A coaxial line amplifier is a small electronic device used to increase RF signal level in a coaxial cable. Coaxial cables are commonly used for Cable TV, DTH satellite TV, CCTV and other RF systems. When the coaxial cable is very long, some signal is lost inside the cable. Splitters, connectors and other equipment can also reduce the signal level.
A coaxial line amplifier helps to compensate for this signal loss. It is normally installed between the signal source and the receiving device.
How Does a Coaxial Line Amplifier Work?
A line amplifier receives the RF signal from the coaxial cable, amplifies it and sends a stronger signal to the next cable or device.
For example, if a long coaxial cable is causing signal loss, an amplifier can increase the signal level before the signal reaches the TV, receiver or distribution system.
The main work of a coaxial amplifier is:
– Increase RF signal level
– Compensate for long cable loss
– Compensate for splitter and connector loss
– Help distribute signals to multiple points
– Maintain enough signal level at the receiver
But there is one important point.
A line amplifier can increase the signal level, but it cannot create a better satellite signal if the original signal quality is already poor.
Does a Line Amplifier Really Increase Gain?
Yes.
A line amplifier provides real electronic gain. The gain is normally measured in dB.
For example, if an amplifier has 20 dB gain, it can increase the RF signal level by around 20 dB under normal operating conditions.
But higher gain does not always mean better signal quality. An amplifier also adds some noise. If the signal is already strong, adding an amplifier may give no benefit and sometimes signal quality can even become lower.
Coaxial Line Amplifier for DTH
DTH satellite systems also use coaxial cables. The satellite dish receives the signal and the LNB converts it into a lower satellite IF frequency. This signal then travels through the coaxial cable to the DTH receiver or set-top box.
Most DTH satellite IF signals are carried in approximately the 950 MHz to 2150 MHz frequency range. If the coaxial cable is very long, the satellite signal can become weaker before reaching the receiver.
A satellite inline amplifier can be used to compensate for this cable loss.
Typical connection:
Dish → LNB → Inline Amplifier → Long Coaxial Cable → DTH Receiver
In most cases, installing the amplifier near the LNB or before the main long cable run gives better results.
Does an Inline Amplifier Give More Power to the LNB?
Normally, no.
The DTH receiver sends DC power to the LNB through the same coaxial cable. This voltage is also used for LNB control and polarization switching. A normal satellite inline amplifier usually allows this DC voltage to pass through the amplifier to the LNB.
Its main work is to amplify the RF signal. It normally does not increase the LNB power voltage.
However, long coaxial cables can also cause some DC voltage drop. Very long cable, poor-quality cable, bad connectors or other equipment can increase this voltage loss. If the voltage drop becomes too high, the LNB or polarization switching may not work correctly.
Some powered satellite amplifiers, multiswitches and power inserters can provide a separate power supply for the LNB, but these are different from a normal inline amplifier.
Does Low LNB Voltage Reduce LNB Gain?
A small voltage drop does not always mean that LNB gain will become lower. Most LNBs are designed to work within a specified voltage range. If the voltage is still within this working range, the LNB can normally continue to work correctly.
A serious voltage drop can create problems such as:
– LNB not working correctly
– Horizontal or vertical channels not switching properly
– DiSEqC or other control problems
– Signal becoming unstable
So a normal inline amplifier should not be used only for increasing LNB power.
Can an Inline Amplifier Reduce DTH Signal Quality?
Yes, this can happen.
I have also seen that in some DTH installations, after connecting an inline amplifier, the receiver signal quality reading can reduce by around 1 or 2 dB. This can happen because an amplifier also adds some noise to the signal. If the original signal is already strong, the amplifier may not be required.
Too much amplification can also overload the receiver input.
Other reasons can include:
– Low-quality inline amplifier
– High amplifier noise
– Too much gain
– Bad F-connectors
– Impedance mismatch
– Receiver input overload
So do not use an amplifier only because you want a higher signal quality number.
Signal Strength and Signal Quality Are Different?
This is very important in a DTH system.
Signal strength shows how strong the RF signal is.
Signal quality normally depends on things like C/N, SNR, MER and how clean the received digital signal is.
A line amplifier may increase signal strength but may not increase signal quality. If the dish alignment is poor or the satellite signal itself is weak, an amplifier cannot correct it.
First check:
– Dish alignment
– LNB condition
– Cable quality
– F-connectors
– DiSEqC switch
– Cable length
After that, use an amplifier only if cable or distribution loss is the real problem.
Where Are Coaxial Line Amplifiers Used?
Coaxial amplifiers are commonly used in:
– Cable TV systems
– DTH satellite TV
– MATV and SMATV systems
– CCTV systems
– RF distribution systems
– Broadband coaxial networks
Different systems need different types of amplifiers. For example, a CATV amplifier and a DTH satellite amplifier may use different frequency ranges. Always check the supported frequency before buying an amplifier.
Types of Coaxial Line Amplifiers
Common types include:
– One-way line amplifier
– Two-way or bi-directional amplifier
– CATV line amplifier
– Satellite inline amplifier
– Distribution amplifier
– Powered satellite amplifier
The correct amplifier depends on the system and frequency being used.
When Should You Use a DTH Inline Amplifier?
You may use an inline amplifier when:
– Coaxial cable is very long
– Cable loss is high
– Signal is being divided through multiple devices
– Receiver signal level becomes too low because of distribution loss
You may not need an amplifier when:
– Cable is short
– Signal level is already good
– Dish alignment is poor
– LNB is faulty
– Signal quality is already low at the LNB
– Receiver is already getting a strong signal
In these conditions, an amplifier may not help.
Important Tip
- Do not think that an inline amplifier is a device that can improve every weak DTH signal.
- Its main job is to compensate for RF signal loss in the cable and distribution system.
- If the original satellite signal is bad, first correct the dish, LNB, connectors and cable.
Also read: How Coaxial Line Amplifiers Work and Their Benefits?
Frequently Asked Questions
What is the function of a line amplifier?
A coaxial line amplifier increases the RF signal level to compensate for signal loss caused by long coaxial cables, splitters and connectors.
Does a line amplifier increase signal strength?
Yes. It increases RF signal level or gain.
Does a line amplifier increase DTH signal quality?
Not always. It may increase signal strength, but signal quality can remain the same or sometimes become slightly lower because the amplifier also adds noise.
Does a satellite inline amplifier increase LNB voltage?
A normal inline amplifier usually does not increase LNB voltage. It normally passes the receiver DC voltage through to the LNB while amplifying the satellite RF signal.
Where should I install a satellite inline amplifier?
If the problem is long cable loss, it is normally better to install the amplifier near the LNB or before the main long coaxial cable run.
Can too much amplifier gain create problems?
Yes. Too much gain can overload the receiver and may reduce signal quality. If you need a coaxial amplifier for your TV or distribution system, you can buy a coaxial line amplifier here.
