Hybrid Types
HPS/RFL 10-watt hybrids are installed in a 1RU rack-mounted chassis, and each chassis can hold up to 3 hybrids. This is enough for the most-common carrier coupling schemes (occasionally a second hybrid chassis must be used which can be stacked on top of the other).
HPS/RFL 100/200-watt hybrids are stand-alone 4RU rack-mounted devices that are used in combination with 50/100-watt PLC amplifiers.
Quick Links
- RFL Power Line Carrier Hybrid Pro™ System
- About Hybrids
- Example Applications and Recommended Configurations
- Hybrid Types
Balanced Hybrid
The balanced hybrid is most often used to combine two transmitters onto a single coax connection while providing high isolation (trans-hybrid loss) between the two transmitter inputs. This isolation prevents the PLC transmitters from mutually loading each other, and from creating intermodulation distortion products which can interfere with other PLC systems.
Balanced Hybrid Specifications:
- Operating Impedance: 50 ohms (75 ohms available by request)
- Insertion Loss (either input port to output port): approximately 3.5 dB
- Isolation / Trans-hybrid loss (input port to input port): greater than 30 dB
- Power Rating: 10 Watts, each port
- Second Harmonic Distortion: At least 80 dB below the fundamental frequency
- Third Order Intermodulation Products: At least 60 dB below the fundamental frequency
Skewed Hybrid
The skewed hybrid is used to combine a transmitter and a receiver (or multiple transmit signals and multiple receivers) onto a single coax connection while providing high isolation (trans-hybrid loss) between the transmit and receive ports. This high level of isolation is necessary to prevent the high-energy transmit signal from leaking over and interfering with the incoming low-level receive signal, and to prevent the termination impedance of the receiver from loading the transmitter. Since PLC channels are commonly grouped tightly together in a small frequency band, the transmit signal could easily appear as noise inside the bandwidth of the receiver. The isolation provided by the skewed hybrid is what allows a 10-Watt transmitter to be spaced closely next to a much lower-level receive signal. The skewed hybrid is typically the last hybrid in the hybrid “chain” and the connection to the line tuner.
- Operating Impedance: 50 ohms (75 ohms available by request)
- Insertion Loss (TX to LINE): approximately 0.5 dB
- Insertion Loss (LINE to RX): approximately 13 dB
- Isolation / Trans-hybrid loss (input port to input port): greater than 40 dB
- Power Rating: 10 Watts, each port
- Second Harmonic Distortion: At least 80 dB below the fundamental frequency
- Third Order Intermodulation Products: At least 60 dB below the fundamental frequency
Skewed Hybrid Front Panel Test Switch
The sample below shows the functional circuit of the test switch on the skewed hybrid front panel. The switch is most commonly used for taking reflected power measurements when the channel is in service. With the switch in the NORM position, connections are made from HYB OUT to the input of the reflected power measurement device (instrument), and from the output of the instrument to the TO TUNER port. Once the connections have been made up and the instrument is ready to measure, the switch is placed in the TEST position. This diverts the signal energy through the instrument and the measurement is then recorded. After the measurement has been recorded, the switch is placed back in the NORM position, and then the cables may be removed. Throughout this process, the power line carrier channel is never out of service.
Splitter
Sometimes called a “balance transformer”, the splitter is used to “split” signals for phase-to-phase coupling applications (center-phase-to-outer-phase). It is typically installed between the skewed hybrid and the line tuners – one-line tuner for each phase of the “phase-to-phase” coupling scheme. The 180-degree phase relationship between the outputs LINE 1 and LINE 2 is required for maximum propagation down the transmission line in center-phase-to-outer-phase coupling schemes.
Splitter Specifications
- Operating Impedance (each port): 50 ohms (75 ohms available by request)
- Phase relationship (LINE 1 to LINE 2): 180°
- Power Rating (each port): 10 Watts
Splitter/Combiner
The splitter/combiner is used to “split” and “combine” signals for phase-to-phase coupling applications (center-phase-to-outer-phase). It is typically installed between two skewed hybrids and the line tuners – one-line tuner for each phase of the “phase-to-phase” coupling scheme. The 180-degree phase relationship between the outputs LINE 1 and LINE 2 is required for maximum propagation down the transmission line in center-phase-to-outer-phase coupling schemes.
Splitter/Combiner Specifications
- Impedance (each port): 50 ohms (75 ohms available by request)
- Phase relationship (LINE 1 to LINE 2): 180°
- Power Rating: 10 Watts, each port
Bypass Hybrid
The “bypass” hybrid has a unique application and is not commonly used. When deployed correctly, any signals from Station A are “dropped” at Station B and “bypassed” to Station C; signals from Station B are inserted and sent to both Station A and Station C; and signals from Station C are dropped at Station B and bypassed to Station A. This device will pass signals around a discontinuity, while also inserting / dropping signals at the discontinuity.
Bypass Hybrid Specifications
- Impedance (each port): 50 ohms (75 ohms available by request)
- Insertion loss: approximately 6.5 dB
- Power Rating: 10 Watts, each port
