RF Amplifier Quick Start Guide

STARLINE 5
RF Amplifier Quick Start Guide
If necessary, to achieve the gain specification, you can use the interstage pad or output pads
to reduce the gain of the amplifier. However, this will affect amplifier performance. Output
padding degrades the station distortion performance while having minimal effect on the
carrier-to-noise (c/n) performance. Interstage padding is the opposite and therefore has little
effect on distortions but degrades the c/n performance. In general Motorola recommends
that you pad to the amplifier gain specification on the output (where possible). However, if
you are unsure about the optimal padding technique for your system, split the required
padding evenly between the interstage and output pad(s).
It is recommended that you contact Motorola’s TRC or your account representative for more
specific information regarding use of the interstage and output pads.
Thermal Drive Unit
To use the thermal drive unit (TDU):
1 Place the jumper on the TDU to the LOW, MEDIUM, or HIGH position to specify the amount of
cable for which the TDU compensates at the highest frequency preceding the amplifier
station.
Low = 0 dB to 15 dB, medium = 15 dB to 30 dB, and high = 30 dB or more of cable.
2 Position the drive control select jumper 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 DRIVE UNIT.
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 stated in Step 7 under Manual Gain Control.
Automatic Drive Unit
To use the automatic drive unit (ADU):
1 Position the drive unit 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 pilot or available NTSC television channel not scrambled using
sync suppression.
3 Position the drive control select jumper to DRIVE UNIT.
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) fully clockwise and then reduce to obtain
the level stated in Step 7 under Manual Gain Control.