UHF Analog Driver/Transmitter/
Chapter 5, Detailed Alignment Procedures
Translator
LX Series, Rev. 3
5-6
5.2.8 Frequency Response Delay
Equalization Adjustment
NOTE:
Perform the following procedure
only if a frequency response delay
equalization problem is suspect.
The procedure for performing a
frequency response delay equalization
adjustment for the transmitter is done at
IF and is described in the following steps:
The center frequency for the first stage is
45 MHz. Adjust R103, the top frequency
response equalizer pot, located on the
front panel of the IF Processor Module,
for the best depth of frequency response
correction at 45 MHz.
The center frequency for the second
stage is 42 MHz. Adjust R106, the
middle frequency response equalizer pot,
located on the front panel of the IF
Processor Module, for the best depth of
frequency response correction at 42 MHz.
The center frequency for the second
stage is 43.5 MHz. Adjust R274, the
bottom frequency response equalizer pot,
located on the front panel of the IF
Processor Module, for the best depth of
frequency response correction at 43.5
MHz.
After the three delay attenuation
equalizers have been adjusted, fine tune,
as needed, for the best frequency
response across the channel.
5.2.9 Calibration of Output Power
and Reflected Power of the
transmitter
NOTE:
Perform the following procedure
only if the power calibration is suspect.
Switch the transmitter to Standby and
place the Upconverter into Manual Gain.
Preset R205, the aural null pot on the
Amp Control board, fully CCW. Adjust
R204, the null offset pot on the Amp
Control board, for 0% visual output.
Perform the following adjustments with
no aural present by removing the aural
IF carrier jumper on the back of the
chassis assembly. Connect a sync and
black test signal to the video input jack
of the test modulator. Switch the
transmitter to Operate.
Next, set up the transmitter for the
appropriate average output power level:
Example is for a 100 Watt Transmitter.
•
Sync + black 0 IRE
setup/wattmeter=59.5 watts
•
Sync + black 7.5 IRE
setup/wattmeter=54.5 watts
NOTE:
The transmitter must have 40 IRE
units of sync.
Adjust R202, visual calibration, on the
Amp Control board for 100% on the front
panel LCD display in the % Visual Output
position.
With the spectrum analyzer set to zero
span mode, obtain a peak reference on
the screen. Reconnect the aural carrier
jumper on the rear of the chassis
assembly. Turn the power adjust pot on
the front panel until the original peak
reference level is attained. Adjust R203
for a 100% aural power reading. Switch
to the Visual Output Power position and
adjust R205 (aural null pot) for 100%
visual power.
To calibrate the reflected output power
reading of the transmitter. Reduce the
manual gain pot R3 to a 10% reading on
the LCD front panel display in the %
Output Power position. Place the
transmitter in Standby. Remove the PA
Module Sled. Remove the load from J4
on the (A4) Directional Coupler Board
and switch the LCD Display screen to the
Reflected Output Power position.
Reinstall the PA Module. Switch the
transmitter to operate. Adjust the
reflected power calibration adjust pot
R163 on the power amplifier module to a
10% reading. A reflected power fault
Содержание INNOVATOR
Страница 99: ...APPENDIX A LX SERIES ANALOG SYSTEM SPECIFICATIONS...
Страница 102: ...APPENDIX B DRAWINGS AND PARTS LISTS...
Страница 105: ...APPENDIX C TRANSMITTER LOG SHEET...