Motorola BLE*/* - Manual (Page 32)

Amplifier Setup 3-11
BLE*/* Installation and Operation Manual
2 Position the drive control select jumper (Figure 2-8) temporarily in the MAN position and
perform the complete procedure described in Manual Gain Control if not already completed.
3 Position the drive control select jumper to AUTO .
4 Connect a signal-level meter to the FWD OUT test point and tune the meter to the high
band-edge carrier.
5 Turn the thermal level potentiometer on the TDU fully clockwise and then reduce to obtain
the level obtained in Step 9 under Manual Gain Control.
Automatic Drive Unit
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.
Figure 3-6
ADU
AUTOMATIC
DRIVE UNIT
ADU/ _______________
Pilot frequency
To set-up the ADU:
1 Position the drive control select jumper temporarily to the MAN position and perform 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 AUTO .
4 Connect a signal-level meter to the FWD OUT test point and tune the meter to the high
band-edge carrier.
5 Turn the auto level control potentiometer (ADU) (illustrated in Figure 2-8) fully clockwise
and then reduce to obtain the level obtained in Step 9 under Manual Gain Control.