TV Antenna Amplifiers

A reception problem does not automatically mean the preamplifier itself has failed. Many apparent preamplifier failures are actually caused by the coaxial cable, connectors, power inserter, power supply, or another component between the indoor power inserter and the mast mounted preamplifier.

The first step is to verify that the preamplifier is receiving power.

On Channel Master preamplifier systems equipped with status LEDs, check the LED on the power adapter or power inserter and the LED on the preamplifier. Under normal operating conditions, both should indicate that the system is receiving power.

If either LED is not illuminated, or if an LED is flashing or otherwise indicating an abnormal condition, do not immediately assume the preamplifier is defective.

One of the most useful troubleshooting procedures is an indoor bench test.

Remove the preamplifier and power components from the installed antenna system and connect them together indoors using a short, known good Channel Master coaxial cable. This temporarily eliminates the home's installed coaxial cable, outdoor connectors, splitters, grounding blocks, and other components from the DC power path.

Apply power and observe the LEDs again.

If the preamplifier LED now illuminates normally, or an abnormal flashing condition disappears during the bench test, this strongly indicates that the preamplifier and power supply are functioning and that the problem is somewhere in the installed coaxial path between the power inserter and preamplifier.

Possible causes include:

A damaged coaxial cable

Excessive DC resistance in poor quality coaxial cable

Loose or improperly installed F-connectors

Corroded connectors

Moisture inside the cable or connectors

A short between the center conductor and shield

A damaged grounding block

A splitter, filter, diplexer, or other passive component that does not pass DC power

The last item is particularly important. A mast mounted preamplifier receives its operating voltage through the coaxial cable. Any component installed between the power inserter and preamplifier must be compatible with the required DC power path. A passive RF device can pass television signals while simultaneously blocking the DC voltage required by the preamplifier.

If the preamplifier behaves abnormally even when connected directly to its correct power components with a short known good coaxial cable, the preamplifier, power inserter, or power supply can then be investigated individually.

Bench testing is valuable because it isolates the powered components from the installed coaxial network before replacement parts are purchased.

A preamplifier is useful when the antenna receives usable signals but additional gain is needed before those signals experience downstream losses from coaxial cable, splitters, and other distribution components.

A preamplifier is normally mounted at or near the antenna so that amplification occurs near the beginning of the signal path.

A preamplifier may be beneficial when:

Desired stations have relatively weak predicted or measured signal levels.

The antenna is located a significant distance from the television.

Long coaxial cable runs create substantial attenuation.

Splitters will distribute the signal to multiple televisions.

The combined distribution losses would otherwise leave insufficient signal level at the receivers.

A preamplifier should not automatically be added to every antenna installation.

If signals at the antenna are already very strong, unnecessary amplification can overload the preamplifier or television tuner and make reception worse.

A preamplifier also cannot correct poor signal quality caused by severe interference or multipath. It primarily helps preserve usable signals through losses that occur after the antenna.

The best approach is to evaluate the signal available at the antenna and calculate the expected coaxial cable, splitter, and other distribution losses before deciding whether amplification is necessary.

Select a preamplifier based on the signal conditions at the antenna and the losses in the distribution system, not simply by choosing the amplifier with the highest advertised gain.

Important specifications include:

Gain: The amount by which the amplifier increases RF signal level. Gain should be sufficient to compensate for downstream losses while avoiding unnecessary amplification.

Noise figure: Every amplifier adds some noise. Because a preamplifier is installed near the beginning of the receiving system, a low noise figure is desirable, particularly for weak signals.

Overload capability: The preamplifier must be capable of handling the total RF environment at the antenna. Strong local television, FM, cellular, or other signals can overload an amplifier even when some desired television stations are weak.

Frequency coverage: The amplifier should support the UHF and VHF frequencies required by the antenna system.

Filtering: In some RF environments, appropriate filtering can help prevent strong out of band signals from reaching the amplifier.

More amplifier gain is not automatically better. For example, if the distribution system has approximately 12 dB of downstream loss, adding substantially more gain than necessary can provide little benefit while reducing the system's available overload margin.

The objective is to provide adequate signal level at the receivers while maintaining good signal quality.

A mast mounted preamplifier normally receives electrical power through the same coaxial cable that carries the television signals.

The system generally consists of three primary components:

Preamplifier: Installed near the antenna.

Power inserter: Installed indoors in the coaxial signal path.

Power adapter or power supply: Provides the required DC voltage to the power inserter.

The power inserter places DC voltage onto the coaxial cable leading toward the preamplifier. The coax therefore performs two functions simultaneously. It carries the received television RF signals from the antenna toward the television while also carrying DC electrical power toward the mast mounted preamplifier.

This is possible because RF television signals and DC power occupy very different electrical conditions and can coexist on the same properly designed coaxial system.

This also explains why coaxial cable quality is important. A cable can carry RF television signals while having excessive electrical resistance for reliable DC power delivery.

Any splitter, filter, grounding device, or other component installed between the power inserter and preamplifier must also provide the appropriate DC path. A component that blocks DC voltage can prevent the preamplifier from operating even though RF signals can pass through the component.

A preamplifier should normally be installed at or near the antenna, before significant coaxial cable and splitter losses occur.

The typical signal path is:

TV Antenna → Preamplifier → Coaxial Cable → Power Inserter → Distribution System → TV or Receiver

The reason for installing the preamplifier near the antenna is important.

Suppose the antenna receives a relatively weak but usable signal. If that signal first travels through a long coaxial cable and several passive components, signal level is lost before it reaches an amplifier installed indoors.

Installing the preamplifier near the antenna allows the usable signal to be amplified before those downstream losses occur.

The power inserter is normally installed indoors at an appropriate point in the coaxial system. Its connections must be oriented correctly because one port provides the DC path toward the preamplifier while the receiver side isolates or routes power as designed by the manufacturer.

Any passive device placed between the power inserter and preamplifier must be verified as compatible with DC power passing. A splitter that does not pass DC on the appropriate port, for example, can prevent the preamplifier from receiving power.

Outdoor coaxial connections should use high quality connectors and appropriate weather protection. Channel Master recommends high quality RG6 coaxial cable because the cable must provide both reliable RF performance and sufficiently low DC resistance for powering mast mounted equipment.

After installation, verify normal power indication before troubleshooting reception. If the preamplifier does not indicate normal power, correct the DC power path first before evaluating its effect on television reception.

Both devices add RF gain, but they are intended to solve different problems within an antenna system.

A preamplifier is normally installed at or very close to the antenna. Its purpose is to increase the level of usable signals before they experience attenuation from long coaxial cable runs, splitters, and other downstream components.

A distribution amplifier is normally used farther downstream when a good antenna signal needs to be distributed to multiple televisions or through a larger coaxial network. Its primary purpose is to compensate for the insertion loss of splitters and the attenuation of the distribution system. Channel Master describes its distribution amplifiers specifically as devices intended to raise received signal levels above the losses associated with the distribution network.

For example, suppose the antenna already provides good signals, but the system needs to feed four televisions. A passive four way splitter can introduce approximately 7 to 8 dB of loss to each output. A properly selected four output distribution amplifier can compensate for that loss so each television receives an appropriate signal level.

The important distinction is where amplification is needed.

If the signal is already weak at the antenna, amplifying it only after it has traveled through a long cable and splitter network is generally less effective than using an appropriate preamplifier near the antenna.

If the signal is good at the antenna but becomes too weak because it must be divided among several televisions, a distribution amplifier may be the more appropriate solution.

Some larger systems can use both, but the total gain and signal levels must be considered carefully to prevent overload.

A distribution amplifier can be useful when an antenna receives adequate signals but those signals must be divided among multiple televisions or transported through long coaxial cable runs.

Every passive splitter introduces insertion loss. As the number of outputs increases, the signal available at each television decreases.

A distribution amplifier combines amplification and signal distribution so that this loss can be compensated for at the point where the signal is divided.

Channel Master currently offers TV Antenna Booster distribution amplifiers with 2, 4, and 8 outputs, specifically designed for Over the Air antenna systems. For example, the four output CM-3424 provides approximately 7.5 dB of gain at each output rather than introducing the approximately 7 to 8 dB loss expected from a passive four way splitter.

A distribution amplifier is most appropriate when the signal entering the amplifier is already usable and the primary problem is the loss created by the distribution network.

It should not be viewed as a way to repair a poor signal arriving from the antenna.

If a desired station is already unreliable at the antenna, determine why before designing the distribution system around additional amplification.

Yes. More amplification is not always better.

An amplifier increases RF signal level, but it does not automatically improve the underlying quality of the signal.

If the desired signal is contaminated by interference, multipath, or electrical noise, an amplifier can increase the level of the unwanted energy along with the desired television signal. Channel Master's antenna pointing guidance specifically cautions that amplifiers do not correct interference, reflections, or poor signal quality and can sometimes make reception worse.

An amplifier can also become overloaded.

Every amplifier has limits on how much RF energy it can process while remaining linear. If strong television stations or other RF signals drive the amplifier beyond those limits, the amplifier can produce distortion and intermodulation products.

The result can be counterintuitive. Adding an amplifier can produce:

More pixelation

Missing channels

Intermittent reception

Lower signal quality

A worse signal indication on the television

Complete loss of channels that previously worked

This is why amplifier gain should be selected based on actual signal conditions and system losses rather than automatically choosing the highest gain available.

The Channel Master PreAmp 1 (CM-7779HD) has selectable gain because the amount of amplification required varies substantially between antenna installations.

The PreAmp 1 provides approximately 30 dB in High gain mode and 17 dB in Low gain mode. The adjustment switch is located on the indoor power inserter, so the gain can be changed without accessing the mast mounted amplifier.

This feature addresses a common misconception that more amplifier gain is always better.

It is not.

An installation with weak signals and substantial downstream losses may benefit from the High setting. Another installation with stronger signals or less distribution loss may perform better using the Low setting because excessive gain can reduce overload margin and potentially make reception worse.

A practical installation approach is to establish the antenna and amplifier system, evaluate reception, and select the gain setting that provides the most reliable overall results.

The High and Low switch is generally intended as an installation adjustment, not something that needs to be changed while watching television.

Once the appropriate gain setting has been determined for the completed antenna system, it can normally be left in that position.

Channel Master also recommends avoiding the 30 dB High setting when the PreAmp 1 is installed indoors directly behind a television because that amount of gain can easily be excessive in that application.

Yes. An amplifier can be used with a passive indoor TV antenna when insufficient signal level is contributing to reception problems.

However, indoor antenna installations require particular caution because signals may already be strong, and the antenna can also receive electrical noise and reflected signals from inside the building.

An amplifier cannot distinguish between a clean desired television signal and every unwanted signal entering its passband. If the problem is primarily multipath, interference, or poor antenna placement, additional amplification may not help.

For this reason, the first step with an indoor antenna should usually be to experiment with antenna location and orientation. Moving an indoor antenna closer to an exterior wall or window, farther from electronic devices, or to a higher location can sometimes improve reception more effectively than amplification.

If signals remain usable but weak, an indoor amplifier may then be beneficial.

Channel Master's Indoor Antenna Booster CM-3421 was specifically designed for passive indoor TV antennas. It provides up to 30 dB of amplification, an ultra low noise figure, three selectable fine tuning modes, and built in FM, LTE, and out of band filtering.

The Channel Master PreAmp 1 can also be installed indoors, but when installed directly behind a television, Channel Master recommends not using its 30 dB High gain setting.

The objective with an indoor antenna is the same as with an outdoor system: use only as much amplification as the installation actually requires.

An antenna receives RF energy across a range of frequencies, not only the television stations you want to watch.

Strong signals outside the desired television spectrum can enter a broadband amplifier along with the TV signals. Even when those unwanted frequencies are not displayed by the television, they contribute to the total RF energy that the amplifier must process.

This can become important when strong nearby FM radio, cellular, or other RF transmissions are present.

A properly designed filter attenuates unwanted frequency ranges before they can unnecessarily consume amplifier headroom or contribute to overload and interference problems.

Channel Master's current PreAmp 1 incorporates LTE and out of band filtering intended to reduce unwanted 4G, 5G LTE, FM, LoRa/Helium, and other signals outside the desired television reception path.

Channel Master's current Booster 2, Booster 4, and Booster 8 distribution amplifiers also incorporate out of band and 4G/5G LTE filtering and are optimized around the current US television broadcast frequency ranges.

Filtering does not eliminate every possible source of television interference, and a filter should not be added simply because it exists. Its value is in preventing known unwanted frequency ranges from unnecessarily entering the active amplifier circuitry.

Amplifier gain is only one specification, and it should not be used by itself to judge amplifier quality.

A high quality antenna amplifier should be designed to increase usable RF signal level while adding as little noise and distortion as practical and while maintaining reliable operation in the environment where it is installed.

Important characteristics include:

Low noise figure: A preamplifier is located near the beginning of the receiving system, so noise introduced at this point can affect the performance of the entire system.

Good overload capability and linearity: The amplifier needs to process the combination of signals reaching the antenna without creating excessive distortion or intermodulation.

Appropriate gain: More gain is not automatically better. Adjustable gain can be valuable when installations have very different signal conditions.

Proper filtering: LTE, FM, and other out of band signals can consume amplifier headroom even though they are not desired television signals.

High quality electronic components: Component tolerances, circuit design, power supply quality, thermal performance, and manufacturing quality can affect noise, stability, and long term reliability.

Weather resistant construction: A mast mounted preamplifier may remain outdoors continuously for many years. The enclosure, connectors, seals, circuit board protection, and hardware need to tolerate heat, cold, moisture, sunlight, and repeated temperature cycles.

High quality RF connections: Poorly constructed or inadequately weather protected F-ports can become sources of moisture intrusion, corrosion, signal loss, and unreliable DC power delivery.

Channel Master's PreAmp 1 uses a die cast metal housing with weatherproof ports, is designed for indoor or outdoor installation, provides selectable 17 or 30 dB gain, includes integrated filtering, and uses an ultra low noise amplifier design.

Channel Master's current distribution amplifiers similarly use heavy duty weatherproof housings and premium internal components and are designed specifically for Over the Air television frequency ranges.

This is particularly important for a preamplifier because it may be installed outdoors in a difficult to access location. A small difference in purchase price is considerably less important than having an amplifier that provides stable RF performance and remains reliable over years of outdoor service.

For a professionally designed antenna system, the best amplifier is therefore not necessarily the amplifier with the largest gain number. It is the amplifier whose gain, noise performance, filtering, overload capability, construction quality, and environmental durability are appropriate for the installation.

Download Installation Diagram (PDF)

Download Installation Diagram (PDF)

Download Installation Diagram (PDF)

Download Installation Diagram (PDF)

Download Installation Diagram (PDF)