ABB ETL600 Instruction Manual page 335

Revision:
A
C.5 Transmitter
The Tx RF level and the Tx alarm threshold levels were adjusted during final testing in the works.
They need to be changed only if the return loss is too low.
C.5.1 Adjust Tx RF level
The Tx RF level is adjusted using the HMI600, a level meter and a termination resistor or
attenuator.
1. In the Tuning & testing dialog box click Adjust Tx RF level. This opens the Adjust Tx
RF level dialog box.
2. Remove the remote equipment by disconnecting the coaxial cable. The local equipment
has to be terminated with 45, 75 or 125 Ω, depending on the application.
3. Click Start.
4. Measure RF test tone level in dBm at the coax socket "RF line monitor" on the frontplate
of the RF hybrid P3LE with a level meter set to an input impedance of 50 Ω. Alternatively,
measure the test tone level at the RF line socket (X175) via an attenuator with impedance
45, 75 or 125 Ω and a level meter set to the same input impedance (The attenuator is
required in order not to overdrive the input of the level meter).
5. Adjust the value in the Tx RF level [dB] field, download it by clicking Set and measure
the test tone level again. Continue until the measurement corresponds to the permissible
value displayed in the dialog box.
C.5.2 Adjust Tx alarm threshold level, if output power was modified
The Tx alarm level threshold is adjusted using the HMI600, the jumper CH and the potentiometer
on the amplifier P1LA.
1. In the Tuning & testing dialog box, click Adjust Tx alarm level.
2. Set the jumper CH/CL to the position CH if not jet done.
3. Click Activate Tx alarm level.
4. Turn the potentiometer R116 on P1LA anticlockwise until the Tx alarm LED goes on.
5. Check that Tx alarm LED on the hybrid (also on the combiner in case of 80 W equipment)
lights. After the programmed delay time, the Hardware alarm on the front plate of
P4LT/P4LW appears. The relay contacts on the cable V9OT Pin 2-3 are closed.
6. Turn the potentiometer R116 on P1LA slowly clockwise until the Tx alarm LED goes off.
7. Click OK. The LEDs go off and the contacts open after the programmed delay.
Note: Exact measurement of the programmed delay times is not essential.
C.6 Receiver
C.6.1 Adjust Rx RF level
The Rx RF level is adjusted using the HMI600.
1. In the Tuning & testing dialog box click Adjust Rx RF level.
2. Follow the instructions given in the dialog box.
Note:
Note:
Language:
EN
It is really necessary to disconnect the RF line coaxial cable of the local equipment
as well as to plug out the Rx filter P4RX!!!
The number of adjustment steps depends on the presence of the Rx filter P4RX
(configured with Configuration / System / Equipment settings / Assemblies in
rack P7LC).
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