Instruction Manual OM2500 HF SHORTWAVE POWER AMPLIFIER OM POWER, s. r. o. 930 30 Báč 126 SLOVAKIA E-mail: om-power@om-power.
TABLE OF CONTENTS 1. GENERAL INFORMATION 1.1. Introduction ……………………………………………………………….. 4 1.2. Specification …………………………………………………………….... 4 1.2.1. Parameters …………………………………………………………………. 4 1.2.2. Protection Circuits ………………………………………………………… 4 1.2.3. Indicators ………………………………………………………………….. 5 2. SAFETY INSTRUCTIONS ……………………………………………… 5 3. GENERAL DESCRIPTION ………………………………………………. 6 3.1. HF part ……………………………………………………………………. 6 3.2. Power Supply …………………………………………………………….. 7 3.3.
7. APPENDIX ……………………………………………………………... 16 7.1. Band Blocking …………………………………………………………… 16 7.2. Block Diagram of OM2500 HF Power Amplifier (USA version) ………...
1. GENERAL INFORMATION 1.1. Introduction The OM Power model OM2500HF is a manual tuning, full legal limit amplifier, designed for heavy duty use on all short wave amateur bands from 1.8 to 29.7 MHz (including WARC bands) and all modes with no time limit. It is equipped with one GU84b ceramic tetrode. 1.2. Specification 1.2.1.
1.2.3. Indicators There are couples of LED and bar graph indicators visible on the front panel to inform you about value of some parameters or operation status: Bar graph indicators Power output - 50 LED Reflected power – 20 LED Current at screen Ig2 – 10 LED Anode voltage, anode current, tuning – 30 LED LED Indicators Current at control grid (Ig1 – 2 LED) WAIT – preheating of tube (180 sec) STBY – standby OPR – operation condition FAULT – failure, switching off for abt. 4 sec 2.
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! 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.) CAUTION! The amplifier must be properly grounded during operation.
Top view on the opened OM2500 HF Tetrode GU84B Output Pi-L Circuit PWR meter Blower Switch-on board Tuning capacitor Power supply board Subpanel 3.2. Power Supply Power supply of the amplifier is comprised of two of 2,0 kVA toroidal transformers. A soft start is provided using relays and resistors. The high anode voltage is made by combining 8 x 350 V (total 2800V) @ 2A. Each has its own rectifier and filter.
3.3. Safety Devices Control and monitoring circuits ensure control and safety during malfunctions of the PA. These are on the Control board, which is located on the chassis subpanel. 4. INSTALLATION NOTE Read this chapter carefully prior you will start installation. Before unpacking inspect shipping woody container first, if it is not damaged. Keep all of packing parts for possible future shipment. Check unpacked power amplifier.
Rear view of the amplifier OM2500 HF MAINS CABLE FUSES CONTROL 4.3. OUTPUT INPUT 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 OM2500 HF have to be switched earlier than HF is applied (cold switching).
4.4. Main Supply WARNING! Power Amplifiers OM2500 HF are manufactured for several different power systems. For US territory only one mains cable is used for two phases (2x120V) system. Cord is not removable from PA. Amplifier is equipped with two mains fuses (see rear panel). 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.
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 in 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.
In STBY, if WAIT-LED is on or the amplifier is OFF, the amplifier is in bypass-mode and your transceiver is directly connected to the antenna. Maximum allowed power in bypass mode is 400 Watts! RF OUTPUT Bar graph – shows output power . REFLECTED POWER Bar graph – shows reflected power from the antenna. Maximum level is 350W otherwise amplifier switches to STANDBY mode. Ig2 Bar graph – measures the current of the second grid from -20mA to +80mA.
The toroidal transformers are switched on step by step. The cooling blower for the final tube is switched on. The multi-meter bar graph measures the high voltage; the normal value is 2.8 kV The WAIT LED lights up CAUTION After switching on, please confirm that the blower is operating properly. Air must be flowing from the ventilating aperture above the tube. If there is any concern, or no air flow, press the “OFF”-button immediately ! Heating the tube takes about 150 seconds.
8. Set TUNE knob in such a way, that the TUNE-LED lights up maximum left. 9. Set LOAD in such a way, that the TUNE LED on the TUNE scale lights up under the “V” sign. If it is possible to obtain the LOAD in 2 positions, set the position that is father to the right 10. Repeat tuning several times according to 8 and 9 11. Increase the input power until an output power of approximately 1500 W is reached. 12. Repeat steps 8 and 9 13.
CAUTION If the fault will repeat 3 times after each other the control circuits will turn the amplifier to STBY. Bringing the amplifier to OPR is enabled by using the OPR/STBY switch only. After reaction of safety circuits, the FAULT LED will be lit up for approx. 5 sec, depending on the nature of the fault.
6.3. Tube Replacement In the case of vacuum tube damaging, contact the manufacturer or your dealer for ordering new one. You will get instructuions how to change tube and how to preset proper parameters, too. If you are not comfortable to replace vacuum tube itself, contact your Service Center, please. In the USA call or write to: Array Solutions 2611 North Belt Line Road Suite # 109 Sunnyvale, TX 75182 Tel: (214)954-7140 Email: sales@arraysolutions.com 6.4.
7.2.
