Acom 2020S User manual

ACOM 2020S
1.8-54 MHz
Linear Power Amplifier
with Touch-Screen Remote Control
User's Manual
Installation, Operation
and Maintenance
June 2022
OUTSTANDING HF POWER PRODUCTS

User's Manual | ACOM 2020S | 1.8-54 MHz Linear Power Amplifier
Page 2 of 76 | S e c t i o n ABOUT DOCUMENTATION
June 2022
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 2020S | 1.8-54 MHz Linear Power Amplifier
June 2022
Sec t i o n ABOUT DOCUMENTATION | Page 3 of 76
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:
[e-mail]
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.
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PDF readers.

User's Manual | ACOM 2020S | 1.8-54 MHz Linear Power Amplifier
Page 4 of 76 | S e c t i o n ABOUT DOCUMENTATION
June 2022
Title of Documentation
ACOM 2020S 1.8-54 MHz Linear Power Amplifier
with Touch-Screen Remote Control
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 2020S 1.8-54 MHz linear power amplifier.
Record of Revisions
Description
Release Date
Notes
ACOM 2020S User's Manual
30.06.2022
First 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
© 2022 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.
Trademarks
ICOM, KENWOOD, YAESU, ELECRAFT, and other product names or brands
mentioned in this documentation are either registered trademarks or
trademarks of their respective holders.
Published by
ACOM Ltd.
Bulgaria | Bozhurishte 2227
Sofia-Bozhurishte Industrial Park | 6 Valeri Petrov Str.
GPS coordinates: 42.748616о| 23.209801о
Web: www.acom-bg.com
E-mail: [e-mail]
Note
This manual has been printed on chlorine-free bleached paper.

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June 2022
Sec t i o n ABOUT DOCUMENTATION | Page 5 of 76
Contents
ABOUT DOCUMENTATION ................................................................................................................................ 3
1. GENERAL INFORMATION........................................................................................................................... 9
1.1. Introduction and Description.......................................................................................................... 9
1.2. Product History and Documentation Validity ............................................................................... 10
1.3. Owner Assistance.......................................................................................................................... 10
1.4. Equipment Supplied...................................................................................................................... 11
1.5. Features......................................................................................................................................... 12
1.6. Safety Considerations, Explicit Definitions.................................................................................... 13
2. INSTALLATION.......................................................................................................................................... 16
2.1. Unpacking and Initial Inspection................................................................................................... 16
2.2. Line Voltage Selection................................................................................................................... 16
2.3. Amplifier Location Selection ......................................................................................................... 16
2.4. Connections................................................................................................................................... 18
2.4.1. Connections on Amplifier rear panel............................................................................... 18
2.4.2. Connections on RCU rear panel....................................................................................... 22
2.5. Connecting to External Devices (transceiver, computer, etc.)...................................................... 24
3. FIRST POWER-ON, CONTROL SYSTEM, AND INITIAL CHECK.................................................................... 28
3.1. Low Energy STANDBY Mode of the Power Supply........................................................................ 28
3.2. RCU Remote Control Unit ............................................................................................................. 29
3.3. Initial Turning On........................................................................................................................... 30
3.4. Basic Screen................................................................................................................................... 30
3.5. Control System - Buttons and Menus ........................................................................................... 33
3.6. Test Transmission.......................................................................................................................... 34
4. OPERATION.............................................................................................................................................. 38
4.1. Change of Modes RX/TX and OPERATE/STANDBY; AUTO OPERATE User Settings ...................... 38
4.2. Band Change, Standard and Expanded Frequency Coverage....................................................... 39
4.3. Automatic Protection System ....................................................................................................... 40
5. MENUS - SETTINGS AND SERVICE FUNCTIONS........................................................................................ 42
5.1. Menu USER PREFERENCES ............................................................................................................ 43
5.2. Menu AMP SERVICE ...................................................................................................................... 46
5.3. Menu CAT SETTINGS ..................................................................................................................... 47
5.4. Menu FAULTS LOG ........................................................................................................................ 49
5.5. Menu RESTORE DEFAULT SETTINGS.............................................................................................. 50

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5.6. Menu NETWORK SETTINGS........................................................................................................... 51
5.7. Menu AMP UPDATE ...................................................................................................................... 53
5.8. HELP information .......................................................................................................................... 53
6. REMOTE CONTROL .................................................................................................................................. 54
6.1. Remote Control via Ethernet Interfaces ....................................................................................... 54
6.2. Remote Control via RS-232 interface............................................................................................ 55
7. MAINTENANCE ........................................................................................................................................ 56
7.1. Periodic Maintenance ................................................................................................................... 56
7.2. Cleaning......................................................................................................................................... 56
7.3. Fuse Replacement......................................................................................................................... 57
7.4. Using the Fault Codes (signatures) for Diagnostics....................................................................... 58
7.5. Firmware ....................................................................................................................................... 59
7.5.1. Firmware Versions........................................................................................................... 59
7.5.2. Prequistments.................................................................................................................. 59
7.5.3. Firmware update of amplifier ACOM 2020S (unit only).................................................. 60
7.5.4. Firmware update of Remote Control Unit model R05 .................................................... 61
8. SPECIFICATIONS....................................................................................................................................... 62
8.1. Parameters.................................................................................................................................... 62
8.2. Functions....................................................................................................................................... 64
8.3. Regulatory Requirements ............................................................................................................. 64
8.4. Storage and Shipment................................................................................................................... 68
8.4.1. Storage Environment....................................................................................................... 68
8.4.2. Shipping Size and Weight ................................................................................................ 68
8.4.3. Transportation................................................................................................................. 68
8.4.4. Returning to the Service Provider ................................................................................... 69
8.5. Information on Disposing and Recycling of Old Electrical and Electronic Equipment.................. 71
NOTES.............................................................................................................................................................. 72

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June 2022
Sec t i o n ABOUT DOCUMENTATION | Page 7 of 76
Figures
Figure 2-1 | RCU model R05 - Front panel with Touch screen........................................................................ 17
Figure 2-2 | Amplifier - Front view.................................................................................................................. 17
Figure 2-3 | Amplifier rear panel - Connections.............................................................................................. 18
Figure 2-4 | ACOM 2020S - RCU R05 connection cable .................................................................................. 21
Figure 2-5 | Power supply cable...................................................................................................................... 22
Figure 2-6 | RCU model R05 rear panel........................................................................................................... 22
Figure 3-1 | Amplifier and RCU Front panels - Controls and Readouts........................................................... 28
Figure 3-2 | Basic screen ................................................................................................................................. 30
Figure 3-3 | Basic screen - Operating values................................................................................................... 31
Figure 4-1 | Appearance of an alarm message ............................................................................................... 40
Figure 5-1 | MENU SELECTION........................................................................................................................ 42
Figure 5-2 | Menu USER PREFERENCES........................................................................................................... 43
Figure 5-3 | Virtual keyboard .......................................................................................................................... 44
Figure 5-4 | Classic skin interface - time proven and ergonomic.................................................................... 45
Figure 5-5 | Dark skin interface - sleek and elegant........................................................................................ 45
Figure 5-6 | Menu AMP SERVICE..................................................................................................................... 46
Figure 5-7 | Menu CAT SETTINGS.................................................................................................................... 47
Figure 5-8 | Menu FAULTS LOG....................................................................................................................... 49
Figure 5-9 | Menu RESTORE DEFAULT SETTINGS............................................................................................ 50
Figure 5-10 | Menu NETWORK SETTINGS ....................................................................................................... 51
Figure 5-11 | Virtual keypad............................................................................................................................ 52
Figure 5-12 | HELP information....................................................................................................................... 53
Figure 6-1 | Web-interface running in web browser on a PC ......................................................................... 54
Figure 6-2 | Web-interface running in web browser on a smart phone......................................................... 55
Figure 7-1 | ACOM Terminal S screenshot...................................................................................................... 60
Figure 8-1 | Packaging cardboard box............................................................................................................. 68

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Tables
Table 1-1 | Production versions history.......................................................................................................... 10
Table 1-2 | Package contents.......................................................................................................................... 11
Table 2-1 | ACOM 2020S - RCU R05 connection cable wiring......................................................................... 21
Table 2-2 | Signals and pin out of the CAT/AUX connector ............................................................................ 25
Table 2-3 | Signals and pin out of the RCU's SERIAL connector...................................................................... 25
Table 2-4 | Signals and pin out of the amplifier's RS-232 connector.............................................................. 26
Table 2-5 | Signals and pin out of the RCU's LAN socket ................................................................................ 26
Table 2-6 | Signals and pin out of the RCU's USB type A connector............................................................... 27
Table 5-1 | Transceiver interface type and command set selection............................................................... 48
Table 7-1 | Firmware versions history ............................................................................................................ 59
Table 8-1 | RF exposure distance chart........................................................................................................... 66
Table 8-2 | Different antenna gain chart ........................................................................................................ 67

User's Manual | ACOM 2020S | 1.8-54 MHz Linear Power Amplifier
June 2022
Sec t i o n GENERAL INFORMATION | Page 9 of 76
1. GENERAL INFORMATION
Congratulations on purchasing one of the finest solid-state 1.8-54 MHz linear amplifiers 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 amplifier.
1.1. Introduction and Description
This manual explains:
•Installation
•Operation and
•Maintenance
of the ACOM 2020S solid-state linear power amplifier.
The ACOM 2020S is a state-of-the art 1500 W heavy-duty, solid-state linear amplifier, covering all amateur
bands from 1.8 to 54 MHz.
The amplifier employs two powerful modules in power splitting/combining technique which is well time-
proven in high-power commercial applications to provide sufficient output headroom. Thanks to input and
output ports isolation from each other, the intermodulation is reduced, and SWR toughness, self-excitation
resistance, and reliability are improved.
It features a Remote Control Unit model R05 (abbr. RCU hereinafter) with the operating information shown
on a multi-functional, high resolution color touch screen. All indicators and controls (except the primary
mains switch and power indicator) are accessible via the touch screen RCU, as well as, all command input to
the RCU is menu-driven.
As standard, the ACOM 2020S is equipped with Ethernet interface facilitating its usage in Remotely
Operated Stations.

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1.2. Product History and Documentation Validity
The ACOM 2020S amplifier serial production started in April 2022.
This manual refers to the ACOM 2020S amplifiers and describes the operating possibilities of all amplifiers
produced till the publishing date of this manual.
This manual is valid till a new manual is issued.
Table 1-1 | Production versions history
Production Version
Release Date
Notes
04.2022
Basic design;
Table 1-1 | Production versions history
1.3. Owner Assistance
If assistance is needed, you should contact your local dealerfirst. 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: [e-mail]
Bulgaria | Bozhurishte 2227
Sofia-Bozhurishte Industrial Park | 6 Valeri Petrov Str.
GPS coordinates: 42.748616о| 23.209801о

User's Manual | ACOM 2020S | 1.8-54 MHz Linear Power Amplifier
June 2022
Sec t i o n GENERAL INFORMATION | Page 11 of 76
1.4. Equipment Supplied
The ACOM 2020S amplifier (including Remote Control Unit model R05) is shipped in a cardboard carton.
The ACOM 2020S is shipped as package, consisting of:
Table 1-2 | Package contents
Nr.
PACKAGE CONTENTS
Pcs.
1
Amplifier ACOM 2020S (unit only)
1
2
Remote Control Unit with Touch Screen (model R05)
1
3
Cable (ACOM 2020S to RCU R05 connection), 1.5 m
1
4
Power supply cable, 1.8 m (with free cable end)
1
Table 1-2 | Package contents
The User's Manual is available as PDF-file only.
The latest version of the User's Manual is available at www.acom-bg.com.

User's Manual | ACOM 2020S | 1.8-54 MHz Linear Power Amplifier
Page 12 of 76 | S e c t i o n GENERAL INFORMATION
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1.5. Features
•Easy to operate
The overall operation of ACOM 2020S is extremely simplified: the touch screen menus are intuitive and
easy to follow, and no special skill is required from the operator when changing frequency bands.
•User-friendly automatic control
When connected to a transceiver with CAT capability, the amplifier will track the operating frequency
and will change bands accordingly.
Even if not CAT connected, the amplifier monitors the input signal frequency through the built-in
frequency counter and automatically switches bands.
•High resolution color display with Touch screen
Amplifier status indications are explained via detailed text displayed on the RCU 7" high-resolution
color touch display (155x90 mm, 1024x600 pixels, and 24-bit color)
All indicators and controls (except the primary mains switch and power indicator) are accessible via the
RCU's touch screen, as well as, all command input to the RCU is menu-driven.
•Transceiver-independent
Compatible with all transceiver models - does not need any special signals: "ground on transmit" and
RF drive power is sufficient.
•Two power modules
Employs two powerful modules in the power splitting/combining technique.
•LDMOS transistor technology
The two final PA stages use a rugged LDMOS transistor - MRFX1K80HR5 or equivalent.
•Broadband input circuit
Broadband input circuit, providing a perfect transceiver load with SWR below 1.2 (typically 1.1),
without retuning throughout the whole frequency range from 1.8 to 54 MHz.
•Intelligence
Takes care of itself during operation via continuously working protection circuits in all modes.
The operator can monitor 11 (eleven) parameters of the amplifier in operation.
•Easy maintenance
Detailed data (55 parameters) about each of the last 28 hard-fault protection trips is stored in the
amplifier's memory.
•Remote control capabilities
Remotely controlled via the Internet through integrated Web interface and built-in Ethernet RJ45 port
and Wi-Fi adapter.
•Compact and lightweight construction
Extremely compact and lightweight construction with built-in switching-mode power supply (SMPS)
that operates with an extended mains voltage range of 200-240 VAC, ±10% (180-264 VAC limiting
values), with no internal switch over. The consumed current is purely sinusoidal, Power Factor
Corrected (PFC) and inrush current limited. This makes the operation of unstable mains and generators
easy and trouble free.
•Electromagnetic compatibility
Complies with the CE electromagnetic compatibility (EMC) requirements and FCC regulations. Perfect
compatibility with both highly sensitive devices and the powerful devices in the radio station
(receivers, computers, other amplifiers) due to the used PFC and built-in radio-frequency filters.

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June 2022
Sec t i o n GENERAL INFORMATION | Page 13 of 76
1.6. Safety Considerations, Explicit Definitions
The ACOM 2020S linear power amplifier is a Safety Class I unit regarding protection against electric shock.
The third grounding lead of its mains cord (which is colored yellow with two green stripes) and the ground
stud on the rear panel of the amplifier (marked GND, see Figure 2-3 | Amplifier rear panel - Connections,
Pos. (a)) must be connected to the station's grounding system for safe operation.
The amplifier 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 amplifier 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 amplifier but also to connected equipment.

User's Manual | ACOM 2020S | 1.8-54 MHz Linear Power Amplifier
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June 2022
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.

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June 2022
Sec t i o n GENERAL INFORMATION | Page 15 of 76
PRECAUTIONS:
DANGER
Both the mains voltage and the high DC voltage up to 500 V inside the ACOM 2020S
amplifier are LETHAL!
For your safety, pull the amplifier power plug out of the mains wall outlet and WAIT AT
LEAST 3 minutes EACH TIME BEFORE you remove the cover of the amplifier.
DANGER
Never allow anyone, ESPECIALLY CHILDREN, to push or put anything into holes in the
case - this will cause electric shock. NEVER TOUCH AN ANTENNA or antenna insulators
during transmission or tuning - this may result in an electric shock or burn. NEVER
EXPOSE the amplifier to rain, snow or any liquids. AVOID placing the amplifier in
excessively dusty environments or in direct sunlight. DO NOT OBSTRUCT COOLING ducts
or vents. Keep a minimum clearance distance of 10 cm (4 inches) to any other devices or
objects.
WARNING
Do not undertake on your own repairs or changes in hardware or software of the
amplifier in order not to endanger your or other's health and life and not to damage the
amplifier 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.
WARNING
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 amplifier, please, consult your dealer.
WARNING
NEVER operate the equipment if you notice an abnormal odor, sound or smoke.
Immediately turn off the power and contact your dealer for assistance (see Section
1.3 Owner Assistance).

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June 2022
2. INSTALLATION
2.1. Unpacking and Initial Inspection
Before you install your amplifier, thoroughly read this manual.
First, carefully inspect the cardboard carton and its contents for physical damage. ACOM
ships amplifiers 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.
Keep all packing materials for possible future amplifier shipment (See Section 8.4.4 Returning to the Service
Provider).
2.2. Line Voltage Selection
The ACOM 2020S amplifier is supplied with built-in switching-mode power supply (SMPS).
The amplifier operates in an extended mains voltage range of 200-240 VAC, ±10% (180-264 VAC limiting
values), with no internal switch over. The consumed current is purely sinusoidal, Power Factor Corrected
(PFC) and inrush limited. This makes the operation from unstable mains and generators easy and trouble
free.
Thanks to the built-in SMPS, the ACOM 2020S has no mains line voltage selector to take
care of!
2.3. Amplifier Location Selection
CAUTION
The weight of the unit (RCU excluded) is about 22 kg, which should preferably be
handled by two persons.
Position the amplifier near the place where it will be used. You will need an easy access to the rear panel
cabling.
NOTICE
The ACOM 2020S is forced air cooled. Keep a minimum clearance distance of 10 cm
(4 inches) to any other devices or objects.

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June 2022
Sec t i o n INSTALLATION | Page 17 of 76
The exhaust air can reach 65 oC (150 oF) and if the surrounding devices are sensitive to heating from outside
or use forced air cooling themselves, increase the distances accordingly.
Figure 2-1 | RCU model R05 - Front panel with Touch screen
Figure 2-1 | RCU model R05 - Front panel with Touch screen
Figure 2-2 | Amplifier - Front view
Figure 2-2 | Amplifier - Front view
For ergonomic operation you can place the RCU on your desk, near to your transceiver. Please, have in
mind that the length of a connecting cable between ACOM 2020S and RCU R05 is 1.5 m.
NOTICE
Do not leave accidental paper, cloth or other lightweight pieces around and under the
amplifier. They may be drawn in by the cooling air stream and block the vents. This will
lead to overheating and accelerated material aging, not covered by the warranty.

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2.4. Connections
Please, see Figure 2-3 | Amplifier rear panel - Connections and Figure 2-6 | RCU model R05 rear panel.
Connection to your station must be accomplished in the order described below, before you apply mains
voltage to the amplifier.
Before you connect the amplifier to external grounding, you should advise with a
licensed electrician and confirm such kind of connection is allowed by your national and
local electrical code, safety rules, and regulations in force. Simultaneous connection to
the earth grounding and protective earth may be inadmissible or may fall under special
requirements in some countries!
DANGER
Never use the gas installation pipes for grounding. This can cause an EXPLOSION!
DANGER
Do not use the steam-heating or water-supply network pipes for grounding! You may
expose to dangerous voltage not only yourself but also other people using the same
installation.
2.4.1. Connections on Amplifier rear panel
Figure 2-3 | Amplifier rear panel - Connections
Figure 2-3 | Amplifier rear panel - Connections
2
f)
c)
e)
d)
h)
g)
a)
3
1
b)

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June 2022
Sec t i o n INSTALLATION | Page 19 of 76
a) GROUND stud
First, connect the wing-nut grounding stud of the amplifier (on the rear panel, marked GROUND) to the
station's grounding system (see Figure 2-3 | Amplifier rear panel - Connections, Pos. (a)).
WARNING
Note that the grounding system may have to withstand currents over 20 A with
insignificant voltage drop on it. Therefore, it may be necessary to improve it
considerably, i.e., to become less resistive, with heavier leads and lower-resistive ground
path. The grounding leads should be at least 8mm² (AWG 8 or SWG 10).
For details and recommendations on the grounding and RF counterpoise system concerning the
electromagnetic compatibility see also Section 3.6.f) Elimination of electromagnetic compatibility (EMC)
problems.
b) KEY-IN connector
This is the amplifier's input for receive/transmit control from the transceiver.
The transceiver controls the amplifier from receive mode into transmit mode (RX/TX) by grounding of the
KEY-IN input.
Run a shielded cable from the "ground on transmit" connector or terminal on your transceiver to the
amplifier rear panel KEY-IN connector (see Figure 2-3 | Amplifier rear panel - Connections, Pos. (b)). The
KEY-IN connector uses a standard RCA phono plug.
The switching voltage presented from amplifier KEY-IN connector to the transceiver
"ground on transmit" output does not exceed 12 V (positive to the ground). The closed-
circuit current is below 6 mA (see Section 8.1.j) Receive / Transmit control).
Your amplifier will not work if KEY-IN input is not connected properly.
Transceiver producers give different names to this output and they are for instance
TX-GND, SEND, T/R-LINE, PTT, etc. Some transceivers require that "ground on transmit"
is implemented via a software command, or by changing the setting of a switch on the
rear panel, or interior of the transceiver. Check your transceiver's manual.
c) KEY-OUT connector
This is the amplifier's transmit-enabling control output to the transceiver.
The KEY-OUT connector provides an extra control signal from the amplifier to the transceiver. This can be
used for improving the receive/transmit (RX/TX) switching safety.

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NOTICE
KEY-OUT is a low-power open-drain output, make sure that the signal voltage coming
from the respective transceiver connection does not exceed 50 VDC (open circuit) and
the closed-circuit current is below 20 mA.
If your transceiver has a suitable input that disables transmission unless grounded externally, we
recommend that you connect it with a shielded cable terminated in a Phono (RCA) connector to the
KEY-OUT connector (see Figure 2-3 | Amplifier rear panel - Connections, Pos. (c)) of the amplifier.
ACOM 2020S will operate normally with KEY-OUT unconnected if your transceiver has
no such input.
Transceiver producers give different names to this input and they are for instance
TX-INHIBIT, MUTE, LINEAR, etc. Check your transceiver's manual.
d) RF INPUT connector
Connect a suitable coaxial cable from the transceiver output to the amplifier RF INPUT SO-239 connector
(see Figure 2-3 | Amplifier rear panel - Connections, Pos. (d)), using PL-259 plug.
NOTICE
In order to avoid a damage (not covered by the warranty), turn off your transceiver's
internal antenna tuner.
e) RF OUTPUT connector
NOTICE
If this is the first time you will use a power amplifier in your station, pay attention to the
coaxial cable type from the amplifier's output to the antenna. It must handle the
increased power safely, particularly on the 10- and 6 meters bands. We recommend that
you use RG213 cable or better. Check the same for the antenna switch and tuner, as
well as the whole antenna system (especially multi-band trap antennas).
Connect a suitable coaxial cable with a PL-259 plug from the RF OUTPUT (see Figure 2-3 | Amplifier rear panel
- Connections, Pos. (e)) to the antenna switch or tuner, or to antenna for the respective frequency band.
f) RCU connector
Connect the ACOM 2020S - RCU R05 connection cable (part of delivery - see 1.4 Equipment Supplied, Pos. 3)
from the connector RCU (see Figure 2-3 | Amplifier rear panel - Connections, Pos. (f)) to the connector
AMPLIFIER located on the RCU rear panel (see Figure 2-6 | RCU model R05 rear panel, Pos. (i)).