If you live more than 35 miles from the closest TV Towers or if the terrain in your area makes TV reception difficult there is a possibility that a Antenna Preamplifier can boost your signal enough to provide good quality signal.
In this How To we will look at how to understand when a preamplifier is a good choice and when it should not be used. We will also look at how they are installed and the requirements for your system. Then we will look at the different types of amplifiers including antennas that come with built in amplifiers.
The first thing you must understand about a preamplifier is that signal has to be present for you to amplify it. When looking at your TV Signal Report from www.TVFool.com you will be presented with a directional bulls eye and a table listing each channel and its approximate signal strength in your area.
Now you have to take these signal charts with a grain of salt they are not always completely accurate but if the report shows you have a large number of really strong signals or a number of weak signals in your area then you will understand which direction you should go when trying to improve your reception by the use of an Antenna and maybe a preamplifier.
Why a strong antenna is more important than a Preamplifier
It is always important to understand that to obtain a good TV signal requires larger and more accurate antennas to capture signals from distant or weak stations. But how poor can a signal be and still be watchable for both signal power and signal quality?
Lets think about signal power as if it was light. You can have the Sun, a House Light or a Birthday Candle representing TV Signal from different towers in your area. Now when we say area that could be 5 miles away or 100 miles away and we will get into how distance effects things later.
Ok so lets say you live in a great area where most of the signals are like a bright sun.. dozens of suns all around you and everything is happy at your TV. Your TV is showing a Signal Power of 70 or above for all your stations and they are beautiful. Then a cloud comes in and starts obscuring the Sun’s light. Your TV starts freaking out the signal becomes choppy and pixelated and flickers on and off as clouds go by.
This is the difference of having really great signal power and really bad signal quality. The Sun is still shining but its behind the clouds. The clouds obscure the light and your TV can’t hold on to the signal. Your power level probably still says 90 but the quality is not there.
Now lets say you have a candle in the distance and you can see it but not very well. You can see it much better at night but still not so great. But it is always there and constant. Well this is the same as having a distant TV Tower broadcasting signal that is very weak to your area. Unfortunately Digital Signals have a threshold and below a set power level you just won’t pickup those weak distant stations. The same would be true for low power stations that are reasonably local if the power to your area is low you just won’t get the station to be recognized by your TV’s internal Tuner.
By adding an Preamplifier you can grab those weak signals and increase them to a point your TV Tuner will pick them up.
However remember if a cloud passes by locally or anywhere between you and that candle way out there in the distance you will have bad quality signal. This is the big problem with picking up distant stations even if they are relatively strong. I have stations that are 50 miles away and they provide from 20 to 30db to my area and they should be viewable with a strong antenna and preamplifier but any storm or shower or cloud formation or electrical disturbance will knock them out due to signal quality.
For the House Light stations that are relatively strong but you may have quality or power issues from time to time the use of a Preamplifier will increase the power level and also the quality. For relatively local stations the signal distribution should be rather abundant but there are issues such as natural obstructions from hills, trees or man made obstructions from houses or buildings. Both signal quality and power will increase with the use of a large antenna and preamplifier.
TV Antenna Preamplifier Strength and Noise Ratio
When you are considering trying a preamplifier on your antenna you must first consider buying a larger antenna. Like we said only signal that can be captured by the antenna is able to be amplified. If you slap a really strong preamp on a really weak antenna it will be like one of the kids is flicking the light switch on and off.. maybe not that bad but you will see really poor signal quality throughout different times of the day.
When selecting an antenna based on your TVFool Report I suggest that you always jump up to the next level. If you think you can get away with rabbit ears on each TV you will need a 2bay antenna, If you think you can get away with a 4 bay large UHF Antenna and you are trying to pickup distant stations over 40 miles or only providing 15 to 25db then you probably need to go with a very large more directional Yaggi Antenna.
If your antenna is in your home you will be better off putting it in your attic. If it is planned for an attic then a rooftop install is suggested and if you expect that you will need a rooftop antenna then a tall tower is probably needed.
If you will be serving your entire home it is best to go larger too. Although you won’t be losing signal because more TVs means more energy sucked out of the antenna the splitters and extra cable required will lose you signal. So if you think your report which is for one TV could be served with a 2bay antenna I suggest you get a 4bay and possibly consider a distribution amplifier which is used to boost the signal within your home after the antenna and possibly a preamplifier has already picked up good signal.
How are Antenna Preamplifiers installed
An Antenna Preamplifier is used to amplify the signal that an Antenna captures and the most important thing to do is amplify it right at the antenna so no other noise or loss happens due to splitters or cable.
The best situation would be to connect your preamplifier directly to the 75ohm coax connector that comes out of the antenna. However not every antenna will allow this so you will probably need to install a short piece of coax cable to allow attachment and it should be the shortest length possible to allow this. Don’t try to run a 25 foot cable down the side of your house or into your attic to get that preamplifier closer to the electrical outlet it will need. Preamplifiers use a technology where the amplifier box that attaches at the antenna is provided power over the coax cable and the injector or power supply connector can be placed down the line where it is easier to manage an attachment to the DC Power Supply.
It is important to use solid copper coax cable from the injector power supply all the way up to the antenna. Normal Consumer Grade Coax cable is Steal with a copper coating and it will not allow the electricity to pass through it to the preamplifier box or it will restrict it partly.
If you have trouble finding solid copper core coax this type of cable is standard for Dish installs because of this specific problem. Standard Copper Clad Coax is fine for Cable TV because no power is sent through the line.
Selecting a Preamplifier for your Antenna
Now this is all the way down at the bottom of the how to and you were probably thinking you should start here but if you read the above you now understand more about how these things work and when you will find a benefit.
Before you go out and buy the most expensive and strongest preamplifier you can get because you want the best reception for your home you need to understand that these devices come in different strengths for a reason.
If you have installed a better antenna and still think you can benefit ask yourself do you have a local tv tower that provides high power to your home. If you have a local tv tower within about 25 miles and you install an amplifier of any size and your current db to your home is high enough then you will overpower your tuner.
TV Tuners can only accept Signals that have a maximum of about 90db and once you get close to that you can run into problems.
If you have a 10db antenna and a 80db station then any amplifier will overpower your tuner. If you start at say 80db then subtract your antenna strength and then the available db to your home you should be ok.
So if you have a 10db antenna and a 20db preamp and all your signals are below 40db or 30db then you can benefit.
However preamplifiers are really for people who have mainly bad signal to their area.
If your highest station has 20db and you add a 10db antenna then you can add a 30db preamplifier and bring those signals up to 60db without problem of overpowering your TV’s Tuner.
So you must do that calculation. You don not want to lose stations because the towers are too close or their signal is too strong and you are trying to get a single distant station. It just won’t work. Preamps increase the entire range of signal and the only way around this is to install expensive line filters that will block signal in a specific range. If you are in an extreme situation this might be reasonable such as you have one tower 10 miles down the road broadcasting garbage.. and you have a city 50 miles away that has a range of quality tv stations. Normally this is an extreme and rural type situation and may require more than one antenna and much more technical planning than we can talk about here.
There are a few different makers of Antenna Preamps and the output is normally about 20db however there are some that will provide 30db. The price is not that much different its the use by you that will require that extra 10db of power as you try to reach out and grasp that weak candle in the dark in hopes of seeing your favorite TV show.
If a Preamp goes bad or if you turn off the power to it normally there is no throughput of signal so in most cases don’t expect to be able to tune to a distant station with the amp on and to a local one with the amp off. You just won’t get any signal once the amp is off or once it breaks.
And that is another problem because the preamp is up at the antenna if it brakes or gets water in it then you will have to fix it so if you can use a bigger antenna that won’t require you to climb a ladder in the middle of winter in the middle of the night when the superbowl goes off line.
Final Note
This has been a pretty in depth description about how and why to use a preamplifier on your antenna.
What we didn’t cover is specific selection of devices. There are a number of good quality models out there and you should read about them before you buy any specific one.
The main idea is. Don’t use them if you have local towers. You can use them if you have medium range towers and bad reception. You will probably need one if you have towers over 50 miles away.
And if you do use one don’t forget that interference from clouds or other things will cause you problems. The chance of this and of you having cutouts and bad signal gets greater the farther you are from the tv towers or the more obstructions there are between you and the towers.