Acom 700S User manual

ACOM Ltd.
Soa-Bozhurishte Economic Zone
6 Valeri Petrov str.
2227 Bozhurishte, Bulgaria
phone: [phone]
fax: [phone]
e-mail: [email protected]
www.acom-bg.com December 2019
Printed in Bulgaria
OPERATING MANUAL

ACOM Ltd.
Soa-Bozhurishte Economic Zone
6 Valeri Petrov str.
2227 Bozhurishte, Bulgaria
phone: [phone]
fax: [phone]
e-mail: [email protected]
www.acom-bg.com December 2019
Printed in Bulgaria

TABLE OF CONTENTS
1. GENERAL INFORMATION .........................................................................................................................4
1-1. Inroduction and description .......................................................................................................4
1-2. Owner assistance .....................................................................................................................4
1-3. Equipment supplied and options ...............................................................................................4
1-4. Features ....................................................................................................................................4
1-5. Safety considerations, explicit denitions .................................................................................5
2. INSTALLATION ...........................................................................................................................................6
2-1. Unpacking and Initial Inspection ...............................................................................................6
2-2. Amplier operating location selection; cooling. .........................................................................7
2-3. Connecting the amplier within the shack ................................................................................7
2-4. Installing options and connecting to external devices, computer, etc. ....................................10
3. POWERING AND OPERATION ................................................................................................................11
3-1. Low energy stand-by mode of the power supply .................................................................... 11
3-2. Front panel - controls and indication ....................................................................................... 11
3-3. Initial turning on ......................................................................................................................12
3-4. Basic screen ...........................................................................................................................12
3-5. Control system – buttons and menus .....................................................................................14
3-6. Test transmission ....................................................................................................................14
4. AMPLIFIER OPERATION .........................................................................................................................17
4-1. Change of modes, RX / TX and Operate / Stand-by; option AUTO OPERATE ......................17
4-2. Band change, standard and expanded frequency coverage ..................................................18
4-3. Operation with an external antenna tuner ...............................................................................19
4-4. Automatic protection system ...................................................................................................19
5. MENUS – SETTINGS AND OPTIONS .....................................................................................................20
5-1. Menu “Measurements in the amplier” – AMP MEASURE .....................................................21
5-2. Menu “Service functions in the amplier” – AMP SERVICE. ..................................................22
5-3. Menu CAT/AUX SETTINGS....................................................................................................22
5-4. Menu “USER PREFERENCES” .............................................................................................24
5-5. FAULTS LOG ..........................................................................................................................25
5-6. RESTORE DEFAULT SETTINGS ...........................................................................................25
6. REMOTE CONTROL ................................................................................................................................26
6-1. General information ................................................................................................................26
7. MAINTENANCE ........................................................................................................................................26
7-1. Periodic maintenance; general checks and cleaning ..............................................................26
7-2. Replacement of fuses .............................................................................................................27
7-3. Using the fault codes (signatures) for diagnostics ..................................................................28
7-4. FIRMWARE UPDATES............................................................................................................28
8. SPECIFICATIONS.....................................................................................................................................28
8-1. Parameters..............................................................................................................................28
8-2. Functions.................................................................................................................................29
8-3. Storage and shipment .............................................................................................................30
9. DISCLAIMER ............................................................................................................................................30

44
1. GENERAL INFORMATION
1-1. Inroduction and description
This manual describes the installation, operation, and maintenance of the HF+6m solid-state linear
power amplier ACOM 700S.
ACOM 700S is a state-of-the art linear amplier, covering the amateur bands from 1.8 to 54MHz with
700W output power (PEP or continuous carrier) with less than 40W of drive. The amplier operating
information is shown on a multi-functional, high resolution color display. ACOM 700S may by controlled
either by the six front panel buttons or remotely – via an RS232 port.
NOTE
ACOM 700S is designed to work with the ACOM 04AT Remote
Automatic Antenna Tuner. The connection of ACOM04AT will
make accessible the features that are inactive on the amplier
display when ACOM 700S operates without the ACOM 04AT. The
operation of ACOM 700S with ACOM 04AT is described in the
ACOM 04AT Operation manual.
1-2. Owner assistance
If technical or operating assistance is needed, please contact your local dealer rst. In the unlikely
case of you needing further information, you may get in touch with ACOM via: fax (+ 359 2 920 96 56),
telephone [phone]), e-mail ([email protected], [email protected]) or by post (6
Valeri Petrov str.,Bozhurishte 2227,Bulgaria). Website: www.acom-bg.com.
1-3. Equipment supplied and options
The amplier is supplied in a single box including:
- the amplier ACOM 700S;
- this manual with a CE declaration of compliance;
- four pieces of spare fuses;
1-4. Features
• 5“ high resolution color display (108x65mm), 800x480 pixels, and 24-bit color.
• The nal PA stage uses a rugged LDMOS transistor - MRFE6VP61K25N or equivalent.
• Compatible with all transceiver models available on the market - does not need any special
signals: „ground on transmit“ and less than 40W of RF drive power is su󰀩cient.
• Broadband input circuit, providing a perfect transceiver load with SWR below 1.2:1 (typically1.1:1),
without retuning throughout the whole frequency range from 1.8 to 54MHz.
• The overall operation of ACOM 700S is extremely simplied : the screen menus are intuitive and
easy to follow, no special skill is required from the operator when changing frequency bands.

5
• Automatic control – when connected to a transceiver with CAT capability, the amplier will track
the operating frequency, and will change bands accordingly.
• Even if not CAT connected, the amplier monitors the input signal frequency through the built-in
frequency counter and automatically switches bands.
• Remotely controlled by RS232 port.
• Takes care of itself during operation via continuously working protection circuits in all modes.
• The operator can monitor more than 10 parameters of the amplier in operation.
• Easy maintenance – detailed data (55 parameters) about each of the last 28 hard-fault protection
trips is stored in the amplier’s non-volatile memory.
• Convenient for expeditions and eld operation due to the extremely compact and lightweight
construction and the built-in switching-mode power supply (SMPS) that operates with extended
mains voltage range of 100-240VAC, 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 troublefree.
• Perfect electromagnetic compatibility (EMC) with both highly sensitive devices and the powerful
devices in the radio station (receivers, computers, other ampliers) exceeding the standard
EMC requirements due to the used PFC and built-in radio-frequency lters.
1-5. Safety considerations, explicit denitions
The ACOM 700S linear amplier is a Class I apparatus regarding protection against electric shock, i.e.
the third grounding lead of its mains cord (colored yellow with two green stripes) and the grounding stud
on the rear panel, marked GND (Fig. 2-1), must be connected to the grounding system of the shack for
safe operation.
The ACOM 700S amplier is designed to meet international safety standards and complies with the CE
electromagnetic compatibility requirements, as well as the FCC regulations.
This operating manual contains precautions, cautions, and warnings that MUST BE CОMPLIED TO
by the user to ensure safe operation and maintaining of the ACOM 700S amplier in a safe working
condition.
PRECAUTIONS:
The EXPLICIT DEFINITIONS described below apply to this operating manual:
W A R N I N G notes call attention to a procedure which, if not correctly performed,
could result in personal injury or re hazard by electric shock or lightning.
C A U T I O N notes call attention to a procedure which, if not correctly performed, could result
in equipment damage, not only in the ACOM 700S amplier.
N O T E notes call attention to a procedure which, if not correctly performed, could result in
inconvenience.

66
W A R N I N G HIGH VOLTAGE!
Both the mains voltage and the high DC voltage up to 500V
inside the ACOM 700S amplier are LETHAL! For your
safety, disconnect the power plug from the mains and WAIT
AT LEAST three minutes EACH TIME, BEFORE removing the
cover of the amplier.
W A R N I N G HIGH VOLTAGE!
NEVER ALLOW, ESPECIALLY CHILDREN, to insert anything
into holes in the case - this may cause ELECTRIC
SHOCK! Never touch an antenna or antenna isolators
during transmission or tuning - this may result in an
electric shock or burn. Never expose the amplier to rain,
snow or any liquids. Avoid placing the amplier in
excessively dusty environments or in direct sunlight. DO
NOT OBSTRUCT COOLING ducts or vents.
W A R N I N G
Do not undertake repairs or changes in hardware or rmware
of your ACOM 700S amplier. Doing so will endanger your
or others‘ health or life, or damage the amplier and
the equipment connected to it. Such repairs or changes
are not covered by the warranty and may void
the warranty. The manufacturer is not liable for any
such repairs or changes. Any such repairs or changes are
sole responsibility of the person or persons engaging in
them.
C A U T I O N
To avoid damage (not covered by the warranty) please read the
INSTALLATION - Section 2 of this operating manual carefully.
If you have any doubts or questions regarding the installation,
operation or safety of the ACOM 700S amplier, please consult
your dealer immediately.
2. INSTALLATION
2-1. Unpacking and Initial Inspection
C A U T I O N
Before you commence installing the ACOM 700S amplier,
please read this manual thoroughly. Carefully inspect the
shipping carton and its contents as described below for missing
items (S. 1-3) or mechanical damages. If anything is missing or
is damaged (scratched, bent, crushed or something is rattling
inside or moving freely when turning the amplier over, notify
your dealer immediately! Delaying this notication may infringe
the insurance conditions of the carrier.

7
N O T E
Keep the original packing for possible future transportation.
Unpack and inspect carefully the contents of the cardboard carton for possible transportation damages.
On the amplier, check-up the chassis, front panel, display, buttons, rear panel connectors, main power
switch and fuses.
2-2. Amplier operating location selection; cooling.
Locate the amplier close to the place where will be used. You will need an easy access to the rear panel
for connecting cables, and of course, to the buttons and screen on the front panel.
The ACOM 700S is forced air cooled. Locate the amplier so that there are no objects or other devices
closer than 10cm (4”). The exhaust air can reach 65ºC (150ºF) and if the surrounding devices are
sensitive to heating from outside or use forced air cooling themselves, increase the distances accordingly.
C A U T I O N
Do not leave free paper, cloth or other light materials around
and under the amplier. 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.
2-3. Connecting the amplier in the shack
W A R N I N G
Before you connect the amplier to external grounding,
you should advise with a licensed electrician and conrm
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!
W A R N I N G
Never use the gas installation pipes for grounding. This can
cause an EXPLOSION!
W A R N I N G
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.
C A U T I O N
Bear in mind that the grounding installation may have to withstand
emergency currents over 15A with minimal voltage drop on it.
Therefore it may be necessary to improve its conductivity using
heavier leads and lower-resistance grounding path.The grounding
lead should be at least 4mm2 (AWG 11 or SWG 13).
For details and recommendations on the grounding and RF counterpoise system concerning the
electromagnetic compatibility see also S. 3-6(f).

88
a) GND stud - First connect the grounding stud of the amplier (located on the rear panel and
marked GND – Fig. 2-1) to the grounding system of the shack.
b) KEY-IN jack - amplier input for receive/transmit control from the transceiver.
The transceiver switches the amplier from receive mode into transmit mode (RX/TX) by grounding of
the KEY-IN input.
Run a shielded cable from the output of your transceiver, providing “ground on transmit”, to the KEY-IN
input on the amplier rear panel (RCA (PHONO) jack – Fig. 2-1). Use a standard RCA (PHONO) plug for
connection to the amplier.
Transceiver manufacturers give di󰀨erent names to this output, for example: TX-GND, SEND, T/R LINE,
RELAY, and others. In some transceivers “ground on transmit” output should be activated by a menu
or via changing a switch on the rear panel or inside the transceiver. See instructions in your transceiver
manual.
N O T E
Voltage on the KEY-IN jack does not exceed 12V and the current
is below 6mA. See also S. 8-2(a).
N O T E
Your amplier will not work if the KEY-IN input is not connected
correctly. If you experience any di󰀩culty consult your dealer.
Fig. 2-1 Rear panel connections
c) KEY-OUT jack - transmit-enabling control output from amplier to the transceiver.
The KEY-OUT jack on the rear panel provides an extra control signal from the amplier to the transceiver.
It can be used for improving the receive/transmit (RX/TX) switching safety.
C A U T I O N
KEY-OUT is a low-powered open-collector output, make sure
that the signal voltage coming from the respective transceiver
connection does not exceed 50VDC (open circuit) and the closed-
circuit current is below 20mA.

9
If your transceiver has a suitable input, that disables transmission unless grounded externally, we
recommend this to be connected to the KEY-OUT jack of the amplier. Use shielded cable terminated
with а standard RCA (PHONO) plug.
The transceiver manufacturers give di󰀨erent names to this input, for example: TX-INHIBIT, MUTE,
LINEAR, and others. Check the manual of your transceiver. Approach your dealer for details. If your
transceiver has no such input, do not worry – ACOM 700S will operate normally with KEY-OUT
unconnected.
d) RF INPUT - Connect a coaxial cable with a PL-259 plug from the transceiver output
(antenna jack) to the amplier RF INPUT jack.
C A U T I O N
In order to avoid a damage, turn o󰀨 your transceiver’s internal antenna tuner.
e) RF OUTPUT - Connect a suitable coaxial cable with a PL-259 plug from the RF OUTPUT
on the rear amplier panel to the antenna switch, tuner or antenna intended for the
respective frequency band.
C A U T I O N
If you use an amplier for the rst time in your shack, pay serious
attention to the size of coaxial cable from your amplier output
to the antenna. The cable must be capable of handling the
increased power safely, particularly on the 10m and 6m bands.
This warning applies equally to the antenna switch, tuner, and
the whole antenna system, especially multi-band trap antennas.
We recommend using RG213 or better. Consult your local coax cable supplier.
f) Preparation of the mains outlet for the amplier, requirements for the installation and
the mains voltage.
C A U T I O N
Before connecting your amplier to the power grid, be sure
that the outlet is correctly wired and is capable of providing the
required current i.e. (up to 10A from 200/240VAC mains and up to
16A from 100/120VAC mains). Also make sure that the grounding
lead is connected properly in the outlet, intended for the amplier.
If subsequently you connect the amplier to a di󰀨erent outlet,
check it as well.
It is preferable to use the mains outlet closest to the source. Make sure that the respective fuses and
voltage of your power mains match the ACOM 700S amplier’s specications (see S. 8-1(g)).
g) Main fuses.
C A U T I O N
Make sure you check whether the main fuses installed in
your amplier correspond to your local mains nominal voltage
and if necessary replace them as described in Section 7-2!
h) Power cord. Due to di󰀨erent standards in di󰀨erent countries, the ACOM 700S is
delivered without a power plug for the mains cable. You dealer might be able to provide
the correct Safety Class I plug. The ground lead of the power cable is colored yellow
with two green stripes. If you have any doubts about the correct way to connect these
wires, consult your dealer..

1010
2-4. Installing options and connecting to external devices (transceiver,
computer, etc.)
a) CAT/AUX interface – used for connecting and operating with various transceiver models (see
table 2-1 below and the respective menu in S. 5-3, table 5-1 and Fig. 5-3).
Most of the modern transceivers can be connected by CAT to the ACOM 700S. This will allow the
amplier to track the transceiver frequency without any transmission and change the bands automatically
when in Operate mode. The cable can be supplied optionally, ordered separately or home brewed
according to table 2-1 and the transceiver’s manual.
The CAT connection requires a cable made especially for the ACOM 700S and your transceiver. Wiring
diagrams of such cables can be found at www.acom-bg.com.
Note that some of the connections - to the transceiver’s BCD band data outputs and Band Voltage
outputs do not provide an exact frequency data, but only band data. Those connections cannot be
used when ACOM 700S works together with ACOM 04AT because the tuner needs to know the exact
frequency, not the band.
Table 2-1 shows the signals and the pin out of the CAT/AUX connector - rear panel of the amplier
Table 2-1
CAT/AUX
interface
PIN
NO. PIN NAME DESCRIPTION SPECIFICATIONS
Rear panel
view
1 RxDReceived Data TTL input
2RxDReceived Data RS232 input
3 TxDTransmitted Data RS232 output
4TxDTransmitted Data TTL output
5 GND Ground 0 Volt
6BAND voltage Analogue input 0 to +8V
7Band data 0 Bit 0 TTL input
8 Band data 1 Bit 1 TTL input
9 Band data 2 Bit 2 TTL input
10 Band data 3 Bit 3 TTL input
11 ON RMT Remote Pwr On +4.5 to + 15V / 3mA max
12 Debug mode CPU only Pwr Input +8 to + 15V / 0.4A
13 KEY-IN Tx Request Less than +12V / 6mA
14 KEY-OUT Tx Ready O.C. output, up to
+50V / 20mA
15 GND Ground 0 Volt
b) RS232 port. Table 2-2 shows signals and pinout of the RS232 port on the amplier’s rear panel.
This connector may remain unused until you decide to control the amplier remotely.

11
Table 2-2
RS 232
interface
PIN
NO. PIN NAME DESCRIPTION SPECIFICATIONS
Rear panel
view
1 - Not connected -
2TxD Transmitted Data RS232 level output
3 RxD Received Data RS232 level input
4- Not connected -
5 GND Ground 0 Volt
6DSR Remote Power On RS232 level input
7- Not connected -
8 CTS Remote Power On RS232 level input
9 - Not connected -
3. INITIAL POWER ON AND OPERATION
C A U T I O N
Do not turn the amplier on at least two hours after unpacking it
and installing in its nal operating position. Pay special attention
whenever the amplier is moved from a very cold place to a very
warm one because condensation may develop on the inside
resulting in damage to the high voltage circuits of the amplier.
Under these circumstances, do not turn the amplier on for at least
4 hours. A similar e󰀨ect could occur following a rapid warming of
the room, such as winter usage of a powerful electric heater.
After following all instructions in Section 2 INSTALLATION, check whether the rear panel mains switch
is turned o󰀨. Then plug the amplier in the mains outlet.
3-1. Low energy standby mode of the power supply
Now you can turn on the mains switch on the rear panel. This will activate only the low-energy
stand-by mode of the amplier power supply and will light up the red LED above POWER button,
while the main power supply is still o󰀨 and the display is dark.
3-2. Front panel - controls and readouts
a) POWER button. When the rear panel mains switch is turned on, push and hold 1-2 seconds to
start the amplier up. When the amplier is turned on, push to turn it o󰀨 (back to standby mode).
b) LED indicator above the POWER button. When lit red and the screen is dark, the amplier is in
standby mode and may be turned on by pushing the POWER button.

1212
Fig. 3-1 Front panel
c) 6 functional buttons keypad for manual (local) control of the amplier. The function of each
button is indicated on the display above it. Depending on the displayed menu, the buttons may
have di󰀨erent functions.
d) A color display showing the operating information.
3-3. Initial turning on
In order to start up the amplier, push and hold the POWER button on the front panel for one or two
seconds - аbout ten seconds later (boot sequence) the display will ash and show the basic screen with
the amplier information - Fig. 3-2.
The amplier may start either in Stand-by or in Operate mode – see S. 5-4 USER PREFERENCES -
AUTO OPERATE.
3-4. Basic screen
There are 9 information areas on the basic screen:
a) Information area for the frequency band – the edges of the currently selected BAND are
displayed.
If the amplier doesn’t receive any operating frequency data from CAT or via RS232, it will switch to the
last used band.

13
Fig. 3-2 Basic screen
b) Operating values and alarm messages area.
Any two operating values selected in the AMP MEASURE menu (S. 5-1) will be shown here.
The alarm messages (either WARNING or SOFT FAULT) appear on yellow background on the same
area and are ashing frequently in order to attract the operator’s attention (Fig. 4-1).
The WARNING messages appear only temporarily (for about three seconds), afterwards the indication
of the operating values is restored automatically (S. 4-4(a).
The SOFT FAULT messages appear in the same eld but they remain on the screen until the AUTO
OPERATE time is elapsed (S.4-1(c)) or until the operator pushes any button, then the operating values
indication is restored too.
c) Working mode indicator - OPR, STB or AUTO OPER (S. 4-1).
d) RX/TX indicator - reads the request for transmit (KEY-IN input). The RX indication is green and
the TX is red. The indicator will ash frequently if switch over is impossible.
e) Forward power bargraph and digital readout. Displays the power fed into the antenna.
f) Reected power bargraph and readout. Entering the red zone is not allowed.
g) PA transistor temperature bargraph and readout. Entering the red zone is not allowed.
h) CAT interface information. When CAT is deactivated, this eld is shaded.
i) REMOTE CONTROL information eld–ashing represents RS232 port dataow.

1414
3-5. Control system – buttons and menus
a) The OPR/STB and the BAND buttons are used for manual (local) control of the (Fig. 3-2):
- the left-most button OPR/STB switches over the amplier between Operate and Stand-by
modes;
- the next two buttons – BAND up and down arrows - change the frequency bands in ascending
or descending order;
b) The right-most button MENU (Fig. 3-2) provides access to the amplier’s settings and service
functions;
- in each menu the left-most button is always HELP and the right-most – always EXIT;
- the HELP button provides information about the current screen;
For more details of the control system and use of the menus see Section 5. MENUS – USEFUL TOOLS
AND OPTIONS.
3-6. Test transmission
To make sure that you have installed the amplier correctly, make a test transmission as described
below. Repeat these tests for each new band and antenna, as well as after installing a new or repaired
antenna, antenna switch, tuner, and / or the connecting cables.
a) Check of RF by-pass path of a non-driven amplier.
For this check the amplier must be completely installed and connected according to Section 2, but not
powered by the mains, i.e. the POWER ON switch on the rear panel must be turned o󰀨. In any case the
LED above the POWER button must be dark for this test.
First, check if the transceiver’s reception is normal. If you observe a signicant worsening of reception,
rst check for a problem in the coaxial connections to the amplier (S. 2-3(d),(e)).
If reception is normal, prepare the transceiver as follows:
- select a continuous carrier mode (CW, RTTY, FM);
- switch the microphone o󰀨 (decrease the mic gain), disable FSK;
- reduce the output power control to a minimum;
- select a suitable indication so that you can watch the RF power and SWR at the transceiver
output;
- if the transceiver has a built-in antenna tuner – switch it o󰀨.
Now in receive mode select a frequency which is not occupied at the moment and press shortly the
PTT or TX key while watching the output power and the SWR readings. If the power or SWR at the
transceiver output are too high (over 5W or SWR over 2:1) release the key and check for the reason as
follows:
- check again whether the power control is set at minimum;
- check whether the frequency is within the operating range of the selected antenna;

15
- check the good working order of the coaxial cables, connectors, and feed lines from the
transceiver antenna jack through the amplier, the antenna switch or external tuner (if there is
one) to the BALUN transformer, and the antenna itself (S. 2-3(e)).
If the power and SWR are as expected, transmit again and while watching the power and the SWR
readings, increase transceiver power gradually from minimum to maximum (but not more than 200W in
order to not overload the RF by-pass circuit of the amplier).
If SWR remains below 2:1 (preferably below 1.5:1) at the last test, decrease the power from the
transceiver to minimum again and continue with the next check-up.
b) Check-up in Stand-by mode.
Turn the amplier on, as described in Sections 3-1 to 3-4 (Fig. 3-2).
Make sure that the amplier is in Stand-by mode. Push the OPR/STB button if needed.
Repeat receive and transmit tests as it was done with the amplier turned o󰀨. During these tests note
also whether the forward and reected power bargraph and digital readout (S. 3.4(e),(f)) show respective
RF power presence. If the reected power exceeds the forward power, verify that the input and output
coaxial cables to the amplier are not interchanged (S. 2-3(d),(e)).
N O T E
The power indication accuracy is optimized around the 700W level and
usually it is unreliable below 40W.
c) Entering Operate mode.
At Operate mode the transceiver receiving should not su󰀨er. If it worsens and together with this the
indicator RX changes into TX although the transceiver is in receive mode, check the control cable
connected to the KEY-IN input – S. 2-3(b) for a short. The connection to the transceiver could be
wrong too.
d) Test transmission.
Switch to the same band as the transceiver and antenna.
Set the transceiver to a continuous carrier and minimum power. In Operate mode choose a free frequency
and push the PTT or CW key briey, while watching the amplier’s behavior:
- RX mode must has changed to TX;
- the reected power must read below 20W;
- the forward power must read between 20 and 150W with minimum drive power from the
transceiver (between 1 and 5W);
If the above test goes normally, push briey the PTT once again, this time watching the transceiver’s
SWR reading (i.e. the input SWR of the amplier) – this must be below 1.2:1.
e) Setting of drive level and typical operation.
After the successful passing of the above tests push PTT or CW key for several seconds, watching
the forward and reected power. Increase the drive power until the forward power at the amplier’s
output reaches 700W.

1616
Upon reaching 700W forward power check the following parameters (continuous carrier operation):
- the reected power must not exceed ~78W (for SWR 2:1) or better still to be below 28W (for
SWR 1.5:1);
- PA DC CURRENT must be between 23 and 30A; it is normal that the current varies within these
limits when changing operating frequency and antenna impedance;
- PA DC VOLTAGE must be within 42 – 44V;
- the transceiver’s SWR reading must be below 1.2:1.
Enter the MEASURE menu and check:
- the drive power from the transceiver must be between 15W and 40W;
- PA BIAS, which must be between 2.4 and 2.8V;
- PA TEMPERATURE, which must be between the ambient and 95ºC (203ºF), depending on the
power level and the duration of transmission.
f) Elimination of electromagnetic compatibility (EMC) problems.
If you use an amplier for the rst time in your shack, you may need to make some improvements in the
setup. It is possible you might experience tingling from metallic objects due to the stronger radiated RF
eld. It could a󰀨ect the operation of your station or systems outside, if they are too sensitive – typical
examples are the microphone, CW keyer, computer keyboard / mouse, as well as TV receivers, Hi-Fi,
intercom or telephone setups and others.
For instance, induction of RF currents into the microphone, CW keyer or computer keyboard, may lead
to distortion in the peaks or self-oscillation in SSB mode, “sticking” or breaking o󰀨 the dots or dashes
from a Morse keyer, or garbling computer screen images. For the elimination of such problems we
recommend that you take the following general measures:
- minimize the radiation from the feed lines by reducing the common mode currents in them,
improve the balance of antennas and feedlines;
- in case you use asymmetric antennas (GP and similar) install as many radials as practical (use
a well-developed counterpoise system);
- add current chokes on the coaxial feeders;
- place as far away as possible (also by height) the radiating elements of antennas from the
premises, where the a󰀨ected devices are located; in this sense, asymmetrical antennas without
a separate feeder (Long Wire, Windom, and similar) may cause more interference because their
radiating element begins immediately from the shack (part of it is the feeder itself);
- if the use of asymmetrical directly fed “wire” antennas is inevitable, use mainly half wave or half
wave multiple – they have a high input impedance, operate respectively with a small current
in the feed point, and in the grounding of the shack; thus you can reduce the strength of the
disturbing RF elds more than 10 times (at the same radiated power) compared to the case
with quarter-wave and multiple to quarter-wave antennas of this class – you should avoid them
because they have a low input impedance and operate with a large RF current in the grounding
system and in the power supply network respectively, i.e. they create stronger disturbances
(RFI);

17
- improve the RF grounding system: use the shortest and widest possible metal strips for the
connections to ground and between the di󰀨erent gear in the shack; connect one or more
counterpoises (sized for the problematic band) to the feeder shield at the point, where it enters
the building, and the same point - with the possibly shortest and widest connections - to the
grounding system: this is a very e󰀩cient measure, in particular if the shack is located on a high
oor above ground;
- to reduce the RF impedance of the grounding connections sheet metal stripes instead of exible
braids are preferred;
- thread ferrite beads or snap-in ferrites with medium permeability (800-4000) over the power
cord, the feeder and the signal cables leading to the a󰀨ected devices (TV etc); besides the
size, consider the frequency range in which the o󰀨ered ferrites are e󰀨ective – normally they
are optimized for suppression of interferences on HF (with larger permeability), with medium
permeability for HF-VHF or with low permeability - only the VHF range. The latter are ine󰀨ective
for HF;
- whenever possible use shielded cables and ground their shields at both ends;
- the addition of even quite simple low pass L/C or R/C lters directly to the disturbed inputs or
outputs of the devices is very e󰀨ective, provided it is practically applicable.
Last but not least, bear in mind that the benet of the above measures is two-fold. Firstly - they reduce
the interferences from your transmissions to the ambient environment and secondly - they reduce the
background noise oor for your reception. Practically, with no great e󰀨orts, implementing the above
measures, you can reduce the background noise oor with one or more S-units across the di󰀨erent
bands. This will allow you not to miss weaker stations, which will hear you because of your increased
transmission power.
4. AMPLIFIER OPERATION
4-1. Change of modes RX/TX and Operate/Stand-by;AUTO OPERATE
option
a) In Stand-by mode, as well as in the unpowered state, receiving and transmitting (no
more than 200W) with the transceiver is done via RF bypass between RF INPUT and
RF OUTPUT of the amplier. In Standby, the transceiver’s RF power is not amplied, the
control KEY-IN input does not a󰀨ect the operation, and the KEY-OUT output (S. 2-3(c))
follows the state of the KEY-IN input unconditionally. The bands cannot be changed neither
manually nor by CAT or remotely.
b) In Operate mode the receive-transmit (RX/TX) direction is controlled by the KEY-IN input:
- at open KEY-IN (Operate/RX mode), the transceiver receives the signals from the antenna
through the same RF by-pass path between RF INPUT and RF OUTPUT as with amplier
turned o󰀨 or in Stand-by mode;
- at grounded KEY-IN ((Operate/TX mode) the RF drive is amplied and fed to the antenna
through the RF OUTPUT connector.

1818
C A U T I O N
In order to provide time for the relays to switch safely from receive
to transmit, the transceiver should provide a dead time i.e. must
“notify” the amplier in due time by grounding the control KEY
IN input not later than 10ms before feeding drive power toward
the amplier RF input. Otherwise, the protection system will read
“HOT SWITCHING ATTEMPT” and will trip o󰀨.
In Operate mode the KEY OUT output (S. 2-3(c)) follows the state of the KEY-IN input only after all
conditions for safe transmission have been found good by the amplier control unit. The KEY OUT
output duly disables transmission, if the amplier is not ready.
The two modes - Operate and Stand-by - may alternatively be changed:
- either manually (locally) – by pressing the OPR/STB button – see the basic screen in Fig. 3-2,
or automatically – when if the AUTO OPERATE option is activated – see S. 5-4(c).
N O T E
Access to the Operate mode can be locked in the AMP SERVICE
menu, the OPERATE ACCESS option (S. 5-2 and Fig. 5-2).
c) AUTO OPERATE option can be turned on/o󰀨 by the operator in the USER PREFERENCES
menu – S. 5-4 and Fig. 5-4 - or by a remote control command.
When the AUTO OPERATE option is OFF, the two modes Operate and Stand-by can be changed
alternatively by the OPR/STB button or by a remote control command. At a SOFT FAULT protection trip,
the amplier will revert to Stand-by and wait for the operator to return it to Operate by pressing the OPR/
STB button.
When AUTO OPERATE is ON (S. 5-4), the amplier will start up in Operate mode. At a SOFT FAULT
protection trip, the amplier will rst revert to Stand-by, but will return automatically to Operate mode in
about 4 seconds.
Even at AUTO OPERATE on, the operator can revert to and remain in a Stand-by mode manually
by the OPR/STB button or by a remote command. The next OPR/STB button push will switch the
amplier to the Operate mode and restore the normal operation of the AUTO OPERATE option.
4-2. Band change, standard and expanded frequency coverage
When connected to a transceiver with CAT, the amplier will change frequency bands automatically,
following the transceiver’s operating frequency changes.
Without CAT connection, the bands can be changed either manually or automatically (by the built-in
frequency counter).
The bands are changed manually by the up and down BAND buttons.
For an automatic band change via the built-in frequency counter, make a quite short pre-transmission
(100ms is enough) – a CW dit, or a sound on SSB) and release a PTT for a moment before the main
transmission.
If the new frequency is out of the amplier’s frequency range (S. 8-1(a)), the transmission request will
be denied and the following fault message will appear on the screen:
“FREQUENCY OUT OF RANGE”
The amplier specications are guaranteed within the bands listed in S. 8-1(a)). Frequency coverage
changes could be negotiated with the manufacturer.

19
4-3. Operation with an external antenna tuner
At antenna SWR over 1.5:1, it is advisable you use an external tuner. The ACOM 04AT Remote
Automatic Antenna Tuner is designed to work with the ACOM 700S. Use of other antenna tuners is not
recommended.
4-4. Automatic protection system
The control unit (S. 7-3(b)) keeps track of most amplier analogue and logic signals in all modes.
Those are the receive/transmit control signal, the output relay contact state and switching times, the
RF drive frequency and drive power (the input power), the nal transistors DC current and DC voltage
on the drains as well as, the gates bias voltage and the heat sink temperature, the main power supply
components temperature, the RF output forward and reected power, and others. Some derivative
parameters, as the power gain, the SWR, the heat power dissipated by the nal transistors dynamically
and others, are watched too.
In the event a parameter maximum is exceeded, the amplier will assess the risk and will trigger one
of the three levels of protection, as described in items (a) to (c) below. Every event is accompanied by
a warning text on the screen (Fig. 4-1). A sound alarm will be also produced, if set on in the “USER
PR E FER E N CES ” – g . 5 -4.
Fig. 4-1 – Appearance of an alarm message
a) The rst protection level is WARNING. When a value watched by the control unit approaches
the protection threshold, the transmission is not interrupted, but a message appears – for
example “Drive Power too High”, “Drain Current too High”, or another – Fig. 4-1.
You can continue to transmit in these conditions, but you have to take some measures, for example, to
reduce a bit the drive power from the transceiver. The warnings remain on the screen for at least three
seconds so that they can be read through and will disappear after the reason has dropped o󰀨.
b) The second protection level is a SOFT FAULT – when a value exceedsed the safe level,
but does not put the amplier in a danger of a failure.

2020
At the second level (SOFT FAULT) the amplier reverts to Stand-by mode for four seconds or permanently
depending on whether the “AUTO OPERATE” option had been activated. A respective message is
shown on the screen, for example “Excessive Reected Power”, “Excessive Drain Current”, and others,
as well as with a sound alarm (unless the sound had not been muted – S. 5-4).
Unlike those for a WARNING, the SOFT FAULT messages remain on the screen and persist until the
operator pushes any button - in order to conrm that the message is read - or until the OPERATE mode
will be resumed automatically when the AUTO OPERATE is active – S. 5-4)
SOFT FAULT’s call for fast and simple correcting actions by the operator, such as, for example, reducing
the drive power, improving of load SWR through retuning the antenna tuner, antenna change, etc.
c) The third and most serious protection level is a HARD FAULT. The amplier will be turned
o󰀨 automatically to avoid possible further damages.
When the protection trips o󰀨, the data about the fault is stored in the memory and the front panel screen
is blanked. There is also a sound alarm - a series of CW letter F.
If the reason for tripping the protection is not obvious, you can try to turn on the amplier. If the amplier
allows it after the fault, a fault message will appear with information about the reason for the latest
automatic shutdown (for example, overheating of the power supply unit or of the PA stage).
After pushing any button, the fault message will disappear, and if there are no current problems (for
example, the overheated unit has already cooled down), the amplier operation will be restored. In
the event a parameter maximum is exceeded again, a new message will appear on the screen, or the
protection will trip again immediately after the recovery attempt.
If the problem persists, contact your dealer – S. 1-2.
At each “HARD FAULT” shutdown the amplier stores data, concerning the controls and values, the trip
time, and others. Your dealer or his service may ask you to read this data out from the amplier screen
or by RS232 interface and store it in a computer le – see menu FAULTS LOG, Sections 5-5 and 7-4.
5. MENUS – SETTINGS AND OPTIONS
By pushing the MENU button (the rightmost) the user invokes the menu selection screen (Fig. 5). Each
menu can be selected by the ITEM (up and down) buttons and SELECT.
The items in each menu are selected and controlled by the same six buttons as in the basic screen,
but they have new functions.