Emtron DX-2 Manuel utilisateur

OPERATING MANUAL

EMTRON DX-2

HF LINEAR AMPLIFIER

Emtron North America

Distributed Exclusively in North America By:

Emtron North America

6531 Boundary Run Drive

DX-2, Serial No…………

INITIAL SETTINGS FOR PLATE AND LOAD CAPACITORS

TEST

FREQUENCY

BAND FACTORY SETTINGS

50 OHM LOAD

USER SETTING

ANTENNA

PLATE LOAD PLATE LOAD

21.200 MHz 15m

18.100 MHz 17m

14.200 MHz 20m

7.070 MHz 40m

3.600 MHz 80m

1.800MHz 160m

1.850 MHz 160m

1.900 MHz 160m

TABLE 1

TABLE OF CONTENTS

1GENERAL DESCRIPTION.................................................................................................................................1

1.1 DX-2 –INTERNAL VIEW............................................................................................................................. 2

2TECHNICAL SPECIFICATIONS ......................................................................................................................3

3UNPACKING.........................................................................................................................................................3

3.1 OPENING THE CARTON................................................................................................................................4

3.2 OPENING THE DX-2 COVER ........................................................................................................................4

4INSTALLATION I ENVIRONMENT.................................................................................................................4

4.1 REQUIRED ENVIRONMENT ..........................................................................................................................4

4.2 POWER REQUIREMENTS ..............................................................................................................................4

5REAR PANEL .......................................................................................................................................................4

5.1 POWER /EARTH CONNECTIONS...................................................................................................................4

5.2 RF CONNECTIONS .......................................................................................................................................4

5.3 TRANSCEIVER CONTROL .............................................................................................................................4

6FRONT PANEL.....................................................................................................................................................5

6.1 CONTROLS..................................................................................................................................................5

6.2 DISPLAYS ...................................................................................................................................................5

7ELECTRICAL CONNECTIONS ........................................................................................................................6

7.1 CONNECTIONS TO TRANSCEIVER /EXCITER ............................................................................................... 6

7.2 EARTH AND MAINS CONNECTIONS ..............................................................................................................6

7.3 TERMINATING THE POWER CABLE (EXPORT VERSION) ................................................................................7

7.4 OPERATION AT 230V, 220V AND 200V (EXPORT VERSION)........................................................................ 7

8DX-2 DESCRIPTION............................................................................................................................................7

8.1 RF SECTION................................................................................................................................................7

8.2 MAINS TRANSFORMER ................................................................................................................................8

8.3 H. V. POWER SUPPLY .................................................................................................................................8

8.4 SOFT START MODULE.................................................................................................................................. 8

8.5 SENSOR MODULE ........................................................................................................................................8

8.6 ANTENNA RELAY /QSK MODULE...............................................................................................................8

8.7 DISPLAY BOARD .........................................................................................................................................8

8.8 CONTROLLER BOARD..................................................................................................................................8

9POWERING UP ....................................................................................................................................................9

10 OPERATION .........................................................................................................................................................9

10.1 TUNNING PROCEDURE - ......................................................................................................................9

10.1.1 General........................................................................................................................................................9

10.1.2 Preliminary tuning ......................................................................................................................................9

10.1.3 Final tuning...............................................................................................................................................10

10.1.4 Potential problems during tuning..............................................................................................................10

10.2 ALC ADJUSTMENT ..............................................................................................................................10

10.3 USING YOUR DX-2 ...............................................................................................................................11

10.3.1 CW / RTTY and all digital modes..............................................................................................................11

10.3.2 Voice modes (SSB) ....................................................................................................................................11

10.3.3 Hints on good linearity and efficiency.......................................................................................................11

11 SWITCHING THE POWER OFF .....................................................................................................................11

12 TROUBLESHOOTING - IF SOMETHING GOES WRONG ........................................................................ 12

12.1 NO POWER ................................................................................................................................................12

12.2 FAN GOES TO HIGH SPEED .........................................................................................................................12

12.3 FAN NOT WORKING ...................................................................................................................................12

12.4 IF THE FAULT LIGHT TURNS ON............................................................................................................... 12

12.5 OVER-TEMPERATURE CUT-OFF .................................................................................................................12

12.6 OVER-CURRENT CUT-OFF .........................................................................................................................12

12.7 IG2BLINKS FAST -NO PLATE VOLTAGE ....................................................................................................12

12.8

PARKS

ISCHAR

GES IN

AREA

................................

..........

14 GLOSSARY .........................................................................................................................................................13

15 SERVICE .............................................................................................................................................................14

15.1 GENERAL..................................................................................................................................................14

15.1.1 CONTROL BOARD...................................................................................................................................14

15.1.2 DISPLAY BOARD ADJUSTMENTS .........................................................................................................18

15.1.3 RF SENSOR ADJUSTMENT.....................................................................................................................19

16 DIAGRAMS AND SCHEMATICS....................................................................................................................21

16.1 DX-2 BLOCK DIAGRAM ...........................................................................................................................21

16.2 CONTROL BOARD CONNECTIONS AND ADJUSTMENT POINTS ...................................................................22

16.3 DISPLAY BOARD ADJUSTMENT POINTS ....................................................................................................23

16.4 CIRCUIT DIAGRAM –HIGH VOLTAGE POWER SUPPLY ....................................................................24

16.5 CIRCUIT DIAGRAM –AC INPUT AND SOFT START WIRING –U.S. VERSION .....................................25

16.6 CIRCUIT DIAGRAM –RF MODULE .........................................................................................................26

16.7 CIRCUIT DIAGRAM –DISPLAY BOARD ................................................................................................27

16.8 CIRCUIT DIAGRAM –SOFT START –240 VOLT VERSION.......................................................................28

16.9 CIRCUIT DIAGRAM –QSK........................................................................................................................29

16.10 CIRCUIT DIAGRAM –CONTROL BOARD ..............................................................................................30

16.11 CONTROL BOARD –COMPONENT LEGEND ...............................................................................................31

16.12 CONTROL BOARD –SOLDER SIDE TRACK WORK ......................................................................................32

DX-2 LINEAR AMPLIFIER

Serial No …………

OPERATING MANUAL

January 2003

CAUTION

1 GENERAL DESCRIPTION

The Emtron DX-2 Linear Amplifier is a 1500 watt carrier output power, for the 160m through 15m amateur bands (7 bands), housed in a desk-top

cabinet with self-contained power supply and cooling system.

It utilises a single high performance tetrode, type GU84B (4CX2500), a ceramic metal tube with a plate dissipation of 2500W. The tube is air cooled by

a commercial grade forced air turbine blower system with 2 speeds, controlled by a temperature sensor. Tetrodes offer exceptionally stable operation

and levels of quality performance far exceeding that which can be expected from triodes. The harmonic output and intermodulation distortion achieved

with this tube are exceptionally low. This is especially important when dealing with a high output power.

The Emtron DX-2 is supplied as standard with a host of features including solid state metering, comprehensive protection systems and extremely long

duty cycle. In addition, a unique Emtron QSK module is available as an option. With this installed, extremely rapid switching times between transmit

and receive are possible, with consequent advantages when using the digital modes.

Operation of the DX-2 is greatly simplified by the absence of meter switching, mechanical displays and front panel level setting controls. The front

panel moving LED display systems indicate plate voltage, plate current, output power, reflected power, screen grid current, ready, overdrive warning,

and high SWR cut-off indication.

The Emtron Electronic Bias Switch (EBS) automatically switches the standing current (typically 0.37 A) off when there is no modulation. This reduces

the average tube dissipation. On initial switch on, the unique Emtron "soft start" circuitry ensures that no damaging AC surge currents are generated.

Professional, fine output tuning adjustment is possible, due to the 6: 1 reduction mechanism fitted.

The DX-2 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-2 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. Before

any component inside the high voltage, power supply or output section is

touched, unplug all rear panel leads and allow at least 5 minutes of 'off

time'. After that, you should further check thisby momentarily shorting the

tube anode to the chassis with a suitable insulated lead.

1.1 DX-2 – Internal View

The main components of a DX-2 amplifier are shown in the picture below.

2 TECHNICAL SPECIFICATIONS

FREQUENCY COVERAGE: Complete (manually tuned) coverage of the seven HF amateur bands:

1.800 – 1.900 MHz

3.500 – 4.000 MHz

7.000 – 7.500 MHz

14.000 – 14.350 MHz

18.000 – 18.500 MHz

21.000 – 21.500 MHz

TRANSMITTING MODES: Both continuous and low duty cycle modes are supported. That is, the DX-2 supports SSB, CW, AM,

FM, RTTY and SSTV.

OUTPUT POWER: Typical 1500 watts PEP

DRIVE POWER: Nominal 50-60 watts for full rated output.

INPUT IMPEDANCE: Nominal 50 ohm passive impedance, unbalanced. VSWR 1.4:1 or less.

OUTPUT IMPEDANCE: Tuned circuit, nominal 50 ohm load, VSWR maximum 2.6:1 set by protection circuit.

DISTORTION: Third order intermodulation products are more than 35 dB below rated output.

HARMONICS: Harmonic output is better than 47dB below the rated output.

FAULT PROTECTION: The extremely comprehensive fault protection systems include circuitry to monitor:

•plate current: should the plate current exceed a safe value, the amplifier goes to standby mode for 2 minutes.

•screen grid over-current: Absolute tube protection is offered with visual warning and a reduced power level being enabled if

the screen current exceeds a pre-set limit.

•temperature: Should the tube's temperature exceed a specific level, amplifier operation is suspended until the temperature

drops to a safe level.

OPERATIONAL PROTECTION

•Overdrive protection: Should the DX-2 be overdriven, a LED warning indictor will light up when the linearity limit is

reached. If the drive is increased further, a 2 second cut off (by-pass) will follow.

•SWR protection: Should the DX-2 sense a load impedance with SWR exceeding 2.6:1, an LED warning indicator will light

up, simultaneously with a 3 second cut off (by-pass).

METERING: The front panel moving LED display systems indicate:

•plate voltage

•plate current

•output power

•reflected power

•screen grid current

•ready and fault conditions

•overdrive warning

•SWR cut-off indicator

ALC: Negative going, adjustable output level.

EBS: Electronic Bias Switch - automatically switches the standing current (about 0.37 A) to a lower ("pre-bias") value - when there is

no input drive.

PRE-BIAS: A small current will flow in the tube when the amplifier is keyed on, but there is no modulation. This will prevent a harsh

sound at the beginning of each word, when the EBS is activated and the tube goes through a non-linear zone, before reaching the

correct initial bias.

QSK: is an option that makes possible the antenna switching at very fast rate - typically 3ms switching time in each direction.

FACTORY INSTALLED ONLY.

SOFT START: when switched on, the mains power is gradually applied to the transformer, over a period of about 5 seconds, to avoid

the high in-rush current typical for such high loads (transformer “Bang” and filament over-current).

COOLING: the cooling fan has 2 speeds, with electronic temperature control. Most of the time the fan runs at low speed, for reduced

noise.

OPERATING TEMPERATURE: 0 to 40° Celsius

FUSING: Two 20A fast acting fuses on the rear panel

DIMENSIONS: 435mm wide, 190mm high, 465mm deep WEIGHT: 4lkg (90 lb) unpacked

3 UNPACKING

The DX-2 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 commercially rated mains transformer does mean, however, that dropping the amplifier would without

doubt result in some damage.

3.1 Opening the carton

Save the packing material for possible further re-use. Shipment of your DX -2 in other than factory packing may result in non-warranty

damage.

3.2 Opening the DX-2 cover

An inspection of the interior of the amplifier should reveal no damage or adversely affected components. Remove the 4 screws on each

side and remove the cover. Should there be any form of problem, notify your supplier immediately.

4 INSTALLATION I ENVIRONMENT

4.1 Required environment

The DX-2 amplifier can be operated at an ambient temperature between 0 and 40° Celsius. It should be installed in a place with a good

ventilation and protected from the direct sunlight. At least 5 cm (2 inches) of free space must be left at the rear and left and right, for

ventilation. Do not place any object on top of the amplifier, especially above the ventilation opening.

An environment free of dust, smoke and high humidity is required, as for any high powered RF amplifier. Dust, or particles resulting

from burning fire wood or coal could be responsible for sparks or electrical discharges between the capacitor plates, or in other parts of

the RF section.

4.2 Power requirements

When operating at full power, up to 16A from the 240 VAC mains is required. Ensure that the AC supply you intend to use is fully

rated and properly fused. The Emtron "soft start" circuitry ensures that there are no momentary surges of current at power-up, therefore

the fuse does not need to be over-rated. However, the wiring of the mains supply for the amplifier should be able to handle the power at

full load with minimal drop in the voltage, to insure the performance of your DX-2 does not suffer.

5 REAR PANEL

The following connectors and controls are present on the rear panel

5.1 Power / Earth connections

A wing-nut Earth connection is provided at the rear of DX-2. A good Earth link must be provided here. Connect this first, before

making any other connection to the amplifier. The AC power input is protected by two 20A fuses.

5.2 RF connections

RF INPUT

The RF input is an SO-239 female connector. A 50 ohm coaxial cable line of good quality terminated with a PL-259 coaxial

connector is required to connect the transceiver or exciter output to the input connector of your DX-2 amplifier.

RF OUTPUT

The RF output is also a female SO-239 connector. The use of a high quality RG-8A/U, RG-213 or similar 50 ohm coaxial

cable line terminated with a ‘VHF’ type PL-259 connector is essential. Similarly, a VSWR of 2: 1 or better is

mandatory. Remember too, that the EMTRON DX-2 amplifier can deliver 1.5 kW continuously in the SSB mode. Not all antennas can

handle such power.

5.3 Transceiver control

ALC

The ALC output is via a black female RCA connector.

This is an ALC system for use with transceivers or transmitters having a negative-going ALC system and possessing an external ALC

input jack. A shielded patch lead with an appropriate connector at one end and a male RCA connector for the DX-2 at the other end is

required. Check the specifications of your transceiver for a suitable connection.

PTT

The PTT input is a female RCA connector (red). This line controls the transmit/receive switching system. This jack must be connected

to transceiver or exciter relay contacts which are open on RECEIVE and closed on TRANSMIT. In the standard version (DX-2 fitted

with a l2V antenna relay), the PTT input presents an open circuit voltage of + l2V with respect to the chassis, with an impedance of

about 70 ohm. Therefore, a current of typically 0.17 A must be switched by the transceiver or exciter.

In the QSK version, the voltage at the PTT input is typically 28V (and up to 36V unloaded), with an impedance of about 240 ohm. A

current of about 0.12 A has to be switched in this case.

ALC CONTROL

This is a user-accessible control for setting the negative voltage at the ALC output. Further details are given in section 10.2

6 FRONT PANEL

The following controls and indicators are present on the front panel:

6.1 Controls

BAND SWITCH

A nine position switch selects the desired frequency range. The 7 operating bands are indicated in metres. The last two switch positions

are not used in the U.S. version of DX-2. If a special licence is produced, the amplifier can be delivered with all 9 bands operational.

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 initial switch on, the standby mode is enabled. Note also the appropriate switch down sequence,

given in Section 11.

OPR/STBY

Enables the amplifier once it has warmed up. In STANDBY mode, the screen voltage is removed and any RF power applied to the

input, is bypassed to the output. If this switch is changed to OPERATE before the READY light comes on, the FAULT light will turn

on. This is not a fault, but it is better to leave the switch in STBY position until the amplifier is ready to operate.

6.2 Displays

All the DX-2 indicators are concentrated in a single, solid state, "moving LEDs" display (See drawing). The following parameters are

displayed (top to bottom):

Output Power - Scale up to 2kW. Yellow LEDs, with red indicating power over 1.5kW.

Reflected Power - Scale up to 250W. The colour is green, yellow and red, indicating progressively higher reflected power and possibly

problems with your antenna.

Ig2 - Zero-centred display. The left (green) side has a full scale of about 25 mA of negative screen current. The right (red) side has a

full scale of about 50 mA of positive screen current. Above this value, the red LEDs will flash, warning you to increase the loading, or

reduce the drive. At about 60 mA, the protective current limiting will cut in.

Plate Voltage - Scale up to 3.3kV, green.

Plate Current - Scale up to 2.0A. Yellow, with a green zone indicating the standing current bias (when EBS is disabled only. NOTE:

the factory adjustment could be slightly different from the green zone indication). The area above 1.8A is red. It indicates excessive

plate current, due to high drive level and improper tuning (especially plate tuning - see "Tuning" chapter, Section 10.1).

ON Air - single LED, green. When pressing PTT, this LED turns on (while in OPERATE)

READY - single LED, yellow. Turns on at the end of warm-up period, when the mains power to DX-2 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 (if switch on OPR).

FAULT - single LED, red. Turns on in 3 situations:

when the over-temperature protection is triggered, the FAULT turns on until the tube cools to a safe level. During this time,

the operation of the amplifier is disabled, the screen voltage is off and any RF power applied to the input is bypassed directly to

the output.

when the over-current protection is triggered, FAULT turns on for 2 minutes, while READY turns off

at DX-2 power up, if the OPR/STBY switch on the front panel is left in OPR position. The FAULT light will go off when

the DX-2 is ready for operation, after warm-up.



SWR - single LED, red. A three second cut-off will happen if your antenna has a SWR worse than 2:1 (typical 2.6:1) at the operating

frequency. During the cut-off, the RF from the input is directly by-passed to the output.

OVER-DRIVE - single LED, yellow. Flashes when the input drive is exceeding the linear operation level. If even more drive is

applied, the overdrive protection will cut off (by-pass) the operation for about 2 seconds.

Figure 1. DX-2 Front Panel Display

7 ELECTRICAL CONNECTIONS

7.1 Connections to Transceiver / Exciter

Signal connections

Before making any connections, ensure that DX-2 is not connected to AC power, and the transceiver is not transmitting. Connect the

antenna first to the DX-2 output. Then connect the transceiver output to the DX-2 RF input. Plug the PTT lead into the RCA socket

marked PTT on the rear panel. If required, connect the ALC.

The most appropriate interconnection layout is shown in Figure 1 below. In this set-up, the transmit/receive relays in the DX-2 are

controlled directly by the transceiver or exciter.

Figure 2. Connections between DX-2 and station transceiver

7.2 Earth and mains connections

Power connections

Before connecting any power to the amplifier, make a good Earth connection to the screw with wing nut at the rear of DX-2. Make sure

the POWER switch on the front panel is in the OFF position. Then plug the power cable into the power point.

RF OUTPUT POWER

(

)

REFLECTED POWER

(

)

PLATE VOLTAGE

(

)

PLATE CURRENT

(

)

OVE

DRIVE

ON AIR

READY

SWR

FAULT

EMTRON

DX-2

STATION

TRANSCEIVER

RF IN RF

OUT

ANTENNA

ALC ALC

PTT

Relay

PTT

Relay

Out

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