Persistent or Foolish?

I failed to mention I am talking about achieving 1-3 miles via a Part 15 FM transmitter, sorry. I would not say money is no object but I do not mind spending 1,000 or less if that is even possible on a transmitter and antenna setup that would help me achieve what I am looking for. I realize AM is probably more realistic but if at all possible FM is preferred.

Is 3 miles legally totally out of the question?

Just to note that FCC Part 15 does not restrict the coverage radius of any unlicensed transmit system operating in the AM or FM broadcast bands.

But unfortunately, such single setups functionally complying with Part 15 Rules would be unlikely to provide a useful signal to typical consumer-level receivers at that distance.

However this does not mean that compliant, unlicensed operators are prohibited from providing useful signals to typical receivers within the coverage areas of an unlicensed system functionally compliant with Part 15 -- which for FCC 15.219 in the AM band is closer to a radius of 1/2 mile, and for 15.239 is much less for FM.

Sorry if some may take this information as being "anti Part 15" when in fact it is not, and might even save some operators from FCC attention.

I am currently running a part 15 FM station on 101.5 using a legal transmitter (Music Gear BIG-FMT) and I'm barely able to squeeze out 500 feet on a car radio. I hate to burst your bubble, but I haven't heard of anyone getting 3 miles out of FM legally. I have seen other sites where people have gotten 1 mile or so out of FM, BUT they were using illegal, uncertified equipment that uses powers way over the FCC limit for part 15 FM.

I know AM isn't as good as FM in terms of sound quality, but with some effort, it might be possible to squeeze 3 miles out of a legal AM setup. The only problem is the third mile will be a fringe area, where the signal comes and goes.

I've heard of stations getting as much as 6 miles with a procaster AM transmitter. BUT, those stations are using illegal 60 foot ground wires and towers.

I hope my advice has helped.

Scott,

The only answer I can think of to your question about part 15 range is "It depends". Sorry that this answer isn't more satisfying. The major limit to range on AM is at the receiving end. Ultimately the signal to noise ratio determines reception quality. The signal gets weakened going the distance and through walls and poor receiving aerials and the noise increases with all the electrical noise now present in most environments.

Case in point, a few years ago while I was scanning the X band for a suitable operating frequency I came across a "Talking House" type real estate announcement and from the address given I determined it was 2.8 air miles from my home. I did a drive by and saw nothing so I can't attest to the transmitting equipment but can only assume it was a legal part 15 setup. The reason I was able to hear it 2.8 miles away (and about 1 mile away in my truck) is because at my house I have a dipole antenna installed in the woods behind and away from my house which gives a good receiving site with little man made noise. This, plus using a communications grade receiver, gives a high enough signal to noise ratio to yield decent reception. So, it does depend as illustrated by my anecdote.

If you saw my posted report of my field test of a ground mounted loaded radiator with radials with a part 15 compliant AM transmitter of 100 mW input you will note that the range observed while driving around was at least a mile. Being short on time I never did get to the fringe to tell how far it was going. If time permits I will try it again but I can state from this experience that 1 mile range for a listenable signal on a car radio is possible on AM.

Neil

But I did find your reply informative! If you get a chance to revisit your experiment, I would love to hear about your results!

-Scott H.

Thanks everyone, your advice was very helpful. I will keep everyone informed as my equipment comes in the mail and some of my results. I am fairly new to radio broadcasting and accidentally fell into something I now love. Brief background: I started on a station in Charlotte, NC 103.3 FM terrestrial radio. It is a former AM station that turned FM when the FCC passed some law a few years back. They charged me 1,000 per month for a 1 hour show/ once a week. What originally seemed like a good idea I later felt was a scam and unfair rip off out of spite I venture doff to start my own terrestrial station and was met with the FCC indefinite denial of new applications being accepted. I then decided on starting a internet radio station and ran is professionally. I average about 40-50 listeners (Hip Hop, R&B) and gained a few sponsors but I could never take it to the next level. I googled options and came across Part 15. I think this is a great start and a combination of internet radio and at least some option on the FM dial I think can be successful. Wish me luck in socking it to "the man". I will keep everyone posted.

I was intending to address the OP in my salutation and apparently didn't scroll up far enough to get the correct name.

Ooops!

Neil

The only reason I mentioned it was with my being new here, I didn't want anyone thinking I hijacked the thread.

I honestly am interested in your antenna experiment results if you get a chance to revisit it. I’m trying to learn everything I can before I start working on my own system.

-Scott H.

Scott has been talking about the Whole House FM tx, not the Talking House AM tx. Not the same thing...

Part 15 FM is restricted by field strength alone. It's just physics ... regardless of antenna or height, there simply is no legal way to get any 'miles' of listenable range from a Part 15 FM station, even with a good car radio, or hi-end FM receiver.

AM broadcast band is much different. This is why it is always the choice for range, even though it's monophonic (except for C-QUAM stereo units ... however, I've never met anyone with a C-QUAM stereo receiver, no one in my area has one).

"except for C-QUAM stereo units ... however, I've never met anyone with a C-QUAM stereo receiver, no one in my area has one"

meduci PRO 1K

Darn good one too. 🙂

RFB

Just trying to clear up Who's Who... 🙂

I'm not even up to the point of thinking about broadcasting.

-Scott H.

To those that have come on here
asking questions.

You have nothing to worry about.

Everything you are doing is what
we did, too. It's just that we
explored all of these questions
before you did, that's all. And
we don't have ALL of the answers
either, but some of the guys on
here do have a tremendous amount
of knowledge.

The fact that you are interested
is good for all of us. And Part 15
can be an "on again, off again" kind
of thing. It's not the easiest thing
in the world. I have stopped and
started my station many many times.

But every time, it got a little bit
better.

Best Wishes,
Bruce, DRS2

Well Said Micro !!!

To sum it up, in some circumstances, with special antennas and receiving equipment, you might be able to get that 3 miles range on Part 15 AM.

Typically, with no or few obstructions, you can expect to get less than 2 miles with an ideal, legal setup and a sensitive car radio at the receiving end. For consumer type radios, much less.

But even then, that range comes at a cost. Part 15 AM signals tend to get rather noisy the further you get from your antenna. How much noise is acceptable to your listeners will also factor in determining your USEABLE range. And that's totally subjective.

All you can do is test it out in your locale, complete with obstructions, the quality of the available ground, etc.