Motorola BT100 - Manual (Page 36)

Amplifier Setup 3-11
BT100 Installation and Operation Manual
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/QAM Automatic Drive Unit
The ADU and QADU operate by using surface acoustic wave (SAW) filters to select a pilot
frequency and then monitoring 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) and QADU (Figure 3-7) maintain a more precise output level than
using the TDU or leaving the BT100 in manual control.
Figure 3-6
ADU
Figure 3-7
QADU
To set-up the ADU/QADU:
1 Position the drive control select jumper (Figure 2-13) temporarily to the MAN position and
perform the complete procedure described in Manual Gain Control if not already completed.