Quote:
Originally Posted by GroundUrMast
You need to be able to add the noise margin of the signal in the air together with the net gain of the antenna minus any balun and cable losses ahead of any active device such as a preamp. (Amplifier gain does not add to the antenna gain, because it amplifies noise received by the antenna while adding some of it's own noise. If the antenna can't get the job done, an amp won't fix it.) If the number is positive, you are getting to a point that may produce reception. But the NM figure listed in your report does not account for the effects of co-channel, adjacent channel, FM or any other source of interference. Also, at that distance, atmospheric conditions are going to govern a great deal of the path. As a result you're going to see a wide range of path loss variation as the weather changes. Sometimes the atmospheric conditions will be in your favor... but at least as often, not. On any given day the real and predicted NM on such a path could differ by well more than 10 dB.
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For 100+ mile reception (which is DXing), fractions of signal make all the difference. Pre-amps add noise. Cable has losses. To avoid adding noise while avoiding cable loss, the tuner could be placed at the antenna. Then either a data stream or a video/audio signal is brought into the house; both survive long cable runs better than a weak signal from an antenna.
There are at least two ways that can be done:
1. Put a silicon dust HDHR in a weather proof enclosure up with the antenna. Run power and network to it.
2. Put a tuner box in a weather proof enclosure up with the antenna. Run power, and IR control to it; run video and audio from it. For HD, the best bet would likely be component which can be run through RG6 with RCA-F adapters. For SD, the CH3/4 modulator output could be brought down on coax. Audio could be run on coax with RCA-F adapters, as could composite video.
The advantage of that is other than a short coax jumper from the antenna (or balun) to the tuner, there is not noise being added by an amp and no loss from a long cable run. (A disadvantage is a potentially expensive piece of equipment is on the mast which could be a lightning rod.) The noise of any active electronics in close proximity to the antenna could be picked up by the antenna, so a shielded enclosure may be advisable.
You are probably not going to reliably get stations from 110 miles away 24-7-365. The best to hope for is seasonal luck and/or time of day luck. I have a station WBOC 85 miles away. It is co channeled pretty bad in my area. It is also 70 degrees off axis from where my antenna points. In the summer late at night and early in the morning it comes in well enough to watch. Something about the atmosphere is causing the RF21 signal to come in loud and clear even though the predicted NM is -11.3. A NM is -11.3 is quite doable, but WBOC is still coming in with off axis loss and preamp noise; my antenna should be 15 to30dB down on CH 21 70 degrees off axis.