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Propagation, Isotron Antenna
As a new non technical member of the Forum here are two topics for the tech people that I haven’t found discussed in the Threads and for which I’d like some insight. First, part 15 and propagation. I notice that on cloudy humid days my signal is stronger than on clear dry days. Also, night propagation and part 15. The big fellows ride the skywaves, some for thousands of miles, yet at 100mw and 3 meter antennas what happens to our skywaves, and at night what happens to our ground waves. Is part 15 night time broadcasting worth it? Second, the Isotron. I haven’t a clue about the subject of antenna gain and if it’s applicable to AM broadcasting. Does the Isotron antenna have any advantage over the Magum or its SSTRAN incarnation? Go to http://www.pcs-electronics.com, click on AM transmitters, scroll down to the 10 watt model and just below that is an Isotron which the manufacturer claims legitimate for part 15 regulations in that it’s under 3 meters, although it has all of those radiating surfaces. If it is worthwhile for part 15 are there any plans out there to build one? Thanks JimB
Total posts : 45366Welcome to Part 15.
I’ll answer one question if “Nighttime Broadcasting is worth it?”
Yes and No. It will pay to find a place on the dial that is quiet all the time. Once you find that, your in business. Good luck. Most of the time you’ll hear a very weak station. When your transmitter is on, the weak station will cause your range to be reduced somewhat. If your using a channel with a 50,000 watt blowtorch 800 miles away, It would eat you alive and you would be in violation of FCC rules. If the channel was 100% clear, your station’s skywave could carry all over the globe, though your ground wave would have little improved range gain.
If you want to go 24 hours, I’d put my Best on in the Mornings, Afternoon and Evenings. I would put stuff that was less popular on after 9PM and before 7AM and for Part 15, after 10 AM and 2PM. This is to keep reception complants down.
I go 24/7 on AM 980, and have had little problems with other stations on the same channel. I place Talk overnights, and Old Time Radio and Music on the Daytime Schedule. Another good night program would be your local NOAA Weather Radio station. That’s info you can use anytime.
Study the Channel for a week or so. Make sure it’s clear, away from local stations as much as possible and conduct tests as much as you can. Do test programming or run Music while you make adjustments and find out how far you reach. If, for some reason you can’t use the channel, you can move it without problem. Once you are sure of everything, you can launch the station knowing you did it right.
This info applys to AM olny. FM will not carry around the world, and would be good for 24 hour broadcast. But the FCC is more strict on FM and you will have to be more careful about power and range. I’m still thinking of FM Part 15.
Mark Shannon
AM 980 WOQ/Omaha’s Independent Radio
Total posts : 45366Ummm, does the interferrence rule of the FCC kick in “harder” when DX is better than usual??? A dead channel isn’t necessarily dead when DX booms in. Some days are better propagationally than others.
FM DX does carry further during certain ionospheric events and tho it’s rare on the lower FM bands such as broadcast, sometimes one gets meteorite DX. More common on UHF, tho.
With the effects of recent solar activity, I’d give the study more than a week, too.
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