I am looking for a low-profile AM antenna that can broadcast in the 500-1700 KHz range, has a 50 ohm connection, and can handle wattage up to 80 Watts ? Isotron is a great idea but it’s not practical for my area of useage. Anyone have any suggestions, I need one that uses a PL-259 connector and is about 6 feet or less in height.
80 watts?
So, you have some sort of special waiver FCC license to operate an 80 watt AM radio station?
I’d like to know more about that … how does one obtain such a license?
Only waiver I can think of
Ken would be experimental license. Which really isn’t a waiver but authorization to operate in a particular band with x amount of power. Usually one would apply for an experimental license to prove a concept or create a new type of radio service or equipment.
Here is what the fcc has to say: sorry i dont know why that posted twice and here is a good link to pdf.
https://apps.fcc.gov/oetcf/els/misc/elsweb.pdf
Be careful
Be careful.
The max power limit in the USA for unlicensed broadcasting on the AM band is 100 milliwatts (1/10th of a watt).
Is there an antenna that’s less than 10 feet in 1200 khz range ?
I need an antenna that is at or less than 10 feet because of space limitations in my area. I don’t intend to broadcast any higher than allowed by FCC guidelines but finding the antenna is the most important thing right now for me. The Isotron is more than 10 feet, I thought you could make a wire-dipole lead antenna like SW use to transmit ? Do they exist ?
Do wire-dipole antennas transmit in MW ?
I’m trying to find an antenna that can be low-profile and broadcast in 1200 khz ? The idea of 80 watts is not presently relative. Without the antenna I can’t broadcast any distance. I just want to reach my own neighborhood area. 1 mile max, not 80 miles for sure.
Low Power AM Antenna suggestions?
YCDB,
Your specifications are way off from any sort of practical antenna.
Covering the extremely wide frequency range of 500-1700 KHz with any antenna and expecting a 50 ohm impedance implies the antenna would have an elaborate integrated antenna tuner.
A 6 ft high antenna fed with 80 watts isn’t realistic. It would likely act more like a Tesla coil. There could be a corona discharge on the antenna due to the extremely high RF voltage at the output of the antenna tuner feeding the very low capacitance of the 6 ft antenna.
RE: Low Power AM Antenna suggestions?
I’m afraid I was being a bit facetious in my original response to YCDB’s query. The whole idea of building an 80 watt AM BCB station with any antenna at all would cause severe interference, and likely never get CP or license approval, even in experimental category.
Further, it did cross my mind that pumping that much into a 6′ antenna would be dangerous.
Several Cases All At Once
There have been several cases recently of people declaring high power levels, as if they didn’t understand where they where nor know any previous history.
It could be related to spring, or maybe a strange fallout effect.
It would be paranoid to suspect that an official agency was trying to stimulate pirate activity by luring a bold response, like, “High power is good civil disobedience.”
Dangerous voltage….
Ken, if the input impedance to a part 15 antenna theoretically is 1 Ohm with input current of 100 milliamps, what would the voltage be? Now raise the impedance at the end of the antenna (away from the feed point) to 2000 Ohms. What happens to the voltage present at the end of the antenna?
Now at 80 watts, what would the voltage potential be? Use Ohms law to calculate the proper values in this theoretical situation. Then, ask yourself the question, would this amount of voltage be dangerous. You bet your watt meter it would.
Besides being patently illegal for Part 15 use, an 80 watt transmitter (unless in the hands of of an educated operator) could be very dangerous to pets and kids who might get tangled in the wires.
And finally, RF energy burns from the inside out. A radio frequency (RF) energy burn is very painful because it damages so much tissue and nerve endings. Avoiding RF burns at any cost is always worth it, especially to those of us who have learned the lesson the hard way.
Maybe the whole post was just
Maybe the whole post was just an April fools joke
Local Area Fool
The April fool idea makes sense.
The 80-watt guy seemed to have certain facts, i.e., 50-ohms and isotrope antenna, but was other wise seemingly uninformed about power levels.
And where is this brave new station?
And what is the make of the 80-watt transmitter?
It’s in Georgia & not operating yet
My transmitter is a P.E.P. model, whatever that is. No, I haven’t got my experimental license but I’m already airing and have been for 2 1/2 years on 87.7 FM 100 mw and recently went to AM 1250 100 mw but this passive antenna isn’t doing anything with my signal. I want to try get try getting something that might put out a 1/2 mile radius from my base. SW dipole-wire antennas exist but I don’t know if any MW wire exist. What do you think I should try looking for oh wise one ?
More facetiousness
Hi Marshall,
Sorry, I should’ve put a smiley, I guess. Yeah, what, umm, assuming some inefficiencies, E= something around 1-1/2 million?
Talk about setting your hair on fire!!
Sometimes I wonder if Tesla’s free energy expriments, impact point miscalculated due to the Coriolis effect, really did cause the Tunguska crater in Russia 😉
Sometimes I wonder if Tesla’s
Sometimes I wonder if Tesla’s free energy expriments, impact point miscalculated due to the Coriolis effect, really did cause the Tunguska crater in Russia 😉
Ah Ken, you’re still listening to C2C too!
Zapping All Cars…
The early Public Safety Police band was just above the AM broadcast band in the 30’s. Cruisers had receivers only to hear broadcasts from the Police Station.
Two way radios came to be in the late 30’s-early 40’s. They would be using loaded whip antennas probably not much longer than 8 or 9 feet on a vehicle.
Wonder what kind of output power was available and if the exceptionally high voltage on the antenna was a problem. They must have been using at least 10 or 20 watts.
Old Mobile Radio Transmitters
Mram,
The older mobile police and mobile telephones used tubes in the receiver and transmitter sections. The B-plus voltage was produced from energy drawn from the 6 volt battery, through a mulitvibrator circuit, then a step-up transformer, a rectifier and finally to the output tube. B-plus plate voltage was from 80 to 110 volts; plate current 200 to 300 milliamps. Output was 20 to 35 watts AM. After being applied to the antenna, the terminal voltage at the end of the antenna could, under certain conditions, produce corona effect. the end of the antenna could definitely produce a burn. I have had old military and ham transmitters from that era and, yes, they can RF burn the crud out of you if you happen to come in contact with the business end of the antenna.
Surprise!
We had a Fire Truck obtained through a merger. The transceiver used tube finals at 60 watts. It was VHF, 1950/60 vintage.
The high voltage was obtained using a dynamotor, a motor/generator unit. It developed 600 volts DC at 200 mA.
Needless to say we were surprised when we found it.
What antenna is a good 1200 khz range transmitting type ?
What do you think I might look for Rich in a antenna that can broadcast in the 1200 khz range ? Isotron is more than 10 feet high and I don’t have the space for that.
I need something that can boost my antenna strength to 1 mile from my broadcaster. So far I can hear my signal down the street and that’s all.
Is this an automated
Is this an automated messaging system that spits out a new post every two mintes?
Antenna Suggestion
Unfortunately if we operate under the part 15 rules (15.219) we are not only limited by the laws of physics but also the laws of man regarding antenna options. One “tried and true” design which is considered by most to be effective is the 3 meter vertical radiator with a base loading coil and a ground radial system. This antenna can be constructed by most hobbyists. The length of the antenna, transmission line, and ground lead is restricted to 3 meters or less so it is a small antenna to begin with.
The antenna depends on a loading coil of the proper inductance for operation. Most designs published are for the high end of the AM band but with a larger inductor they can be tuned to 1200 kHz as you desire.
Click on the SSTRAN link in the left panel here and look for antenna construction plans. SSTRAN has provided a good guide which will give you an idea of what is needed and what to expect.
One not so good requirement for legal operation by default means that the transmitter be mounted at the base of the antenna. This is because the part 15 rules limit the total length of the antenna, transmission line, and ground lead to less than 3 meters so in effect no transmission line from an inside transmitter to an outside antenna can legally be used. Many of us enclose the transmitter in a weather proof box at the antenna base and run power and audio lines from the indoor studio to the outdoor transmitter.
This is my suggestion where you can begin to plan for a legal part 15 installation.
Neil
Yep, What Neil said …
Also, as far as Part 15 FM goes, the restriction is field strength. There is no legal way to get a Part 15 FM signal to go a mile in the U.S.
As far as 80 watts goes, or for that matter, even 100mw out on FM, that will generate an illegal signal.
The FCC certainly does create wavers in certain locations and situations, but for experimental radio licensing, you have to apply for and complete the application forms, just as you would for any other license. The requirements in those forms will take some time and experience to complete before they will issue a construction permit.
Further, if they determine you can’t operate in the band you want without causing interference to existing stations, they may assign a frequency outside that band.
My question was really is there an antenna that is low-profile ?
I’m not really going to air at 80 watts but I need something that can transmit that far out if I can get an experimental license. The bigger question is do you know if there is an antenna that is in the range of 1200 khz and is less than 10 feet is height (like a whip) ?
Dynamotors
I remember those from when I was a kid … they were popular among HAMs for mobile work. My friend’s dad, a double eagle, was a HAM and had one under the hood of his ’57 Ford.