User's Manual
VHF UNIDIRECTIONAL AMPLIFIER TECHNICAL MANUAL
13
- All cables used in the DAS system shall be 50 ohms and clamped properly to insure the cables 50 ohm
impedance characteristics. Improper clamps will change the impedance of the cable at that location thus
changing the efficiency of the system.
- Antenna placement through the DAS system is important to impose a balanced distributed signal. The
use of proper valued (dB) decouples, power dividers, and signal taps is important to promote a balanced
system.
UDA Installation
1) Verify that the frequencies listed on the Amplifier Box label agree with the channel assignments
for the filter and/or the duplexer on use. If they are not the same, contact the factory for
advice and instructions. Please read the Warnings and Notices at the bottom of the next page
before proceeding.
2) Mount the UDA on a grounded rack, in a cabinet or on the wall. The UDA is all-metal and the
mounting screws can be used as attachment points for a ground wire.
3) If the UDA is used in a bi-directional scheme, check the isolation between the Donor antenna
and the Distribution antennas. It should be 20dB above the Gain of the Amplifier.
4) Connect the Donor Antenna Port and Antenna Output to Distribution Network port through
the Duplexer Box using solid-shield or double-braided 50 ohm coaxial cable with suitable
connectors.
5) Verify the MSA#1 setting of both Up-link and Down-link VGA. These attenuators should be
set at maximum attenuation (i.e. dial at position “F”).
6) Install the external UPS/Battery system if it is need. Connect the UDA to the AC power
source. Turn on the UDA unit by pressing the power button on the UDA box. If DC power
sources (+48 and +6 Volts) are applied to the D-Sub 9 pins connector, the UDA can be turned
on by changing the AC/DC sliding switch to the DC position.
7) Verify if all power LEDs on the VGAs and PAs sections are on (green color). Verify if the
PA_IN_PWR LEDs are on green.
8) After the unit is on, verify the RSSI LEDs on both Down-link and Up-link VGA. At 30dB
attenuation at the input, normally only the LOW LED could be on. Decrease the MSA#1
attenuation gradually (i.e. do not jump directly from “F’ to “0” position) until both LOW and
HI LEDs are on. If the HI LEDs cannot be on even at MSA#1 = 0dB attenuation, verify if
the input signal is present and at the expected level, then just leave the MSA#1 dial at “0”.
9) The UDA output powers are now at its maximum operable level in both up-link and down-link
direction. By mean of the MSA#2 (and if needed, use additional attenuator pads), optimize the
output power to the desired (lower) level, according to the specific distribution system
environment.
Installation is now complete.