Motorola BT100 ユーザーズマニュアル

3-12 

2 

Verify that the frequency stamped on the ADU/QADU control unit is the same as the system 

pilot frequency. For the ADU, the pilot frequency is a CW pilot or an available NTSC 
television channel not scrambled using sync suppression and not a digital channel. For the 

QADU, the pilot signal is a QAM modulated 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 (ADU) potentiometer (illustrated in Figure 2-13) fully clockwise and 

then reduce to obtain the level obtained in Step 9 under Manual Gain Control. 

This subsection provides information regarding the proper ADU/QADU padding requirements 
for the BT100. 
A JXP-*B pad is installed in the input line to the ADU/QADU location. This pad adjusts the 
ADU/QADU input level for the standard application of the BT100 but you can change this pad 

depending on the operational output of the BT100.  
In the BT100 analog ADU circuit, a JXP-7B pad is generally recommended. This is the standard 
ADU pad value as shipped from the factory and is appropriate for an amplifier output level 
range from 

+43 dBmV to +49 dBmV at 550 MHz. Use a JXP-1B pad for output levels below 

+43 dBmV and a JXP-11B for output levels above +49 dBmV. 
The standard pad for the QADU is a JXP-0B. This pad value works for a BT100 output level 
from 

+38 dBmV to +47 dBmV at 550 MHz. Use a JXP-7B when operating above +47 dBmV at 

550 MHz. 

+46 dBmV at 550 MHz. 

Use of an ADU or QADU is recommended for improved output level stability although you can 
operate the BT100 in the manual mode. Select manual mode by placing the drive control select 

jumper, illustrated in Figure 2-13, in the 

MAN

 position. The gain of the BT100 is then 

determined by the potentiometer marked 

MAN

 on the amplifier cover. 

The following subsections describe the BT100 alignment procedures required for proper 

performance in the return path. 

Before you begin to set-up the amplifier and perform return-path alignment, please read the 

following instructions and recommendations. 
For proper return alignment obtain: 

ƒ 

RF alignment levels and insertion points for all BT100s 

ƒ 

RF reference output level of the headend optical receivers 

Equipment required for return-path alignment includes: 

ƒ 

Full complement of JXP-*B pads and STARLINE Return Equalizers (SRE-100-*)