BEXT PJ 250 Manuel utilisateur
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PJ 250
FM Power Amplifier
87.5 - 108 MHz Range
TECHNICAL
MANUAL
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INDEX
PRELIMINARY INSTRUCTIONS AND WARRANTY INFORMATION........................................... 2-3
INSTALLATION ....................................................................................................................................... 4
MECHANICAL / ELECTRICAL .............................................................................................................. 4
OPERATION ........................................................................................................................................... 4-5
TECHNICAL SPECIFICATIONS ............................................................................................................. 6
FRONT AND REAR PANEL CONTROLS .............................................................................................. 7
FIGURE 1 FRONT PANEL ....................................................................................................................... 8
FIGURE 2 REAR PANEL .......................................................................................................................... 9
GENERAL AND ELECTRICAL DESCRIPTION ............................................................................. 10-11
RECOMMENDED TEST EQUIPMENT ................................................................................................. 11
MAINTENANCE AND ADJUSTMENTS ......................................................................................... 11-14
SETUP 1 ................................................................................................................................................... 15
SETUP 2 ................................................................................................................................................... 16
FIGURE 3 AMPLIFIER BLOCK DIAGRAM ......................................................................................... 17
FIGURE 4 AC POWER CONNECTIONS ............................................................................................... 18
FIGURE 5 SCHEMATIC, UNREGULATED POWER ........................................................................... 19
FIGURE 6 SCHEMATIC, REGULATED POWER ................................................................................ 20
FIGURE 7 SCHEMATIC DRIVER AMPLIFIER (PJ250 L/D ONLY) .................................................. 22
FIGURE 7a IPA RF AMPLIFIER (PJ250 L/D ONLY) ........................................................................... 23
FIGURE 8 SCHEMATIC, POWER AMPLIFIER ................................................................................... 25
FIGURE 9 SCHEMATIC, ALARMS CARD .......................................................................................... 27
FIGURE 10. COMPONENTS ARRANGEMENT, ALARMS CARD .................................................... 28
FIGURE 11. SCHEMATIC, LOW PASS FILTER .................................................................................. 31
FIGURE 12. SCHEMATIC, VSWR BRIDGE ......................................................................................... 33
FIGURE 13. SCHEMATIC, TELEMETRY CARD ................................................................................ 34
FIGURE 14. COMPONENTS ARRANGEMENT, TELEMETRY CARD ............................................. 35
FIGURE 15. WIRING DIAGRAM, TELEMETRY INTERCONNECT ................................................. 36
PARTS LIST POWER SUPPLY .............................................................................................................. 21
PARTS LIST RF DRIVER BOARD (PJ250 L/D ONLY) ....................................................................... 24
PARTS LIST RF POWER AMPLIFIER .................................................................................................. 26
PARTS LIST LOW PASS FILTER .......................................................................................................... 32
PARTS LIST DIRECTIONAL COUPLER .............................................................................................. 32
PARTS LIST ALARMS PROTECTION CARD ................................................................................ 29-30
PARTS LIST TELEMETRY CARD ........................................................................................................ 37
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PRELIMINARY INSTRUCTIONS AND
WARRANTY INFORMATION
1. Please observe all safety precautions when handling this unit. This equipment contains
dangerous currents and voltages.
2. This manual is written as a general guide for those having previous knowledge and
experience with this kind of equipment. It is not intended to contain a complete statement
of all safety precautions which should be observed by personnel in using this or other
electronic equipment.
3. BEXT Inc. does not assume responsibility for injury or damage resulting from improper
procedures or practices of untrained/unqualified personnel in the handling of this unit.
4. Please observe all local codes and fire protection standards in the operation of this unit.
5. CAUTION: Always disconnect power before opening covers or removing any part of this
unit. Use appropriate grounding procedures to short out capacitors and high voltage
points before servicing.
6. Any damage to the goods must be reported to the carrier in writing on the shipment
receipt. Any discrepancy/damage discovered subsequent to delivery shall be reported to
BEXT Inc. within five days of receipt.
7. BEXT Inc. extends to the original end-user purchaser all original manufacturer’s
warranties which are transferable and all claims are to be made directly to BEXT Inc. per
indicated procedures.
8. All manufacturer’s warranties will be supported by BEXT Inc. to ensure precise and
speedy service where possible.
9. BEXT Inc. shall not be liable for damages of any nature arising out of or in connection
with the product or its use thereof.
10. BEXT’s warranty shall not include:
10.1 Reshipment of the unit to BEXT for repair purposes.
10.2 Any unauthorized repairs/modifications.
10.3 Incidental/consequential damages as a result of any defect.
10.4 Nominal non-incidental defects.
10.5 Reshipment costs or insurance of the unit or replacement units/parts.
11. Warranty shall commence on the invoice date and for the period of the manufacturer’s
warranty.
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12. To claim your rights under this warranty:
12.1 Contact the dealer or distributor from whom this product was purchased. Describe
the problem and ask if they have an easy solution. Dealers and distributors are
supplied with information on problems which may occur and usually can repair
the unit more quickly than going directly to the factory. It is also often true that
errors in installation or use will be discovered by your dealer.
12.2 If your dealer cannot help, contact BEXT Inc. at (619) 239-8462 and explain the
problem. If it is determined that the unit needs to be returned to the factory,
BEXT will provide a return authorization number with instructions.
12.3 When you receive the return authorization, you can return the unit. Pack the unit
carefully for shipment. Preferably, use the original packing materials and assume
that the shipping carton will be dropped several times during the transportation
process. We recommend the use of UPS or similar freight services and would
discourage the use of the postal system. The customer assumes the risk of loss,
(i.e. BEXT Inc., is not responsible for damage or loss) until the package is
received by BEXT, so we advise taking out insurance for the full replacement
value of the unit. Ship the unit PREPAID to the address specified by BEXT’s
service manager on the return authorization. DO NOT RETURN UNITS
WITHOUT A RETURN AUTHORIZATION, AS THEY WILL NOT BE
ACCEPTED.
12.4 Be sure to enclose a written descriptive statement of the problem experienced and
a copy of your original invoice establishing the starting date of the warranty.
13. BEXT Inc. reserves the right to modify the design and specifications of the equipment in
this manual without notice.
14. Replacement and warranty parts may be ordered from the address below. Be sure to
include equipment model and serial number and part description and part number.
BEXTInc.
1045 Tenth Avenue
San Diego, CA 92101 USA
(619) 239-8462 • FAX (619) 239-8474
24-Hour Pager: (619) 529-4711
http://www.bext.com
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INSTALLATION
INSTALLATION
A. Read the BEXT warning, shipping and warranty information at the front of the manual.
B. Handle the unit as carefully as possible.
C. Unpack the amplifier and, before any other operation, check that the amplifier isn't damaged and
that all controls on the front and rear panel are in good condition.
D. Save the original packing materials.
MECHANICAL / ELECTRICAL
A. Operate the unit with adequate ventilation in a relatively cool environment.
B. Check that the A.C. supply is adequate for the expected power consumption and that the line
voltage matches the taps in the unit with minimal line voltage variation. If the line voltage
fluctuates frequently and extensively, a voltage regulator is recommended. A surge/transient
suppression system is also highly recommended.
C. Never operate the unit without a dummy load or properly matched antenna load.
D. If you are going to operate solid state equipment as a final amplifier in a very crowded
transmitting site, it is suggested that a fundamental frequency/cavity bandpass filter be inserted in
the line between the equipment and the antenna. The BEXT staff can assist you.
OPERATION
A. Open the cover and check the voltage setting on the transformer. The transformer offers several
taps for different voltages. If it is found necessary to move the taps, move only the A.C. primary
taps. Do not move the fan wires which are connected to the same terminal block.
B. Turn the "power adjust" of the exciter to zero and turn the power switches to the "off" position of
both the amplifier and the exciter. Set the exciter to the desired frequency of operation.
C. Connect the RF output of the exciter to the input of the amplifier. The input of the amplifier uses
a type "N" connector. Use good quality cable to prevent RF leakage. Connect the RF output of
the amplifier to a suitable dummy load or antenna.
D. Connect the exciter A.C. cord to the plug provided on the rear of the amplifier. This will provide
protection by shutting down the exciter when an alarm condition is detected by the amplifier.
Connect the amplifier A.C. cord to the A.C. supply.
E. Turn the amplifier power on. The power indicator should come on and the fans should begin
running. CAUTION: Do not apply RF drive unless the fans are running properly. If the unit does
not come on the user should check the following:
1. Check the A.C. line fuses.
2. Check the A.C. line connections.
3. Check the internal transformer taps and the fan/blower itself.
F. Turn on the exciter. The power indicator light should come on and a lock indication should come
on. The exciter blower should also be running. Check all power supply voltages on the amplifier
and exciter to ensure they are correct before proceeding. The amplifier voltage should be
approximately 28 volts. Exciter voltages will be marked on the front panel of the exciter and will
vary with the type of exciter.
G. Set the power meter switch to the forward power position on both the exciter and the amplifier.
Slowly advance the power on the exciter until RF power output is observed on both meters.
Check now for VSWR. If the standing wave reading appears normal (less than 1.5:1) then
proceed to raise the power. The voltage on the amplifier should remain steady at approximately
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28 volts. The exciter PA voltage will change with drive level. Efficiency of the amplifier will be
approximately 60%.
H. Maximum VSWR should never exceed 2:1. Should the amplifier see a VSWR higher than this it
will trip the alarm board and shut down both the amplifier and the exciter.
I. Alarm conditions which will shut down the amplifier are: VSWR of greater than 2:1; excessive
power output(higher than the rating); high temperature. Should the amplifier sense any of the
above conditions it will shut down and automatically attempt to restart after 90 seconds and will
attempt 4 times to restart. The unit will then shut down for 15 minutes; and again go through the
4 restart attempts. After four of these cycles the unit will go into a permanent shutdown. The
power must be recycled to reset the alarm circuits. The operator should always look at the front
panel to determine which alarm shut the unit down. This will aid in locating conditions which are
causing the problem should one exist.
J. Telemetry is provided on the rear panel to monitor the voltage, current, power, and reflected
power of the amplifier. Terminals are also provided to enable putting the amplifier in standby via
a momentary contact closure. A momentary contact closure will also reactivate the amplifier. A
second input is provided which will place the amplifier and exciter in standby. Two "BNC"
connectors labeled "REMOTE" are provided on the rear of the amplifier and another on the rear
of the exciter. Connect the exciter remote BNC to the either of the amplifier remote BNC
connectors. By placing a ground on the center pin of the second BNC connector the RF drive will
be shut down to the amplifier. This can be accomplished by placing a ground on the exciter
remote connection only.
K. High VSWR conditions may be caused by icing of the antenna during winter storms. Leaking
transmission lines may have moisture or damage may occur to the antenna itself. Do not attempt
to reset the alarm levels to circumvent an external problem. This will cause damage to the
expensive RF output transistors and void the warranty. The user should also provide effective
lightening protection such as sorted quarter wave stubs on the transmission line. Power line
protection is also recommended as lightening hits many time come in on the power or telephone
lines. The telemetry lines should also be protected if connected to the telephone lines or lines
exiting the building. A good grounding system will help ensure many years of reliable operation
from your solid state equipment.
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TABLE A
TECHNICAL SPECIFICATIONS
A.C. Supply 100-130 V or 198-250 V
50-60 Hz
Cooling Forced Ventilation
Frequency Range from 87.5 to 108 MHz or
from 66 to 75 MHz
Power Output Max 300 W, typ. 250 W (Note: Limit power to
250W to maintain a good level of reliability.
RF Drive Power approximately 25 W for
P out=250 W
RF Input Impedance 50 ohm
RF Output Impedance 50 ohm
I/O Connector Standard "N" Connector
Harmonic and Spurious Signal Suppression meets or exceeds FCC and CCIR regulations
Power Consumption 800 w
TABLE B
DIMENSIONAL AND ENVIRONMENTAL SPECIFICATIONS
Cabinet Dimension 122mm(4.8")H x 420mm(16.54")W
350mm(13.78")D
Panel Size 483mm(19")W x 132mm(5.2")H
Operating Temperature -10°C to 45°C
Humidity 90% Max, Non Condensing
Weight 19 Kg
The protection acts for excessive SWR, over-temperature and overdrive. It indicates the problem with
warning lights and disables the pilot exciter.
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FRONT AND REAR PANEL CONTROLS
A. FRONT PANEL
1. Fuse 6.3 amps 220 Vac or 15 amps 120Vac
2. On/Off A.C. power switch
3. A.C. Blown Fuse Indicator
4. A.C. Power Indicator
5. Multimeter
6. Multimeter Switch
7. D.C. Fuse 20 amps
8. D.C. Blown Fuse Indicator
9. Temperature Alarm Indicator Lamp
10. Excessive Drive Alarm
11. VSWR Alarm Indicator
12. Remote Disable Indicator
B. REAR PANEL
1. RF output connector Type "N"
2. RF input connector Type "N"
3. Accessory AC plug for exciter (max 3 amps)
4. Remote protection connector Type "BNC", ground to activate
5. Remote protection connector Type "BNC". ground to activate
6. Telemetry Connections
7. Air Duct
8. A.C. Line Input
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Table des matières
