Rf Hybrids P3Le, Dummy Load P3Lk - ABB ETL600 Instruction Manual

ABB Switzerland Ltd
+12.8V
z6
TX filter 1
d/b/z16
resistors on
heat sink
GND
d/b/z14
TXRF-40W
TX filter 2
d/b/z22
Amplifier 2
d/b/z30
TA1
TX filter 2
d/b/z28 TA2
TA3
d/b/z32
HF signal
GND
d/b/z26
RX RF relay
z2 / b2
OPTO-AL
z8
TXAL
b6
Fig. 3-21
3.3.11.

RF hybrids P3LE, dummy load P3LK

The RF hybrid is used to decouple the receiver from its own
transmitter. Its use is seen where the line attenuation is high,
especially when transmitter and receiver bands are close together.
The transmitter intermodulation products at the receiver input are
correspondingly reduced by the transhybrid attenuation.
As shown by the block diagram Fig. 3-22, the module essentially
consists of a transformer and tuned circuit, which forms a model of the
transmission line impedance. The high ratio of the transformer results
in a low insertion loss between the transmitter and the line model. The
output impedance can be set to either 45 Ohms, 75 Ohms, or
125 Ohms nominal, using jumpers on transformer T1.
Jumpers around the two matching transformers T3, T4 have to be set
according to the bandwidth of the Tx filter.
The RF hybrid also contains the LED to indicate Tx ALARM, the
potentiometer to adjust the receive level and also a coax connector
(RF LINE MONITOR) on the front panel, to measure the Tx signal with
an attenuation of 50 dB (e.g. 100 W output equals 0dBm into a
50 Ohm termination).
3-32
1KHW001489-EN
JR
7.33
select R
15.67
26.67
T202
relay shown not energized
TB1
K201
TB2
TB3
T201
P3LG block diagram
November 2005
Regulator +5V
+5V
TX Alarm
OPTO-AL
Alarm logic
TXAL
default jumpers shown
Structure and Function
ETL600
80W to hybrid
d/b/z24
d8
plug-out
d10
WARN
b8
TX RF AL
d6
GND-CE
z6