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Old 30-Jul-2019, 6:40 AM   #15
GroundUrMast's Avatar
Join Date: Oct 2010
Location: Greater Seattle Area
Posts: 4,758
Perhaps another way to explain "dB" would to use "sea level" as an analogy. Elevation that is higher than sea level is written as a positive number, elevation that is below sea level is written as a negative number. Sea level is the zero reference point for elevation. Even if you move between metric and imperial systems of measurement, the standard of sea level is a constant reference point worldwide.

You ask, "... is there a point where the -xxx db scale "ends"?"; (I presume you are referring to the predicted signal power available at your location per the TV Fool or Rabbitears reports) No, but if a signal is weaker than the random noise that is always present, no tuner will be able to lock on and demodulate the signal. Random noise levels are not constant, there is usually lower noise levels in the UHF band than the VHF band. Most appliances, power tools and home electronics emit some noise.

If you are looking at the gain specification of an amplifier, the "dB gain" value tells you how much stronger the output signal and noise will be as compared to the input.

It's possible to have too much gain. This is more likely to be a problem when there are one or more strong signals present. The CM7777 is known for it's high gain and it's tendency for overloading. It is designed for applications where there are no strong signals present. It's a good amplifier when it's used for what it was designed for (an area with only weak signals). When used improperly you can expect to get less reliable reception due to the distortion of the signals as they're over amplified. The signal levels on your report definitely are too strong for amplifiers like the CM7777.

Bottom line, An amplifier might get you a couple of additional PBS stations. I don't expect an amplifier to make any Canadian signals reliable at your location. You would need to mount an antenna on a mountain top to overcome the terrain between you and Montreal.
If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)

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Last edited by GroundUrMast; 30-Jul-2019 at 6:42 AM.
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