TX RX Systems Inc. Manual 7-9322-5 08/09/06 Page 11
SETTING RESERVE ATTENUATION
Reserve attenuation is adjustable from 0 to 15 dB
in 0.5 dB increments. To adjust the reserve attenu-
ation perform the following steps.
1) Press and hold down the “ENTER” button for 15
seconds. This will place the MCA in the Test
Mode and the display will show the first Test
Mode menu choice
Calibrate LNAs
.
2) Scroll through each of the test mode menu
choices by pressing the “SCROLL” button until
the display shows the
Set Attenuators
menu.
3) Once the set attenuators menu is displayed
press the “ENTER” button. The display will now
show three menu choices. The active menu
choice is indicated by the “>” symbol next to the
menu title. You can move through the menu
choices using the “SCROLL” button. When the
MAIN menu choice is active you can change
the amount of reserve attenuation the system
provides by pressing the “ENTER” button.
Attenuation is increased in 0.5 dB increments
with each button press. The attenuation setting
works in a forward loop fashion, starting at 0
and increasing to 15, a button press after 15
returns the setting back to 0. After the reserve
attenuation is set to the desired value move the
“>” symbol to the OK menu choice and press
the “ENTER” button to exit back to the main
menu.
4) Exit the menu mode and return to normal oper-
ation by pressing down the front panel select
switch. The system will reset.
About Multicoupler Gain and Attenuation
Multicoupler gain (referred to as BASE gain) is also
adjusted after installation to obtain best system
performance. BASE gain allows for proper com-
pensation of the MCA-to-receiver cable loss and
should ideally be set to unity. It is defined as the
gain between the input of the base amplifier and
the input of the station receiver. Typically 2 to 3 dB
of attenuation is usually required for unity gain. The
default factory setting for multicoupler gain is 1 dB.
Use the attenuation values shown in
Table 6
to set
the multicoupler gain to the correct value.
SETTING MULTICOUPLER ATTENUATION
Multicoupler attenuation is adjustable from 0 to 4
dB in 1.0 dB increments. To adjust the multicoupler
attenuation perform the following steps.
1) Press and hold down the “ENTER” button for 15
seconds. This will place the MCA in the Test
Mode and the display will show the first Test
Mode menu choice
Calibrate LNAs
.
2) Scroll through each of the test mode menu
choices by pressing the “SCROLL” button until
the display shows the
Set Attenuators
menu.
3) Once the set attenuators menu is displayed
press the “ENTER” button. The display will now
show three menu choices. The active menu
choice is indicated by the “>” symbol next to the
menu title. You can move through the menu
choices using the “SCROLL” button. When the
BASE menu choice is active you can change
the amount of multicoupler attenuation the sys-
tem provides by pressing the “ENTER” button.
Attenuation is increased in 1.0 dB increments
with each button press. The attenuation setting
works in a forward loop fashion, starting at 0
and increasing to 4, a button press after 4
returns the setting back to 0. After the multicou-
pler attenuation is set to the desired value move
the “>” symbol to the OK menu choice and
press the “ENTER” button to exit back to the
main menu.
4) Exit the menu mode and return to normal oper-
ation by pressing down the front panel select
switch. The system will reset.
POST INSTALLATION TESTS
These tests measure the full range of performance
from the maximum achievable to real-world perfor-
Set base attenuation to
for cable loss of
3 dB
1 dB
2 dB
2 dB
1 dB *
3 dB
0 dB
more than 3 dB
* factory default setting
Table 6
: Base attenuation settings.
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