Do I need a preamplifier for my antenna? (CM-7777HD CM7777HD)

TV SIGNAL; Do I need an Amplifier?

  • You need to start at the source. Your Antenna.
  • Check the TV signals at your antenna without any signal amplification. (If possible..)
  • Ideally you’d have an RF spectrum analyzer or TV analyzer, but only pro’s would have those.
  • If you have a small ATSC HD TV, you could bring that to or close to your antenna this could work very well for your testing.
  • Please understand, we can only provide general testing techniques. There are too many variables to try to cover all possibilities in all system configurations.
  • Please see the attached diagrams at the bottom of this article, to help you understand the proper antenna system connections.

 

  1. Adjust your antenna for the best reception for the channels that you want to receive.
  2. Perform a ‘channel scan’ on your Test TV.
  3. You may need to make multiple tests while pointing your antenna in multiple directions.
  4. Document antenna direction with a compass, document the channels received, and if your Test TV has a signal meter(s), document the signal strength and signal quality on each channel. You will use this information as your baseline to use throughout the rest of your system testing.
  5. Now connect your complete antenna system, to all of your TV’s. Include all splitters and cables that you planned to use.
  1. Now, check the signals/channels at all of your TV(s) that are connected throughout your house.
  2. If you don't receive the same channels on your TV’s, compared to the stations received at your antenna, then you will need to determine why.
  3. You know what signals you can receive at the antenna, (Baseline measurements documented) and you want to get the same results at all of your TV’s.
  4. You have a long RG6 Coax cable connected to your antenna that goes into your house.
  5. Locate the end of that long coax antenna cable in the house. (The other end of that cable is connected to your Antenna.)
  6. Connect your Test TV to the end of that long cable.
  7. If you don’t receive all of the same channels that you were able to receive right at the antenna, then you will need to install a “Preamplifier” at your antenna to compensate for the signal lost while going through the connectors and long cable.
  8. After installing the preamplifier, test the channels you get with your Test TV connected to the ‘TO TV” port of your power inserter. You should have the same channels now as you have documented in your first test.
  9. Now connect the rest of your system to the ‘TO TV’ port of the Power Inserter.
    1. If you do still get all channels at the end of that antenna cable that you were able to receive right at the antenna, then you know that you do not need to install a “Distribution amp”. Your testing is complete.
  10. If you do not get all of the same channels on all of your TV’s, Then you likely will need to install a ‘Distribution Amplifier’ in place of the passive/standard ‘splitter’ that you used to connect all of the cables that run to all of your TV’s.
  11. There is no instruction that we can write that will cover all of the variables that you could encounter while installing an antenna system. If you do not feel comfortable while installing and testing, we highly recommend that you locate a local professional installer to assist you.

Choosing the proper equipment. 

  1. Your amplification must occur/start at a point in your system where the TV signal is still good and complete, and you are able to receive those same channels that you were able to receive right at the antenna. 
    1. Amplifiers cannot fix ‘unusable signals’. It can only amplify good/complete signals to a level, where the signal will not be degraded and rendered useless, while going through your cables and splitters. It will ensure that it remains a good/complete signal when correctly amplified.
  2. The signal levels at your antenna, the cable lengths, splitters, connections, and the number of additional runs to TV's will dictate how much amplification is required to successfully transport the good/complete signals from your antenna, to your TV’s.
  3. Things to consider before deciding on signal amplifiers;
    1. The TV signals are measured in dBmV.
    2. TV signal deteriorates as it goes through long coax cable runs and connectors. 
    3. The amount of signal loss per foot, can be obtained from the manufacturer of the coax cable.
    4. Most RG6 coax will average about a 5db loss in 100ft. (@500MHz)
    5. When using signal splitters, the signal also deteriorates. 
    6. The signal loss (In dB's) is normally printed on the splitter. 
    7. For a quick calculation you could go with about a 5dB loss through a splitter.
    8. Rule of thumb is that you desire 0dBmV (dB) signal level at your ATSC HD TV Tuner.
    9. Signals levels that are considered acceptable are +11dBmv to -11dBmv.
    10. Too high of a signal at your TV tuner can overload the TV tuner and cause problems or process no signal at all.
    11. Too high of a signal at the input of your amplifier can cause problems and pass no signal at all.
    12. For additional information on receiving ATSC HD TV signals, please go to the links below.
      1. http://www.hdtvprimer.com/antennas/fixes.html
      2. http://www.hdtvprimer.com/ANTENNAS/basics.htmlhttp://www.hdtvprimer.com/ANTENNAS/ganging.html
      3. Additional information is available at the main web page.
        http://www.hdtvprimer.com/
      4. These are not affiliated with Channel Master and we are not responsible for their content.
      5. Another great source for technical info about possible causes for reception issues; https://en.wikipedia.org/wiki/Tropospheric_propagation

 

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