B e n c h S e t u p | 3 - 9 |
9Remeasure the output level. It should be within 1 dB of the preferred level. If necessary, adjust the manual gain control. Check the remaining ports and add JXP pads to bring the outputs to the correct level.
10Set the gain reserves using one of the following gain control options. Adjust the selected gain control option using the procedure presented in the appropriate subsection below.
S Manual control only — there is no compensation for changes in amplifier gain due to input level or temperature fluctuations.
T Thermal control — the standard thermal control unit (TCU) is installed at the factory and compensates for gain changes due to temperature fluctuations only.
T Automatic level control — the optional ADU drive unit holds output levels constant despite fluctuations in temperature or input level. The ADU is available as a
M a n u a l G a i n C o n t r o l
1Connect a signal level meter to the FORWARD TEST POINT and tune it to a channel near 750 MHz.
2Position the drive selector horizontally. Figure
3Turn the gain control (MAN ADJ) to maximum (fully clockwise) and then turn it counterclockwise to reduce the output by 4 dB. If the output level is greater than required, change the pad at the receiver output location to obtain the desired level. To calculate the correct pad value, subtract the desired level from the measured level and increase the pad by that amount. Note: Do not install a pad larger than 15 dB at the receiver output. If more attenuation is needed, put the remaining amount at the interstage pad location.
T h e r m a l C o n tr o l , M o d e l T C U
1Perform steps 1 through 3 under Manual Gain Control.
2Position the drive unit selector vertically.
3Turn the level control potentiometer on the TCU to the preferred output level.
A u to m a ti c L e v e l C o n t r o l , Mo d e l A D U
The system must contain a
1Perform steps 1 through 3 under Manual Gain Control.
2Position the drive unit selector vertically.
3Turn the ADU ADJ control on the main board to the preferred output level.
S G 2 0 0 0 I n s t a l l a t i o n a n d O p e r a t i o n M a n u a l
