations for electric
shock protection.
2.5.3. Radio Frequency Grounding or Counterpoise
This grounding is used for protection from transmitted/induced RF signals, and possible radio frequency
interferences. It will not protect you from a possible lightning strike or currents with mains frequency.
These may be e.g., RF counterpoises (radials), which, in particular, could even be isolated from the ground.
When they are placed at the required height and have the proper length, they can resonate and be much
more effective for RF emission and protection than a direct connection to the ground.
However, this only applies to radio frequencies. They have no protective functions against electric shock
from currents with mains frequency, or lightning.
2.6. Connecting RF Cables, Additional Information
All connections between the tuner and the radio station should be executed in the sequence described
below, before the tuner is powered from the amplifier.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 30 of 72 | S e c t i o n INSTALLATION
May 2021
WARNING
Before you start connecting the coaxial cable from the radio station to the tuner, ensure
that its two ends are not connected to anything and take all necessary precautions that
no one has access to them! Place warning signs at both ends reading:
WARNING! DO NOT TURN ON - PEOPLE WORKING!
a) Before doing anything else, connect the tuner's grounding terminal.
DANGER
Do not proceed with the installation, unless you have connected the tuner grounding
terminal marked GROUND to the lightning protection grounding or the radio station
grounding system, according to tuner installation location, see Section 1.5 Safety
Considerations, Explicit Definitions.
WARNING
Before connecting any cable to the tuner, use a voltmeter to make sure there is no AC or
DC voltage above 12 V from the pin of the cable connector to the grounding terminal of
the tuner, from the ring of the cable connector to the grounding terminal of the tuner,
and between the connector pin and ring!
b) Assign the antenna numbers (1 to 4) in advance. After verifying that there is no dangerous
voltage, connect, one at a time, all available antenna cables to the respective antenna
sockets, ANTENNA 1 to ANTENNA 4 of the tuner, without fastening the connector rings at
first, so that the cables may still be axially turned and adjusted.
Lay out the cables in the necessary directions and attach them to the provided holes in the supporting bracket.
Finally, fasten the rings of the coaxial connectors so that swinging and vibrations from the wind will not loosen
them. If you need additional binding points besides the holes in the supporting bracket, affix the cables further,
e.g., up the mast or to other surrounding objects and walls. Use only UV-resistant materials!
NOTICE
Always leave a sufficient U-shaped slack in the cabling below the tuner's bottom level, so
that any water would drip off and not enter the tuner.
c) Connect the RF coax from the radio station to the tuner socket labeled 50Ω RF +26 VDC
Power & Control in a similar way. If the distance to the radio station exceeds 30 m (100 ft),
we recommend using a RG213 type, an equivalent or a better cable. Lay out and attach the
input cable and fasten the connector ring.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n GETTING STARTED | Page 31 of 72
3. GETTING STARTED
NOTICE
Never exceed tuner specifications! Do not transmit with a high SWR!
3.1. Turning ON and OFF
After you complete the tuner installation instructions (see Section 2 INSTALLATION), verify that the amplifier
master power ON/OFF switch on the back panel is in the OFF position, and the plug is pulled out of the mains
socket.
DANGER
Before connecting the coaxial cable from the tuner to the amplifier output, make sure
that the cable and amplifier are securely grounded to the grounding system of the radio
station. Using a voltmeter, check the cable coming from the tuner to verify there is no AC
or DC voltage above 12 V from the pin and the ring of the cable connector to the grounding
terminal of the amplifier and between the connector pin and ring!
Connect the tuner coaxial cable to the RF OUTPUT of the amplifier. Besides RF power, the tuner will be
supplied with DC power from the amplifier (+26 VDC with consumption up to 25 W), and bidirectional control
data (60 kHz FSK), all combined on the same cable.
The tuner is turned on together with the amplifier. Connect the power cable of the amplifier to the wall mains
socket and turn it on from the front panel. To access and operate the menus related to the tuner, you should
explicitly specify that it has been installed. To do that, enter the USER PREFERENCES menu (see Section
4.2 Tuner Assignment and Unassignment) and select:
ANTENNA TUNER / SWITCH INSTALLED: [YES].
The amplifier will assign the connected tuner and will then start taking care of its control and indications. At
the assignment and at any subsequent turning on, the tuner will perform a quick tuning to retrieve from its
memory the last saved tuning for the current frequency of the amplifier.
The tuner is also turned off together with the amplifier. Thus, the four antennas are automatically turned off
and grounded. There is no need to assign the tuner from the menu at any subsequent powering on/off. The
amplifier will remember the tuner is installed and will continue to take care of it.
If, for any reason, you decide to operate the amplifier without the tuner, enter the USER PREFERENCES menu
again and select:
ANTENNA TUNER / SWITCH INSTALLED: [NO].
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 32 of 72 | S e c t i o n GETTING STARTED
May 2021
After unassigning the tuner, you will have to connect a matched antenna operating at the respective
frequencies to the amplifier output. Also, when the tuner is unassigned, you will not be able to use its antenna
switch.
3.2. Indication, controls and menus
3.2.1. Tuner Information Area on the Amplifier Screen
After the operator specifies in the USER PREFERENCES that a tuner is installed, the amplifier indication
changes:
Figure 3-1 Amplifier screen with tuner installed
Figure 3-1 Amplifier screen with tuner installed
- The screen displays a frequency range showing the availability or absence of tuner settings for all
frequency segments in the current band, to which the amplifier is tuned. The light gray segments have a user
tuning stored in the tuner memory, and the black segments do not have one. The current operating segment,
which contains the working frequency of the transceiver, is enclosed in a thin orange frame, which moves as
the transceiver frequency moves from segment to segment.
- The numerical values displayed above the frequency range now show the boundaries of the
current operating frequency segment (rather than of the entire band, if no tuner is present). In front of the
values, there is a label reading "ATU Matched", "Memory Settings" or "ATU in Bypass", according to the tuner
mode at that time. After the values are displayed the number, the selectivity type and the name of the
currently connected antenna (see Section 6.1 ANTENNA ASSIGNMENT Menu). For example, "A2R" indicates the
antenna Nr. 2 with Regular degree of selectivity is selected. The antenna number may be from 1 to 4 and
each antenna may have different type, specified by the operator (up to four degrees of selectivity). The
antenna names after the number may also be edited (see Section 6.1 ANTENNA ASSIGNMENT Menu).
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n GETTING STARTED | Page 33 of 72
When a tuner is assigned (see Section 4.2 Tuner Assignment and Unassignment):
- The information area above the buttons is reserved for messages concerning the tuner;
- The BAND buttons (up and down) become SEGMENT;
- The TUNE and ANT buttons become available and can be used.
The tuner performs a quick tune-up using memorized data for the current operating frequency and antenna.
If there is no suitable setting in the tuner memory, the tuner stays in BYPASS mode.
3.2.2. Segment UP/DWN buttons (Second Function - BAND)
The two SEGMENT buttons with second function BAND only appear if no CAT interface is connected to the
transceiver.
- Pressing briefly either of the two buttons selects the next frequency segment in the respective
direction;
- Pressing and holding either of the two buttons for 1 second selects the next band in the respective
direction;
Simultaneously pressing the two buttons has no function.
When there is a CAT interface connected to transceiver, the buttons do not appear, because the segments
and bands are changed via CAT automatically, following the transceiver frequency.
3.2.3. TUNE button (Second Function - BYPASS)
- Pressing the button briefly starts the full tuning cycle of the tuner (see Section 4.3 Tuning Modes:
FULL, QUICK and BYPASS). The button operates in both OPER and STBY mode, i.e., the tuner can be used with
the transceiver in STANDBY mode;
- Pressing and holding the TUNE button for 1 second alternatively executes the BYPASS mode (see
Section 4.3 Tuning Modes: FULL, QUICK and BYPASS) of the tuner with the current antenna or reverts from
BYPASS mode by returning the tuner setting (Use ATU);
- While the tuner is in BYPASS mode, it does not retune when frequencies and bands are changed,
and the antenna change rules are retained as assigned by bands in the table of the ANTENNA ASSIGNMENTS
menu (see Section 6.1 ANTENNA ASSIGNMENT Menu);
- When the tuner reverts from BYPASS mode, it responds to the actual frequency and antenna at
the time of return. If there is a memorized setting for the current frequency segment and antenna stored in
the tuner memory, it is executed and the segment range is displayed again, with the numerical values of the
boundaries for the frequency segment;
- If there is no setting for the actual frequency segment and antenna stored in the memory at the
time of return from BYPASS mode, the tuner stays in BYPASS mode until the operator starts a full tuning
cycle, using the TUNE button or until the antenna and/or frequency are changed with ones with a tuning
stored in the nonvolatile tuner memory.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 34 of 72 | S e c t i o n GETTING STARTED
May 2021
3.2.4. АNT Button (Change of Antennas)
Antenna outputs are switched automatically, along with the change of frequency band to the values assigned
to bands by the operator in the table of the ANTENNA ASSIGNMENTS menu (see Section 6.1 ANTENNA
ASSIGNMENT Menu).
The ANT button is only available if two or more antennas for the selected band are assigned in the table.
E.g., if Antenna 2 and Antenna 4 have been assigned, the ANT button will switch between them in a
"A2-A4-A2-A4..." loop at each button press, and the unassigned numbers (A1 and A3 in the case) will be
skipped. At each antenna change, the frequency segment indication and tuning setting is refreshed as well
(see Section 3.2.1 Tuner Information Area on the Amplifier Screen).
3.2.5. Tuner Related Menus
When a tuner is assigned (see Section 4.2 Tuner Assignment and Unassignment), the main menu of the amplifier
MENU SELECTION makes available four additional tuner related menus:
- ANTENNA ASSIGNMENTS
- ATU MEASURE
- ATU SERVICE
- ATU TUNING SETTINGS LOOK UP/ERASE.
Each of these four menus will be reviewed in detail in Section 6 ADVANCED FUNCTIONS AND OPTIONS.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n STARTING UP AND MAIN FUNCTIONS | Page 35 of 72
4. STARTING UP AND MAIN FUNCTIONS
Operating the tuner is straightforward and intuitive due to the high degree of automation.
You may start operating right after installation. However, in order to make a better use of the tuner features,
and to fully adapt it to your particular environment, we recommend reading through the following
information.
4.1. What is tuning type / Rate (Selectivity Degree, Sharpness)
This tuning feature indicates how significant are the changes in the quality of impedance matching between
the antenna and amplifier as a result of small changes of the operating frequency. This determines the
necessary width of the frequency segments required in a band, so that a sufficient degree of matching is
retained within any particular frequency segment. Accordingly, the tuning settings made and stored in the
tuner memory will be usable in a specific frequency segment, narrower or wider, depending on the nature
of the antenna used to do the settings.
In addition to narrowing the frequency segments and, respectively, increasing their number per band, the
high sharpness of tuning generally leads to higher heat losses and greater instability of the settings in time
or due to environmental changes.
It is clear that, by all criteria listed above, it is preferable that the tuning rate (sharpness) be as low as possible,
in order to have a few wide frequency segments, with low heat losses and stable (to external impacts) state
of tuning.
Unfortunately, the tuning sharpness cannot be chosen in a random manner. The specific frequencyimpedance characteristics of each antenna determine a minimum of the tuning sharpness (minimum
Q-factor of the tuned antenna circuit in the tuner), which cannot be further reduced, unless heat loss is
introduced by design (which, however, would lead to lower efficiency).
E.g., antennas with reduced dimensions, often used for 160 m and 80 m, or at higher frequencies, recently,
which are "loaded" with coils close to the maximum current or with "capacitive hats / caps" at the maximum
voltage across the length of the antenna, are normally tuned critically, or "sharply".
The higher the degree of physical reduction of the antenna size, compared to its full-size version, the steeper,
more frequency-dependent, narrow-band and unstable its settings are, in comparison with, e.g., the settings
of a regular dipole. Typical examples include physically short verticals or small-size loops. A poor grounding
of the vertical or the proximity of the loops to the ground may in part reduce tuning steepness, but this is
caused by additionally induced heat losses, and is compensated by reduced efficiency of the emitter.
On the contrary, a full-size, "thick" emitter, or an emitter with a custom-designed shape, such as a Nadenenko
(cage) dipole, an exponential ground-plane or log-periodic structure, will have a much wider usable frequency
band of settings than a regular dipole.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 36 of 72 | S e c t i o n STARTING UP AND MAIN FUNCTIONS
May 2021
Because of the wide variety of antennas used, the ANTENNA ASSIGNMENTS menu allows setting a "type"
(selectivity degree) of tuning when they are assigned by bands. This can be done in four different selectivity
ranges, separately and independently for the four antennas (see Section 6.1 ANTENNA ASSIGNMENT Menu), so
that the operator can fit the width of the segments to the specifics of each antenna used:
- SHARP (narrow)
- REGULAR (regular, normal) - default setting
- WIDE (broad-band)
- FIXED (for fixed frequencies).
The selectivity degrees (tuning rates, antenna types) are not related to the output number, i.e., each output
can be declared for each type, regardless of the other ones.
Unless the operator changes it, REGULAR (normal) type is set by default for all four antenna outputs.
4.1.1. SHARP
For moderately reduced dimensions, such as 20-25 m vertical for operation at 160 m, you may select SHARP
(narrow or small-band, with sharp tuning). The width of the frequency segments will be approximately 0.25%
of the operating frequency (e.g., 5 kHz at 160 m).
This option is convenient for small-size and low-band antennas that are artificially lengthened (moderately)
with load coils, or "hats / caps", or antennas with preliminary matching, with dipoles, verticals or loops that
are not too short, with selective circuits (traps or stubs) included in the design, etc.
4.1.2. REGULAR
Full-size dipoles, inverted V, loops, 2-3 element square or delta loops, Yagi, etc. common antennas, should
be declared as type REGULAR (normal) - the option is provided as basic by default. The width of the frequency
segments is approximately 1% of the operating frequency.
4.1.3. WIDE
Naturally broad-band antennas could be declared as WIDE (broad-band). The width of the frequency
segments is approximately 4% of the operating frequency. This option is convenient for special broad-band
radiators, e.g., exponential, log-periodic, "thick" or aperiodic (with absorbing loads) - rhombic etc. similar
antennas.
4.1.4. FIXED
An extreme reduction of the physical dimensions of antennas, such as for a loop of 2-3 m diameter for 80 m
band, would probably limit the capability to operate on a single fixed frequency only. If this is the case, select
FIXED (for fixed frequencies) type. Naturally, you can also make the same choice with more broad-band
antennas, if this is convenient for any other reason. This option is also convenient for reducing the probability
of operating with random settings at specifically set frequencies.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n STARTING UP AND MAIN FUNCTIONS | Page 37 of 72
4.2. Tuner Assignment and Unassignment
Tuner assignment and unassignment is done in the USER PREFERENCES menu of the amplifier.
If the top row of the "Antenna tuner/switch installed NO - YES" menu is not selected (if it is shaded), first
select it with the ITEM or ITEM buttons.
To assign the tuner, use the SELECT button and select YES. To unassign the tuner, use the SELECT button
and select NO. Leave the menu with the EXIT button.
4.3. Tuning Modes: FULL, QUICK and BYPASS
The tuner can operate in two main modes of tuning: full and quick. In addition, the tuner can be switched to
BYPASS mode, without tuning. This is a non-basic mode, but it can be useful.
- "Full tuning" is the basic cycle for active searching the relays setup for a new frequency and
antenna, see details in Section 5 BASIC FULL TUNING CYCLE.
- "Quick tuning" passively retrieves information stored in the tuner non-volatile memory of full
tuning settings prepared earlier - see Section 4.4 Quick Tuning and Non-Volatile Memory.
- "BYPASS" mode eliminates the action of the coils and capacitors in the matching network of the
tuner in order to be able to change frequency segments or bands without retuning, e.g. at broad-band or
preset antenna - see Section 4.5 Operation in BYPASS Mode. In addition to operation, the BYPASS mode can be
used for diagnostics and maintenance of the antenna-feeder path (see Section 7.4 Troubleshooting - Monitoring
the Antenna-feeder Path Status).
4.4. Quick Tuning and Non-Volatile Memory
Quick tuning is performed automatically at each change of frequency segment, band and/or antenna. The
tuner checks if there is a stored tuning setting for the desired frequency and antenna in the non-volatile
memory. If there is none, the tuner automatically stays in BYPASS mode and the amplifier displays the
warning message:
ATU FULL TUNING REQUIRED.
If there is a stored setting, the tuner reads the relay combination settings from its nonvolatile memory and
immediately performs it by switching all relays in one step (and if necessary, switches the antenna as well)
without any emission. The amplifier refreshes its indication - the new frequency segment is enclosed in a thin
orange frame on the frequency range, "Memory settings" is displayed in front of the numerical segment
boundaries and the number, type, and name of the antenna in use are updated. At this moment the amplifier
is ready for transmission.
If the tuning found in memory is too old, the alarm message TUNING OUTDATED is displayed (see Section
6.2.8 Aging and Refreshing of Settings), but the outdated tuning setting can still be used. If the operator wants
to refresh it, he can immediately start a new full tuning cycle and the data in the non-volatile memory will be
refreshed and the message will disappear.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 38 of 72 | S e c t i o n STARTING UP AND MAIN FUNCTIONS
May 2021
If there is no tuning setting stored in the memory, the tuner automatically stays in BYPASS mode and the
operator can proceed in either of the following ways:
- Start a full tuning cycle by briefly pressing the TUNE button (see Section 5 BASIC FULL TUNING
CYCLE);
- Change the frequency and/or antenna to find a stored tuning setting from the tuner nonvolatile
memory.
Organization and use of the tuning settings memory
We recommend preparing custom tuning settings for the frequencies and antennas that will be used most
frequently. They will be automatically stored in the tuner memory, and automatically retrieved when a
frequency and/or antenna is changed.
The tuner memory is divided into four large groups - one per each antenna number. Each group is additionally
divided into 4 subgroups for the four degrees of selectivity (Sharp, Regular, Wide and Fixed). The number of
segments in each band increases with selectivity (sharpness degree - S, R, W, F, see Section 4.1 What is tuning
type / Rate (Selectivity Degree, Sharpness)). For each of the four degrees the segments width increases with
frequency, aiming same relative coverage on all bands (narrower at the LF end and wider at the HF bands).
Retrieving tuning settings from the memory is much faster than the main cycle of full tuning, with no
emissions of RF power. However, in the meantime the antenna may have changed its parameters to a smaller
or larger degree, so an old tuning may be ineffective and may need to be refreshed through a new cycle of
full tuning.
NOTICE
If the conditions at the antenna have changed since the time the tuning was memorized,
using outdated tuning settings may lead to a high SWR at the amplifier end. We
recommend updating the tuning settings with the TUNE button in this case.
For the purpose of quick tuning without CAT, the operator should adhere to the following rules of operation
for frequency and/or antenna change:
- Frequency segments can only be changed during reception using the SEGMENT or SEGMENT
buttons or by sending a short preliminary transmission. Start the main transmission after a pause of at least
0.5 seconds.
- The pause between the short and the main transmission is needed so that the amplifier can first
check the new operating frequency and switch its harmonic filters, if necessary, to send a "quick tuning"
command to the tuner (possibly with a new antenna), to evaluate the response from the tuner and to refresh
the onscreen indication.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n STARTING UP AND MAIN FUNCTIONS | Page 39 of 72
4.5. Operation in BYPASS Mode
If the operator has chosen BYPASS mode, he takes full responsibility for matching the antennas to the
feedline and amplifier - same as without a tuner in place.
In order to place the tuner in BYPASS mode, the operator should press and hold the TUNE button for at least
1 second. The tuner bypasses the matching network in order to eliminate its action. BYPASS is displayed
onscreen (in front of the frequency).
In BYPASS state, the ANT button is still enabled. The antennas can be switched according to their assignments
in the ANTENNA ASSIGNMENTS menu (see Section 6.1 ANTENNA ASSIGNMENT Menu). In this mode, the tuner
can be used as an automatic antenna switch to select antennas using the antenna assignments by bands or
as a manual switch, if more than one antenna is assigned per band.
The tuner stays in BYPASS state until reactivated by pressing and holding the TUNE button again (1s - Use
ATU). Regardless of whether or not a frequency and/or antenna were changed in the meantime, a new quick
tuning is completed from the tuner memory for the current antenna and frequency in use. If there is no
stored tuning in the tuner memory, the tuner will stay in BYPASS mode until it is tuned.
4.6. Changing Frequencies and Antennas
Changing a frequency segment or band with a respective quick tuning can be performed in three ways:
- Automatically - utilizing transceiver CAT;
- Semi automatically (when no CAT is active) - by a short transmission at the new frequency,
followed by a short pause, during which "quick tuning" will be completed (see Section 4.4 Quick Tuning and
Non-Volatile Memory).
- Manually - by pressing the SEGMENT or SEGMENT button (unless there is an active CAT) or
by changing the antenna with the ANT button (only if more than one antenna was declared for the operating
frequency (see section 6.1 ANTENNA ASSIGNMENT Menu). The last used antenna is memorized.
The frequency segment (boundaries of validity of the current tuning) is numerically indicated on the basic
screen of the amplifier, above the tuner setting area. If the new frequency is outside the current frequency
segment, a quick tuning will be performed.
If the tuning found in memory is too old, the operator will see the message
WARNING: TUNING OUTDATED.
Please, see Sections 4.4 Quick Tuning and Non-Volatile Memory and 6.2.8 Aging and Refreshing of Settings.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 40 of 72 | S e c t i o n STARTING UP AND MAIN FUNCTIONS
May 2021
4.7. Specific of Operation in TRANSMISSION Mode
NOTICE
Under no circumstances should operation with antenna output SWR above 10:1 be
allowed!
In many cases, the tuner may be able to handle SWR even higher than 3:1 at the antenna output, but if the
protection for antenna overcurrent, overvoltage, forward or reflected power is activated, the operator
should reduce power input to the tuner (e.g., transceiver excitation).
4.8. Power Reduction at Overload
When matching of loads with SWR above 3:1 (up to 10:1) is possible, the maximum allowed tuner power
must be reduced gradually as per Table 8-1 Maximum input power of the tuner as function of the antenna SWR.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n BASIC FULL TUNING CYCLE | Page 41 of 72
5. BASIC FULL TUNING CYCLE
5.1. What a Full Tuning Cycle Does
The impedance matching is a transformation to resistive 50 Ohm of the complex RF impedance, presented
to the selected antenna output. This is typically done with a residual SWR allowance under 1.3:1 in the
ACOM 04AT. A full tuning cycle is the "seek and find" process for a combination of tuner relays that leads to
this impedance matching condition.
The necessary relay combination depends on the frequency and the complex impedance, presented to the
selected antenna output. Searching for the suitable combination is performed following a specific algorithm.
A series of impedance measurements is performed during the cycle and the results are used to determine
both the necessary configuration of the matching circuit (L or reversed L-shape matching network), and the
necessary values of the coils and capacitors in it.
A full tuning cycle is started by briefly pressing the TUNE button. Next, an RF signal has to be applied from
the transceiver - 25 W continuous carrier at the operating frequency (when using transceivers with CAT this
is automatically done). The RF signal is used to activate the impedance sensors of the tuner.
The automatic tuning process consists of a series of steps, in each one performing measurement and
evaluation of the RF impedance transformed by the matching circuit (L-network). With more than 20 RF
relays, coils and capacitors of various values are added to the circuit or excluded from it. Each switching is
completed with no RF power, to prevent relay contacts from burning. For this purpose, the tuner has a builtin electronic switch for local enabling and blocking of the RF power at the required moment (synchronously
with the algorithm steps), while the transceiver power is maintained continuous during the entire tuning
cycle.
In each algorithm step, a short pulse of RF power (a few milliseconds) is emitted to activate the tuner
impedance sensor and evaluate the current state of the antenna impedance transformed by the matching
circuit. At the end of the pulse, data from the sensor is read and RF power is blocked. The result of the step
is evaluated by analyzing the measured data - R, G, PH, the forward and reflected power at the matching
circuit input. Upon evaluation, the tuner controller makes a decision what switching combination to be
applied at the next step, following the tuning algorithm stored in its program memory. The algorithm is
designed in such a way, that the time needed for seeking is substantially reduced - the combinations checked
are tens of thousands of times fewer than all 2 million possible relay combinations.
The "measurement - evaluation - switching" cycles continue, each subsequent switching decision being made
according to the algorithm logic and accumulated changes of the impedance transformation by the matching
circuit.
Further, the algorithm is designed in such a way that it unambiguously leads the impedance, transformed by
the matching circuit (L-network), to the goal (50 Ohm). This process is complete when the impedance is close
to 50 Ohm with a tolerance less than SWR of 1.3:1, or if the possible steps of the algorithm are exhausted.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 42 of 72 | S e c t i o n BASIC FULL TUNING CYCLE
May 2021
This way, at the end of the matching cycle, the necessary combination of relays to achieve the matching of
the connected antenna impedance to 50 Ohm is found. At the end of the cycle, this relay combination is
stored in the tuner nonvolatile memory. The stored values are organized in memory by the boundaries of
the frequency segments, in separate tables, by antenna number and type of selectivity. The stored data is
used later for quick tuning (see Section 4.4 Quick Tuning and Non-Volatile Memory), when it is required to
operate with the same antenna and in the same frequency segment.
The basic cycle of a full (user) tuning may have different duration, depending on the value of the particular
antenna impedance, but the tuning time will never exceed 5 seconds.
5.2. Operator Actions for a Full Tuning Cycle
If you use more than one antenna for a specific band, you should select the desired
antenna for the operating frequency before starting the tuning cycle.
5.2.1. Full Tuning for Transceivers with CAT
When the capabilities of modern transceivers with CAT control are used, no manual operations for
transceiver control when performing full tuning cycle are required; the transceiver even restores the previous
operating mode afterwards. The operator should only do the following:
- Select the new frequency in receive mode;
- Change the antenna immediately, if another antenna is required (if there is more than one
antenna assigned for the selected band);
- Briefly press the TUNE button at the specified frequency and antenna.
The transceiver, amplifier, and tuner then perform in sync all necessary operations which would be
performed for a manually controlled transceiver, but with CAT this is done automatically, quickly, and
transparently. The amplifier remains in STBY mode throughout the tuning. At the end of the cycle, the state
of the transceiver and amplifier before the tuning cycle initialization is restored (modulation mode, power,
OPER/STBY, etc.).
5.2.2. Full Tuning for Transceivers without CAT Capability
To complete the same cycle of full tuning of the tuner with a transceiver without CAT connected, the operator
should proceed as follows:
- Select the new frequency of the transceiver in receive mode;
- Select a constant carrier mode for the transceiver (e.g., CW or FSK);
- Adjust the RF power of the transceiver to approximately 25 W (unless previously adjusted). You
may apply more power to compensate RF losses if the coaxial cable to the tuner is too long.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n BASIC FULL TUNING CYCLE | Page 43 of 72
NOTICE
Never exceed 50 W during tuning as described above!
- Transmit a short pulse so that the amplifier can measure the new frequency, automatically select
its new frequency band and, possibly, a new antenna as per the assignment in the ANTENNA
ASSIGNMENTS menu (see Section 6.1 ANTENNA ASSIGNMENT Menu);
- Change immediately the antenna, if another antenna is required (if there is more than one
antenna assigned for the selected band in the ANTENNA ASSIGNMENTS menu), see Section
6.1 ANTENNA ASSIGNMENT Menu;
- When the operating frequency and antenna settings are complete, the operator should briefly
press the TUNE button of the amplifier to start a full tuning cycle. The amplifier will prompt him
to apply RF power for tuning:
APPLY 20-30 W RF;
- In this state, the tuner will wait for up to 30 s for the operator to transmit a non-modulated signal
(carrier frequency only) of power between 20 W and 30 W with the required frequency for tuning;
- Unless power is applied within 30 s, a message will be received that the waiting period has expired
and the procedure will be automatically terminated:
TIMEOUT EXPIRED - INCOMPLETE PROCESS;
- For normal tuner operation, the operator will transmit and adjust power with the current level of
the transmitted power being indicated with a green mark on a smaller scale under the frequency
range of the segments. The aim is to get the pointer to the center of the scale;
- The proper tuning process starts automatically after the power stabilizes and remains at
approximately 25 W. "Matching cycle…" is then displayed in front of the numerical boundaries of
the indicated segment;
- The tuning process is completely automated and may continue up to 5 s (depending on the
frequency and impedance connected to the antenna output);
- When tuning is complete, the amplifier prompts the operator to stop transmitting:
TUNING COMPLETED: STOP DRIVE POWER.
After the drive power is removed, the frequency range with the tuner segments is refreshed on the amplifier
screen, and ATU MATCHED is displayed in front of the numerical boundaries of the current segment. If for
any reason a good tune is not achieved, NO MATCH FOUND is displayed instead.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 44 of 72 | S e c t i o n ADVANCED FUNCTIONS AND OPTIONS
May 2021
6. ADVANCED FUNCTIONS AND OPTIONS
6.1. ANTENNA ASSIGNMENT Menu
In this menu, the operator can specify the name, type (degree / rate of selectivity) for each antenna and
frequency bands to be used with it.
On the screen, the antenna attributes row selected for editing is enclosed in a color frame. The next antenna
(row) is selected by pressing the two EDIT buttons simultaneously.
By pressing the ESC button, you will leave the ANTENNA ASSIGNMENTS menu and the current state of the
table will be accepted.
6.1.1. Antenna Assignments by Bands
Using the ITEM and ITEM buttons, the cursor is moved within the band columns from 160 m to 6 m.
When an antenna will be used in a particular range, the cursor should be positioned in the respective column.
Then, after pressing the EDIT button, a tick mark will appear in the respective cell, indicating that the
antenna is assigned to this range. The same antenna may be assigned to operate in multiple ranges, not
necessarily adjacent. The left EDIT button cancels the selection.
During amplifier operation, at a manual antenna change, the ANT button selects only the antennas assigned
in the table for the current band and the unassigned antennas are skipped. For example, if only one antenna
is assigned for a band, it is selected with the band, but the ANT button does not change anything. If antennas
1, 3 and 4 are assigned for a band in the table, but А2 is not assigned, the ANT button will change in order:
А1-А3-А4 – А1-А3-А4 – А1-А3... in a loop.
If no antenna is assigned for a certain frequency band, when a frequency is selected in this band (by CAT, by
delivering power, or by BAND buttons), А1 will be selected by default, and this will be explicitly
communicated to the operator:
A1 SELECTED BY DEFAULT – USE ANTENNA ASSIGNMENTS MENU TO CHANGE
When the table is empty, this message will appear at each new band.
6.1.2. Setting the Tuning type / Rate (Sharpness, Selectivity), (S, R, W, F)
The four degrees of selectivity (tuning sharpness) - Sharp, Regular, Wide or Fixed, set the width of the
segments, in which the user tuning settings will be considered valid (see Section 4.1 What is tuning type / Rate
(Selectivity Degree, Sharpness)).
By moving the cursor more to the left of the 160m band column, you will reach the TYPE column. There, by
briefly pressing of EDIT or EDIT button, you can set the antenna type (tuning sharpness) - the first letter
of the type is displayed: Sharp, Regular, Wide or Fixed. For details about the application of the four types of
tuning settings see Section 4.1 What is tuning type / Rate (Selectivity Degree, Sharpness).
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n ADVANCED FUNCTIONS AND OPTIONS | Page 45 of 72
6.1.3. Editing Antenna Names
At the leftmost part of the table row, below the number of each antenna, there is a text field for its associated
name (set to **No name** by default). You can enter any text, in free format, up to 12 characters. The name
of the currently connected antenna will appear on the main screen, to the right of the numerical boundaries
of the frequency segment.
The selected position of the name character to be edited is highlighted by a small square frame, which can
be moved within the name area using the buttons ITEM or ITEM Replacing the character is done with
the EDIT or EDIT buttons, causing all printable characters of the basic ASCII table to appear (there is a
REPEAT function - just hold the button). The antenna name content or meaning does not affect the operation
of the tuner or amplifier.
6.2. Maintenance Functions - ATU SERVICE Menu
In the MAIN menu you can select the row ATU SERVICE using the ITEM or ITEM buttons, and activate
selected function with the SELECT button. You can leave the function by pressing the SELECT button.
To avoid accidental activation, if you want to intentionally erase the memory, you should press the two
SELECT buttons simultaneously, and hold them for 2 seconds. Deletion can still be cancelled by pressing
the right arrow key.
6.2.1. ATU Individual Data
The screen displays information about: model (04AT), hardware version (HW Ver: ...) and firmware version
(FW Ver: ...) of the Control board of the tuner and the number of working hours - the hours, during which the
tuner was powered up (Working hours: nnn h).
6.2.2. ATU Status
When you select the ATU STATUS function, the tuner returns the tuning mode information (ATU matched,
Memory settings, ATU in bypass), the currently connected antenna number, and the boundaries of the
current frequency segment.
6.2.3. Deletion of Individual or Group of Stored Tuning settings
- ERASE CURRENT TUNING - erases the tune settings of the current frequency segment from the
tuner memory;
- ERASE TUNING SETTINGS FOR: [ANTn] - erases the tune settings for all frequency segments of
antenna "n" from the tuner memory;
- ERASE ALL TUNING SETTINGS w/o names neither assignments - erases all tune settings from the
tuner memory, and also resets the working hour count, but leaves the antenna names and
assignments unchanged in the amplifier memory.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 46 of 72 | S e c t i o n ADVANCED FUNCTIONS AND OPTIONS
May 2021
6.2.4. Erasing the Whole NON-Volatile Memory
ERASE WHOLE N.V. MEMORY - erases the whole tuner memory, resets the working hour count, and also
erases the antenna names and assignments from the amplifier memory.
6.2.5. Checking the Resource Used for the Current Tuning
L-C RESOURCE USED (current tuning) - the percentage of coils and capacitors used for the current tuning (see
Section 6.3 Overview of TUNING SETTINGS and Resources Used).
6.2.6. Dumping the NON-Volatile Memory in a File on a PC
This function allows backup of antenna assignments by band and antenna names, as well as all user tune-ups
from the non-volatile memories of the tuner and amplifier in a computer file. The tuner data will pass through
the amplifier and be available at its serial (RS-232) port to a computer. Please, use the "ACOM Terminal S"
software, distributed by ACOM free of charge, for the dump. Downloaded backup files can be stored and
used later to restore tuning settings and antenna assignments / names you made for various antenna
configurations (see Section 6.2.7 Restoring (Loading) the NON-Volatile Memory from a File - Memory Load from
File).
NOTICE
The ACOM 04AT tuning-memory DUMP/LOAD procedures are initiated ONLY from the
amplifier "ATU Service" menu and NOT from the "ACOM Terminal S" program (see Figure
6-1 ACOM Terminal S screenshot.
Do not use the Firmware Update button for tuning memory DUMP as the AMPLIFIER
Firmware Update procedure will be initiated instead (see the amplifier manual).
Do NOT change the order of the steps in the following procedures.
Figure 6-1 ACOM Terminal S screenshot
Figure 6-1 ACOM Terminal S screenshot
Connect
Firmware Update
Disconnect
Connection Settings (bitrate, port selection, etc.)
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n ADVANCED FUNCTIONS AND OPTIONS | Page 47 of 72
The ACOM 04AT tuning memory dump file generation and download procedure is performed as follows:
a) Turn OFF the amplifier. Connect a serial interface cable between the amplifier rear-panel
RS-232 connector and the PC. See the amplifier manual for details on serial cable connection;
b) With the amplifier powered OFF, launch the ACOM Terminal S program from the PC and:
- Press the CONNECTING SETTINGS button and select a COM port available on your PC.
Configure the connection settings at 9600 bps / 8 bit / No parity / 1 stop bit.
Double check the connection settings before the next step!;
- Press the CONNECT button to open the serial port;
- Do NOT press the FIRMWARE UPDATE button during this procedure!;
c) Turn on the amplifier to STBY mode and assign the tuner (if not assigned already - see Section
4.2 Tuner Assignment and Unassignment). The CAT interface connection is not necessary;
d) Call up the "ATU Service" menu on the amplifier's display (see Section 6.2 Maintenance Functions
- ATU SERVICE Menu);
e) Go to the "MEMORY DUMP IN A FILE (wait 5-10 min)" on the amplifier screen and press the
SELECT button to confirm the selection;
f) A new DOWNLOAD window will open in ACOM Terminal S. In it click on the BROWSE button
and select location and name for saving the newly generated dump file on your computer;
g) Click the SAVE button. The terminal program will then return to the previous window, in which
the DOWNLOAD button should be clicked to start the download of the dump file;
h) A progress bar will appear, showing the state of the download. It can take 5-10 minutes before
the progress bar is full and the following message is displayed:
Operation completed successfully;
i) After the download is complete a short beep sound is generated, signaling that the Download
window can be closed. Press the DISCONNECT button and close the ACOM TERMINAL S
program after that;
j) At the selected location on the hard drive a backup file with a ".bkp" as named above can be
found, containing the dump;
k) Turn OFF the amplifier and disconnect the serial cable between amplifier and PC.
In the rare case something goes wrong and the procedure fails, close the DOWNLOAD
window with the CLOSE button. In the ATU SERVICE menu select a different line on the
amplifier screen and then go back to the DUMP position. Repeat the procedure as
described above.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 48 of 72 | S e c t i o n ADVANCED FUNCTIONS AND OPTIONS
May 2021
6.2.7. Restoring (Loading) the NON-Volatile Memory from a File - Memory Load from File
This function is the reverse of the memory dump (see Section 6.2.6 Dumping the NON-Volatile Memory in a File
on a PC). It is used to load (restore) from a computer file, backed up earlier, the tuner settings memory and
the assignments / names for a particular antenna farm.
All user tunings are restored and the table ANTENNA ASSIGNMENTS is filled-in with antenna assignments and
names by band automatically.
The data is input through the serial (RS-232) channel of the amplifier, and transferred by amplifier control to
the tuner, which in turn writes it in its own memory. Please use the ACOM TERMINAL S software, distributed
by ACOM free of charge.
NOTICE
The ACOM04AT tuning memory DUMP/LOAD procedures are initiated ONLY from the
amplifier ATU SERVICE menu and NOT from the ACOM Terminal S program (see Figure 6-1
ACOM Terminal S screenshot). Do not use the FIRMWARE UPDATE button for tuning
memory LOAD as the AMPLIFIER Firmware Update procedure will be initiated instead see the amplifier manual. Do NOT change the order of the steps in the following
procedures.
The ACOM 04AT tuning memory LOAD FROM FILE procedure is performed as follows:
a) Turn OFF the amplifier. Connect a serial interface cable between the amplifier rear-panel
RS-232 connector and the PC. See the amplifier manual for details on serial cable connection;
b) With the amplifier powered OFF, launch the ACOM Terminal S program from the PC and:
- Press the CONNECTION SETTINGS button and select a COM port available on your PC.
Configure the connection settings at 9600 bps / 8 bit / No parity / 1 stop bit.
Double check the connection settings before the next step!;
- Press the CONNECT button to open the serial port;
- Do NOT press the FIRMWARE UPDATE button during this procedure!;
c) Turn on the amplifier to STBY mode and assign the tuner (if not assigned already - see Section
4.2 Tuner Assignment and Unassignment). The CAT interface connection is not necessary;
d) Call up the ATU SERVICE menu on the amplifier's display (see Section 6.2 Maintenance Functions
- ATU SERVICE Menu);
e) Go to the "MEMORY LOAD FROM FILE (wait 5-10 min)" on the amplifier screen and press the
SELECT button to confirm the selection;
f) A new UPLOAD window will open in ACOM Terminal S. In it, click on the BROWSE button and
from the drop-down menu in the bottom right corner select location and name of an existing
backup file ".bkp" on your computer. After locating the required file, the OPEN button is
pressed;
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n ADVANCED FUNCTIONS AND OPTIONS | Page 49 of 72
g) From the UPLOAD menu in the terminal program locate and click on the UPLOAD button,
starting the procedure;
h) A progress bar will appear, showing the state of the upload. It can take 5-10 minutes before
the progress bar is full and the following message is displayed:
Operation completed successfully;
i) After the upload is complete a short beep sound is generated, signaling that the UPLOAD
window can be closed. Press the DISCONNECT button and close the ACOM TERMINAL S
program;
j) The tuner non-volatile memory and the table ANTENNA ASSIGNMENTS are automatically
restored with tuning settings, antenna types, names, and band coverage from the uploaded
backup file ".bkp" after a successful procedure;
k) Turn OFF the amplifier and disconnect the serial cable between amplifier and PC.
In the rare case something goes wrong and the procedure fails, close the UPLOAD window
with the CLOSE button. In the ATU SERVICE menu select a different line on the amplifier
screen and then go back to the UPLOAD position. Repeat the procedure as described
above.
6.2.8. Aging and Refreshing of Settings
The TUNING SETTINGS OUTDATED function allows the operator to specify a "period of validity" or "time
period allowed" of the settings retrieved by the "quick tuning" commands from the tuner memory. The hours
are presented as a "total time the tuner was powered".
The limits of the aging alarm can be specified by the operator in four stages: [100 - 300 - 1000 - 3000] hours.
Each setting retrieved from tuner memory comes with the number of hours that the tuner has been in
operation since the time the setting was stored, up to the time it was retrieved. If the time period of the
retrieved setting is older than the limit specified by the operator, the alert text TUNING OUTDATED is
displayed on the amplifier screen, but the outdated tuning settings can still be used.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 50 of 72 | S e c t i o n ADVANCED FUNCTIONS AND OPTIONS
May 2021
6.3. Overview of TUNING SETTINGS and Resources Used
When the menu ATU TUNING SETTINGS LOOK UP/ERASE is accessed, data lines start scrolling the screen (for
approximately 5 seconds) - a line per frequency segment with the current operating band, and the current
operating antenna. If up/down arrows appear on the right of the screen, this means there are more
frequency segments to be viewed by scrolling up/down.
The following data is displayed on each line:
- Antenna number, selectivity and name;
- Frequency boundaries of tuning validity (frequency segment);
- Resource used (in percentage of maximum inductors and capacitors usable for the respective
frequency);
- Tuning age in hours ("- - - -" means "no tuning").
ACOM 04AT uses an L-shape matching network configuration. The abbreviations used below mean:
- CT is the capacitor connected in parallel to the transmitter (tuner input);
- L is the inductance connected between transmitter and antenna;
- CA is the capacitor connected in parallel to the antenna (tuner output).
The percentages for CT, L and CA show what part of the coil and capacitor resource was used for this
frequency to achieve the tune. The resource is the maximum useful inductance L and capacitance C
depending on the frequency.
If CT is not zero, then CA is zero and the configuration of the matching network is "L" (typical for low
impedances at the antenna output).
If CA is not zero, then CT is zero and the configuration of the matching network is "reverse L" (typical for high
impedances at the antenna output).
In some cases, it may be that both CT and CA are zero (or a very low percentage on one side). If the inductance
is also a low percentage, then the load is with impedance close to 50 Ohm.
This data may lead you to conclude:
- What reserves you have left for compensating possible fluctuations in antenna impedance as a
result of external effects in the future, such as a change in weather conditions, change in antenna
environment, e.g., newly installed or removed antennas, bulky conducting objects in antenna
vicinity, etc.;
- If you record the data of the tuner resource used in the frequency bands for your antennas, you
can use their changes in the future to determine the stability of the antenna impedance in time,
thus you can prevent possible failures in an antenna or feeder, and you can promptly take
precautions to improve the reserve resource before it is too late.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n ADVANCED FUNCTIONS AND OPTIONS | Page 51 of 72
The ANTENNA or ANTENNA buttons can be used to review the resource table for another antenna in the
same band.
The SEGMENT or SEGMENT buttons are used to select (highlight) a different frequency segment in the
table. Simultaneously pressing the two SEGMENT buttons for more than 1 second selects the next BAND
for review (the preceding band cannot be selected).
Simultaneously pressing and holding for more than 2 seconds the two ANTENNA buttons delete the
shaded segment tuning, and "- - - -" is displayed in place of the hours.
6.4. Measurements in the Tuner - ATU MEASURE Menu
This menu allows remote measurements of some RF values directly at the antenna outputs of the tuner
(without the transformation action of the matching circuit). This data can be used to troubleshoot and
diagnose the status of the antennas and feeders (see Section 7.4 Troubleshooting - Monitoring the Antenna-
feeder Path Status).
Five values are measured for the current operating frequency segment and current antenna output, as well
as three general tuner values:
ANTENNA VOLTAGE: ... V (rms)
ANTENNA CURRENT: ... A (rms)
ANTENNA FORWARD POWER: ... W
ANTENNA REFLECTED POWER: ... W
ANTENNA SWR: ...
ATU PS VOLTAGE: ... VDC
ATU TEMPERATURE: … oC
ATU WORKING HOURS: ...
The measurements can be performed in STBY mode or OPER mode. The operator should manually start and
stop RF power to the tuner when performing these measurements.
NOTICE
In ATU MEASURE menu the tuner protection systems are temporarily blocked, so the RF
power limits (see Table 8-1 Maximum input power of the tuner as function of the antenna SWR)
should be monitored by the operator (see Sections 6.4.1 Voltage and Current at the Antenna
Output, 6.4.2 Reflected Power, Forward Power and SWR at Antenna Output and 6.4.3 Power
Supply Voltage and Temperature in the Tuner Unit).
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 52 of 72 | S e c t i o n ADVANCED FUNCTIONS AND OPTIONS
May 2021
6.4.1. Voltage and Current at the Antenna Output
The antenna voltage and current are indicated in root-mean-square (rms) values.
They should not exceed:
ANTENNA VOLTAGE < 500 V (rms);
ANTENNA CURRENT < 10 A (rms).
6.4.2. Reflected Power, Forward Power and SWR at Antenna Output
The reflected power, forward power and SWR should not exceed:
ANTENNA REFLECTED POWER < 400 W;
ANTENNA FORWARD POWER < 1600 W;
ANTENNA SWR < 10:1.
Note that at SWR>1:1 at the tuner output, the forward power will exceed the tuner input power by the value
of the reflected from the output power. Therefore, it would be normal, e.g., at ANTENNA SWR=3:1, and input
power from the amplifier 1000 W, to measure:
ANTENNA FORWARD POWER = 1250 W and
ANTENNA REFLECTED POWER = 250 W
at the antenna output.
6.4.3. Power Supply Voltage and Temperature in the Tuner Unit
These two values should be within the following ranges:
ATU PS VOLTAGE = 22 … 30 VDC;
ATU TEMPERATURE = -40…+65 °C (-40…+150 °F).
6.4.4. Tuner Working Hours
This is the number of hours during which the tuner has been powered.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n MAINTENANCE | Page 53 of 72
7. MAINTENANCE
The user IS NOT expected to perform any repairs, except replacing fuses (see Section 7.2 Fuse Replacement)
and repairing antennas or coaxial cables on the feeders.
If needed, call your dealer’s service provider or the manufacturer directly (see Section 1.2 Owner Assistance).
7.1. Cleaning
CAUTION
Do not use any solvents for cleaning. They may be dangerous to you and damage tuner
surfaces.
Do not disassemble the tuner. Cleaning of the tuner outer surface can be done with a piece of soft cotton
cloth lightly moistened with clean water.
7.2. Fuse Replacement
NOTICE
For replacement, only use standard fuses from the types recommended below.
There are two fuses in the tuner. They are located under a small cover on the front panel (see Figure 2-1 ACOM
04AT tuner, Pos. 6). The fuses are European size 5x20 mm, ceramic (or glass) body cartridge.
Fuse F1 specification:
• "F" type (fast-acting / quick-acting / fast blow / quick blow);
• Rated for 2 A and 250 V.
Suitable fuses are:
• EATON Bussmann, PN: GMA-2-R (glass body cartridge);
This fuse can be ordered from:
- Farnell (www.farnell.com), PN: 1150627;
- Mouser (www.mouser.com), PN: 504-GMA-2-R.
• Littelfuse, PN: 0235002 (glass body cartridge);
This fuse can be ordered from:
- DigiKey (www.digikey.com), PN: F4724-ND or F2680-ND;
- Farnell (www.farnell.com), PN: 1608243;
- Mouser (www.mouser.com), PN: 576-0235002.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 54 of 72 | S e c t i o n MAINTENANCE
May 2021
Fuse F2 specification:
• "T" or "L" type (time-lag / slow blow / träge);
• Rated for 0.8 А and 250 V.
Suitable fuses are:
• EATON Bussmann, PN: S506-800-R (glass body cartridge);
This fuse can be ordered from:
- DigiKey (www.digikey.com), PN: 283-2708-ND;
- Farnell (www.farnell.com), PN: 1241969;
- Mouser (www.mouser.com), PN: 504-BK/S506-800-R.
• Littelfuse, PN: 0218.800 (glass body cartridge);
This fuse can be ordered from:
- DigiKey (www.digikey.com), PN: F1744-ND;
- Farnell (www.farnell.com), PN: 1271631;
- Mouser (www.mouser.com), PN: 576-0218.800.
NOTICE
If any of the two fuses blows, it is most probably the result of too much power applied
(over 60 W) during tuning (e.g., due to operator error).
If, after fuse replacement, the device does not operate normally, we recommend repair,
performed only by a trained service technician.
Contact your ACOM dealer for assistance (see Section 1.2 Owner Assistance).
Besides specific national standards, the principal fuses standard applied worldwide is
IEC 60127.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n MAINTENANCE | Page 55 of 72
7.3. Block Diagram and Principle of Operation
Please, see Figure 7-1 Tuner Block Diagram.
The ACOM 04AT tuner consists of the following main assemblies:
• Input switch board;
• Input sensor board (located on the Capacitors board);
• Inductors board;
• Capacitors board;
• Output sensor and antenna switch board;
• Control board (includes modem, four service LEDs and two buttons).
The matching RF circuit is an L-shape matching network configuration and is comprised of the Capacitors
board and Inductors board.
The Inductors board contains 9 discrete coils that can be bypassed or added in series by relays KL1 to KL9.
Together, they form an inductor with a maximum value of over 6.25 mH, variable in 0.015 mH increments.
The discretely controlled inductor is connected in series between the tuner input (to the transmitter) and
output (to the antenna).
The Capacitor board contains 10 discrete capacitors that can be switched off or connected in parallel by relays
KC1 to KC10. Together, they form a capacitor with a maximum value of over 2800 pF, variable in 3 pF
increments.
The discretely controlled capacitor can be connected in parallel to the tuner input (from the transmitter) or
to the output (to the antenna) using two relays: KCT and KCA, respectively, forming the two basic
configurations of an L or reverse L matching network, required for the different antenna impedances:
- L-network (KCT on, KCA off) - for matching of mainly low impedances;
- Reverse L-network (KCT off, KCA on) - for matching mainly high impedances.
After the matching circuit, the RF power passes through the output sensor and the antenna switch, reaching
the selected antenna output (1 of 4). The output sensor produces four analog signals for the output forward
and reflected power, antenna current and antenna voltage: fwda, rfla, ia, and ua. The antenna switch is
controlled by four relays, KA1 to KA4. There is a lightning surge arrestor (not shown in the block diagram) at
the output sensor to protect the tuner and the devices connected to it from atmospheric discharges.
The input RF power from the amplifier, along with the +26 VDC power supply and the modem 60 kHz control
signal is fed to the input switch board, at the RF Input connector.
Here, by using suitable filters, the 60 kHz modem signal is separated and fed to and from the Control board.
The power supply +26 VDC is separated and used to derive a +5 V power supply and three auxiliary DC
voltages: +180 V, +12 V, and -12 V for the MOSFET INPUT SWITCH. The CROWBAR relay has a protection
function and is normally open. The +180 V auxiliary voltage is enabled and disabled by the HVON signal from
the Control board.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 56 of 72 | S e c t i o n MAINTENANCE
May 2021
Figure 7-1 Tuner Block Diagram
Figure 7-1 Tuner Block Diagram
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n MAINTENANCE | Page 57 of 72
During tuner operation (after tuning), in normal state of the relays KS1 and KS2, the input RF power is directly
fed from the RF Input to the input of the L matching network.
During the basic cycle of tuning, by switching the KS1 relay over to the Input switch MOSFET, the input RF
power is directed through a 27 Ohm / 100 W resistor to the transistor MOSFET INPUT SWITCH and to the
TUN input of the Sensor board. In this case, the KS2 relay on the Capacitors board is used to connect the
input sensor output to the input of the matching circuit (L-network), so that the sensor measures the antenna
impedance, transformed by the matching circuit.
In tuning mode, the input RF power is fed through the 27 Ohm / 100 W resistor and primary windings of two
current transformers, TA1 and TA2, to two branches - one to the input of the matching circuit and another
to a reference resistor 50 Ohm / 15 W, which is compared to the input impedance of the L-network, thus
forming a RF impedance bridge.
The transformers TA1 and TA2 are located on the Capacitors board, while the block
diagram shows them with their primary windings only.
The secondary windings of TA1 and TA2 feed to the input sensor RF voltages, proportional to the RF currents
in the two branches - the reference 50 Ohm / 15 W resistor and the antenna impedance transformed by the
matching circuit. The relation of amplitudes and phases of these two signals represents unambiguously the
complex value of the antenna impedance transformed by the matching circuit.
By comparing properly selected parts of these two signals and their combinations by module and by phase,
the sensor produces the following three logic output signals, characterizing the position of the antenna
impedance transformed by the matching circuit, towards the target of the tuning, i.e. towards the point
(50+j0) Ohm, on the complex impedance plane:
- "R": logic output - shows whether the real part of the transformed impedance is above or below
50 Ohm;
- "G" logic output - shows whether the real part of the transformed admittance is above or below
1/50 S (20 mS);
- "PH" logic output - shows whether the phase sign of the transformed impedance is inductive or
capacitive.
The three logic signals in question, "R", "G", "PH", and the detected forward and reflected power "fwd" and
"rfl" (from the input of the matching circuit) are the main sources of information, which are fed by the input
sensor to the Control board during the full-tuning process. They are processed by the Control board, which
provides the tuner operation algorithm (including the tuning algorithm).
As mentioned above, in tuning mode, the input RF power is mainly fed to the 27 Ohm / 100 W resistor. The
INPUT SWITCH MOSFET is normally saturated (high level on gate from *RFON signal), so the RF current is
diverted to the ground through its drain-source channel. In this state, almost all input RF power is dissipated
by the 27 Ohm / 100 W resistor and nothing is fed to the matching network. When the MOSFET is saturated,
the control system can switch over the tuner relays without a risk of relay contact arcing and deterioration,
while the tuner input impedance is kept below SWR of 2:1.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 58 of 72 | S e c t i o n MAINTENANCE
May 2021
The process of full tuning runs in a number of steps (see Section 5.1 What a Full Tuning Cycle Does) and at each
step the Control board enables and blocks the RF power through the MOSFET INPUT SWITCH mentioned
above. During that time, the transceiver feeds continuous RF power. At each step the controller first activates
the sensors with a short pulse of RF power by blocking the MOSFET for a short time, and in a few milliseconds
reads out the status of the sensors, then it blocks the power to the relays by saturating MOSFET again, and
in this manner switches the relays synchronously with the power and keeps the contacts safely clean (see
Section 5.1 What a Full Tuning Cycle Does).
After each relay switchover cycle, the control board applies RF power to update sensor measurements and
read their new state. This is done by the *RFON signal and only lasts a few milliseconds (until the sensor
readings are stabilized); then the control analyzes again the information read by the input sensor - "R", "G",
"PH", "fwd" and "rfl", in order to evaluate the current position of the transformed impedance against the
goal (50+j0) Ohm. While the RF power is enabled the relays won't switch.
After analyzing and evaluating the result of the subsequent relay switching, the Controller board makes a
decision which capacitors and inductors to be included and which ones to be excluded from matching circuit
at the next step. The decision is made following a specific tuning algorithm in the program memory of the
Controller board.
The algorithm is built in such a way that the process is always convergent, i.e., the transformed impedance
converges to the circle with SWR < 1.3:1 toward 50 Ohm, regardless of the wide variety of expected antenna
impedances in the frequency range, using the available resource of coils and capacitors to the maximum
possible extent, according to the operating frequency.
At each subsequent step, the Controller board enables RF power briefly, analyzes again the result from the
data of the input sensor, makes a decision for the subsequent commutation, etc.
The tuning proceeds with multiple successive attempts, following the controller algorithm. Before switching
each relay, the power is stopped and the new relay state is set.
After waiting a certain amount of time for the relay contacts to settle, a new RF pulse follows, with sensor
reading power included, etc., until the impedance transformed by the L-network enters the range of
impedances with SWR < 1.3:1, or until the coil and capacitor resource is depleted (e.g., if the SWR of the
antenna is too high, so no tuning can be found).
At the end of the tuning process, the tuner Controller board reports the result of the tuning to the amplifier,
and waits until the operator stops transmitting. Then the tuner Controller board disables the relays KS1 and
KS2 (RF power delivery to the tuner is stopped). This switches the RF output of the amplifier directly to the
input of the already tuned antenna circuit, and the tuner is ready for operation. The combination of relays
found to achieve good tuning is stored in the tuner nonvolatile memory automatically.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n MAINTENANCE | Page 59 of 72
7.4. Troubleshooting - Monitoring the Antenna-feeder Path Status
Using the ATU MEASURE function, you can evaluate the status of the antenna-feeder path and the coaxial
cable from the amplifier to the tuner.
a) We recommend that you access the ATU MEASURE menu, and check the SWR of the antenna
output there, while you are sure of the good working condition of the antennas and feeders.
Run this measurement for both the operating frequencies and at least one non-operating
frequency, where SWR should be poor (if the tuner cannot be tuned to this frequency, use
BYPASS mode during measurements). Copy and store the data for your antennas and then use
it as a reference in diagnostics;
b) When running diagnostics, use the ATU MEASURE menu to check SWR at the antenna output
at a frequency for which you know that the antenna SWR should be poor (if the tuner cannot
be tuned to this frequency, use BYPASS mode). If you measure a good instead of poor SWR at
the antenna output, this indicates high losses in the feeder from the antenna output to the
antenna or in the antenna itself. If SWR in the ATU MEASURE menu is really poor (as it was
earlier), go to the tuner's BYPASS mode and measure the SWR at the input of the coaxial cable
in the radio station: if it is also poor and if the SWR to the amplifier becomes good after a
tuning, then the cable to the radio station is with low losses;
If SWR at the antenna output (in the ATU MEASURE menu) is poor, but bypassing the tuner it
becomes better at the input to the radio station, then probably the losses at the cable from
the radio station to the tuner are high. E.g., there may be moisture in the braid, the dielectric
may be soaked with water (if it isn't solid), or the braid may be corroded. Such coaxial cable
should be replaced with a new one, because it will introduce high losses and impedance
instability in both transmission and reception, and could also induce interference at reception;
c) If after tuning the tuner shows that it has achieved a good SWR, but you find poor SWR at the
amplifier end (e.g., by the SWR indicator of the transceiver or amplifier), this shows that the
feeder from the radio station to the tuner may be unsuitable or faulty (the cable impedance
may differ from 50 Ohm, or there is a poor contact or leakage at some connector);
d) If you receive a TIMEOUT EXPIRED message while trying to tune the unit (even when the tuning
power is increased to 50 W) and, at the same time, SWR at the bottom end of the feeder (in
the radio station) is good during tuning, this means that:
- The losses at the feeder may be so high that out of the 50 W fed, under 12 W reach the
remote unit, which is not enough to tune the tuner;
- There may be a blown fuse F2 at the tuner (see Section 7.2 Fuse Replacement);
e) If you receive a TIMEOUT EXPIRED or UNSTABLE RF POWER message while trying to tune the
unit (even when the tuning power is increased to 50 W) and, at the same time, SWR at the
bottom end of the feeder (in the radio station) is much higher than 2:1 during tuning, this
means that:
- The cable impedance from the radio station to the remote unit may be other than
50 Ohm or may be faulty or disconnected;
- The transceiver power may be modulated or unstable (it should be unmodulated
carrier); check for loose or contaminated connectors;
- There may be a blown fuse F1 at the tuner (see Section 7.2 Fuse Replacement);
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 60 of 72 | S e c t i o n MAINTENANCE
May 2021
f) If you get a COMMUNICATION TO ATU/ASEL FAILING message, then most probably the cable
connection from the amplifier to the tuner is unstable. Check the cable DC resistance (see
Section 8.1.10 Maximum Length of the Input Coaxial Cable). Check if the panel socket holds the
cable pin tightly and there is no solder buildup on the pin tip. Clean and fasten the male and
female connector parts carefully. Check the same at both the amplifier and the tuner sides;
g) If the associated tuner menus are unavailable on the amplifier, check whether the tuner is
assigned (see Section 4.2 Tuner Assignment and Unassignment) and also check the cable as
described in Point f) above.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n SPECIFICATIONS | Page 61 of 72
8. SPECIFICATIONS
8.1. Parameters
8.1.1. Operating Frequency Range
Continuous from 1.8 to 30 and from 50 to 54 MHz, extensions and changes on request.
8.1.2. Minimum Range of the Matched Impedances (at Each of the Four Antenna Outputs)
All impedances with SWR from 1:1 to 3:1 towards 50 Ohm, any phase angle, unbalanced input and output.
NOTICE
For some frequencies and impedances, matching is possible at SWR above 3:1 at the
antenna output (up to 10:1), but the maximum allowed power is reduced (see Section
8.1.3 Maximum Allowed Input Power).
8.1.3. Maximum Allowed Input Power
(PEP, Mean or Continuous Carrier, Without Mode Limitation)
When tuning is possible for antenna SWR above 3:1, the maximum permissible input power is reduced
gradually as per Table 8-1 Maximum input power of the tuner as function of the antenna SWR.
Table 8-1 Maximum input power of the tuner as function of the antenna SWR
SWR
1-3:1
3.5:1*
4:1*
5:1*
7:1*
10:1*
Pin, W
1200
900
700
500
300
200
Table 8-1 Maximum input power of the tuner as function of the antenna SWR
NOTICE
Operation with antenna output SWR above 10:1 is not allowed.
8.1.4. RF Input Characteristics
• Rated impedance: 50 Ohm unbalanced;
• Input connector type: UHF/PTFE (SO-239A) - 1 pc.;
• SWR during full tuning (basic cycle): no higher than 2:1;
• SWR immediately after full tuning: no higher than 1.5:1 (1.3:1 typically).
*
When tuning is possible for SWR above 3:1
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 62 of 72 | S e c t i o n SPECIFICATIONS
May 2021
8.1.5. Antenna Outputs Characteristics, Antenna 1 to Antenna 4
• Rated impedance: 50 Ohm unbalanced;
• Maximum antenna output SWR: 3:1 (up to 10:1 with RF power limitations (see Section 8.1.3
Maximum Allowed Input Power);
• Output connectors type: UHF/PTFE (SO-239A) - 4 pcs.
8.1.6. Full Tuning Duration (Basic Cycle)
Basic cycle for preparation of user full tuning settings, with automatic storage in the non-volatile memory:
• In the range of 1.8 to 10 MHz: no more than 5 seconds (2-3 seconds typically);
• In the range of 10 to 54 MHz: no more than 3 seconds (1-2 seconds typically).
8.1.7. Input Signal Needed to Prepare User Tuning Settings
Non-modulated carrier power 25 W +3/-3 dB (12.5 to 50 W).
8.1.8. Power Supply
• +26 VDC +10/-15%, consumption of 25 W at most;
• Supplied by an amplifier of the ACOM transistor series over the input RF coaxial cable.
8.1.9. Remote Control
The remote control and indication from an amplifier of the ACOM transistor series is provided over the input
RF coaxial cable of the tuner using a 60 kHz / 4800 bps bidirectional FSK modem.
8.1.10. Maximum Length of the Input Coaxial Cable
The maximum length of the RF coaxial cable between the amplifier output and the tuner input (see Sections
8.1.4 RF Input Characteristics, 8.1.8 Power Supply, 8.1.9 Remote Control and 8.2.9 Cable Required from the Radio
Station) is 100 m (330 ft) for a cable of RG213 type or similar. The cable characteristic impedance should be
50 Ohm and the DC resistance should be below 1 Ohm for inner and outer conductors altogether.
NOTICE
To achieve maximum distance the coaxial cable must be of copper, not steel conductors
(even though silver plated).
8.1.11. Size & Weight (operating, excluding fastening elements and connected cables)
• WxDxH: 345x250x190 mm, 4.2 kg (13.6x9.9x7.5 inches, 9.3 lbs.).
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n SPECIFICATIONS | Page 63 of 72
8.1.12. Operating Environment
• Protection class: IP 53 (NEMA Type 3);
• Temperature range: -40 to +65 degrees Celsius (-40
o
F to 150 oF);
• Relative air humidity: Up to 98% @ +40 degrees Celsius (104
o
F);
• Height: up to 3050 m (10000 ft) above sea level without output deterioration.
8.2. Functions
8.2.1. Process of Matching of Antenna Impedance
• Fully automated.
8.2.2. Modes of Tuning
Two modes: Full (basic cycle of user tuning) and Quick (restoring preset full tune settings from the nonvolatile memory).
8.2.3. Memory for the User Tune Settings
Integrated non-volatile memory, separate for all four antenna-selectivity types and outputs.
8.2.4. Types of Antenna Selectivity / Bandwidth
For fitting the width of frequency segments to the natural bandwidth of antennas, four antenna selectivity
types can be declared:
• Sharp (narrow bandwidth): the width of frequency segments is approximately 0.25% of the
central frequency of the band;
• Regular - used by default. The width of frequency segments is approximately 1% of the central
frequency of the band;
• Wide (wide/broad-band). The width of frequency segments is approximately 4% of the central
frequency of the band;
• Fixed - for the tuning to be valid, it requires coincidence of the operating frequency with
tolerance +/-4 kHz to the stored value.
8.2.5. Bypass and Use ATU Modes
In BYPASS mode all components of the matching network are excluded, allowing direct operation of
broadband antennas. The normal mode is USE ATU.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 64 of 72 | S e c t i o n SPECIFICATIONS
May 2021
8.2.6. Overview of Tuning Settings
Method for overview of all tuning settings is provided. Also, provided is method for deletion of individual or
all tuning settings.
8.2.7. Evaluation of the Resource Used
Provided is a method for evaluation of resource of inductors and capacitors used for each stored user tuning.
8.2.8. Backing Up the NON-Volatile Memory
Method for backing up to a file, and restoring from a file the contents of the non-volatile memory of the
tuner using a computer connected through the amplifier RS-232 port (using the ACOM TERMINAL S program,
freely distributed).
8.2.9. Cable Required from the Radio Station
A single cable is required from the radio station to the tuner. Along with the RF power, the coaxial cable from
the ACOM amplifier to the tuner combines also the DC power supply of +26 VDC and the 60 kHz FSK data for
bidirectional control. Note the type and maximum cable length (see Section 8.1.10 Maximum Length of the
Input Coaxial Cable).
8.2.10. Protection Mechanisms
• From too high or too low power supply voltage (22 to 30 VDC);
• From power supply voltage with reverse polarity;
• From excessive RF voltage at the antenna output (above 500 Vrms);
• From excessive RF current at the antenna output (above 10 Arms);
• From excessive reflected power at the antenna output (above 400 W);
• From excessive forward power at the antenna output (above 1600 W);
• From excessive input power during tuning (above 60 W);
• From relay switching under RF power (hot switching);
• From extreme air temperatures within the internal volume of the tuner
(-40…+65 °C / -40…+150 °F);
• From accumulation of atmospheric electricity and lightning strike close to the antenna - by a
leakage resistor and lightning arrestor in the circuit of the operating antenna and direct
grounding of the unused antennas;
• When the power supply is turned off, all antennas are automatically grounded.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n SPECIFICATIONS | Page 65 of 72
8.3. Storage and Shipment
8.3.1. Storage Environment
The antenna tuner may be kept packed in a dry, ventilated and unheated location (with no chemically active
substances such as acids or alkalis) within the following environment ranges:
• Temperature range: -40 to +70 degrees Celsius (-40
o
F to 158 oF);
• Humidity: up to 75% @ +35 degrees Celsius (95
o
F).
8.3.2. Shipping Size and Weight
• WxDxH: Approx. 520x400x300 mm, 7.0 kg (20.5x15.8x11.9 inches, 15.5 lbs.);
Figure 8-1 Packaging cardboard box
Figure 8-1 Packaging cardboard box
8.3.3. Transportation
All types of transportation may be used, including storage in an aircraft baggage compartment at up to 12000
meters (40000 ft) above sea level.
8.3.4. Returning to the Service Provider
NOTICE
Should it be necessary to ship the amplifier, use the original packing as described below.
At first, disconnect all cables from the tuner (disconnect grounding last). Then, uninstall the assembly by
following the requirements of Sections 2.3 Installation and Connection for Indoor Operation and 2.4 Installation
and Connection for Outdoor Operation, but perform the actions in reverse order. Finally, pack the assembly,
and if necessary, the installation accessories in the original boxes.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 66 of 72 | S e c t i o n SPECIFICATIONS
May 2021
8.4. Information on Disposing and Recycling of Old Electrical and Electronic Equipment
The information in this section is applicable for countries that have adopted separate
waste collection systems.
ACOM products cannot be disposed as household waste.
Waste electricals
This symbol (crossed-out wheeled bin) explains that you should
not place the electrical item in the general waste.
Waste electricals
This symbol (three green arrows going in a triangle with electrical
plug in the center) means that according to local laws and
regulations this product should be sent for recycling.
Old electrical and electronic equipment and batteries should be recycled at a facility capable of handling
these items and their waste byproducts.
Contact your local authority for details in locating a recycle facility nearest to you.
Proper recycling and waste disposal will help conserve resources whilst preventing detrimental effects on
our health and the environment.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n APPENDIX 1 | Lightning Protection | Page 67 of 72
APPENDIX 1 | Lightning Protection
Never underestimate the danger of lightning! Lightning may create dangerous current and voltage surges in
antennas, antenna feeders, and the equipment connected to them, measured in tens and hundreds of
thousands of Amperes and Volts, with steep (fast) rises (a few milliseconds) and a huge quantity of energy
dispersed momentarily, comparable to, e.g., an explosion of hundreds of tons of dynamite, yet released in
less than a thousandth part of a second.
The measures for safety and reduction of damage to people, animals, buildings, equipment, etc. that may be
caused by such a terrifying natural phenomenon, with parameters far beyond the range of human activity,
require a clear understanding and strict compliance with clearly defined principles and rules, the most
important or which are stated below:
1) A short and low-impedance path for discharging the lightning charges into the ground is the
key to safeguarding from lightning.
DANGER
Lightning always seeks the shortest path to ground. Regardless of what obstacles it may
meet in its way to it, and regardless of whether such obstacles are good or bad electrical
conductors or excellent electrical insulators, lightning ALWAYS overcomes the obstacles it can burn, destroy or blow-up obstacles, but lightning charges always reach the ground!
Lightning strikes cannot be stopped and it is not possible for protected objects to be "insulated" from them
by any means, because lightning strikes act as "current generators" with an electromotive force (EMF)
exceeding one billion Volts.
The only possibility is to "capture" lightning and "discharge" it along safe paths to the ground. If such paths
are well designed and built, damage will be prevented or minimized.
2) Due to the exceptional speed of rising of the lightning pulses (thousands and tens of thousands
of Amperes per microsecond), the lower HF impedance we provide for the lightning currents,
the lower and less dangerous potential will be generated by such currents in the protected
object and, consequently, the danger of secondary discharges to adjacent objects in the
protected area will be much lower.
3) Due of the exceptional magnitude of lightning currents (tens and hundreds of thousands of
Amperes), they instantly create a huge amount of heat in objects they pass through, so the
objects can ignite, melt down, rupture or explode.
Consequently, the lower active resistance we provide for such currents on their path to the ground, the less
heat will be released in these objects. The main part of the energy will dissipate in the soil, which is considered
a favorable outcome.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 68 of 72 | S e c t i o n APPENDIX 1 | Lightning Protection
May 2021
E.g., a tree with a diameter of 30 cm or more can be split, exploded, broken or set on fire by a branch of the
main channel of the lightning, while a standard metal lightning rod, taking the main strike of the lightning,
survives, although it is much thinner than the tree.
4) The enormous electrical pulses induce high currents and create high mechanical forces in both
the stricken and nearby objects. To prevent mechanical damage, the masts, antennas, antenna
feeders and the entire equipment of the respective grounding system should be mechanically
strong, reinforced and corrosion-proof, in accordance with the expected local effects on the
surface and underground.
5) The grounding system should be built in such a way that the lightning current does not flow
through the protected object, or if it does, it should at least be considerably reduced by
redirecting its main part along the paths provided in the design. For that purpose, the
grounding system should be carefully planned and designed by thoroughly evaluating the
possible paths the lightning currents could go along. Some essential paths for such currents
are antennas, antenna feeders and the mains, because they are widely spread and have low
impedance to the ground.
6) Currents passing through the protected object can be additionally reduced by creating
obstacles along the paths through the object, and redirecting the currents along the planned
protection paths. This can be done by threading ferrite tubes (toroids) along "unfavorable"
paths (i.e. the cables going to and from the protected object). This way, the predominant part
of the currents will be tapped to the planned protection path, i.e., through the main grounding
plate and all wires and cables connected to it and external to the building. The latter are
intentionally left without ferrite tubes - e.g., the system of grounding electrodes, the securing
ring of the building, the connections and the cables of the mains coming from outside.
Apart from lightning protection improvement, threading of ferrite tubes (toroids) on the power and signal
cables of the equipment in the radio station improves the electromagnetic compatibility (EMC) both between
the devices inside the radio station and between them and the outside devices.
7) All objects in the area of antennas and nearby devices (within 6 m radius) – tuners, rotators
and alike - should be connected by low-impedance connections to a common point called main
grounding plate for the antennas and antenna devices, which in turn should be grounded using
low-impedance connection to the closest main grounding conductor of an existing or purposebuilt (individual) low-impedance grounding system for lightning protection in accordance with
all requirements of the local standards and regulations for electric safety, fire safety and
lightning protection.
Where antenna counterpoises exist, their connections to the main grounding plate and the connections of
the antenna devices should be positioned under the level of the counterpoises or buried underground, if the
antennas are designed this way.
To avoid damage or destruction by lightning, the antenna isolators, and the isolators sectioning the antenna
and mast bracings into smaller lengths, should be bypassed by pulse overvoltage limiters (lightning surge
arrestors). The limiter closest to the ground should be grounded to the main grounding plate, and if the
distance is too great, to an individual low-impedance grounding system for lightning protection.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n APPENDIX 1 | Lightning Protection | Page 69 of 72
8) All cables entering the building should only be laid out in one zone, low in building foundation,
and the cable braids and grounding terminals of their pulse overvoltage limiters (surge
arrestors) should be grounded immediately after coming out from underground, in a common
point called the main grounding plate of the building, to which are connected the mains
neutral, (this would not be permitted in the UK) and the structural metal elements of the
building – concrete reinforcement, metal pipe installations, metal frames, electrical panels,
and other electrically conductive elements of the building (dangers with much plastic tubing
in use in domestic water and central heating pipe systems).
The main grounding plate of the building should in turn be equipped with a special individual low-impedance
grounding system, driven or buried directly in the ground, deep enough under the expected frost level of soil
in your area, and in compliance with all requirements of the local standards and regulations for electric safety,
fire safety and lightning protection.
The expected frost level of soil in your area can be obtained from the local electricity company or weather
service. This is very important, since when soil freezes, its resistance dramatically increases. While the frost
level of soil is not normally critical in the case of buried counterpoises of RF antennas, an insufficient depth
of driving or burying in the ground could increase the resistance of the protective grounding system to exceed
the standard requirements several times, i.e., you may be often left without electrical and lightning
protection in the winter.
9) All objects located in the room of the radio station should be grounded to a common point
called the main grounding plate of the radio station, which in turn should be connected
through a low-impedance connection to the main grounding plate of the building (see Point 8)
above).
10) The grounding terminals of all equipment in the room, the shields of all cables coming in and
going out of the room (including telephone, telegraph, network, video, Internet, TV, etc.), as
well as the grounding terminals of all pulse overvoltage limiters (surge arrestors), that normally
supply any of the wires of these cables, should be connected to the main grounding plate of
the radio station.
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
Page 70 of 72 | S e c t i o n NOTES
May 2021
NOTES
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………..……………………………………………………………………………………………………………………..
User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
May 2021
S e c t i o n NOTES | Page 71 of 72
This manual is for electronic distribution mainly.
If you have it on paper and you no longer need it, please, recycle it!
The latest versions of our User's Manuals are available at
www.acom-bg.com
Dealer/Partner's address:
ACOM Ltd.
Bulgaria | Bozhurishte 2227
Sofia-Bozhurishte Economic Zone | 6 Valeri Petrov Str.
GPS coordinates: 42.748616о | 23.209801
о
support@acom-bg.com
ACOM and th e ACOM logo are reg istered trade marks of ACOM Ltd. i n many countries,
includ ing the EU and United St ates. I The used i mages are il lustrave onl y.
Subjec t to change witho ut noce. I Printed i n Bulgaria.
All rig hts rese rved. I D esign and content b y ACOM Ltd.
ACOM 04 АТ User's Ma nual I Four th Edition, Rev ision 01 I May 2021.
www.acom-bg.com
Loading...