Genius 250 User Manual

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

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 technology has allowed to make a more compact unit (only 3 rack spaces) and at the same time a very light unit (only 32 lbs).

INSTALLATION After unpacking the module, check for any mechanical damage or loose parts inside.If there is

any transportation damage, inform the supplier immediately and do not put the module into operation.

The voltage is applicable from 100 to 240 Volts without needing any change. Ensure that the station’s ground system connections have a ground resistance of less than 5 ohms. The equipment’s rack or cabinet must be effectively grounded.

Check that the transmitter’s main switch is off. Connect the power cord to the AC plug. STARTING PROCEDURE

Connect the antenna cable to the ‘N’ connector on the back of the unit. The antenna system must be set up to operate at the transmitter’s working frequency.

ATTENTION

Antenna matching is extremely crucial for FM transmitters. Operate this unit only after verifying good matching. Mismatching will decrease the communication distance and unduly stress the semiconductors. Turn on the transmitter. After 1 or 2 seconds the green LED “PLL LOCK” should turn on. This indicates that the frequency is locked on the programmed value. After 1 more second the “RF ENABLE” green LED will come on. This indicates that RF power is being delivered to the output connector on the back. Now you can input modulation. For MONO operation connect your signal to the XLR connector following the connecting instructions printed on the back of the transmitter and then regulate the input level with the apposite trimmer. For stereo input, use the BNC connector labeled “MPX”. Regulate the audio with the apposite trimmer.

Note:Be sure that the modulation level is close to but not more than 75KHz. 75KHz is 100% modulation. Lower modulation level will decrease the S/N value while over-modulation (>100%) will cause distortion at the receiver and it is against current regulations.

Page 2

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.

NOTE: The CD Rom supplied contains the remote control software of the NT 250.

REMOTE CONTROL SOFTWARE

INSTALLATION

The NT 250 comes with a Serial port RS 232. This port allows a Bi-Directional remote control of the unit from a PC.

INSTALLING THE SOFTWARE

1. Insert the NT 250 CD-ROM into the CD drive.

2. Run Setup.exe file found in the main folder of the CD-ROM. The installation will continue automatically asking only for the name of the folder of the hard drive where the program will be installed. It will be necessary to reboot the computer.

3. Once installed, the Tx_Nicom program icon can be recalled by clicking : Start - Programs Tx_Nicom icon.

CONNECTING THE NT 250

The NT 250 is equipped with a Serial Port (RS232) in the rear panel. To connect the computer with the NT 250 we recommend standard serial cables Pin-to-Pin; the lenght of the cable must stay within 60 feet.

REMEMBER TO CLOSE THE PROGRAM BEFORE REMOVING THE CONNECTING CABLE

Page 3

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 "set Port". The other parameters shown on the screen are the following:

Temperature in Celsius ( remember that Farheneit is Celsius x 1.8 + 20)

2. Lock Indicator showing that PLL circuit of the unit is locked

3. On the Air showing that the unit is transmitting

4. RF Forward giving the amount of Watts radiated

5. RF Reflected giving the amount of reflected power

On the right side of the screen there are four buttons that allow to modify the parameters:

a. Send Button to be used after a change of frequency is made b. Set Frequency allows the change of frequency by clicking the new frequency on

the keyboard on the left side of the screen c. Disconnect allows to disconnect the system d. RF On turns up and down the power

Page 4

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:

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 power.

At this point the Display will show the next parameter:

•

Level Modulation (MOD > );

•

Forward Power (FRW 50.0W);

• Reflected Power (RFL 0.4W).

MOD > FRW 50W RFL 0.4W

WAIT

PROGRAM

SETTING

PROGRAM

SETTING

PROGRAM

SETTING

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

The way for changing the password is the following:

• Press the PROGRAM key for 3 seconds;

• Press the PROGRAM key to move the underscore character position

at the required digit, and press the SETTING key to confirm the digit.

Repeat the same for the two remaining digits.

• If the password is correct press the SETTING key to confirm, otherwise press the PROGRAM key to select again.

PASSWORD

1 2 3

1 2 3 4 5 6 7 8 9

0 1 2 3 4 5 6 7 8 9

PROGRAM

SETTING

PROGRAM

SETTING

PROGRAM

SETTING

If the password is not correct an error is displayed:

After a few seconds the display will show the parameters again.

•

When the password is correct, the display will show:

To change the password press the SETTING key. To change the frequency press the PROGRAM key.

•

For changing the password proceed with the same method for the required password:

The confirmation password will be required.

CONFIRM (Y/N) ?

N=SEL. Y=SET.

ERROR

PASSWORD

NEW PASS . = SET. NEW FREQ . = PRG

NEW PASSWORD

1 2 3 4 5 6 7 8 9

CONFIRMATION

1 2 3 4 5 6 7 8 9

PROGRAM

SETTING

PROGRAM

SETTING

PROGRAM

SETTING

PROGRAM

SETTING

PROGRAM

SETTING

If the password is correct the display will show:

If the confirmation password is wrong the display will show:

IMPORTANT NOTE

NEW PASSWORD

STORED

ERROR

CONFIRMATION

! 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 3 seconds and enter the correct password. At this point press again the SELECT key:

•

Press the PROGRAM key to change the desired digit and press the SETTING key to confirm it.

NEW PASS . = SET. NEW FREQ . = PRG

FREQUENCY ?

MHz 1

03.900

PROGRAM

SETTING

PROGRAM

SETTING

PROGRAM

SETTING

PROGRAM

SETTING

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:

After 7 minutes the display light will switch off and the display will show:

MOD > FRW 50W RFL 0.4W

NICOM

MHz 103.900

PROGRAM

SETTING

PROGRAM

SETTING

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 ( Frequency Range: 87.5 - 108 Mhz

Frequency programming: Digitally in 10 Khz increments. Modulation type: Direct FM at the carrier frequency S/N Ratio (ref. to 50 Khz / 1000 Hz): Mono > 70dB - Stereo > 65 dB. Distortion, THD: < 0.1 %, Typ. 0.05 % Asyncronous AM S/N ratio: 65 dB below reference carrier with 100% AM

modulation, 75 usec de-emphasis (no FM modulation present).

Syncronous AM S/N ratio: 60 dB below reference carrier with 100% AM

modulation (FM modulation

DC input power: 24 V VDC 8 A AC input power: Single phase 100 - 240 V Ambient Temperature Range: 0° to 50° C (+32° to +122° F) Spurious and Harmonic or Subharmonic Emissions: < -80 dB or better Stereo Separation 55 dB @ 1 Khz

500 Hz) , 0 to 50° C.

75 Khz).

Page 10

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 %, measured with a 1 Khz and a 1.3 Khz

tone, 1:1 ratio, at 100% modulation Baseband 30 Hz - 60 Khz within 0.15 dB Crosstalk main to stereo subchannel and stereo subchannel

to main > 55 dB ( 60 dB typical) SCA Inputs 3 unbalanced BNC connectors SCA Input Impedance 10 K Ohms SCA Input Levels 0 dBm (775 mV rms/ 2.2 V p-p) nominal for

75 Khz deviation, adjustable

SCA Amplitude Response Crosstalk 67 Khz SCA to main or to stereo subchannel >65dB

0.8 dB, 40 Khz to 100 Khz

92 Khz SCA to main or to stereo subchannel >70 dB

MONOAURAL OPERATION

Audio Input Impedance 600 Ohms balanced or unbalanced; 50 dB common

mode suppression Audio Input Level 0 dBm (775 mV rms/ 2.2 V p-p) nominal for

75 Khz deviation, adjustable

FM S/N Ratio

> 70 dB below ± 75 Khz deviation at 400 Hz

measured in a 30 Hz - 20Khz bandwidth with

75 usec de-emphasis (RMS) Audio Frequency Response

Intermodulation Distortion

0.8 dB, 30 Hz to 15 Khz

0.05 %, measured with a 1 Khz and a 1.3 Khz

tone, 1:1 ratio, at 100% modulation

Page 11

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

LOCK

PWR ADJ.PWR ADJ.

VDC2

ENABLE

VDC1

PROGRAM

SET

OFF

EXTERNAL POWER SUPPLY CORRECT OPERATION YELLOW INDICATOR

FM TRANSMITTERFM TRANSMITTER

NT 250NT 250

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

- modulation

- forward rf power

- reflected power

7-8-THESE PUSH BUTTONS ALLOW TO TO SELECT ON LCD DISPLAY THE FOLLOWING MENU:

- display parameter

- password

- change of operational frequency

9 - MAINS SWITCH

TITLE

DATE

NICOM

NT250 FRONT PANEL

DRAWING NO.

JULY 2001

Nt250 Front Panel.CDR

RF OUTPUT

50 OHM 250W

REMOTE CONTROL

INTERLOCK

SCA 3

SCA 2

SCA 1

1 GND 2

MONO

MPX

Voltages under equipment cover plate can be hazardous to your life. Equipment only can be handled by qualified personnel.

WARNING

FUSE

MAINS V

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 FOR SUBCARRIERS GENERATORS INPUTS

9-10-11- SCA INPUT ADJUSTING LEVELS

12 - XLR FEMALE BALANCED MODE MONO AUDIO INPUT

13 - MONO INPUT ADJUSTING LEVEL

14 - BNC FEMALE FOR THE COMPOSITE MPX INPUT

15 - MPX INPUT ADJUSTING LEVEL

16 - N FEMALE FOR RF OUTPUT POWER

TITLE

DATE

JULY 2001

NICOM

Nt250 EXCITER

REAR PANEL LAYOUT

DRAWING NO.

Nt250 Rear Panel.cdr

+ 30 hidden pages