Axcera-430B FCC Type Acceptance Report Parts List/Tune-up Info
February 2004
7-10
7.2.12 Board Level Alignment Procedures
7.2.12.1 (Optional) 4.5-MHz Composite Input Kit
If the (optional) 4.5-MHz composite input kit is purchased, the tray is capable of
operating by using either the 4.5-MHz composite input or the baseband audio and video
inputs. The kit adds (A24) the composite 4.5-MHz filter board (1227-1244) and (A25) the
4.5-MHz bandpass filter board (1265-1307) to the transmitter. When the 4.5-MHz
intercarrier signal generated by the 4.5-MHz composite input has been selected by the
4.5-MHz composite input kit, the 4.5-MHz generated by the aural IF synthesizer board is
not used. When the 4.5-MHz intercarrier signal generated by the baseband video and
audio inputs with baseband has been selected by the 4.5-MHz composite input kit, the
composite 4.5-MHz filter board and the 4.5-MHz bandpass filter board are not used.
The tray has been factory tuned and should not need any alignments to achieve normal
operation. To align the tray for the 4.5-MHz composite input, apply the 4.5-MHz
composite input, with the test signals used as needed, to the video input jack (J1 or J2
[loop-through connections]) on the rear of the tray. Select the 4.5-MHz composite input
by removing the baseband select from J18-6 and J18-7 on the rear of the tray.
To align the exciter using baseband video and audio inputs, apply the baseband video,
with the test signals used as needed, to the video input jack (J1 or J2 [loop-through
connections]) and the baseband audio to the proper baseband audio input on the rear of
the tray. For balanced audio input, connect TB1-1(+), TB1-2(-), and TB1-3 (GND). For
composite/stereo audio, connect the composite audio input jack (J3 or J13 [loop-through
connections]) and connect a baseband select from J18-6 and J18-7 on the rear of the
tray.
7.2.12.2 Delay Equalizer Board
The jumper W1 on J5 of the sync tip clamp/modulator board, if present, must be in the
Enable position between pins 2 and 3.
Note: This board has been factory tuned and should not be re-tuned without the
proper equipment.
To tune this board:
1.
Connect a sinX/X test signal into jack J1-2 on the delay equalizer board.
2.
Monitor the video output of the board, at video sample jack J2, with a video
measuring set, such as the VM700, adjusted to measure group delay.
3.
Tune the four stages of the board using the variable inductors (L1 to L4) and
potentiometers (R7, R12, R17, and R22) until the signal attains the FCC group delay
curve. The stages are arranged in order of increasing frequency. Adjust R29, as
needed, to attain the same level out of the board as into the board.
7.2.12.3 Composite 4.5-MHz Filter Board
This board is part of the 4.5-MHz input kit and will only function properly with a 4.5-MHz
composite input signal and the 4.5-MHz composite input selected. To align this board:
1.
Connect the test signal from an envelope delay measurement set to the video input
of the tray at J1 or J2.
2.
Connect an oscilloscope to jack J7, video out, between the J7 center pin and pin 1
or 3 (ground). Adjust C21, frequency response, if needed, for the best frequency
Summary of Contents for 430B
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