January 2016 Page 3–39
Chapter 3. Applications
3
3.10 Hybrid Applications
The table shows the type of Hybrids and their asso-
ciated part numbers.
The purpose of the hybrid is to enable the connec-
tion of two or more transmitters together on one
coaxial cable without causing intermodulation dis-
tortion due to the signal from one transmitter affect-
ing the output stages of the other transmitter.
Hybrids are also required between transmitters and
receivers, depending on the application. The hybrid
circuits can, of course, cause large losses in the car-
rier path and must be used appropriately. High/low-
pass and band-pass networks may also be used, in
some applications, to isolate carrier equipment from
each other. A summary of some of the more impor-
tant application rules are given below:
1. All Hybrids in a chain should be the
Balanced type (resistive Hybrid) except the
last hybrid, that is, the one connected to the
line tuner.
2. The last Hybrid in the chain should be a
skewed or reactive type. However, a
Balanced type (resistive Hybrid) can be used
in place of a reactive Hybrid if you have less
than 10% reflected power at the line tuner.
3. When applying transmitters to reactive
Hybrids, the frequency spacing between the
widest spaced transmitters is about 4% for
frequencies below 50 kHz and 6% for fre-
quencies above 50 kHz. If this rule is not fol-
lowed then the Hybrid cannot be adjusted to
provide the best possible isolation between
all transmitters.
4. When applying transmitters and receivers to
a reactive Hybrid the frequency spacing
between the transmitter group and receiver
group is of no concern; however, all the
transmitter frequencies must meet the fre-
quency spacing rule above. This rule is based
on receivers with high input impedance.
5. The Hybrids should be arranged with the
lesser losses in the transmitter path and the
greater losses in the receiver path to provide
more transmitter signal levels onto the power
line.
6. ON/OFF Transmitters/Receivers should be
arranged with lower losses as compared to
FSK Transmitters/Receivers that can operate
with lower signal/noise ratios.
7. If possible, transmitters used for common
applications should be arranged for equal
attenuation. This would apply to systems that
use dual channels such as Direct Transfer
Trip (DTT) or Segregated Phase
Comparison.
For more details, please refer to the Hybrids System manual.
Table 3–8. Hybrid Options
Description Type Part No. Type Part No.
Resistive Hybrid H1RB 6266D72G05
Balanced CH20-BALMN-001
Resistive Hybrid (40W) H1RB-40 6266D72G07
Skewed Hybrid (50Ω) with terminating resistor H1SB-R 1609C45G03 Skewed CH20-SKWMN-001
Reactance Hybrid H3XB 6266D71G03 None
19” panel for mounting 3 Hybrids 2-RU 670B695H01
19” Chassis for Mounting 4 Hybrids 1-RU 1088-780
2-RU Type (Old Style) 1-RU Type (New Style)
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