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Old 23-Dec-2011, 3:54 PM   #5
Tower Guy
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Join Date: Dec 2009
Location: Delmar, NY
Posts: 1,236
Quote:
Originally Posted by ghz24 View Post
So (even if it's hooked directly to the tuner) how does having a noise floor of 1 or 2 for a low noise amp not better than the stock tuners sensitivity?
Unless you live in the country with buried power lines and no part 15 devices in your house, adding a preamp makes the desired signal and received noise go up by the same amount.

In nearly all real-world situations the noise on low band VHF is higher than the internal noise of the tuner itself.

That said, you can decrease the EVM by the use of a preamp, but the net S/N increase is very small. Amplification helps if there are any splitters.

What can screw up the process is lets say that you make a low band signal work fine during the day, but the earth turns and later the Milky Way is in the main beam of your antenna. The higher sky noise from the Milky Way can kill the signal.

The same effect occurs on UHF if the sun rises in the main beam of the antenna. The sun temperature ruins the NM.

Last edited by Tower Guy; 23-Dec-2011 at 4:07 PM.
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