I have tested my sstran transmitter in the wooded valley were I live and I am getting about 1mile good coverage. I am moving my station to town and I have the possibllity of putting my transmitter on the water tower does any one know if the fcc might frown on this aplication. I do have community support through business and the local school.
please send any comments to
[email protected]
thanks
I have tested my sstran transmitter in the wooded valley were I live and I am getting about 1mile good coverage. I am moving my station to town and I have the possibllity of putting my transmitter on the water tower does any one know if the fcc might frown on this aplication. I do have community support through business and the local school.
please send any comments to
[email protected]
thanks Brian
I have tested my sstran transmitter in the wooded valley were I live and I am getting about 1mile good coverage. I am moving my station to town and I have the possibllity of putting my transmitter on the water tower does any one know if the fcc might frown on this aplication. I do have community support through business and the local school.
please send any comments to
[email protected]
thanks Brian
Brian:
This sounds fascinating. Let us know how it progresses.
Regards,
Scott
http://robinvalley.org/
The FCC will probably frown on the water tower transmitter site because of the distance of the ground conductor run to earth. Also, you should have the most "direct" route for the transmitter ground conductor to terra firma (without actually using the water tower).
Usually 50 feet ABOVE (or less) earth is ok with a very direct route for the 10-12 awg ground conductor. If you stay close to this you should be in the ballpark of acceptablility.
Remember, you are trying to increase "groundwave" not "skywave" radiation. Also, think seriously about adding a professional audio processor like the Inovonics 222. Just explain the importance of remaining legal to your supporters and find out if they will help with the additional expense.
Marshall Johnson, Sr.
Rhema Radio - The Word In Worship
http://www.rhemaradio.org
The FCC will probably frown on the water tower transmitter site because of the distance of the ground conductor run to earth. Also, you should have the most "direct" route for the transmitter ground conductor to terra firma (without actually using the water tower).
To clarify, a "ground conductor" from a Part 15 AM tx running down to an earth connection, but insulated from the water tower will still radiate -- in effect making the Part 15 antenna system much longer than 3 meters.
Remember, you are trying to increase "groundwave" not "skywave" radiation.
Another clarification: antenna engineering principles show that for increasing vertical radiator lengths up to 180 electrical degrees (including the ground lead + ground wire in this case), relative field radiated in the groundwave will increase, and in the skywave will decrease.
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Rich is right on target in theory and interpretation of the rules. In practice however, the FCC has allowed (after inspection) the exact wording and scenario I have outlined previously. I won't get into another engineering theory debate, because there is nothing to debate. Just as in other radio services governed by the FCC, there are the rules and regulations and then there is the day to day practice of what works and what is allowed. The final determination on the question you ask lies with the FCC District Engineer in your area. Make some drawings of your proposal, send it to him in a letter and see what he says. He is the individual you have to ultimately please. My District Engineer allows exactly what I offered previously, regardless of the interpretation of the rules or engineering theory.
Marshall Johnson, Sr.
Rhema Radio - The Word In Worship
http://www.rhemaradio.org
Quick Question..
Taking the above information into consideration, What's more important to focus on..
Sky Waves vs Ground Waves?
What gives the best "Bang" for the Milliwatt?
Radiation most useful for daytime coverage in the medium-wave broadcast band lies in the horizontal plane, along the surface of the earth. Daytime radiation at angles of more than a few degrees above the horizontal plane never reaches a ground-based receiver, in most installations.
The elevated mounting of a Part 15 AM tx with its 3-meter antenna above it, and a long conducting path from the tx chassis to something buried in the earth does not create more skywave. Nor does this system behave like FM broadcast, which for good performance needs a clear line of sight between the tx and rx antennas.
Because of the longer effective length of the vertical radiator when the tx is elevated above the earth (which includes that conducting path from the chassis to the earth), the relative field of an elevated Part 15 AM system increases in the horizontal plane, and decreases at higher angles. But the differences are small in these situations.
The real reason that elevated, 100 mW Part 15 AM txs have better coverage than when mounted just above the ground is because the greater total length of the 3-meter antenna plus the conductor from tx to earth can radiate more of the rated power output of the transmitter, when the tx is elevated.
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If a ground plane was constructed with 120 radials at 1/4 wavelength with the xmtr/ant. mounted at ground level, Would the horizontal pattern be increased?
Thinking on a Part-15 set up..
Anything that reduces losses in the ground system will increase the Part 15 AM radiated field in all directions except toward the zenith -- not just in the horizontal plane.
The radial system you described has very low ground losses, similar to those of a licensed AM broadcast station.
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