OPERATING MANUAL EMTRON DX-3SP HF LINEAR AMPLIFIER February 2009 Emtron DIVISION OF EMONA ELECTRONICS PTY. LTD. 92-94 Wentworth Avenue, Sydney 2010, Australia Tel. +612 92110988 www.emtron.com.
INITIAL SETTINGS FOR PLATE AND LOAD CAPACITORS TEST BAND FREQUENC Y FACTORY SETTINGS USER SETTINGS 50 OHM LOAD ANTENNA PLATE 28.600 MHz 10m 24.900 MHz 12m 21.200 MHz 15m 18.100 MHz 17m 14.200 MHz 20m 10.125 MHz 30m 7.070 MHz 40m 3.600 MHz 80m 1.800 MHz 160m 1.850 MHz 160m 1.
TABLE OF CONTENTS 1 GENERAL DESCRIPTION .................................................................................................................................................... 5 1.1 DX-3SP – INTERNAL VIEW .................................................................................................................................................. 6 2 TECHNICAL SPECIFICATIONS ..................................................................................................................
12 TROUBLESHOOTING - IF SOMETHING GOES WRONG........................................................................................ 21 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9 12.10 NO POWER .......................................................................................................................................................................... 21 FAN NOT WORKING.............................................................................................................................
DX-3SP LINEAR AMPLIFIER Serial No ………… OPERATING MANUAL January 2009 CAUTION The DX-3SP has been designed for 100% safe operation and long life. Interlocking sensing circuitry constantly monitors conditions inside the amplifier. It must be noted however, that the high voltages present inside the DX-3SP are EXTREMELY DANGEROUS. Do not remove the top cover under any circumstances if any leads are still plugged into the rear of the amplifier especially if the AC lead is plugged in the power outlet.
1.1 DX-3SP – Internal View The main components of a DX-3SP amplifier are shown in the picture below. BLOWER Mains Isolation Relay ANT.
2 TECHNICAL SPECIFICATIONS FREQUENCY COVERAGE: Complete (manually tuned) coverage of the nine HF amateur bands: 1.800 – 2.000 MHz 3.500 – 4.000 MHz 7.000 – 7.500 MHz 10.000 – 10.300 MHz 14.000 – 14.350 MHz 18.000 – 18.500 MHz 21.000 – 21.500 MHz 24.000 – 24.500 MHz 28.500 – 29.990 MHz TRANSMITTING MODES: The DX-3SP supports SSB, CW, AM, FM, RTTY and SSTV. OUTPUT POWER: Typical 4000 watts carrier or up to 5000 W PEP DUTY CYCLE: Suitable for SSB operation. CW: 4 minutes transmit, 1 minute receive.
METERING: The front panel moving LED display systems indicate: “Moving light” LED indicators: • output power • reflected power • screen grid current (positive / negative) • plate voltage • plate current Five single LED’s: • on air • ready • fault • overdrive warning • SWR cut-off indicator EBS: Electronic Bias Switch - automatically switches the standing current (about 0.5 A) to a lower ("prebias") value - when there is no input drive.
3 UNPACKING The DX-3SP is packed in a heavy duty package easily sufficient to protect the amplifier during transportation, even in case of fairly rough handling. The weight of the mains transformer does mean, however, that dropping the amplifier would without doubt result in some damage when the transformer is installed inside. 3.1 Opening the carton When opening the packing, do not cut the carton. Save the packing material for possible further re-use.
Move the transformer close to the front panel (do not slide it – lift it and move). This will create more space at the back, so that the high voltage wires can be connected. Plug the two wires from the high voltage power supply into the 2 pins at the lower part of the transformer. Connect also the 4-way connector and the orange / black wire. The mating single wire comes from the blower mounted relay and it is orange / black. It is the only single wire that will mate with the connector. See Fig. 3 below.
5 FRONT PANEL The following controls and indicators are present on the front panel: 5.1 Controls BAND SWITCH A nine position switch selects the desired frequency range. The operating bands are indicated in metres. PLATE TUNE Tunes the amplifier operating frequency. A chart of approximate starting settings is given in Table-1 LOAD TUNE Tunes the amplifier output loading. A chart of approximate starting settings is given in Table-1 ON/OFF Switches the AC power on and off.
ON Air - single LED, green. When pressing PTT, this LED turns on (while in OPERATE and READY). READY - single LED, yellow. Turns on at the end of warm-up period, when the mains power to DX-3SP is switched on. It turns off for about 2 minutes if the plate current protection is triggered. In this case, the FAULT light also turns on. It turns OFF while in an SWR Fault condition or over-temperature Fault. FAULT - single LED, red.
7 ELECTRICAL CONNECTIONS 7.1 Connections to Transceiver / Exciter Signal connections Before making any connections, ensure that DX-3SP is not connected to AC power, and the transceiver is not transmitting. Connect the antenna first to the DX-3SP output. Then connect the transceiver output to the DX3SP RF input. Plug the PTT lead into the RCA socket marked PTT on the rear panel. The most appropriate interconnection layout is shown in Figure 5 below.
PLEASE NOTE: The DX-3SP should not be connected to a mains supply of less than 200VAC! Move the thick brown wire to 240, 230, 220 or 200V.
8 DX-3SP DESCRIPTION 8.1 RF Section The RF section occupies the right hand side of the DX-3SP (looking from the top - front). See picture in 1.1. RF Switch and tuned circuits At the front of the amplifier are two variable capacitors, for plate and load tuning. A 9-position ceramic switch is employed for the 9 operating bands. Next to the switch is the 40 to 160 metre tank coil (torroid). The silver plated, large diameter copper tube is the 10 to 30 metre tank coil.
8.6 Antenna relay / QSK module The QSK module acts as an antenna relay controlled by the transceiver, via the control board. It switches the antenna between the transceiver, during reception, and amplifier, during transmission. It is also used to bypass the RF from the transceiver, directly into the antenna, when the amplifier is in standby mode, or during special conditions like overdrive, bad SWR or other error conditions.
9 POWERING UP Before switching the power on, check all the necessary connections: Earth, Antenna, Transceiver, PTT. Make sure the 2 switches on the front panel are in the positions: OFF, STBY. Switch now the mains power ON (The power switch to ON position). The "soft start" system will take about 5 seconds to fully turn the power on. SWR light will turn on briefly, then off. Wait for the DX-3SP to warm up, until the READY light turns on. This takes about 2 - 3 minutes.
10.1.1 General For each band and operating frequency, the transceiver settings must match the position of the BAND switch on the front panel of the DX-3SP, while the PLATE and LOAD knobs must be adjusted for optimum operation which gives – in conjunction with the input drive level, the maximum output power that can be obtained for that input power. When the tuning is correct, this will also result in a minimum plate current, minimum plate dissipation and good linearity. 10.1.
3. During the preliminary tuning, switch PTT on and off several times, to allow time for tube cooling. The tube dissipation (at a given drive level) is minimum when tuning is optimum. In short, be brief, with tuning "bursts". 4. Preliminary tuning, as described above, is only necessary when operating for the first time in a certain band. When the final settings for PLATE and LOAD have been found for the particular working conditions especially the antenna used, note your settings on Table 1.
If there is green Ig2- indication, for a given input drive, try to minimise it and even to obtain red indication. For this, it is likely that LOAD needs to be moved clockwise, followed by PLATE retuning. If red indication is achieved, try to maximise it by tuning. With low drive / low output it is likely the Ig2 indication to be green, increase as more drive is applied, then decrease and become red at higher output. 10.1.
10.2.3 Hints on good linearity and efficiency Operating with good efficiency: If you are watching the plate current indicator, you must be aware that the total power the amplifier is drawing from the mains is proportional to the plate current. Power that is not sent to antenna is dissipated by the tube. As explained in the Tuning section, the best tuning achieves a maximum power output at the same time with a minimum plate current, drastically minimizing the tube dissipation.
If it is still not working, unplug the power cord from the mains, then remove the fuses from the fuse holders on the rear panel of DX-3SP and check them with an ohmmeter. If a fuse is blown, replace it with a fuse of the same type and try again. If the fuse blows again, or if the fuses were not blown in the first place, contact your supplier. 12.
In such a case, it is possible that the high voltage is still shown on the meter, but it does not reach the tube. In any case, this is a major fault. Put the amplifier on STBY and the flashing will stop. Then switch the power off and contact your supplier. 12.7 Sparks / Discharges in RF area Very high RF voltages are present in the amplifier during the operation at high power. Incursion of dust or even suicidal insects can cause such temporary problems. 12.
14 GLOSSARY AC Alternating Current ALC Automatic Level Control AM Amplitude Modulation BALUN Balanced / Unbalanced Transformer BNC Bayonet Neil-Concelman Connector CW Continuous Wave dB decibel DC Direct Current EBS Electronic Bias Switch FM Frequency Modulation HF High Frequency HV High Voltage IEC International Electro-technical Commission IMD Inter-Modulation Distortion LED Light Emitting Diode PEP Peak Envelope Power RF Radio Frequency RTTY Radio Tele Type SSB Single
15 APPENDIX 1: SCHEMATIC DIAGRAMS 15.1 Block Diagrams 15.1.1 DX-3SP Block Diagram DX-2sp Block Diagram Back Panel Temp sensor Fans Soft start Primary AC power cord Line 1 30 amp fuse Line 2 30 amp fuse Front panel On/Off switch Transformer Stby/Opr switch Control board module High Voltage supply RF/TUBE Module Band switch Plate PTT relay Load ALC output ALC adjust RF input RF output RF relays Display panel RF sensor Block Diagram 3/15/06 by: M.
FAN Brown Brown 4 3 2 1 Red 26 Brown SW LINE 1 (Phase) A 0V FEMALE MALE 1 2 3 Soft Start Module K1 1 2 3 120V Brown 1 Rear Panel 200V Blue Figure 8 Note: The 2 Y2 capacitors (4.7nF) are now on the PCB Yellow Blue 4.7nF/250Vac/Y 2 Yellow/Green 1 MT1 RELAY Neutral/Ground G MT2 4.
10k C1 R3 470k/2W 270k C4 R1a C13 100/2W 100/2W 220uF/25V 4.7nF/250Vac/Y2 D2 1N4007 VC C 9 220uF/25V + R1 110V 13 SC AP R11 200-240V JP1 3.9k/5W R2 NOT INSTALLED 56R/2W 14 D SS RC GN D PC 12 11 6 8 RGT 7 16 AS TPA LS SS 4 LOAD C10 R4 100nF 150/2W C9 100nF C8 + C12 C7 100nF 47nF (TRANSFORMER) R2 56R/2W MT2 GATE C2 220nF/275Vac/X2 3.3uF TRIAC Figure 9 27 100k SR SSC U1 R10 10 3 CL CS VS 15 2.2nF 1 2.
15.2.
15.2.3 RF Module Simplified To QSK switching PLATE VOLTAGE 1000pF/6kV 1000pF/6kV 1000pF/6kV R.F. OUT MODULE (Simplified Diagram) 1000pF/6kV PLATE CHOKE 8 3x150 1 A106 A106 A106 CV1 CV2 500pF 1100pF Lp SAFETY CHOKE V2 8 FU-728F 3 100/13W 2200pF A106 1 100/13W RS1 3 CONTROL BOARD A106 3x150 Lp 330/13W V1 FU-728F 3k 10nF/1kV 140V 10/5W 140V 275V 140V 1 2 3 4 5 6 7 8 9 220k 75k/5W 140V (BLUE) 1N4148 10nF/1kV 10/5W 220k 2.2k 10nF 10nF/1kV 2.
15.2.
JP1 + D5 D1 1N4148 1N4148 RL1 - 15.2.
15.2.6 RF Sensor L1 IN L2 OUT C4 10pF C1 10pF R3 22/2W D1 C2 10pF C12 47pF C3 40pF R1 22/2W C5 10pF D1N4148 C7 C8 220pF 220pF R2 2.2k DIR D2 D1N4148 C13 47pF C6 40pF R4 2.
+5V 1 X3-14 1nF L1 L2 L3 L4 L5 L6 L7 L8 L9 L10 Y Y Y Y Y Y Y Y Y Y L11 L12 L13 L14 L15 L16 L17 L18 L19 L20 Y Y Y Y Y R R R R Y + L21 L22 L23 L24 L25 L26 L27 L28 L29 L30 L31 L32 L33 L34 L35 L36 L37 L38 L39 L40 G G G G G G G G G G G G G G G G G G G G 15.2.
15.2.
15.3 Control Board and Adjustment Points The drawing below shows all the connections to the control board and the adjustment points.
15.3.
15.3.
16 APPENDIX 2: WAVEFORMS 16.1 QSK Switching Figure 20 trace) No “Hot switching”: The output relay (Top trace) switches first, and then the RF drive is applied (Bottom 16.2 Linearity Linear Trapezoid Modulation Pattern Figure 21 Sample of linearity curve obtained by using a two-tone generator and a PC oscilloscope in XY mode.
17 APPENDIX 3: ADJUSTMENTS ADJUSTMENTS TO EMTRON DX-3SP AMPLIFIERS CAUTION Most of the following adjustments require the amplifier to be open and powered up. This also implies defeating the mains interlock safety switch, which is extremely dangerous since high voltage / high power DC and AC and RF voltages are exposed. We do not recommend anyone to do this, since extreme precaution and safety measures are required.
There are 3 bias adjustment potentiometers: POT3 (BIAS), affecting both tubes and POT10 (BS1) and POT9 (BS2) only adjusting the bias to the tube connected to the pins BS1 and BS2 respectively. Adjust initially POT10 and POT9 fully clockwise, then rotate back about 20 degrees (they are likely to be already in the required position). Turn the screen switch (on the sub-chassis) say – to the left. Key the amplifier with NO RF DRIVE and adjust POT3 for ½ of the total standing current, or about 0.25 A.
17.1.4 EBS ADJUSTMENT Adjustment: POT4, marked EBS Usually this adjustment is performed on 20m (14.200 MHz), but it can be done on any band. Transmit into a dummy load or antenna. Apply very low input drive. With the EBS activated (with the EBS jumper in the forward position, or ON): Checking the existing adjustment: increase slowly the input drive, starting from zero, until the EBS system activates the amplifier.
the EG2 pin on the control board. While operating the amplifier at full power, by rotating the LOAD knob, IG2 can be varied and the screen voltage can be measured. This way the current limit of the screen regulator and the ig2 indicator on the front panel can be checked quickly, without the need for a special load. However, the amplifier has to be opened and wires used to extend the screen voltage connection to an external current meter and volt meter. 17.1.
R20 BIAS PRE-BIAS SWR EBS SENSITIVITY EBS ON EBS OFF SCREEN VOLTAGE Ip PROTECTION TP2 SCREEN CURRENT LIMIT Figure 22 Control Board – Component side view 17.2 Display Board Adjustments The display board is pre-adjusted during testing. However, when a new display board is installed in the amplifier, most adjustments need to be fine-tuned. Remove the front panel glass to gain access to adjustments. The ig2+ adjustment is recommended also when the control board is replaced. 17.2.
Adjust potentiometer AMP for correct indication. 17.2.2 PLATE VOLTAGE Adjustment: VR2, marked: VOLT Using a voltmeter with a high voltage probe, measure the plate voltage. Adjust potentiometer VOLT for correct indication on the display. 17.2.3 REFLECTED POWER Adjustment: VR3, marked: RF R Make sure the amplifier is in STANDBY. Reverse the input and output RF connections.
17.3 RF Sensor (Bridge) Adjustment The amplifier is switched off for this adjustment. Check if adjustment is required as per following procedure, before opening the sensor. Unsolder and remove the metal cover. Connect a transceiver to the input and a dummy load to the output of the amplifier. Connect a voltmeter (+) to pin SW1 or SW2 on the control board (with yellow/black wires). Apply 30-50W RF on 20m (14.2MHz) and read the voltage.
Emtron DIVISION OF EMONA ELECTRONICS PTY. LTD. 92-94 Wentworth Avenue, Sydney 2010, Australia Tel. +612 92110988 www.emtron.com.
