OM POWER OM2002+ User manual

OM2002+
SOLID STATE 145 MHz
POWER AMPLIFIER
User Manual
OM POWER, s. r. o.
930 30 Báč 126 E-mail : [e-mail]
SLOVAKIA Web : www.om-powwer.com

2
Welcome to the solid state high power amplifier owners family! Thank you for purchasing a new model for the
2m amateur band. Parameters, the quality of design and functionality meet the requirements of the market and
are the result of our own development.
This product is covered by 3 years of warranty period. We wish you many years trouble-free use of this
equipment, lot of fun and successful connections in the world of amateur radio.
The OM POWER Team
Conventions used in this manual
DANGER / WARNING : Information to prevent injury to yourself when completing a task.
CAUTION: Information to prevent damage to the components when completing a task.
NOTE: Tips and additional information to help you complete a task

3
TABLE OF CONTENTS
1. GENERAL INFORMATION 6
1.1. Introduction 6
1.2. Specification 6
1.2.1. Parameters 6
1.2.2. Protection Circuits 8
2. SAFETY INSTRUCTIONS 9
3. GENERAL DESCRIPTION 11
3.1. Front and Rear Panel 11
3.2. HF Part 15
3.3. Power Supply 16
3.4. Safety Devices 18
4. INSTALLATION 19
4.1. Grounding 19
4.2. Coaxial Cable 20

4
4.3. Control Cable 20
4.4. Main Supply 21
4.5. Cooling 22
5. OPERATION 23
5.1. Operation Elements 24
5.2. Preparing for Use 25
5.3. Setup Menu 26
5.3.1. Language selection 27
5.3.2. Display contrast 27
5.3.3. Display delay 28
5.3.4. Bias switch 28
5.3.5. Preamplifier delay 29
5.3.6. Bias current 30
5.4. Operating Mode 31
6. MAINTENANCE 35
6.1. Fault conditions 35

5
6.2. Fuses 38
6.3. Cleaning 38
7. BLOCK DIAGRAM 39
8. TIMING 40

6
1. General Information
1.1. Introduction
The OM Power model OM2002+ is a single band, solid state amplifier, designed for duty operation on 2 meter’s
amateur band with all modes and no time limit. It is equipped with a Freescale high rugged N-channel double
MOSFETs. This amplifier is characterized by compact design, small size and a low weight.
1.2. Specification
1.2.1. Parameters
Frequency Coverage 144 –148 MHz Amateur Band
Power Output 1800W in CW
1500W in SSB (linearity), RTTY, AM, FM and digi modes,
50% duty cycle
Input Power 10 to 15 W for full output power 1800W
Input Impedance 50 Ohm, VSWR < 1.3 : 1

7
Power Gain Typically 20 dB
Output impedance 50 Ohm unbalanced
Maximum output SWR 1,9 : 1 for full output power 1800W
SWR protection: Automatic switching to STBY , when reflected power is
180W or higher
Intermodulation distortion - 32 dBc
Suppression of harmonics < -70 dBc
MOSFET 2 x MRFE6VP61K25HR6
Cooler 2 axial fans (cooler) + 1 axial fan (power supply)
Supplying 100 –250VAC , 50 –60 Hz
Power Supplies inside 50V DC switching mode PS
12V DC for logic and protection circuits
Size 318 mm x 144 mm x 362 mm [12.5” x 5.7” x 14.3”]
(Width x height x depth)
Weight 11.1 kg ( 24.4 lb )

8
1.2.2. Protection Circuits
There is several special protection circuits used in the amplifier. They are activated when one or more of next
parameters exceed defined values or some unwanted occasion occurs.
Output power too high
Reflected power too high
Drain current too high
Differential drain current to high
Power coupler fault
VSWR too high
DC voltage too low or DC voltage error
Input power too high (hardware protection of input overdrive & software protection)
Inside temperature too high
Soft start for power supply protection (PS feature)

9
2. Safety Instructions
Before you will start to install and operate power amplifier, read carefully next safety instructions!
AVOID CHILDREN to play around PA or to touch power amplifier or connected cables in working
condition, or to push anything into the holes!
Never turn the amplifier on without the upper lid in place.
The OM2002+ amplifier is neither to be used in a WET or HUMID environment nor to be exposed to
RAINFALL!
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!
Before opening the upper lid of the amplifier make sure that power supply has been disconnected.
Take out power cord from the outlet!

10
The amplifier must be installed in such a way that free flow of hot air from inside is allowed. The
amplifier must not be installed in a constrained surrounding (i.e. tight shelves etc.)
The amplifier must be properly grounded during operation.
During operation the amplifier must be installed in such a way that the rear panel will stay
accessible.
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.
Read this manual carefully. Follow 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!

11
3. General description
3.1. Front and Rear Panel
Main switch (green) on the right side and OLED display are visible on the front panel. After switch PA ON, the
display lights up in couple of seconds and shows the controls and indicators.

12
RF Output See Note RF Input Grounding Point
Mains Plug Power Supply Cooler inside

13
LAN - Local Area Network connection for REMOTE CONTROL of PA
PREAMP - RCA Phono, +12V / 100mA for an external RX preamplifier switching
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 in 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 /2 mA)
KEY OUT - RCA Phono –Output signal PTT (maximum switching of 50V / 100mA)
Option. Two SMA connectors for distribution of transmitter and receiver path with local RX preamplifier
connection possibility. Internal circuit ensure cold switching.

14
Top view on the power amplifier
Input board with output coax relay together with SWR
board is visible on the right upper side.
Left side shows the main RF part –two boards with
MOSFETs amplifiers, everyone for max. 1 kW of output
power.
Down are two axial fans on the left side, together with
display board and controller board.
On the right bottom side the PCB of small 12V DC power
supply is visible.

15
3.2. HF part
OM2002+ power amplifier was designed to achieve the RF performance of the MOSFETs, when applied to the
144 –148 MHz frequency band. Design was tuned for performance at 1800W CW output, 50VDC. It consists of
„no tune“ distributed element matching circuits designed to be as small as possible. For operating it is important
that adequate heat sinking was provided in the design.
RF boards are the most important
parts of the PA. Detailed view on the
one board. Freescale MOSFETs are in
use.

16
The coaxial transformer turns ratio was chosen to meet required impedance level and the length of the coax
was tuned to achieve maximum efficiency and maximum power transfer between the device and its load
impedance.
Low Pass Filter is installed behind the amplifier to
attenuate harmonics. Part of the output coupler is
visible, too.
3.3. Power Supply
The amplifier uses two power supplies. A professional switching mode power supply 50V / 60A for power
amplifier, and small 12V power supply for logic and protection circuits.

17
Main power supply contains special soft start
circuits, uses its own fan, which is visible from
the rear side of the PA. It has its own
overloading protection and logic to control
fan speed. Power amplifier should be
connected to any external source of AC in the
range from 100 VAC to 277 VAC, from 45 to
60 Hz. It can be powered by a portable
generator, for example.
Small Power Supply for logic and protection circuits. This PS is using for an external
preamplifier, too. Current consumption of external preamplifier is limited to 200mA.
It is powered from the main power supply.

18
3.4. Safety Devices
Control and monitoring circuits ensure control and safety during malfunctions of the PA. These are on the
Control board and the Protection board. Control board is located behind the front panel. Protection board is
visible on the right hand side of PA, close to the input/output relay.
Protection board with Input circuits. Input splitter together with HW
protection is visible down on the board. Some of protection circuits are
installed on the Control board (behind the front panel), too.

19
4. Installation
Read this chapter carefully prior starting with 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 next parts.
4.1. Grounding
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.

20
Connect your transceiver to the same grounding system of your shack carefully!
Use minimum length of cables and make sure that the connections are both physically and electrically sound.
With poor grounding, you may risk damaging to 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, Belden 9913 or similar coaxial cable suited for high
power is recommended. Both the INPUT and OUTPUT N sockets with Teflon insulation are used.
4.3. Control Cable
Control cable maintains TX / RX switching of the PA (TX GND). The cable must be 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.