NiCOM USA NT20FP03 BROADCAST TRANSMITTER User Manual USERS MANUAL

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Document ID	393661
Application ID	ps9bXTQbgf7SVKYpKBz3+A==
Document Description	USERS MANUAL
Short Term Confidential	No
Permanent Confidential	No
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Document Type	User Manual
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Filesize	28.91kB (361347 bits)
Date Submitted	2004-02-03 00:00:00
Date Available	2004-02-03 00:00:00
Creation Date	2004-01-15 12:10:12
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Document Lastmod	2004-01-15 12:20:38
Document Title	USERS MANUAL
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INiCOM
CHAPTER 3
INSTALLATION
3.1 INTRODUCTION
This chapter contains the information required for installation of the NT 20 exciter
and for preliminary checks,
3.2 UNPACKING
Remove the unit from its packaging and before any other operation, check for
any damage that the unit may have suffered in transit and that all front and rear panel
controls are functioning.
3.3 INSTALLATION
1)
2)
You don't need to select the AC power input because the power supply accepts
all voltages between 90 and 240 Volts.
The current capacity of the fuse are as follows:
220-240V - 2A
100-120V - 3.15A
Now you must check that the PWR ADJ control is rotated fully counterclockwise,
using a small screwdriver. Units are usually shipped with this control already at
10 W.
WARNING' When the unit is switched on with the control at its minimum position power
3)
4)
5)
6)
7)
8)
output is about 1W.
Connect R.F. Output connector to the antenna cables
Inject Audio signal coming from external source, to the BNC connector.
Connect line power to the unit via the VDE socket, then swltch on the equipment
Select PWR/FWD power measuring, through the selector placed on the front
panel, and adjust the PWR ADJ trimmer to obtain the reading of 20W on the
analog meter (1 Fig.1A-1B),
Now, Select DEV measuring through the selector PWR/DEV and adjust INPUT
LEVEL trimmer, to obtain a reading of 75 KHz on the analog meter.
If you are transmitting in MONO, you should insert the Pre-emphasis switch that
is in the front panel, if you transmit in STEREO this switch has to be OFF.
) NiCOM
3.4 PRE'INSTALLATION
Before the installation of the equipment, we suggest to execute a complete check
on it, to avoid problems during the installation itself.
Power Output Checking
1) New ensure that the PWR ADJ control is turned fully counter clockwise, using a
small screwdriver. Units are usually shipped with this control already at 10 W.
WARNING: When the unit is switched on with the control at its minimum position WWEI’
outpgt is about 1W,
2) Connect a dummy load with a power rating of at least 20 W continuous to the RF
output , situated on the rear panel of the unit . It is advisable to connect a bypass
wattmeter in series with this load in order to verify the accuracy of the unit’s
internal wattmeter.
3) Connect a switch, via a cable, to the INTERLOCK connector on the front panel
so that the switch is able to short the central conductor to the ground. Leave the
switch in the shortclrcuit position.
4) Set the unit’s ON/OFF switch to the OFF position.
5) Connect line power to the unit via the VDE socket . (Note: It is essential that the
unit be properly grounded to ensure both the safety of the operator as well as the
correct performance ofthe equipment).
6) Switch the power switch to the ON position and check that the both green
voltages presence leds and the green LOCK led are ON. Select the desired
operating frequency using the corresponding selector . The green LOCK LED
should light on within 30 seconds, indicating that the oscillator has locked onto
the operating frequency.
Furthermore. if a frequency is selected beyond the two limits of the 87.5-
108MHZ band, the amplifier will continue to work even though the displayed
frequency no longer corresponds to the operating frequency of the unit.
Warning! Transmitting outside the legal band (87.5408 MHz) is an offense and
may lead to prosecution.
7) After having verified that the LOCK led is on and that the unit is therefore locked
to the selected operating frequency, move the switch connected to the
INTERLOCK connector in order to remove the short circuit between the central
conductor and ground. The RF output is now enabled and should correspond to
3)
NiCOM
a power level of about 1W. To check this reading, select FORWARD POWER,
and then read the power on the 25W full scale meter.
Using a small screwdriver, rotate the F’WR ADJ control clockwise; the power .
output should increase progressively to a maximum of 20-25W. Check the value
with the bypass wattmeter which should be within t10%.
Deviation reading check
1)
Put the selector in the DEV position. Connect a low-distortion audio generator to
the MONO and/or MPX inputs. Inject a 400 Hz tone at a level of OdBm (775mV
RMS = 2.2Vpp on the 600 Ohm impedance). Check that the deviation reading is
100% (or 75 KHz).
Connection of an External Stereophonic Source
1)
2)
3)
4)
5)
Connect the stereo source's output to the MPX input of the unit.
Adjust the stereo encoder to obtain just the 19 KHz sub-carrier output (without
pre-emphasis) and ensure the total absence of signals on the left and right inputs
of the encoder.
Adjust the output level of the encoder to obtain the correct level (-14dB under the
carrier) as displayed on the Modulation Analyzer connected on” an RF. TEST .
Inject audio signals into the left and right inputs of the encoder and adjust the
sensitivity of the input to obtain a peak reading of MAX=75KHz with both
channels enabled.
Disconnect right and left channels on the encoder and verify that the reading is
now of about 7.5 KHz.
Monophonic Transmission .
1)
2)
3)
Connect the signal source (audio mixer, receiver, compressor etc.) to the MONO
input This input is unbalanced.
Adjust INPUT LEVEL trimmer on the desired level.
Adjust the signal level of the equipment connected to the NT 20 (with the audio
signal present) for a peak reading of MAX DEV=75KHz.
Note that international standards allow a maximum deviation (DEV MAX) of 75
KHz for frequency modulated radio transmissions. Exceeding this limit will only
result in the degradation of the signal quality. in case of mono transmissions, the
MPX input is available for frequencies between 40 KHz and 100 KHz. le: Sub-
carriers for SCA, RDS etc., with a sensitivity of 0 dBm (775mVrms = 2,2Vpp, 600
Ohm) for a deviation of 75KHz.
E Nicom
CHAPTER 4
MAINTENANCE
4.1 SAFETY REQUIREMENTS
WARNING WARNING WARNING WARNING WARNING WARNING WARNING
Removing the top cover when the exciter is operational, will expose the operator
to lethal voltages on the main AC line and heavy currents on the power supply filter
terminals and power transistors Use insulated tools for any type of maintenance work
and do not touch any internal components when the exciter is switched on
Ensure that the exciter is disconnected from the line supply before carrying out any
maintenance work.
MAINTENANCE LEVEL 1
4.2 ROUTINE MAINTENANCE i
The only routine maintenance required by the NT 20 challenger is the periodic
replacement of the cooling fan and the removal of accumulated dust. The period
between such action will depend on ambient operating conditions such as temperature,
air-borne dust levels and humidity. It is advisable to check the unit every 6 months and
to replace noisy or worn fans. Fans should be replaced as a matter of course after no
more than 18 months of operation.
1 — MAIN SWITCH
2 - POWER SUPPLY INDICATOR
5 - ON AIR INDICATOR (OPERATIVE 5TATU6 )
4 - PLL LOCK INDICATOR
5 - PREENPHASIS CIRCUIT SWITCH
6 - MULTIMETER SELECT FUNCTION
7 - MULTIMETER
5 — POWER ADJUSTING TRIMMER
9 - INTERLOCK BNC CONNECTOR
NICOM - U 5 A
“‘ E NTZO FM EXCITEK'TKANSMITTEK
-FKONT PANEL—
0~UIJ>OOI\)—'
AC LINE SOCKET
MPX COMPOSITE INPUT CONNECTOR
MODULATION LEVEL ADJUSTING
RF OUTPUT CONNECTOR
SCA INPUT .
FAN
NICOM - U S A
I NT20 FM EXCITER-TRANSMITTER
-REAR PANEL-
FREQUENCY SETTlNG
Example for 98.1 Mhz
Example for 101.7 Mhz
MHZX 10
MHZX1
KHzX 10
"63
®
® KHzX100
NT20 FM EXCITER-TRANSMITTER
-TOP PAN -

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