Motorola RF Amplifier ユーザーズマニュアル
STARLINE 3
RF Amplifier Quick Start Guide
Forward Path Alignment
The following subsections describe procedures required to obtain proper forward path
alignment.
alignment.
Before You Begin
For proper forward path alignment obtain:
1
RF output levels and tilts of all amplifiers
2
RF input level for the amplifier being set up (from system design or as-built map)
3
A carrier at the system’s highest frequency. It can be modulated or continuous wave (CW)
and should be inserted in the headend at standard video levels. This carrier is used to
simplify field set up.
and should be inserted in the headend at standard video levels. This carrier is used to
simplify field set up.
It is recommended that you:
1
Install the system design value SFE-
*-* and a high value (20 dB or above) forward input pad
before you install or remove the electronics chassis or activate the system.
Leave the forward input pad location open if a high value pad is not available. A more
accurate forward input test point reading is achieved with a high value pad installed.
accurate forward input test point reading is achieved with a high value pad installed.
2
Do not use wire jumpers to bypass the SFE-
*-* location.
3
Recognize that actual pad and SFE-
*-* values may differ slightly from their design values.
This is caused by factors such as walkout errors, worst-case data utilization during design
and temperature variation from 70ºF.
and temperature variation from 70ºF.
4
Secure the electronics chassis in the housing and torque to 18 to 22 in-lbs to facilitate heat
transfer.
transfer.
5
Perform a bench alignment. Pre-aligning the amplifier response on the bench for system
signature simplifies field alignment. (If the unit is bench aligned properly, only minor
adjustments may be necessary in the field.)
signature simplifies field alignment. (If the unit is bench aligned properly, only minor
adjustments may be necessary in the field.)
6
Field sweep the entire bandwidth of the amplifier in the field to correct frequency response
for passive signature and roll-off.
for passive signature and roll-off.
7
Close the housing in accordance with the instructions provided in the subsection Closing the
Housing at the end of this guide.
Housing at the end of this guide.
Manual Gain Control
To adjust manual gain control:
1
Verify that the electronics chassis is installed correctly.
2
Ensure that there is continuity in the forward path by installing the design value SFE-
*-*
and design value input JXP-
*B attenuator.
3
Ensure that the drive control select jumper is in the
MAN
position.
4
Use a signal-level meter to measure the high band-edge carrier-input-level at the input test
point: 750 MHz = channel 116, 870 MHz = channel 136. This carrier should be at standard
analog level, non-scrambled.
point: 750 MHz = channel 116, 870 MHz = channel 136. This carrier should be at standard
analog level, non-scrambled.