Emtron North America DX-2 HF Amature User Manual 308274
Emtron North America HF Amature 308274
Users Manual
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OPERATING MANUAL
EMTRON DX-2
HF LINEAR AMPLIFIER
Emtron North America
Distributed Exclusively in North America By:
Emtron North America
DX-2, Serial No…………
INITIAL SETTINGS FOR PLATE AND LOAD CAPACITORS
TEST
FREQUENCY
BAND
21.200 MHz
18.100 MHz
14.200 MHz
15m
17m
20m
7.070 MHz
3.600 MHz
1.800MHz
1.850 MHz
1.900 MHz
40m
80m
160m
160m
160m
FACTORY SETTINGS
50 OHM LOAD
PLATE
LOAD
TABLE 1
USER SETTING
ANTENNA
PLATE
LOAD
TABLE OF CONTENTS
1 GENERAL DESCRIPTION .................................................................................................................................1
1.1
DX-2 – INTERNAL VIEW .............................................................................................................................2
2 TECHNICAL SPECIFICATIONS ......................................................................................................................3
3 UNPACKING.........................................................................................................................................................3
3.1
3.2
OPENING THE CARTON ................................................................................................................................4
OPENING THE DX-2 COVER ........................................................................................................................4
4 INSTALLATION I ENVIRONMENT.................................................................................................................4
4.1
4.2
REQUIRED ENVIRONMENT ..........................................................................................................................4
POWER REQUIREMENTS ..............................................................................................................................4
5 REAR PANEL .......................................................................................................................................................4
5.1
5.2
5.3
POWER / EARTH CONNECTIONS...................................................................................................................4
RF CONNECTIONS .......................................................................................................................................4
TRANSCEIVER CONTROL .............................................................................................................................4
6 FRONT PANEL.....................................................................................................................................................5
6.1
6.2
CONTROLS ..................................................................................................................................................5
DISPLAYS ...................................................................................................................................................5
7 ELECTRICAL CONNECTIONS ........................................................................................................................6
7.1
7.2
7.3
7.4
CONNECTIONS TO TRANSCEIVER / EXCITER ...............................................................................................6
EARTH AND MAINS CONNECTIONS ..............................................................................................................6
TERMINATING THE POWER CABLE (EXPORT VERSION) ................................................................................7
OPERATION AT 230V, 220V AND 200V (EXPORT VERSION)........................................................................7
8 DX-2 DESCRIPTION............................................................................................................................................7
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
RF SECTION................................................................................................................................................7
MAINS TRANSFORMER ................................................................................................................................8
H. V. POWER SUPPLY .................................................................................................................................8
SOFT START MODULE ..................................................................................................................................8
SENSOR MODULE ........................................................................................................................................8
ANTENNA RELAY / QSK MODULE ...............................................................................................................8
DISPLAY BOARD .........................................................................................................................................8
CONTROLLER BOARD ..................................................................................................................................8
9 POWERING UP ....................................................................................................................................................9
10 OPERATION .........................................................................................................................................................9
10.1
10.1.1
10.1.2
10.1.3
10.1.4
10.2
10.3
10.3.1
10.3.2
10.3.3
TUNNING PROCEDURE - ......................................................................................................................9
General........................................................................................................................................................9
Preliminary tuning ......................................................................................................................................9
Final tuning...............................................................................................................................................10
Potential problems during tuning..............................................................................................................10
ALC ADJUSTMENT ..............................................................................................................................10
USING YOUR DX-2 ...............................................................................................................................11
CW / RTTY and all digital modes..............................................................................................................11
Voice modes (SSB) ....................................................................................................................................11
Hints on good linearity and efficiency.......................................................................................................11
11 SWITCHING THE POWER OFF .....................................................................................................................11
12 TROUBLESHOOTING - IF SOMETHING GOES WRONG ........................................................................12
12.1
12.2
12.3
12.4
12.5
12.6
12.7
NO POWER ................................................................................................................................................12
FAN GOES TO HIGH SPEED .........................................................................................................................12
FAN NOT WORKING ...................................................................................................................................12
IF THE FAULT LIGHT TURNS ON...............................................................................................................12
OVER-TEMPERATURE CUT-OFF .................................................................................................................12
OVER-CURRENT CUT-OFF .........................................................................................................................12
IG2 BLINKS FAST - NO PLATE VOLTAGE ....................................................................................................12
14 GLOSSARY .........................................................................................................................................................13
15 SERVICE .............................................................................................................................................................14
15.1
15.1.1
15.1.2
15.1.3
GENERAL ..................................................................................................................................................14
CONTROL BOARD...................................................................................................................................14
DISPLAY BOARD ADJUSTMENTS .........................................................................................................18
RF SENSOR ADJUSTMENT.....................................................................................................................19
16 DIAGRAMS AND SCHEMATICS....................................................................................................................21
16.1
16.2
16.3
16.4
16.5
16.6
16.7
16.8
16.9
16.10
16.11
16.12
DX-2 BLOCK DIAGRAM ...........................................................................................................................21
CONTROL BOARD CONNECTIONS AND ADJUSTMENT POINTS ...................................................................22
DISPLAY BOARD ADJUSTMENT POINTS ....................................................................................................23
CIRCUIT DIAGRAM – HIGH VOLTAGE POWER SUPPLY ....................................................................24
CIRCUIT DIAGRAM – AC INPUT AND SOFT START WIRING – U.S. VERSION .....................................25
CIRCUIT DIAGRAM – RF MODULE .........................................................................................................26
CIRCUIT DIAGRAM – DISPLAY BOARD ................................................................................................27
CIRCUIT DIAGRAM – SOFT START – 240 VOLT VERSION .......................................................................28
CIRCUIT DIAGRAM – QSK........................................................................................................................29
CIRCUIT DIAGRAM – CONTROL BOARD ..............................................................................................30
CONTROL BOARD – COMPONENT LEGEND ...............................................................................................31
CONTROL BOARD – SOLDER SIDE TRACK WORK ......................................................................................32
DX-2 LINEAR AMPLIFIER
Serial No
…………
OPERATING MANUAL
January 2003
CAUTION
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 this by momentarily shorting the
tube anode to the chassis with a suitable insulated lead.
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.
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.
RF OUTPUT POWER (kW)
OVER
DRIVE
REFLECTED POWER (W)
SWR
Ig2
ON AIR
PLATE VOLTAGE (kV)
READY
PLATE CURRENT (A)
FAULT
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.
TO
ANTENNA
RF IN
RF
OUT
STATION
TRANSCEIVER
EMTRON
DX-2
PTT
Relay
Input
Figure 2.
7.2
ALC
ALC
PTT
Relay
Output
Connections between DX-2 and station transceiver
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.
7.3
Terminating the power cable (export version)
As different countries have different standards for their power connections, all DX-2 amplifiers exported from Australia are supplied
with un-terminated power cables.
The green/yellow wire is connected to the amplifier chassis and MUST be connected to the safety ground of the AC mains supply. It
must NEVER be connected to one of the AC 'hot' wires. The brown and blue wires connect to the mains transformer input. The brown
wire is the "active", or "live". The blue wire is the mains neutral. Both wires are fused.
7.4
Operation at 230V, 220V and 200V (export version)
The Emtron DX-2 will normally arrive pre-set for the power source of the country the amplifier has been sold to. However if operation
to another mains voltage is required, the appropriate connection changes will be needed.
Figure 2 shows the transformer connections for 200V, 220V, 230V and 240V operation. If a change is required, this should be done
only by a qualified technician, after taking all the necessary safety precautions. See CAUTION on page 1.
PLEASE NOTE: The DX-2 should not be connected to a mains supply of less than 200V AC !
240
240 volt:
200
FAN
220
230
230 volt:
200
FAN
200
FAN
200 volt:
FAN
Figure 3.
240
230
200
240
220
220
220 volt:
230
240
220
230
DX-2 Transformer AC Input Connections
8 DX-2 DESCRIPTION
8.1
RF Section
The RF section occupies the right hand side of the DX-2 (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 and a band switch. Next to the switch is the “Pi” coil.
The “L” coil is wound on a ferrite torroid.
RF Sub-chassis
The GU84B tube is positioned on a separate RF sub-chassis. All the connections to the tube, except for the plate, are under this subchassis. A 9-way heavy duty connector is used for inter-connections. The fan blows air into this sub-chassis, which is forced out
through the ventilation fins of the tube. The air temperature is sensed by two sensors placed above the tube. The sensors must stay in a
position close to horizontal. Make sure you are not pushing them down, too close to the tube, as high voltage exists between them. The
plate is connected to the RF network and to the choke supplying the 2500VDC voltage to the plate of the GU84B tube.
8.2
Mains transformer
The transformer is the heart of the amplifier, a high performance type, designed to reduce the size and weight. It is built with a
generous reserve of power, handling easily the DX-2 requirements in continuous operation. The primary can be wired for 200VAC,
220VAC, 230VAC or 240VAC operation. See Figure 2. There are several secondary windings, as follows:
Filament supply
Low voltage supply to the controller board
QSK module supply
Bias supply
Screen grid supply
High voltage supply
8.3
H. V. Power Supply
A full wave bridge rectifier and filter converts the high voltage AC into high voltage DC with a huge reserve capacity of 58
microfarads.
8.4
Soft start module
At power up, the mains power is gradually applied to the transformer by the soft start module. The power is gradually applied over a
time of about 5 seconds, avoiding the high inrush current typical for such big loads.
8.5
Sensor module
A small metal box positioned at the output of the DX-2. It detects the forward and reverse power, for measurement and display, as well
as for SWR monitoring and to activate the protection, when needed.
8.6
Antenna relay / QSK module
In the standard DX-2, the antenna relay is 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.
When the QSK option is installed, this is a module with two very fast, high power vacuum relays, and the control circuitry. The
purpose of QSK is to allow very fast switching between transmit and receive, during digital communications. See Annex 1 showing
oscilloscope displays of fast switching times and contact bounce-free operation of the QSK module.
8.7
Display board
This board has a number of inputs where various voltages are connected. The board converts these voltages into a "moving LED" type
of display. Two of these displays have flashing light indication (Ig2 and plate current).
8.8
Controller board
The brain of the amplifier is the Controller Board. The following circuitry is part of this board:
Bias voltage regulator, also incorporating a sensitive grid current detector for overdrive detection . Adjustable pre-bias,
removes the distortion at the beginning of the word, when EBS is activated.
Screen voltage regulator, with adjustable voltage and adjustable current limiting, for tube protection.
Overdrive protection and timer - based on detecting grid current, it initially gives visual warning and, at higher level of
overdrive, it cuts off the amplifier for 2 seconds. It ensures a clean signal, making it virtually impossible to overdrive the DX2
SWR detector and timer - switches the amplifier to bypass mode for about 3 seconds when high SWR is detected.
Adjustable SWR level. Factory adjusted to about 2.6: 1
EBS - the Electronic Bias Switch - senses the presence of RF input power and turns on the bias to start transmission.
Factory adjusted for about 0.5W. When the input power exceeds this limit, the plate current starts flowing. When there is no
speech, even for a very short time, the tube dissipation is cut to a low value, as set by the pre-bias adjustment.
Interlocking, timer for filament warm-up
Relay control: ready relay, SWR relay, over-drive relay, antenna relay
QSK switching control
Display control: Ig2 measurement and display, SWR cut-off display, overdrive warning display, READY display, FAULT
display
Logic circuitry, low voltage supply to the various electronic circuits
9 POWERING UP
Before switching the power on, check all the necessary connections: Earth, Antenna, Transceiver, PTT, ALC (if used). 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. After 5 seconds, the display will indicate the plate voltage, typically 2450 V. The FAULT light will turn on briefly, then off.
Wait for the DX-2 to warm up, until the READY light turns on.
This takes about 2 - 3 minutes. This is a minimum required. If you are not in a hurry, give it another minute or two before transmitting.
WARNING!
WHEN YOU SWITCH THE POWER ON, YOU MUST HEAR AIR FLOW NOISE.
IF THERE IS NO AIR FLOW NOISE, SWITCH THE POWER OFF IMMEDIATELY
AND CONTACT YOUR SUPPLIER
10 OPERATION
10.1 TUNNING PROCEDURE 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-2, 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.
10.1.2 Preliminary tuning
•
•
•
•
•
Turn the BAND switch to the same band setting as the transceiver. (Also, make sure the right antenna is used).
Put LOAD and PLATE knobs in the initial positions given in Table 1.
DX-2 must be powered ON and "Ready", with the OPR/STBY switch in OPR position.
Start with the transmitter at minimum power, in a "carrier" mode e.g. RTTY or CW - key down.
Key the transceiver ON and gradually apply power to the DX-2. When 0.5 to l W of drive is reached, the EBS is activated and
the plate current jumps from zero to about 0.3 - 0.4A
• Increase the drive until there is some output power indicated. If the current plate Ip reaches about l A and there is still no
output indication, turn PTT off and check the connections, the band and the initial settings.
• As soon as there is any power indication, tune PLATE for maximum output (and minimum plate current).
• Apply more drive and adjust PLATE again for maximum output. Keep PTT ON for short time only (about 10 seconds). Go
gradually, in several steps. When about 700 - 1000W output is reached, adjust LOAD for maximum output. If there is no red
Ig2 indication, it is likely that LOAD needs to be turned clockwise, towards higher numbers on the dial.
• Apply more drive and adjust both knobs again. When screen current appears (red Ig2 indication), increase loading by turning
anti-clockwise the loading capacitor. (LOAD towards lower numbers on dial) until Ig2 drops almost to zero. Then adjust
PLATE for maximum output power and maximum Ig2. At this point, Ig2 is the most sensitive indicator of resonance on
the working frequency. If Ig2 goes too high (e.g. starts blinking), increase the loading again, then tune PLATE.
• Repeat the above steps, while gradually increasing the input drive power, until the overdrive indicator just starts turning on.
Now the DX-2 is tuned for operation at full power on that particular operating frequency.
NOTES:
1. The maximum power is obtained from a DX-2 when:
onset of the overdrive indication
PLATE is tuned for maximum output power, maximum screen current Ig2 and minimum plate current, Ip
Ig2 indicator shows 2 or 3 red LEDs.
2. The above conditions will also give the best linearity.
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. The new settings will normally differ to some extent from the ones indicated, depending on the "purity" of your antenna load.
Note that the settings (especially LOAD) will be different at lower output power – See “Tuning for less than full power”.
10.1.3 Final tuning
Once the preliminary tuning has been done for each band / antenna combination, the values found for PLATE and LOAD can be used
for final tuning, with no need to repeat the preliminary tuning every time.
Tuning for full power
• Start with low drive level and the PLATE and LOAD knobs in the known initial positions
• Put PTT ON and increase the power (fairly quickly), to the onset of the overdrive indication. If the screen current (red Ig2)
goes too high, adjust LOAD, by turning the knob to the left (increasing the load).
• Adjust the drive level and LOAD until the overdrive indicator is just about to turn ON, and at the same time Ig2 shows two or
three red LED's ON.
• Fine tune PLATE for maximum output and maximum Ig2.
• Repeat the last two steps above if required.
Tuning for less than full power
• Start at low power, with the initial values for PLATE and LOAD
• Put PTT ON and apply drive until the output is about 1/2 of the desired power.
• Adjust LOAD for maximum output. Most likely, the knob will have to be rotated to the right, towards higher numbers on the
dial.
• Adjust PLATE for maximum output
• Apply more power
• Repeat the 3 steps above until the required power is achieved. If screen current is indicated by Ig2, is should, display two or
three red LED's. Maximise this Ig2 indication (and the output power at the same time), by tuning PLATE
• If the output goes higher then desired, reduce the drive and re-tune. Never reduce the output by de-tuning the amplifier!
NOTE: If the output is low (say, less than about 700W), Ig2 will never show any screen current at all. Ig2 might even indicate a
negative current, in green - this is normal and is no cause for concern).
However, if there (green) negative current indication, usually this will go away with better tuning of the PLATE control.
If there is no Ig2 red indication., simply rotate LOAD to the right in small steps, and each time maximise the output by turning PLATE,
until the highest possible maximum in the output power is achieved.
10.1.4 Potential problems during tuning
The tuning operation. should be completed fairly quickly. If the tuning process takes a longer time, it should be done by switching the
transmission on and off several times, to allow the tube time to cool.
• If the fan changes to high speed, the operation can continue, as there is ample reserve of cooling power. However, it is the best
to make a pause (about 1 minute will be sufficient) and wait for the tube to cool.
• If the FAULT light comes on, it is possible that the plate current has reached too high values due to incorrect plate tuning. In
this case, reduce the excitation power, wait for the FAULT light to turn off (about 2 minutes) and resume tuning.
• If the overdrive protection is activated, by cutting off the amplifier for 2 seconds. It is likely in this case that you are applying
too much power at the input. Reduce the power and watch the "overdrive" LED. Increase the power only until this light starts
flashing.
• If the SWR protection cuts in - it is likely that your antenna is not a good 50 ohm match at the operating frequency. In
principle, the SWR protection level in DX-2 is adjustable, but it is far preferable for you to fix your antenna.
10.2 ALC ADJUSTMENT
The DX-2 can be operated without any ALC connection. However, if you wish to use it, and your transceiver has an ALC input, then
the potentiometer on the rear panel must be adjusted. This adjustment is not critical, since its voltage output is zero under normal
operation and it increases sharply (towards a negative value - up to -11 V), when the overdrive limit is approached. The ALC in DX-2
amplifier is not a conventional design, this circuit operates for only one reason - to prevent overdriving and to keep the signal clean.
To adjust the ALC potentiometer:
• Turn the potentiometer initially all the way to the right (minimum ALC voltage)
• In CW mode, after tuning, apply increasingly higher drive, until the "overdrive" LED just starts to turn on
• Increase the drive slightly more, to have the light fully on, but make sure the DX-2 overdrive protection does not cut you off.
At this power level, adjust the ALC potentiometer to the left, until the transceiver drops its power output.
Alternatively, in voice mode, increase the RF gain or the microphone gain until the overdrive led is flashing at peak of modulation.
Then, increase ALC (rotate potentiometer to the left) until the transceiver begins to limit the drive to DX-2.
NOTE: Some types of transceivers (e.g. YAESU FTI00MP, FT920 and others) are not compatible with this type of ALC. They require
an ALC signal proportional with the output power. DX-2' s ALC is zero until the drive reaches the over-drive limit, when the negative
voltage increases sharply. YAESU operating manual indicates that this type of ALC might not work well with their transceivers, since
grid current could be generated by amplifier mis-tuning not related to excessive drive conditions. If this is the case, simply do not
connect it.
10
10.3 USING YOUR DX-2
While tuning and adjusting the amplifier, a CW mode is normally used. When these operations are finished, you can change to the
operating mode you wish to use and start operating.
10.3.1 CW / RTTY and all digital modes
In CW, the setting up of the amplifier is similar to that of the tuning mode. After adjusting the input power level to the amplifier,
according to the desired output level, and tuning the plate and load capacitors, you can simply start operating by applying the same
carrier level as during tuning. If the amplifier is set to deliver full output power, or close to, then screen current will be present. As in
the case of tuning, the best operation is achieved when there is a certain amount of screen current flowing, corresponding to two or
three red LED's turning on in the Ig2 display.
10.3.2 Voice modes (SSB)
When a voice modulation is applied to the amplifier, the drive level is not precisely defined, as in the case of tuning with continuous
carrier. If there is screen current flowing, or an input overdrive, they will be indicated only at peak of modulation, by the respective
indicators flashing. You will have to adjust the microphone gain, or the RF drive, or both, in an attempt to achieve input driving
conditions similar to those you have used while tuning. Occasional flashing of the overdrive indicator is acceptable. If the over-driving
is severe, a momentary cut-off will occur.
10.3.3 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
minimising the tube dissipation. Be aware that at a low power level, slightly different tuning is required than is for full power.
Achieving the best linearity: The amplifier must be tuned and operated all the time in the linear mode. This is important because a nonlinear operation will generate harmonics which will disturb RF communications in other bands and frequencies.
We must distinguish two situations:
Less than full power.
With less then full power (say 1000W or less), correct tuning, no screen current and no input overdrive indication, you will always
have your DX-2 operating with a good linearity and clean signal.
Full power operation.
At full power, there are two things that must be watched to see when you reach the limit of linear operation: the screen current, Ig2, and
the grid current, indicated by the "Over-drive" LED.
In this case a good linearity is maintained up to the moment when the screen current is approaching the full scale value of the Ig2
indicator and it starts flashing, or when the overdrive indicator begins to turn on.
A high screen current, indicated by 4 LED's on in the Ig2 display, will create a moderate level of distortion.
Even a small amount of grid current will cause severe distortion. When the "Over-drive" indicator just begins to turn on, there is
already a small amount of distortion, created by a grid current of about 100 microamperes.
With this indicator flashing, you are at the limit of the RF carrier clipping. This is probably more acceptable in a voice mode of
operation. In CW or digital modes, the best is to slightly reduce the drive, just below this level. A severe level of over-driving is not
possible anyway, due to the cut-off protection. The cut-off will happen at about 400 microamperes of grid current.
See the Appendix 2 and the Troubleshooting section for oscilloscope displays showing examples of a two tone generator driving the
DX-2 in linear mode, and an overdrive situation, when a DX-2 with the overdrive protection disabled is being overdriven by the twotone generator.
The Ig2 indicator should have two to four LED's flashing on at peak of modulation. This (combined with a correct plate tuning),
indicates an optimum loading, good efficiency and good linearity. A lower screen current, due to excessive loading, will reduce the
output power, with an equal amount of extra power dissipated by the tube. A higher screen current, making all four LED's in the Ig2
flashing, will increase the distortion.
11 SWITCHING THE POWER OFF
When you have finished using the amplifier and you want to switch it off, the following procedure is recommended:
Stop transmitting.
Put the switch on STBY.
Leave the DX-2 running idle for a few minutes, to cool the tube, then switch the power off.
11
12 TROUBLESHOOTING - If something goes wrong
12.1 No power
•
When you switch on a DX-2, it takes about 3 - 5 seconds for the lights on the front panel display to come on. This is due to the
"soft start" circuit. If nothing happens after turning the power on, switch off at the front panel, then check the following:
• make sure the power outlet has power
• make sure the power plug is fully pushed in into the power outlet.
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-2
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.
12.2 Fan goes to high speed
This could happen especially during tuning, or when the ambient temperature is high. It could also happen when the ventilation is
restricted, for example by blocking the openings at the back, sides or on the top of the amplifier. In normal operation, with correct
tuning, the DX-2 should be able to handle the maximum power with the fan still running at low speed. Usually driving the amplifier
with high power and bad tuning can make the fan to go high speed. When this happens, the tube temperature is nominally 120° Celsius.
This offers a margin of 30°C before a temperature cut-off occurs, and way below the tube rating, of 200°C. That means you can
continue to operate the amplifier with the fan at high speed, but the best is to let it idle until the fan drops back to low speed. This
usually takes less than one minute.
12.3 Fan not working
As soon as you switch the power on, you should notice two things about your DX-2: the display should indicate about 2500V of plate
voltage, and you should be able to hear the fan running. The amplifier is not supposed to be powered without the fan, even in idling
mode. If the fan does not operate when you power up, or if it stops while using the amplifier, switch the mains power off immediately
and contact your supplier.
12.4 If the FAULT light turns on
The FAULT (red) light turns on in two situations:
• Over-current in the plate circuit
This could happen due to a flash-over in the tube, or as a result of a momentary high plate current during tuning. This completely
disables the amplifier for about 2 minutes. The same timer is activated as when the amplifier is switched on, causing the READY light
to turn off. If the OPR/STBY switch on the front panel is put on STBY, the FAULT will turn off, but the READY will be also off.
When the READY comes on again, the FAULT will disappear (if the amplifier was left in OPR), and the DX-2 is ready to operate
again.
• Over-temperature cut-off. See below.
12.5 Over-temperature cut-off
This would normally happen after a change of the fan to high speed. The operation of the amplifier is disabled, but the timer is not
activated. The FAULT light turns on.. When the tube cools down, the FAULT turns off and the operation can resume. This type of
fault should never happen. DX-2 has a very efficient air cooling system. When the ventilation is not restricted, in normal ambient
conditions, when properly tuned, a DX-2 can operate at full power for extended periods of time, with the fan not even going to high
speed. The temperature cut-off happens when the tube reaches 150º Celsius, with ample safety margin to the specified limit of 200ºC
for the GU84B tube.
12.6 Over-current cut-off
If the plate current exceeds even for a brief time a pre-set safe limit, an over-current detector will activate the power up timer, disabling
the amplifier for about 2 minutes. During this time the READY light is off, and the FAULT light is on, if the amplifier is left in OPR
mode, as explained under 12.4, "If the FAULT light turns on".
12.7 Ig2 blinks fast - No plate voltage
If the high voltage is lost due to a fault in the amplifier, the screen current tends to reach very high values. This is an unlikely situation,
but if did happen, this would normally guarantee a tube failure in unprotected amplifiers that do not have a current limiting circuit. The
screen current limiting in DX-2 is so efficient, that the tube is fully protected even in such a situation and test bench DX-2's have been
extensively run with no plate voltage and maximum screen voltage, with no effect on the tube. If this loss of high voltage should
happen to your DX-2, the Ig2 display will have the red LEDs flashing, due to the screen current exceeding the pre-set limit, with no
input power applied to the amplifier, while switched to OPR.
In such a case, it is possible that the high voltage is still shown on the display, 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
12.8 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.
12.9 SWR cut-off
The factory adjustment for SWR protection is about 2.6: 1. This adjustment can be changed, but the best is to operate with a properly
matched antenna. Should your DX-2 'see' bad SWR, it will shut down for 3 seconds (in bypass mode).
12.10 Frequent over-drive protection cut-off
As previously described in the tuning and operation sections, there is a protection acting on DX-2 input overdrive. When the drive
reaches the limit where signal distortion begins to occur, the overdrive indicator on the front panel will warn you to reduce the drive. If
you increase the drive even further, a cut-off protection is activated.
After about 2 seconds of amplifier bypass, the operation is resumed, but if you have not reduced the drive, the protection will be
activated again. To stop it, you must reduce the input power drive. This protection is not adjustable, you must not exceed the limit. If
this happens too often, you obviously do not have a fine control over the transmit level of your transceiver. In this case, try using the
ALC, See section 10.2.
12.11 Tube replacement
It is very unlikely that you will ever need to replace the GU84B. If there is a need for that, the tube is easy to replace, but a bias
adjustment is required for the new tube. See the service section of this manual.
13 WARRANTY I SERVICE
The full FOUR YEARS warranty for DX-2 amplifiers covers all parts and labour, except for the tube. The tube is under a limited
warranty, also for FOUR YEARS.
14 GLOSSARY
AC
ALC
AM
CW
DC
EBS
FM
HF
LED
PEP
RF
RTTY
SSB
SSTV
SWR
VAC
VDC
WARC
VSWR
Alternating Current
Automatic Level Control
Amplitude Modulation
Continuous Wave
Direct Current
Electronic Bias Switch
Frequency Modulation
High Frequency
Light Emitting Diode
Peak Envelope Power
Radio Frequency
Radio Tele Type
Single Side Band
Slow Scan Tele Vision
Standing Wave Ratio
Volts, Alternating Current
Volts, Direct Current
World Administrative Radio-communications Conference
Voltage Standing Wave Ratio
13
15 SERVICE
15.1 General
All Emtron amplifiers are built in a modular for. Most modules are common for the entire DX-n range.
This makes it easier to service the amplifier. However, this should only be attempted by suitable qualified people, with proper tools and
test equipment. Apart from the damaged that could be caused to the amplifier by unqualified intervention, the high voltages and
high RF power present in these amplifiers makes them extremely dangerous. Extreme care is recommended event to those very
experienced in this area.
The following pages describe the main adjustments required on the DX-2 linear amplifier.
15.1.1 CONTROL BOARD
This procedure refers to adjustments made to the board already installed in the amplifier.
This would be required, for example, after replacing the tube or after certain repairs.
After a tube replacement only one or two adjustments are required: BIAS and (if EBS used): PRE-BIAS
15.1.1.1
PRE-BIAS ADJUSTMENT (Adjustment: POT7, marked PRE_BIAS)
The pre-bias is required when the Electronic Bias Switching (EBS) is used. If the EBS link is kept in OFF position, the prebias does not need to be adjusted. PRE-BIAS must be adjusted before BIAS.
When EBS is activated (the default situation), keying the amplifier causes the plate current to stay cut off (as if the PTT
was off), until a small amount of drive is applied. The “Pre-bias” establishes a small plate current as soon as PTT is on.
The transition to full on is then less abrupt, while the tube dissipation is still reduced by using EBS.
PTT Off:
Ip = 0
PTT On (no drive) and EBS on:
PTT On (no drive) and EBS off:
Ip = Ipb (pre-bias current)
Ip = Ip0 (standing current)
PROCEDURE:
Remove the cover and connect a voltmeter (+) to the test point TP2 (top corner). (-) to the chassis.
Make sure the EBS link is in the lower position (EBS ON).
With the amplifier running, wait the warm-up time.
When READY, put OPR switch on and key the amplifier with NO
INPUT DRIVE. Read the voltage at TP2. Adjust POT7 (PRE-BIAS) to obtain the desired pre-bias current.
Recommended pre-bias currents (POT 7, PRE_BIAS):
DX1b:
DX2 and
DX2SP:
DX3:
10 to 30 mA
15 to 40 mA
10 to 30 mV on the voltmeter
15 to 40 mV on the voltmeter
Clockwise to reduce current
Clockwise to reduce current
20 to 60 mA
10 to 30 mV on the voltmeter
Clockwise to increase
current
NOTE: the pre-bias current is not critical.
15.1.1.2
BIAS ADJUSTMENT (Adjustment: POT3, marked BIAS)
Adjust Pre-Bias before adjusting Bias.
This adjusts the plate standing current, with the EBS Off and the amplifier keyed with NO INPUT DRIVE.
PROCEDURE:
Remove the cover and connect a voltmeter to the test point TP2 (top corner).
Put the EBS link is in the upper position (EBS Off).
With the amplifier running, wait the warm-up time. When READY, put OPR switch on and key the amplifier with NO INPUT
DRIVE. Read the voltage at TP2. Adjust POT3 (BIAS) to obtain the desired bias current.
CAUTION: With a new tube, start at a low plate current. Rotate POT3 for minimum current before keying the amplifier.
With the adjustment in the wrong position, the plate current could reach very high values.
During this adjustment there is no output power. All the power taken from the high voltage supply is dissipated by the tube.
Be brief and quick. Put PTT on for a few seconds, then on. Repeat several times until the desired standing current is
achieved.
14
Recommended bias currents (POT3, BIAS):
DX1b:
DX2 and
DX2SP:
DX3:
290 to 310 mA
370 to 380 mA
290 to 310 mV on the voltmeter
370 to 380 mV on the voltmeter
Clockwise to reduce current
Clockwise to reduce current
740 to 760 mA
370 to 380 mV on the voltmeter
Clockwise to increase
current
NOTE: After adjustment, move the EBS link back in the ON position (default) if EBS is desired.
The above 2 adjustments are required when changing the tube or when changing the control board.
The remaining following adjustments are pre-adjusted with a new control board and normally there is no need to change
them. A possible exception could be the SWR protection which might require some fine tuning after changing the control
board or the RF sensor module, but usually the factory pre-adjustment is close enough. Also EBS might need adjustment
depending on the personal preference of the operator.
15.1.1.3
SWR Protection adjustment
Adjustment: POT5, marked SWR.
This adjustment require a special jig with a load made of 2 non-inductive, high power resistors (at least 300W).
They can be switched between 130 ohm and 140 ohm. With a 50 ohm output these 2 loads give an SWR of 2.6:1 and
2.8:1 respectively. The adjustment is nominally for a ratio of 2.7:1 to trigger the protection in the form of antenna by-pass.
Usually this adjustment is performed on 20m (14.200 MHz) at full power.
With a 50 ohm dummy load, transmit and adjust for full power (or close to full power).
Stop transmitting and replace the 50 ohm dummy load with the special dummy load described above.
Switch the dummy load to 140 ohm and key the amplifier for just one second.
If the protection wasn’t activated immediately, increase the sensitivity (Rotate clockwise for DX-1, DX-2, and DX-2SP and
anti-clockwise for DX-3).
Repeat applying power for a short time only, until the protection is triggered.
Switch the special dummy load to 130 ohm and repeat. This time the protection should not trigger. If it triggers, reduce the
sensitivity. Try several times using 130 and 140 ohm load. The protection threshold should be between these 2 values
(135 ohm, corresponding to 2.7:1 SWR).
15.1.1.4
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 lower position, or ON):
Checking the existing adjustment: increase slowly the input drive, starting from zero, until the EBS system activates the
amplifier. This can be checked by watching the plate current or the RF output power or the current or power taken from the
AC mains. Any one of these can be monitored and a jump in reading happens when EBS switches.
Check that this happens for an input drive between 0.5 – 1 Watt.
Adjusting EBS: if the adjustment is not correct or you prefer a lower or higher setting, apply the desired amount of power
and then adjust POT6 until you find the limit where the EBS activates.
NOTE 1: a higher threshold is likely to give reports of the beginning of the words being cut off. If this is the case, a lower
threshold (higher sensitivity) can be used.
A low threshold can make the EBS activate erratically, for example due to the ambient noise of in the room, or even due to
the noise generated by the fan. This is not a problem in itself, except that the tube will dissipate extra power during the
times when you hold the key down but do not speak (eg between the words, while speaking). However, these moment are
usually brief and it won’t make much difference.
NOTE 2: for factory adjustment, a negative voltage with the value of 1.6 V is applied to the RFIN pin on the control board
when this board is checked, then the adjustment is only checked with RF when the amplifier is tested.
15
15.1.1.5
SCREEN VOLTAGE ADJUSTMENT (Adjustment: POT2, marked SCREEN)
The screen voltage can be measured on the pin marked EG2 on the control board (close to the jumper EBS, this pin has a
blue wire connected to it; in DX-3 it is easier to measure on either side of R18).
The nominal adjustment is 356V unloaded.
NOTE: the screen voltage does not need adjustment unless the value was altered by somebody.
15.1.1.6
SCREEN CURRENT LIMIT ADJUSTMENT (Adjustment: POT1, marked IG2LIMIT)
Do not adjust this potentiometer, it has been factory adjusted and there is no need to change.
With the amplifier switched off or on STANDBY, remove the blue wire on pin EG2.
Connect an analogue mA-meter with a 100 mA full scale range (+ to the control board) and then (-) to an adjustable
resistive load with a range from 3-5 kohm to about 20 kohm (this jig is also required for the display board adjustment, it is
convenient to adjust the ig2 indicator at the same time). The other end of the resistor goes to the chassis.
The power rating must be 20 – 25 W (short time loading only).
Connect also a voltmeter to measure the screen voltage.
Put the front panel switch on OPR.
Start with a higher value (20 kohm) of the resistor and reduce the resistance gradually. At 10 kohm the reading will be
about 35 mA.
Continue reducing the resistance until the current reaches about 60 – 70 mA. The screen voltage must drop to about 300
V or less under this load.
If not, adjust POT1.
NOTE 1: While adjusting ig2 limit, the ig2 indicator on the display board can also be checked / adjusted at the same time.
NOTE 2: IG2 LIMIT can be checked / adjusted also by simply putting a mA-meter in series with the blue wire connected to
the EG2 pin on the control board. While operating the amplifier at full load, 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 the blue wire to an
external current meter and volt meter.
15.1.1.7
7. IPTRIP ADJUSTMENT (Adjustment: POT6, marking: IP TRIP)
This is the sensitivity of the high plate current protection (cut-off).
When the plate current exceeds the adjusted limit, even for a very short time, the start-up timer is reset. The screen
voltage is cut off and the FAULT light turns on. To make FAULT light go off, the amplifier must be put on STANDBY. If left
on OPR, the operation will resume automatically at the end of the (about) 2 minutes warm-up time. During this time, any
RF power applied to the input is bypassed into antenna.
Connect a DC supply to pin TP2 on the control board (in the top corner).
With the amplifier powered and the READY light on, put the front panel switch on OPR.
Apply a current gradually increasing from zero and check that the protection is triggered at about 1.85 A of current. When
this happens, the FAULT light will turn on.
If the current value found is much different from 1.85 A, adjust POT6.
To repeat the adjustment or checking, you need to wait every time for the READY light to turn on again (about 2 minutes).
To speed up, the resistor R20 (5.6 Mohm) can be paralleled briefly with a lower value resistor (1k – 100k). Touch R20 with,
say 10 kohm in parallel and the Ready light will turn on immediately.
16
BIAS
SWR
SCREEN
VOLTAGE
EBS
SENSITIVITY
SCREEN
CURRENT
LIMIT
EBS OFF
EBS ON
Ip
PROTECTION
PLATE
CURRENT
PROTECTION
EBS OFF
EBS ON
SCREEN
CURRENT
LIMIT
EBS
SENSITIVITY
SWR1
SWR4
SCREEN
VOLTAGE
PRE-BIAS
SWR
17
BIAS
(Ip0)
15.1.2 DISPLAY BOARD ADJUSTMENTS
The display board is pre-adjusted during testing. However, when installed in the amplifier, most adjustments need to be fine-tuned.
Remove the front panel glass to gain access to adjustments.
15.1.2.1
1. PLATE CURRENT (Adjustment: VR4, Marked: AMP)
Connect a power supply to pin TP2 on the control board: negative to TP2, positive to the chassis.
Apply a current with a value between 1 A and 2 A. Choose a convenient value close to the full scale on the Ip LED row on
the display board.
Adjust potentiometer AMP for correct indication.
15.1.2.2
2. PLATE VOLTATE (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.
15.1.2.3
3. REFLECTED POWER (Adjustment: VR3, marked: RF R)
Reverse the input and output RF connections:
- connect the transceiver or exciter to the output
- connect the dummy load to the input of the amplifier
Apply 100W drive and adjust “RF R” for 100W indication
Reverse again the RF cable - connect them the right way.
15.1.2.4
4. FORWARD POWER (Adjustment: VR1, marked: RF F)
On 20m, operate the amplifier at the full nominal power, as indicated by an external power meter:
1500W for DX-2
2000W for DX-2SP
3000W for DX-3
Adjust potentiometer “RF F” for correct display indication
15.1.2.5
5. SCREEN CURRENT (Adjustment: VR6, marked IG2+, VR5, marked IG2-)
ig2-: put VR5 in the middle position
ig2+: connect a mA meter in series with the screen supply, between the control board pin EG2 and the blue screen wire.
(See also the control board adjustment for IG2 LIMIT).
Generate a current in the mA meter, either by connecting a load, or by operating the amplifier close to full power.
Adjust VR6 for 4 LED's on, at the limit of starting to flash, for a current ig2+ of about 50mA.
18
15.1.3
RF SENSOR 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.
Move the voltmeter on pin SW3 or SW4 (red/black wires) and read the voltage.
Typical readings:
- Yellow / black wires: 1 – 1.5 V
- Yellow / red wires: 100mV or less
Adjust the trimmer on the output side (left hand side) in the RF sensor for minimum reading on the yellow / red wires.
(Use an RF screwdriver).
Reverse the 2 RF cables: apply power to the output of the amplifier and put the dummy load on the input.
Apply power again.
The typical readings are the same, but reversed:
- Yellow / black wires: 100mV or less
- Yellow / red wires: 1 – 1.5 V
Adjust the trimmer on the input side (right hand side) in the RF sensor for minimum reading on the yellow / black wires.
Re-position the RF sensor cover and solder.
NOTE: the above voltages can be measured as explained above and if the readings are correct, no adjustment is
necessary (the sensors are pre-adjusted before being installed).
19
OUTPUT
SIDE
TRIMMER
INPUT
SIDE
TRIMMER
20
16 DIAGRAMS AND SCHEMATICS
16.1 DX-2 Block Diagram
Vp
POWER
SUPPLY
MODULE
DISPLAY MODULE
Ip
FAULT
ON AIR
Pf
O/D
Pr
+5V
HV DC
HV AC
Ig2
Eg2
READY
RF / TUBE
MODULE
SWR
-Eg1
SWR PROT.
EBS
AC
FILAM.
RF In
(From ANT Relay
or QSK)
AC SCREEN
RF
SENSOR
CONTROL
BOARD
MODULE
AMPLIFIER OUT
(Antenna)
AC GRID
TRANSFOMER
AC LOGIC
ANTENNA
RELAY
(or QSK)
Relay
AC QSK
TEMPERATURE
CUT-OFF
STBY
/OPR
RF In
(To RF/TUBE
Module)
SOFT START
MODULE
&ISOLATION
RELAY
ON/
OFF
AMPLIFIER IN
(Transceiver)
TEMPERATURE
SENSORS
FUSE
AC MAINS
21
SPEED
CONTROL
FAN
16.2 Control Board Connections and Adjustment Points
The drawing below shows all the connections to the control board and the adjustment points.
Unless you know very well what you are doing and you have a reason to do it, do not modify any adjustment!
CONTROL BOARD - Bottom View
(Solder side)
QSK ONLY
GRY/BLK
RED
RED
BLUE
ORN ORN Y/GRN ORN/BLK
Y/GRN
VI
TP2
Ip
YELLOW
YELLOW
GREEN
GRY/BLU
GRY/BLU
STBY2
RLY1 12VP
QSK1
RLY2
STBY1
OD/TX
IPDispl
TXON
SWR
22Vac QSK2
PTT2
PTT1
IPTRIP
T110-1
T110-2
GND
GND
300VAC2 300VAC1
YELLOW
100VAC1
YELLOW
PINK
PINK
PINK
PINK
100VAC2
10VAC1
10VAC1
10VAC2
10VAC2
Ip
IpTRIP
FAULT
SWR/FLT
PTT2
DISP
Off
Ig
EBS
Ig2Lim
PNK/BLK
ALC1
Y/BLK
Y/BLK
Y/RED
Y/RED
GREEN
SWR2
SWR1
SWR4
SWR3
ALC2
Pre-BIAS
SCREEN
O/DRV
BIAS
READY
RFIN
HLSW2
BIAS
HLSW1
Ip
Ip
Sensitivity
SWR
LEGEND: WIRE COLOURS
X – Spare or no connection
Y/BLK – Yellow / Black
GRY/BLK – Grey / Black
PNK/BLK – Pink / Black
RED/BLK – Red / Black
Y/RED – Yellow / Red
GRY/BLU – Grey / Blue
WHT/BLK – White / Black
ORN/BLK – Orange / Black
GRN/RED – Green / Red
WHT/RED – White / Red
RED/GRN – Red / Green
Y/GRN – Yellow / Green
22
W/BLK
RED
GRY/BLU
ORN/BLK
BLUE
EBS
W/R
GRY
PNK/BLK
On
Sensitivity
Eg2
DISP
IG2F
IG2R
EG2
GND
Y/GRN
VIOLET
WHITE
RED/GRN
BROWN
GRN/BRN
GRN/BRN
16.3 Display Board Adjustment Points
The drawing below shows the adjustment points on the display board. The display glass has to be removed in order to access these
adjustments, on the front panel of the DX-2.
Unless you know very well what you are doing and you have a reason to do it, do not modify any adjustment!
ALL POTENTIOMETERS: Rotating counter-clockwise will increase the sensitivity and increase the indication.
Po R
RF OUTPUT POWER (kW)
OVER
DRIVE
REFLECTED POWER (W)
SWR
Po F
+Ig2
Ig2
ON AIR
-Ig2
VOLT
PLATE VOLTAGE (kV)
READY
PLATE CURRENT (A)
FAULT
AMP
23
16.4 Circuit Diagram – HIGH VOLTAGE POWER SUPPLY
HV
6A100
1000pF
470uF/450V
25R
75k
1000pF
6A100
1000pF
6A100
1000pF
6A100
1000pF
6A100
1000pF
6A100
330k
6A100
1000pF
470uF/450V
75k
330k
6A100
1000pF
470uF/450V
75k
330k
6A100
1000pF
470uF/450V
75k
330k
6A100
1000pF
AC1
AC2
1000pF
6A100
1000pF
6A100
1000pF
6A100
1000pF
470uF/450V
470uF/450V
470uF/450V
75k
330k
330k
75k
470uF/450V
1000pF
6A100
1000pF
6A100
1000pF
6A100
1000pF
6A100
75k
6A100
1000pF
6A100
75k
6A100
1000pF
IP
10k
1R
6A100
6A100
VP
6A100
GND
24
16.5 Circuit Diagram – AC INPUT and SOFT START WIRING – U.S. version
FAN
Brown
Blue
Red
To LOOM (+12V)
Brown
Blue
0V
SW
Yellow
Brown
FEMALE
Soft Start Module
ACTIVE
MALE
K1
120V
Brown
200V
25A
4.7nF/250Vac/Y 2
Yellow/Green
EARTH
RELAY DPST
MT2
Blue
4.7nF/250Vac/Y 2
Blue
NEUTRAL
MT1
220V
Brown
Blue
MT2
25A
230V
BTA40-600B
(On Chassis)
Yellow
S1
Blue
COVER INTERLOCK
MT1
240V
Brown
S2
TRANSFORMER
ON / OFF
Front Panel
TRIAC
Bottom View
MT2
MT1
Title
SOFT START WIRING U.S. Version
Size
A4
Date:
25
E M T R O N
Document Number
Rev
Sof tStartWiring US
Monday , January 07, 2002
Sheet
of
16.6 Circuit Diagram – RF MODULE
PLATE VOLTAGE
R.F. OUT MODULE (Simplified Diagram)
C14
PLATE CHOKE
2200pF
C1
1000pF/6kV
C2
1000pF/6kV
C3
1000pF/6kV
A106
D9
A106
D8
R11
100
CV1
500pF
C4
1000pF/6kV
A106
D7
R10
100
F.O.
PROTECTION BOARD
RS1
Lp
100
D6
A106
D5
A106
D4
R9 A106
CV2
1100pF
D3
A106
R2
V1
GU84B
C13
2.2nF
3k
100
R3
RV4
140V
RV3
140V
RV6
275V
RV5
140V
(BLUE)
C5
C6
2.2nF
RV2
140V
1N4148
C7
2.2nF
75k
R4
2.2k
C9
RV1
140V
L1
2.2nF
C10
22nF
C11
2.2nF
1N4148
D2
C8
1500p SM
10
R1
D1
C12
22nF
22nF
(White)
R7
50/100W
EBS
(Brown)
9-Way
COAX
COAX
26
C6
66pF
16.7 Circuit Diagram – DISPLAY BOARD
+5V
X3-14
C4
1nF
L1
L2
L3
L4
L5
L6
L7
L8
L9
L10
L11
L12
L13
L14
L15
L16
L17
L18
L19
L20
L21
L22
L23
L24
L25
L26
L27
L28
L29
L30
L31
L32
L33
L34
L35
L36
L37
L38
L39
L40
C1
100uF
X3-1
50k
L73
L72
L71
L75
L76
L77
L78
18
17
16
15
14
13
12
11
10
LED10
LED9
LED8
LED7
LED6
LED5
LED4
LED3
LED2
LED1
REF OUT
U5
LM3914
R4
R3
V-
1k2
V+
V-
MODE
SIG IN
1nF
V+
1k2
L74
1nF
REF ADJ
RHI
RLO
VR2
MODE
SIG IN
V+
C12
REF ADJ
RHI
RLO
V-
MODE
SIG IN
LED10
LED9
LED8
LED7
LED6
LED5
LED4
LED3
LED2
LED1
REF OUT
LED10
LED9
LED8
LED7
LED6
LED5
LED4
LED3
LED2
LED1
REF OUT
1k2
REF ADJ
RHI
RLO
V+
R2
1k2
C6
U4
LM3914
MODE
SIG IN
5k
1nF
V-
REF ADJ
RHI
RLO
VR1
C15
VOLT
R1
FORWARD POWER
X3-4
U3
LM3914
U2
LM3914
X3-11
18
17
16
15
14
13
12
11
10
C5
1nF
LED10
LED9
LED8
LED7
LED6
LED5
LED4
LED3
LED2
LED1
REF OUT
18
17
16
15
14
13
12
11
10
18
17
16
15
14
13
12
11
10
X3-12
L51
L52
L53
L54
L55
L56
L57
L58
L59
L60
L61
L62
L63
L64
L65
L66
L67
L18
L69
L70
18
17
16
15
14
13
12
11
10
18
17
16
15
14
13
12
11
10
R14
100
V-
L42
L43
L44
L45
L46
L47
L48
L49
L50
V+
V-
47uF
MODE
SIG IN
VR4
C2
U8
LM3914
V+
R9
560
AMP
R12
2k2
C8
1nF
R13
2k2
L41
18
17
16
15
14
13
12
11
10
U7
LM3914
X3-2
REF ADJ
RHI
RLO
R8
100
LED10
LED9
LED8
LED7
LED6
LED5
LED4
LED3
LED2
LED1
REF OUT
LED10
LED9
LED8
LED7
LED6
LED5
LED4
LED3
LED2
LED1
REF OUT
18
17
16
15
14
13
12
11
10
V+
V-
MODE
SIG IN
MODE
SIG IN
V+
C3
47uF
R15
560
5k
MODE
SIG IN
V-
R11
C9
2.nF
5k
REF ADJ
RHI
RLO
VR5
U10
LM3914
VR6
REF ADJ
RHI
RLO
Ig 2+
U9
LM3914
Ig2-
REF ADJ
RHI
RLO
LED10
LED9
LED8
LED7
LED6
LED5
LED4
LED3
LED2
LED1
REF OUT
X3-9
LED10
LED9
LED8
LED7
LED6
LED5
LED4
LED3
LED2
LED1
REF OUT
X3-8
5k
X3-6
C10
2.2nF
SWR/FLT
L81
D1
R6
1k2
R7
2k2
4V3
18
17
16
15
14
13
12
11
10
X3-3
LED10
LED9
LED8
LED7
LED6
LED5
LED4
LED3
LED2
LED1
REF OUT
X3-13
FAULT
C7
2.2nF
U6
LM3914
V-
MODE
SIG IN
REF ADJ
RHI
RLO
TX
V+
R5
2k2
X3-16
O/D
X3-10
L79
5k
X3-15
SWR
REFLECTED POWER
VR3
C11
2.2nF
X3-7
X3-5
C14
2.2nF
OD/T X
T itle
READY
Size
A3
Date:
27
E M T R O N
DISPLAY PANEL
Document Number
Rev
DP-1 V.3
Monday, January 07, 2002
Sheet
of
16.8 Circuit Diagram – SOFT START – 240 Volt version
R9
PHASE
10k
D1
R3
R8
470k/2W
R7
470k/2W
C6
2.2nF
C4
220uF/25V
D2
C13
4.7nF/250Vac/Y 2
1N4007
SCAP
MT2
R2
56R/2W
R4
150/2W
C12
100nF
C5
220uF/25V
LOAD
C10
100nF
C9
100nF
14
DSS
12
PC
11
RC
GND
RGT
LOAD
470nF/250Vac/X2
13
100k
100/2W
VCC
10
SR
15
SSC
CL
CS
TPA
LS
AS
R10
VS
U1
SS
16
100/2W
C1
R6
270k
C11
2.2nF
SWITCH
R1
1N4007
220/2W
SWITCH
R1
R2
56R/2W
C7
47nF
C8
3.3uF
C2
220nF/250Vac/X2
MT1
C3
2.2nF
NEUTRAL
GATE
C14
4.7nF/250Vac/Y 2
NOTE: 200V to 240V operation
For 110VAC, replace C1 by 3.9k or
resistor
4.3k / 6W
E M T R O N
Title
SOFT START
Size
A4
Date:
28
Document Number
SOFTSTART240V
Monday , January 07, 2002
Rev
Sheet
of
16.9 Circuit Diagram – QSK
JP1
D5
1N4004
D3
D1
1N4148
1N4004
RL1
RL2
R2
1k
D2
D4
C1
20uF
1N4148
1N4004
NR-HD-16V
Jenings TJ1A-26S
AMP
RF OUT
R1
680
(TO RF SENSOR)
RF DECK IN
RF DECK OUT
Rin
50
RF IN (SO239)
Title
E M T R O N
QSKv2 DX-2
Size
A4
Date:
29
Document Number
QSK2DX2
Monday , January 07, 2002
Rev
Sheet
of
5K
POT4
RFIN
X6. 3
X2.5
GND
WO6
C34
C11
100nF
2K2
R47
50K
GND
Q8
T9
U1
LM358
8k2
R29
100K
8k2
R69
GND
T10
GND
BC557
Q9
Q7
MPSA92
(4=GND, 8=12V)
U14
U12
OUT
10uF
SW1
OUT
R73
C37
4.7nF
Q18
BC557
12V
2(4=GND, 8=12V)
GND
C26
BC547
Q16
GND
C35
T8
R27
4K7
C3
100nF
R26
1K GND
1N4007
4.7nF
C43
GND
C2
C1
400
T12
PC521
U6 2
T11
D26
1nF/1KV
Q1
ZTX658
BZX79C24V
GND
C18
C50
5V6
R30
D10
1K
1K
R28
12V
GND
PC521
U8
Q22
BC547
D33
5K
GND
POT1
39K
22
R7
MPSA92
Q23
T2
HLSW2
X6. 2
X6. 1
HLSW1
Q25
POT7
100k
GND
BC547
Q3
500R
R33
1M5
R74
R6
1K
Q2
MJE16002
160K
R78
GND
C36
BC547
4.7nF
C27
-12V
ZTX558
Q4
C40
330K
R32
T5
5V
U9
PC521
POT8
5k
C56
22uF
10nF
C21
GND GND GND
10pF
C55
BR3
12V
GND
C5
C10
1uF
4V3
D23
100k
R91
4V3
D13
Q6
ZTX658
GND
3 U2
6 U2
18K
R46
OUT
4k7
R88
(4=-12V, 8=12V)
C28
-12V
4.7nF
C29
OUT
12V
100nF
LM358
(4=-12V, 8=12V)
100nF
R87
T13
BC557
Q17
8K2
R72
12V
4V3
8k2
R54
GND
T14 D15
5K
U1
OUT
C12
10uF
GND
D17
R19
BC547
RC
CLK
TH
T18 6
OUT
RC
GND
VCC
OUT
LMC555
U3 VC 7
GND
GND
C13 2 CLK LMC555
U4 VC 7
10uF 5 TH
10uF
R23
VCC
V2
RL1
V1
OUT
TH
T19
R60
8k2
C1
12V
C41
Q13
GND
BC547
GND
BC547
Q11
T17
8k2
1N4148
D19
D18
Q14
1N4007
4.7nF
OUT
5V
X3. 5
PTT1
PTT2
GND
X5. 1
4.7nF
C32
X8. 5
5V DISPLAY
4.7nF
C54
X3.3
F8
22VAC2
X3.2
QSK2
WO6
X9.3
QSK1
X4. 2
X4. 5
RLY2
RLY1
X4. 4
EG2
X8. 2
STBY2
X4. 1
GND
10uF/25V
C17
7805
COM
IN
U13
100nF
C16
C15
100uF/50V
BR4
F7
22VAC1
X3.1
GND
12V
GND
C53
NC1 NO1
NC2 NO2
V1
RL4 M4-12H
V2
C1
T20
GND
1N4148
D21
M4-12H
C2
NO2 NC2
STBY1
X4.3 X9.1
C2
R63
2k2
BC547
Q12
T110-1
T110-2
X7. 6
X7. 5
R59
T110-2
10nF
C42
GND
LP2
10nF
22k R25
R24 22k
X5. 3
FAULT
V2
RL2
V1
BC547
Q15
NO1 NC1
READY
X6. 4
R92 BC547
R64
8k2
X6. 6 X5.6
GND
1K
X5.4 X5. 2
O/DRIVE OD/TX X5.5
SWR SWR/FLT
TXON
R61
LP1
T110-1
GND
U11 3
PC521
C8
10uF/16V
GND
470R
8k2
R58
GND
12V
D16
10nF
C51
T6
M4-12H
C2
NO2 NC2
U5
CLK LMC555 7
VC
RC
C45
GND
100R
IPTRIP
X3. 4
C24 C25
VCC
C23 5
500R
8 4.7nF
C1
NO1 NC1
10nF
12V
F6
4.7nF
C46
C7 22uF
GND
C14 10uF
T16
Q10
4.7nF
C30
1N4148
(4=GND, 8=12V)
LM358
T15
C6
100R
GND
10VAC2 12VP
X2. 1
X2. 2 X4. 6
R89POT6
C52 4k7
LBA291
F5
C22
10uF
X8. 1 X7. 4 X7. 3
D28
D3
1N4148
1N4148
U10
1N4148
D27
1N4148
D2
T4
IG2F
X8. 4
DISPLAY
FORWARD
IG2R
X8. 3
10VAC1
X2. 4
DISPLAY REVERSE X2. 3
4K7
R17 5V PC521
2k2
R16
GND
22nF/630V 10uF/450V
C33 C20
EMTRON
AMPC v.3E JAN2002
10nF
C19
Q5
TIPL760A
T3
BIAS
ALC2
ALC1
LM358 3
1 U14 +
X6.5
X1. 1
X1. 6
OUT
2 10nF
C48
4.7nF
C49
C47
TP2
(4=-12V,
8=12V)
C4
4.7nF
2.2uF
4.7nF
X9.
12k
GND 4.7nF
IPTRIP2
C39
R90
X3. 6
R70
X1.
X1.
X1.
X1.
12V
1N4148
100k
22k
100R
SWR1 SWR2 SWR3 SWR4
R44
D12
R57
R43
300K
1N4148
330K
R31
240R
R10
3M3
62V
1N4148
1N4148
D30
R38
D34
D29
D29
WO6
F2
300VAC2
POT3
BC557
GND
C9
12K
T7 R35
100VAC2
BR2
100VAC1
X2.6
F3
GND
R36
4700uF/16V
R3
150uF/400V
150uF/400V
X7. 2
330k
100nF
X7. 1 BR1
R37
4.7nF/1kV
F4
25uF/160V
15K
1M
R75
R1
220K
8k2
D20
22R
33K
BZX79C5V6
12K
R4 220K
R5
220K
2K2
R40
POT2
R2
220K
4.7nF/1kV
R39
D11
R48
300k R83
D32
1N4148
10K R76
6k8
6K8
R66
22K
1N4148
D5
R12
R13
R42
1K
160K
100K
R34
300k R86
1N4148
56R
D1
R45
R8
1uF/160V
R18A
R18
1N4148
56R
D24
R71
1k R85
R84
2K2
R50
5M6
D6
1N4148
1K
R51
100R
100K
8k2
R52
R67
100k
D22
1K
R68
1N4148
R15
100k
R14
2K2
8K2
R49
8k2
15V
POT5
8k2
D7
T1
R55
R53
100nF
8k2
R41 33k
12V
D14
D25
R20
R56
4.7nF
D4
300k
100K
1K
1K
D8
D9
1K
1N4007
1N4007
R21
R65
R62
30
4.7nFC31
R22
1N4148
300VAC1
F1
16.10 Circuit Diagram – CONTROL BOARD
R78
R8
D14
POT5
R71
X1.
R13
R12
D10
R28
R50
R49
R51
R52
R34
R30
R75
C27
SWR
R32
R31
R37
R33
PRE-BIAS
C48 1 C39
R41
U1
Q18
C3
R27
R26
R73
1 C37
C30
D24
R29
POT7
R69
Q6
C50
R84
D33
R86
Q2
R87
C28
C29
D32
R83
R74
U2
R91
C26
R88
R56
R85
D15
Q7
U3
U4
C5
EBS
SW2
SW1
R15
Q4
Q1
U8
C43
R5
U13
X8.
U9
C31
U10
C18
D27
D28
D3
D2
C32
BR1
AMPC v.3D
X2.
D26
C33
R38
R4
D1
R14
R10
R17
R16
R18
BR2
+~
~ -
R6
R7
D12
R70
R42
Ig2LIM
Q5
EBS
C47
R21
R47
R48
POT4 R40
POT1
C9
R54
C14
R53
D16
D17
R55
Q10
C12
C13
SCREEN
R46
R67
C40
R61
R72
Q9
X6.
R66
R39
D13
D23
R43
D25
R44
R45
POT2
Q25
R36
D11
C10
R76
C11
C35
Q23
BIAS POT3
R35
C49
Q22
Q8
C19
C36
Q3
Q17
D35
C45
C1
D29
+~
~ -
C2
R3
C8
D21
D22
R92
C42
C41
C15
C56 IPTRIP
1 C16
R23
C22
R89
Ig2
POT8
RL4
Q12
Q14
Q15
D5
D20
R25
R24
R20
R19
D4
RL1
C24
C54
C7
D8
D6
D7
R22
D9
U6
R57
U11
C25
R60
R59
R58
Q11
C17
X5.
C53
RL2
C4
POT6
R2
U14
C51
- ~
~+
BR4
C21
C23
U5
C46
R90
Q13
D19
D18
R68
R65
R64
R63
R62
C52
X4.
C55
TP2
X9.
Q16
BR3
C6
C34
31
R1
EBS OFF
GND
X3.
Ip
X7.
C20
16.11 Control Board – Component Legend
AMPC V.3E
SILK SCREEN LAYER COMPONENT SIDE
16.12 Control Board – Solder Side Track work
AMPC V.3E
COPPER LAYER SOLDER SIDE
32
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