Automatic Drive Unit; Adu Pads And Levels - Motorola BLE Series Installation And Operation Manual

4
Connect a signal-level meter to the
band-edge carrier.
5
Turn the thermal level potentiometer on the TDU fully clockwise and then reduce to obtain
the level obtained in Step 3 under Manual Gain Control.
Au t oma ti c D r ive Un i t
The ADU operates by using surface acoustic wave (SAW) filters to select a pilot frequency and
then monitors the amplitude of this frequency. Any change in signal level is fed back to the Bode
equalizer. It is assumed that the encountered signal level changes are due to changes in cable
attenuation and hybrid output associated with a change in temperature. The Bode equalizer
then changes its insertion loss to maintain a constant output level. The ADU (illustrated in
Figure 3-6) maintains the most precise output level of the three available methods.
F i g u r e 3 - 6
A D U
To set-up the ADU:
1
Position the drive control select jumper temporarily to the
complete procedure described in Manual Gain Control if not already completed.
2
Verify that the frequency stamped on the ADU control unit is the same as the system pilot
frequency. The pilot frequency is a CW or an available NTSC television channel not
scrambled using sync suppression and not a digital channel.
3
Position the drive control select jumper to
4
Connect a signal-level meter to the
band-edge carrier.
5
Turn the auto level control potentiometer (ADU) (illustrated in Figure 2-9) fully clockwise
and then reduce to obtain the level obtained in Step 3 under Manual Gain Control.
AD U Pa d s a n d L ev e l s
This subsection provides information regarding the proper ADU padding requirements for the
BLE*/*.
A JXP-ZXT pad is installed in the input line to the ADU location. This pad adjusts the ADU
input level for the standard application of the BLE*/*. This pad can be changed depending on
the operational output of the BLE*/*. In general, a JXP-6T pad is recommended in the BLE*/*
ADU circuit. This is the standard pad value as shipped from the factory and is appropriate for
an amplifier output level range from +42 dBmV to +50 dBmV at 550 MHz.
test point and tune the meter to the high
FWD OUT
AUTOMATIC
DRIVE UNIT
ADU/
.
AUTO
test point and tune the meter to the high
FWD OUT
B L E * / * I n s t a l l a t i o n a n d O p e r a t i o n M a n u a l
A m p l i f i e r S e t u p
position and perform the
MAN
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