OM POWER OM2000+ User manual

MADE IN SLOVAKIA
OM2000+
SHORTWAVE PLUS 50 MHz
POWER AMPLIFIER
WWW.OM-POWER.COM
OM POWER, s.r.o. 93030 Báč 126,
SLOVAKIA
Contact : [phone]
e-mail : om[email protected]

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TABLE OF CONTENTS
1. GENERAL INFORMATION ..................................................................... 3
2.1. Introduction …………………………………………………………………. 3
2.2. Specification …………………………………………………………………. 3
2.2.1. Parameters …………………………………………………………………. 3
2.2.2. Protection Circuits …………………………………………………………………. 3
2.2.3. Indicators …………………………………………………………………. 4
2.2.4. Features …………………………………………………………………. 4
2. SAFETY INSTRUCTIONS …………………………………………………………………. 5
3. GENERAL DESCRIPTION …………………………………………………………………. 6
3.1. HF part …………………………………………………………………. 6
3.2. Power Supply …………………………………………………………………. 7
3.3. Safety Devices …………………………………………………………………. 8
4. INSTALLATION …………………………………………………………………. 8
4.1. Grounding …………………………………………………………………. 9
4.2. Coaxial Cable …………………………………………………………………. 9
4.3. Control Cable …………………………………………………………………. 9
4.4. Main Supply …………………………………………………………………. 10
4.5. Cooling …………………………………………………………………. 10
5. OPERATION …………………………………………………………………. 11
5.1. Operation Elements …………………………………………………………………. 11
5.2. Preparation for operation ………………………………………………………………. 13
5.2.1. Display menu …………………………………………………………………. 14
5.2.2. Settings menu …………………………………………………………………. 16
5.2.3. Service menu …………………………………………………………………. 19
5.3. Operation mode …………………………………………………………………. 22
5.4. Tuning of the Power Amplifier ……………………………………………………… 23
6. MAINTENANCE …………………………………………………………………. 27
6.1. Indication of Fault Conditions ……………………………………………………… 27

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6.2. Fuse Replacement …………………………………………………………………. 31
6.3. Tube Replacement …………………………………………………………………. 31
6.4. Cleaning …………………………………………………………………. 31
7. APPENDIX …………………………………………………………………. 32
7.1. Primary AC selection …………………………………………………………………. 32
7.2. Removing the HV Transformer ……………………………………………………. 33
7.3. Block Diagram of the OM2000+ Power Amplifier ………………………… 34

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1. GENERAL INFORMATION
1.1. Introduction
he OM Power model OM2000+ is designed for all short wave amateur bands from 1.8 to 29.7 MHz
(including WARC bands) plus 50 MHZ and all modes. It is equipped with a ceramic tetrode
FU-728F.
1.2. Specification
1.2.1. Parameters
Frequency Coverage Amateur Bands 1.8 –29.7 MHz including WARC + 50 MHz
Power Output 2000+ W in SSB/CW on HF bands, 1500 W in CW/SSB on 6m
1500 W in RTTY
Input Power Usually 40 to 60W for full Output Power
Input Impedance 50 Ohm, VSWR < 1.5 : 1
Power Gain 15 dB
Output Impedance 50 Ohm unbalanced
Maximum Output SWR 2 : 1
SWR protection Automatic switching to STBY, when reflected power
is 250W or higher
Intermodulation distortion 32dB below nominal output
Suppression of harmonics < -50 dBc
Tubes FU-728F Ceramic tetrode
Cooler Centrifugal blower + Axial fan
Power supply Switchable 220V, 230V, 240V, 50/60 Hz
Transformers One toroidal transformer 3kVA
Dimensions 390 x 195 x 370 (width x height x depth)
Weight 24 kg
1.2.2. Protection Circuits
There are several protection circuits used in the amplifier. They are activated when one or
more of next parameters exceed defined values or some unwanted occasion occurs.
VSWR too high
Anode current too high
Anode voltage error
Screen current too high
T

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Screen voltage error
Grid current too high
Grid voltage error
Heating voltage error
Mistuning of PA
Temperature to high
Soft start for fuses protection
“switch-on blocking “ at opened amplifier
1.2.3. Indicators
Number of indicators visible on the front panel will inform you about value of some parameters
or operation status:
OLED display 4 x 20 characters
Analog Wattmeter Double system meter for forward and reflected power
measuring
LED Indicators ON AIR –amplifier in transmitting mode
STBY –standby mode
FAULT –failure, switching off for abt. 4 sec
ON –ON status
1.2.4. Features
Manufacturer implemented some of the company’s current development results with most
wanted operating and safety features into this new model:
High level of protections
Antenna switch for 3 different antennas
Memory for faults and warnings, easy maintenance
Automatic set-up anode current (BIAS) –no need to adjust manually after changing
the tube
Temperature controlled 2-speed centrifugal blower ( turbine ) + axial blower
Full QSK with silent relay
Many operational parameters to display
Easy transport due to detachable HV transformer
The smallest and lightest 2000 W PA on the market

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2. SAFETY INSTRUCTIONS
WARNING!
DANGEROUS HIGH VOLTAGE INSIDE!
The power amplifier is using high voltage up to 3000V DC, which is very dangerous for human life!
Read next safety instructions carefully first, before you will start to install and operate power
amplifier! NEVER VIOLATE NEXT RULES!
WARNING!
NEVER ALLOW CHILDREN to play around PA or to touch power amplifier or connected cables in
working condition, or to push anything into the case holes!
WARNING!
Never turn the amplifier on without the upper lid in place. DO NOT ATTEMPT TO SHORT OR BYPASS
safety switch under upper lid!
WARNING!
The OM2000+ amplifier is neither to be used in a WET or HUMID environment nor to be exposed to
RAINFALL!
WARNING!
Do not turn the amplifier ON without having connected the ANTENNA or properly rated DUMMY
LOAD! A hazardous HF voltage may build up on the antenna connector after turning the amplifier on
with no antenna or dummy load connected!
WARNING!
Before opening the upper lid of the amplifier make sure that power supply has been disconnected
AT LEAST 10 minutes allowing the electrolytic capacitors to discharge fully. Disconnect power cord
from the outlet!
WARNING!
Any work inside the PA (internal fuses replacement, tube replacement, etc.) can be carried out only
by professionally qualified person!

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CAUTION
The amplifier must be installed in such a way that free flow of hot air from the tube is allowed. The
amplifier must not be installed in a constrained surrounding (i.e. tight shelves etc.). During long time
operation ventilation grid can reach high temperature. Do not touch it!
CAUTION
The amplifier must be properly grounded during operation.
CAUTION
During operation the amplifier must be installed in such a way that the rear side remains accessible.
CAUTION
The amplifier is an A category product. In a household it can influence other electric appliances. In
such cases the user is to take proper actions to mitigate this disturbance.
CAUTION
Read this manual carefully. Fallow all of instructions during installation and operation to avoid
damage to the amplifier not covered by manufacturer´s warranty! Do not attempt to perform any
change of hardware or software!
3. GENERAL DESCRIPTION
3.1. HF part
his amplifier is using a ceramic tetrode FU-728F in a grounded-cathode circuit (input into control
grids). The OM2000+ amplifier achieves excellent linearity by the voltage stabilization of the
control grid bias and the screen voltage. The power input is given to the control grids, using a
broadband input circuit with an input impedance of 50 Ohms. This adaptable input circuitry ensures a
good input SWR (better than 1.5 : 1) on all amateur bands.
T

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The output of the amplifier is a Pi-L circuit. The ceramic capacitor for TUNE and LOAD are divided. This
enables the amplifier to be tuned exactly and makes it possible to easily return to the previously set
positions after band changes.
Top view on the opened OM2000+
Tetrode FU728F Antenna Switch Blower Power Supply Board Switch-ON Board
Output Pi-L Circuit Tuning Capacitor Subpanel HV transformer
3.2. Power Supply
Power amplifier is using one 3 KVA toroidal transformer. A soft start is provided using relays and
resistors (placed on the switch-ON board). The high voltage is made by combining 4 x 530V AC (total
abt. 2950V DC) @ 1.2A. Each has its own rectifier and filter. In the high voltage circuit, safety resistors
are employed to protect the amplifier against overload (placed on the power supply board).
The separated supply for screen grid is regulated by stabilization with MOSFET and delivers abt. 330V
DC at 100mA. Control grid voltage is also stabilized (-120V DC). Change of stabilized first grid voltage
is controlled by the software (EBS for example).

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3 kVA toroidal transformer is visible on the left
side. Switch-ON board is in the front, Power
supply board behind it.
CAUTION
Primary section of the transformer is switchable for 220 - 240 VAC. Factory setting is 230VAC. If the
AC voltage in your network is 220 or 240 Volts, you need to set the correct value before first starting
of the PA. See part 7.1. for more information.
3.3. Safety Devices
Control and monitoring circuits ensure control and safety during malfunctions of the PA. These are
placed on the Control board, which is located on the chassis subpanel.
One of the important safety element is
mechanical switch for AC blocking at opened
amplifier.
4. INSTALLATION
NOTE
Read this chapter carefully prior you will start installation. Before unpacking inspect shipping carton
first, if it is not damaged. Keep all of packing parts for possible future shipment. Check unpacked power
amplifier. If you find some damaging, contact your dealer immediately to keep full warranty.
During installation go step by step according to the next parts.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.

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4.1. Grounding
CAUTION
The amplifier has to be grounded properly! Connect the screw on the rear panel of the amplifier to
your local grounding system with a copper cable; use a cross-section of 4 mm2 at least.
Connect your transceiver to the same grounding system of your shack carefully! Use minimum length
cables and make certain that the connections are both physically and electrically sound. With poor
grounding, you may risk damaging your equipment, having problems with TVI/BCI or your transmitted
signal may be distorted.
4.2. Coaxial Cable
The output of the transceiver is to be connected to the input of the amplifier via RG58 or similar
cable. For the connection between the power amplifier and the antenna, RG213 or similar coaxial
cable suited for high power is recommended. All the INPUT and three OUTPUT (ANT1, ANT2, ANT3)
SO-239 sockets with Teflon insulation are used.
Rier view of the amplifier OM2000+
Fuses Mains Plug HF Outputs
Auxiliary fan Grounding point Control HF Input
4.3. Control Cable
Control cable maintains TX / RX switching of the PA (TX GND). The cable is shielded. On the side of the
power amplifier a CINCH-socket is used. On the side of your transceiver you have to use a socket
suitable for this transceiver. During transmitting the middle pin is connected to the ground. The relays
of the OM2000+ have to be switched earlier than HF is applied (cold switching). Modern transceivers
they have a time delay between PTT switching and power output.

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CAUTION
If you are using an older transceiver or transmitters without time delay, we recommend to connect
the PA in such a way that the transmit/receive switch (foot switch for example) is connected with
the KEY IN socket of the amplifier. The KEY OUT socket is to be connected with the PTT socket at the
transceiver.
The amplifier is equipped with safety devices, which ensure that the output relay is not switched under
power mistakenly (hot switching).
KEY IN RCA Phono - Input signal PTT switching voltage / current - 5V /2mA)
KEY OUT RCA Phono - Output signal PTT (maximum switching of 30V / 50mA)
4.4. Main Supply
CAUTION
Be sure you got PA with properly terminated line cable, corresponding with your power system’s
outlet. If not, contact your dealer. In such a case you should make the necessary changes using a
licensed electrician.
WARNING!
Be sure that your power system is correctly wired and properly rated! To use adequately sized and
connected grounding system is also very important.
4.5. Cooling
CAUTION
The amplifier must be installed in such a way that free flow of hot air from the tube is allowed. Do
not obstruct air intake and exhaust areas of the PA.
The centrifugal blower provides basic cooling of the amplifier. Blower is activated by switching the PA
on and it is turned off when cooling is finished (approx. 1-5 min after switching off the PA depending
on the temperature of the tube). Blower speed (2 steps) is setting automatically according to the tube
temperature. For long time operation (contests) the PA is equipped with an auxiliary fan, which can
operate in three modes (go to Settings menu for more details).
Detailed view on the tube and blower area.
Antenna switch (above) is installed inside the
metal box.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.

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5. OPERATION
WARNING!
Before switching PA on, make sure that amplifier is grounded, antenna or dummy load is connected,
and line cord is putted to the outlet. Be sure you selected AC input by 7.1.
CAUTION
Before switching PA on, check all connections between PA and TCVR.
CAUTION
Do not turn PA on for at least 2 hours after unpacking it and locating in its operating location.
Especially when amplifier is moved from a cold place to a warm one because not visible
condensation may develop, and this could result in damage to the high voltage circuits of the PA.
CAUTION
Never try to change antenna output during a transmission to avoid warranty loss.
NOTE
When you decide to have a short operating break, place the amplifier to the standby mode rather than
switch it off.
5.1. Operation elements
There is couple of operational elements accessible or visible on the front panel.

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BAND - Band selector switch
TUNE - Anode capacitor for tuning
(higher frequencies to "0"; lower frequencies to „100“).
LOAD - Output capacitor tunes antenna load resistance to the amplifier.
Capacity is low at „100“ and high at "0" on the scale.
TUNE LED - Three LEDs assists in tuning the amplifier
WATMETER - Analog double system meter for forward and reflected power measuring
ON / OFF - Long press (abt. 1 sec.) to switch PA ON/OFF
RESET - Short press to reset faults or warnings
0 / I Power ON small 12V APU for logic and protection circuits
You can switch Antenna ports even if PA is switched OFF.
S1 S2 S3 S4

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ON AIR - Transmitting mode LED
STBY - Standby mode LED
FAULT - Failure LED
ON - PA is „ON“ LED
S1 - OPER / STBY - Press to switch between Standby and Operation mode
ESC - Return to the previous level
S2 - MENU - Enter the Menu
DOWN - Scroll down
S3 - DSP - Change display (DSP1, DSP2, DSP3)
UP - Scroll up
S4 - ANT - Change Antenna output (ANT1, ANT2, ANT3)
ENT - Confirm the selection
More functions of S1-S4 buttons will be described in next parts of this manual.
5.2. Preparation for use
The first necessary thing after connecting AC to the power amplifier is switching main (green) switch
to „ I “. Welcome message and then starting information appears on the display:
After switching main switch ON welcome
message appears shortly.
Starting message shows which antenna is
connected. To switch PA ON press ON-OFF
button for abt. 1 second.
Warming time takes abt. 210 seconds. It is
possible to enter MENU during this time, but
with limited possibilities (display settings can
be changed, for example).
You can change ANT output, if necessary.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.

14
If you change DSP during warming time, you lost count down information. Press BACK (S1) to restore
starting message.
When warming time expires, PA switches
itself automatically to the STBY mode.
You have two possibilities now - switch PA to
OPER mode and start operation, OR to go
thru MENU and submenus to set display
parameters, some hardware parameters or to
enter the service menu.
In the STBY or OPER mode Antenna output can be changed (ANT1, ANT2, ANT3) by pressing S4. This
feature is active also if PA is switched OFF. However, the main switch (green) must be ON in order to
switch the antenna.
Display information can be changed, too.
Press S3 to do it.
There are 3 different display settings possible
in the OM2000+. To set display parameters,
go to the next part of this manual for more
details.
5.2.1. Display menu
The OLED display shows couple of parameters or texts. Display has 4 lines. Three of them are editable.
In every line user can select different parameters, using MENU. See next pictures.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.

15
After pressing MENU (S2) S1–S4 buttons
changed their functions. To edit display
parameters, press DISP button.
Press DIS1 to edit first display.
Now you can define parameters for first three
rows. Start with first line, press 1Row button.
Go UP or DOWN to select desired parameter.
Press ENT to confirm selection.
There are 4 possible settings for the first line (one bar-graph or three pairs of different parameters):
Forward bar-graph
Forward Power _ Reflected Power
Forward Power _ SWR
Plate voltage Up _ Plate current Ip
Second and third line are divided to the left and the right side, editable independently. To each of these
positions one of the 15 different parameters should be set.
If you finish first line settings, press ESC to go
back to the row selection.
To start edit second line, press 2Row button.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.

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S2 and S3 now changed their functions.
To edit left side of the second line, press LEFT
button.
Go UP or DOWN to select desired parameter.
Press ENT to confirm selection.
If you finish left side settings, press ESC to go
back to the side selection.
To start edit right side, press RIGHT
button….etc.
Second and third line programmable parameters are:
Forward Power
Reflected Power
Input Power
SWR
TUNE
Temperature
Frequency
Plate voltage –Up
Plate current –Ip
Screen voltage –Us
Screen current –Is
Screen current –graph
Grid voltage –Ug
Grid current Ig
Heating voltage –Uf
5.2.2. Settings menu
Settings menu offers EBS settings, factory default parameters restoring, display contrast settings and
auxiliary fan operating modes.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.

17
Electronic Bias Settings (EBS) is one of significant feature of the power amplifier. It allows to set low
plate current after pressing the PTT regardless of whether you have CW or SSB mode, until RF signal
is no present at the input. At the moment when RF signal comes to the input of PA, bias will
automatically change to its working value.
EBS level means level of the Input power, where EBS starts working. Default EBS value is 0.2 W. We
recommend using EBS ON. Significant accompaniment of used EBS is temperature reducing.
To enter Settings menu, go to MENU first,
then press SET button.
Use UP or DOWN button to select EBS
ON/OFF. Press ENT to enter EBS status
settings.
Press ON or OFF to set status of EBS. Press
ENT to confirm selection.
Press ESC to go one level back.
Use UP or DOWN button to select EBS level
parameter. Press ENT to enter EBS level
settings.
Use UP or DOWN button to set EBS level
value. Press ENT to confirm EBS level value.
Press ESC to go one level back.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.

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If you wish to restore factory default
parameters, use UP or DOWN button to
select Restore default parameters. Then press
ENT.
Press YES for 1 second to confirm restoring.
Use UP or DOWN button to select LCD
contrast. Press ENT.
Use UP or DOWN button to set contrast value.
Press ENT to confirm settings.
Use UP or DOWN button to set auxiliary fan
working condition.
Press ENT to confirm settings.
Use UP or DOWN button to set first mode. The
fan will activate at a fixed temperature
(programmed in uP).
Press ENT to confirm settings.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.

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Use UP or DOWN button to set second mode.
The fan will activate together with PTT.
Press ENT to confirm settings.
Use UP or DOWN button to set the third
mode. The fan will turn always when PA will
be ON. Press ENT to confirm settings. Press
ESC twice to release Settings mode.
5.2.3. Service menu
In the Service menu it is possible to verify software version. This menu allows user to check total
operating hours and listing in the memory, where reported faults and warning messages are stored.
You can display particularly warning messages and particularly error messages. See chapter 6 for more
information regarding to warnings and faults occurrence. There you can find a coding table together
with a limited values for the safety circuits activation also.
In the Service menu a value of EBS1 and EBS2 can be automatically adjusted. This is used for example
when it is necessary to make adjustment after replacing the tube. Automatic control of EBS, however,
can be done at any time. EBS1 default value is 20mA of Ip, EBS2 default value is 250mA of Ip.
Minimal turns of the blower are the matter of settings in the Service menu, too.
Use Service menu after replacing the tube.
This is step No. 1.
To enter Service menu, go to the MENU first,
then press SERV button.
Use UP or DOWN button to check software
version.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.
Type of supported TCVR and working
frequency are visible on the display.
AUTO LED is ON.