Motorola BT100 operation manual Return Path Alignment, ADU/QADU Pads and Levels, Before You Begin

3-12 Amplifier Setup

2Verify 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.

3Position the drive control select jumper to AUTO.

4Connect a signal-level meter to the FWD OUT test point and tune the meter to the high band-edge carrier.

5Turn 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.

ADU/QADU Pads and Levels

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.

Motorola does not recommend operating the BT100 above +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.

Return Path Alignment

The following subsections describe the BT100 alignment procedures required for proper performance in the return path.

Before You Begin

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:

ƒRF alignment levels and insertion points for all BT100s

ƒRF reference output level of the headend optical receivers Equipment required for return-path alignment includes:

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

BT100 Installation and Operation Manual