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NT 250 Technical and Maintenance Manual NicomUsa Inc
TABLE OF CONTENTS
CHAPTER 1
Transmitter General Description And Installation Procedures Page 2
Remote Control Feature Page 3
Programming the NT 250 Page 5
CHAPTER 2
Electrical & Mechanical Specifications Page 10
Front Panel Description Page 13
Rear Panel Description Page 14
CHAPTER 3
250 W schematics and components list Page 15
Page 1
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NT 250 Technical and Maintenance Manual NicomUsa Inc CHAPTER 1 GENERAL DESCRIPTION NT 250 Transmitter Exciter INTRODUCTION The NT 250 FM Exciter is the latest in state of the art products available from Nicom. This Transmitter is designed with high reliability components and is intended to give many years of trouble free continuous service. This unit incorporates many features including a switching power supply and a PLL frequency synthesizer. The latest SMD tec
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NT 250 Technical and Maintenance Manual NicomUsa Inc REMOTE CONTROL FEATURE The NT 250 is equipped with a 9 pin RS 232 connector that allows all the mains telemetry functions. The software is supplied with the unit and with this CD rom it's possible to monitor and to change the main parameters ot the NT 250 on the computer's screen. The NT 250 is also supplied with the interlock connector that allows to switch the power on and off simply by grounding the inner conductor of the BNC. N
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NT 250 Technical and Maintenance Manual NicomUsa Inc RUNNING THE PROGRAM Once the program is running, from the main screen it is necessary to click the POWER ON button; the screen will light up and a message" COMMUNICATION IN PROGRESS" will appear. After few seconds, on the left side of the screen, the operating frequency will appear together with all the other parameters. If not, check the Communication port setting (COM1-COM 2). To change it, click the File menu and then select
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NT 250 PROGRAMMING Connect a 50 ohm load or 50 ohm antenna to the RF output, connect the equipment into a mains supply (100÷240 VAC). The equipment is factory pre-set to 50 W. Switch ON the power and the yellow V POWER LED will light. The Display will show: PROGRAM WAIT SETTING After 3 seconds the green PLL LOCK led will light and the Display will show an increasing bar. After a further 5 seconds the green ENABLE will light and there will be output powe
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The default frequency is 98.000 MHz. To display the frequency push the SETTING key. In order to display the parameter push the SELECT key. Display Password The Password mode is factory set to enable, and is not possible change this setting. The default password is 1 2 3. The way for changing the password is the following: • Press the PROGRAM key for 3 seconds; PROGRAM PASSWORD 0 1 2 3 4 5 6 7 8 9 SETTING • Press the PROGRAM key to move the underscor
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PROGRAM CONFIRM (Y/N) ? N=SEL. Y=SET. SETTING If the password is not correct an error is displayed: PROGRAM ERROR PASSWORD SETTING After a few seconds the display will show the parameters again. • When the password is correct, the display will show: PROGRAM NEW PASS . = SET. NEW FREQ . = PRG SETTING To change the password press the SETTING key. To change the frequency press the PROGRAM key. • For changing the passw
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If the password is correct the display will show: PROGRAM STORED NEW PASSWORD SETTING If the confirmation password is wrong the display will show: PROGRAM ERROR CONFIRMATION SETTING IMPORTANT NOTE ! BE CAREFUL ! Once the password is set, it must be remembered, otherwise neither the frequency nor the password can be reset and the unit will have to be returned to Nicom for resetting. Display Change of Frequency. • Press the PROGRAM key for
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The underscore character indicates which digit can be change. To move the underscore character hit the PROGRAM key. When the new frequency is chosen, then press the SETTING key confirm it. After a “WAIT CYCLE”, the display will show the parameters: PROGRAM MOD > FRW 50W RFL 0.4W SETTING After 7 minutes the display light will switch off and the display will show: PROGRAM NICOM MHz 103.900 SETTING
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NT 250 Technical and Maintenance Manual NicomUsa Inc CHAPTER 2 ELECTRICAL SPECIFICATIONS NT 250 TECHNICAL DATA Power output: 2 to 270 Watts continuously variable Frequency of operation: Sinthesized with TXCO crystal reference RF output connector/ Impedance: Type "N" Female / 50 Ohms Frequency Stability: Better than 5ppm (± 500 Hz) , 0 to 50° C. Frequency Range: 87.5 - 108 Mhz Frequency programming: Digitally in 10 Khz increments. Modulation type: Direct FM at the carrier frequenc
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NT 250 Technical and Maintenance Manual NicomUsa Inc COMPOSITE OPERATION Composite inputs four total, 1 for MPX and 3 for SCA MPX input 1 unbalanced bnc connector MPX input impedance 2 K ohms MPX input level 3,5 V p-p (1,237 Vrms/3.64 dBm) Composite FM unweighed S/N ratio > 78 dB below ± 75 Khz deviation at 400 Hz measured in a 30 Hz - 100Khz bandwidth with 75 usec de-emphasis (RMS) Composite Total Harmonic Distortion 0.05 % typical Composite Intermodulation Distortion 0.05 %, measur
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NT 250 Technical and Maintenance Manual NicomUsa Inc MECHANICAL SPECIFICATIONS Chassis Dimensions: 132 mm (5.1") H 326 mm (12.83")D 445 mm (17.51) W Front panel dimensions: 483 mm (19") W 132 mm (5.1") H Ambient operating temperature: from 0 to + 50 C (+32 to +122 F) Humidity: 90% maximum, non condensing. Weight: 32 Lbs ( 14.5 Kg) Shipping Dimensions: 22" x 23" x 8" Page 12
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LOCK ENABLE PROGRAM 6 3 4 7 5 PWR PWR AD ADJ J.. 2 1 SET 8 VDC2 VDC1 ON 9 OFF FM FM TRANSMITTER TRANSMITTER NT NT 250 250 EXTERNAL POWER SUPPLY CORRECT OPERATION YELLOW INDICATOR 1- 2 - POWER STAGE SUPPLY CORRECT OPERATION YELLOW INDICATOR 3 - PLL LOCK FREQUENCY CONTROL CORRECT OPERATION CIRCUIT GREEN INDICATOR 4 - PRESENCE OF RF POWER AT FREQUENCY SET ON OUTPUT CONNECTOR GREEN INDICATOR 5 - RF OUTPUT POWER ADJUSTING FROM 0 TO OVER 250W 6- LCD MULTIMETER DISPLAY SHOWING: - operational frequency
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RF OUTPUT 3 50 OHM 250W REMOTE CONTROL 50 1 GND MONO SCA 3 SCA 2 SCA 1 MPX 75 2 + S 8 3- 6 7 14 4 16 11 9 10 13 12 15 INTERLOCK 5 MAINS V WARNING Voltages under equipment cover plate A can be hazardous to your life. Equipment only can be handled by qualified personnel. 1 2 CE 1 - MAIN SUPPLY CONNECTOR 2 - AC FUSE 3A 3-FAN 4 - DB 9 PIN INPUT / OUTPUT CONNECTOR FOR TELEMETRY ( opt.01 ) 5 - BNC FEMALE FOR CONNECTION OF THE INTERLOCK LOOP - A CONNECTION TO GROUND INHIBIT RF POWER 6-7-8- BNC FEMALES
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N COM e Si Rev B 1.0 1 of 1 et She 24, 2003 Friday, October Date: Mod. NT 250 Document Number ze IC FUNCTIONAL SCHEMAT Titl SUPPLY MHz 98.000 MICROCONTROLLER VDC POWER VAC NICOM DISPLAY MHz RS232 12.8 TCXO SCA SIGNAL INTERFACE PLL AUDIO INPUT MONO ADJ MPX COUPLER RF OUTPUT VCO DIRECTIONAL LIMITER LPF RF AMPLIFIER RF DRIVER
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1 2 3 32 ERLOCK MPX MONO SCA SCA SCA RS2 INT RF OUTPU T G JR1 GND 5 9 with F1 BNC BNC BNC BNC BNC 4 8 3 + - C 7 2 1 2 F2 1 2 6 E E E E E E E 1 L N L1 L2 L3 L4 L5 L6 L7 CHOK CHOK CHOK CHOK CHOK CHOK CHOK X MP RF OUTPUT SCA2 SCA1 SCA3 MONO- L MONO+ Interlock GND MPX GND SCA1 GND SCA2 GND SCA3 N GND MONO GND Interlock DJ3-RS232 GND GND RF REFLECTED RF OUTPUT GND RF OUTPU T R R POWER ATE MPERATURE FORWARD POWE V- G TE DISPLAY REFLECTED J4-LED & ADJ POWE TEMPERATURE +27V GND GATES -12V 1 2 R1 F3 POW
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5 1 6 0.8mH L OUT 2 GND HEART SW1 3 7 0.8mH N OUT N COM Titl e Document Number A 1 1 of Sheet Friday, January 31, 2003 Date: Mod. EMC-03 1.0 Rev Size EMC FILTER N IN TERM TERM L9 275V 2.2nF / 350V RV3 C3 275V 1uF / 350V RV2 C2 TERM 275V 2.2nF / 350V RV1 C1 L IN TERM TERM L8 FUSE B FUSE A TERM TERM4
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+24 V R1 +24 V V V V V +15 GND +24 +15 +5V -15 Protection & Meter 1 +15 V 2 1 3 2 4 3 LED RF 5 6 7 8 +24 V +24 V -15V 1 -5V -5V LED RF LED RF 10 -15 V -15V D1 V-GAT E LL414 8 LED RF C1 + C2 + LED RF 1 22MF / 16V 22MF / 16V 2 3 -5V 2 1 Interlock L1 1 +15 V RFL PW R2 RF RFL METER 1 2K2 DB9_FWD 2 DB9_RFL C3 C4 DB9_RFL_PW 1nF 1nF R3 10K 1 L2 -15 V -15V 2 V V 1 +15 +5V GND +15 GND C5 C6 1nF 1nF 1 L3 2 2 -5V -5V C7 C8 4 1nF 1nF 2 1 L4 3 3 C9 C10 PLL LOCK 1nF 1nF 1 RF PLL L5 2 4 RFL PWR C11 C12 1nF 1nF
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C26 60p F R5 8 R6 OP275 27K R7 47K R8 OP27 5 12K 5 + 7 47K 3 + 6 1 - 2 - R9 4 R10 27K R11 47K C29 R14 470p F D3 D4 C27 12K R12 10pF R15 R16 R17 1K2 20 0 3K9 C28 +15 V -15 V 22p F R18 R19 1K2 3K9 C31 R13 C32 + 1000MF / 35V 10K R21 470p F 12K R20 C30 + 100MF / 16V C33 R23 470p F +15 V 12K R22 R24 33 C34 R25 10MF / 35V 220 K R179 20K + C35 C36 D5 R26 R28 470MF / 35 V 470MF / 35 V 8 LL41 8 100 K 4K7 R27 + 3 + + 1 5 + 2 7 - 6 R29 - D6 R30 C37 C38 10K + 3V3 560 K 2.2MF / 50V 4 10MF / 35V D7 D8 LL414 8
