The TV signal from your TV antenna becomes weaker as it travels through the coax cable to your TV.
The farther it must travel the weaker it becomes. Signal splitters also weaken the signal. The more times the signal is divided the weaker it becomes. The splitter itself creates the signal loss, it doesn't matter if the TV's are on or off or even if all of the connections on the splitter are used the loss still occurs, it's called insertion loss. The line loss that occurs getting the signal from the TV antenna to the TV or TV's can be overcome by installing a preamplifier near the TV antenna amplifying the signal before the signal loss occurs.
The degree a signal amplifier increases the signal strength is measured in decibels (dB). The higher the amplifiers dB rating is the greater the strength of the signal is increased. "Wait a minute, I know what your thinking "I'll just get the biggest high output amplifier I can get and that will solve all my problems. I have one word for you, OVERLOAD. When too much signal is present overload can and does happen. Signal overload can occur in the amplifier, the TV tuner or both. Use the guidelines below, to select the proper amplifier for your system.
Selecting the correct TV antenna amplifier is a simple mathematical process.
Add-up the total amount of signal decibel loss that will occur as the signal travels from the TV antenna to the TV with the longest cable run. Add the signal loss from the cable length and any splitters between the antenna and the TV. Choose the amplifier with the dB gain rating that is from 5 to 10dB greater then the total loss. EXAMPLE: 100 feet of coax cable and a 2 way splitter have a signal dB loss of 8.7 dB. A perfect amplifier match for the above example would be the The LNA 200 preamplifier >. The LNA 200 preamplifieramplifier has a gain rating of 20dB.
- AVERAGE LOSS PER 100 FEET OF RG6 COAX CABLE IS 5 dB
- 2 way splitter 3.7 db
- 3 way splitter 7.5 db
- 4 way splitter 7.5 db
- 6 way splitter 13 db
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8 way splitter 13.5 db
Good question!!!
I found your web site and really app. the info you make available. so much so I would like to give you my business when I upgrade. Question I read where you can overpower your tuner with too much signal strength. I'm trying to pull in transmitters from as close as 17 miles to as far as 60miles. I supply two tvs with a total cable run of about 40 ft. Would a preamp and a distribution amplifier be too much amp power. I live in Burlington, In. and am receiving Indianapolis.
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Yes, a preamplifier and a distribution amplifier is likely too much at your location and for the system configuration you described. The purpose of an amplifier is to overcome the signal loss that is present from the amplifier installation location to the TV. It doesn't actually make the antenna receive the signals any better it just appears that it does. A 2 way signal splitter creates a 3.5 dB signal loss. Plus 40 feet of cable has about 3 to 4 dB loss depending on the quality of the cable equaling a total loss of about 7 dB. The proper signal amplification should be about 10 dB greater then the total signal loss created by the cable and splitter getting the signal from the antenna to the TV. With that said you would get optimum reception using the AP 8700 mast mounted preamplifier. The AP 8700 is rated at 19 dB gain.
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If the reception is not satisfactory using the AP 8700 then the next place to look is the antenna. The AP 8700 is delivering everything the antenna has to offer so the only way to improve reception would be a higher signal gain antenna. In other words, TV signals can't be amplified into existence the antenna must receive an adequate signal so the amplifier has a signal to amplify.
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Sometimes both a preamplifier and distribution amplifier are required. If an 8 way signal splitter were installed the signal loss (13.5 dB) of the splitter and coax cable would increase the signal amplification requirements. The total signal loss would be greater then the LNA 200 preamplifier can supply. In this case in addition to the LNA 200 preamplifier a distribution amplifier would be installed ahead of the signal splitter on the antenna side of the splitter to compensate for the signal loss created by the 8 way splitter.
See: Design a TV antenna signal distribution system >
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Preamplifier Basics & Troubleshooting
Denny,
Thank you for all your help with my amplifier problems. The TV antenna amplifier I got from you was my third one and it works great. Now I know there probably wasn't anything wrong with the first two, it was how I had them installed. You should let everyone know what you taught me.
Thanks Again,
Robert |
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Robert,
Excellent Idea, since 60% of all reception problems are related to Preamplifier-amplifiers. There are two parts to a mast mounted TV antenna Preamplifier-amplifier. The mast mounted portion is mounted on the mast close to the TV antenna. The power supply/injector is located indoors. The coax lead-in wire runs in and out of both parts.
The outdoor amplifier is located near the TV antenna because that is where the signal can be amplified before signal line loss occurs. The indoor power inserter function is to supply electricity to the amplifier, it does this by sending it up the coax cable, the same cable that sends the TV signal down to your TV. This is where most problems occur. To transfer electricity through the coax cable you need two conductors (wires). With coax cable the conductors are the center copper wire and the silver wire braid and shield located just under the rubber coating on the cable. The wire between the two parts can not have any interruptions in the power flow. If it does your amplifier will not work. An antenna amplifier that isn't working provides worse reception than if you had no amplifier at all. Damaged wire, signal splitters and screw on (non crimping) type cable connectors are the number one causes of amplifier failure.
To test your amplifier tune your TV to a channel that has a picture, unplug the power inserter from the 110v electrical outlet, the signal strength should weaken on your TV, if it doesn't chances are your amplifier isn't working. Next check your wire for damage (some wire damage occurs inside the wire and cannot be detected by examination). Next remove any signal splitters located between the power supply and the TV antenna amplifier. Next check your connections to be sure the connectors are making contact with the cable braid. If you are using screw on (non crimping) cable connectors be sure ample braid is folded back over the outside of the coax and connection to the braid is being made as you screw the connector onto the cable. Using a voltage meter you can test the coax cable at the antenna preamplifier to determine if the electricity from the indoor power supply is reaching the mast mounted preamplifier. Most power supplies have the output power indicated somewhere on the unit.
If you don't have a voltage meter and the preamplifier is a Winegard unit disconnect the down lead cable at the mast mounted preamplifier. This is the cable that is connected to the connection on the preamplifier and it leads to the indoor power inserter. Using a screwdriver touch the tip of the screwdriver to the center copper wire of the cable and at the same time touch the edge of the screwdriver to the connector end: See picture below. This will create a short between the center copper wire and the connector end. When this is done the green light on the indoor power inserter will dim if the wire and connections are good. If the light does not dim then either the cable or the connections are bad and the operateing voltage is not reaching the mast preamplifier. Check your connections, be certain a signal splitter isn't inline between the mast preamplifier and the indoor power inserter. If needed replace the coax cable. The electricity from the indoor power inserter must reach the mast preamplifier or it won't work.
Continue to Preamplifier Help page 2 >
Have a question about TV antenna preamplifiers???
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Denny's TV Antenna Service
"Helping America Watch Free TV Since 1988"
