Scosche - BTFREQ Mini FM Transmitter - Black

@richardpowers  Twice I looked over the specs and did not see it's frequency range nor an FCC certification/

@carl-blare Dont know@, their website doesnt say either. I read some Amazon reviews and the general consensus is "Meh". They say the range is weak, the volume to low, and the rechargablr battery runs out to fast... other than that it works. What do you expect for under $20.

I've tried to get interested in Part 15 FM, but it doesn't give me the same jollies that Part 15 AM does, for a number of reasons. The field strength allowance is restrictively low plus, the way that signals on the much lower frequencies of the AM BC band propagate is more interesting to me.

For anyone here who does "broadcast" on Part 15 FM - why do you do it? I'm genuinely interested. If we were allowed 1 watt on specific channels, as is the case in NZ, I'd be all over it, but a field strength allowance that limits us to a maximum coverage of 200 feet radius is hard for me to get excited about.

Please be honest with me if you think I'm being a Debbie Downer, but I'm genuinely curious to know why people do Part 15 FM.

@rugster I agree with you, with no extended range liberties it tends to extinguish any hopes of getting out..

But keep in mind Radio Sausalito was originally a network of part 15 FM transmitters spread around the town.

Also remember what Commissioner Pie said to the church's a few years ago when they wanted a power increase for part 15 FM? He told them to just "use more part 15 FM  transmitters"..

So, though I agree with your "why bother" with part 15 FM" attitude, a part 15 FM station network is certainly feasible and has been accomplished before.

But with that said, the above transmitter would not be a good option

@rugster  As far as 'broadcasting' is concerned, I agree with you, Rugster, but I enjoy the equipment and th fact that I can use air instead of wires to move Signals around. One example is my C.Crane FM3 Transmitter at 87.5 MHz which is only 4-feet from my Sangean ATS 505 Radio which is used for 'inside purposes', including audio editing, YouTube audio and movie soundtracks. And a C.Crane FM1 Transmitter simulcasts the main daily schedule of KDX, my station also heard on AM 1680 from a Procaster Transmitter. Most of the day I monitor the AM station but the FM signal is there when I want extra high fidelity.

It means very little to me whether anyone in the neighborhood tunes into any of what I do. I am only doing it as an act of 'self entertainment'.

At the same time it is entertaining to fantasize that an unknown undetectable stranger is enjoying my signals. I suppose that psychologically this is a form of invisible anonymous exhibitionism.

Great comments gentlemen and @richpowers - you do have a point that in certain cases, a network of Part 15 FM transmitters could provide meaningful coverage. For instance, a large apartment building, or even a small micro-neighborhood, could be covered with a network of transmitters.

@carl-blare - I can certainly relate to the appeal of using "air instead of wires to move signals around." The concept of "invisible anonymous exhibitionism" struck a chord within me. I think you've hit on something!

I may have to rethink my stance on Part 15 FM. I do have an EDM FM transmitter. With the power dialed down to the minimum setting of 1mW, and running into a purposely inefficient antenna, I can stay within the FCC guidelines. Now, I just have to think how to distribute the same audio signal to two transmitters. A splitter cable, or a distribution amplifier? Hmmm......another thing to ponder.

Thank you for your thoughtful replies!

Posted by: @carl-blare

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@rugster  ...  And a C.Crane FM1 Transmitter simulcasts the main daily schedule of KDX, my station also heard on AM 1680 from a Procaster Transmitter. ...

I didn't realize you used a C. Crane to feed your audio to the Procaster. What made you decide to use that method? You had to run power lines out to your transmitter anyway, why not the audo feeds too?

Not that a wireless feed is a bad idea, but it's doesnuse additional power and adds another thing that could go wrong in the chain.

Back in the 1940s and 50s College campus stations often -or rather for certain programs - would use some FM stations as an audio feed to their AM transmitters.. but that was because most people did not have FM receivers. They were too expensive and more complicated for a diy build... But obvisously that's not the situation here .

Posted by: @richpowers

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I didn't realize you used a C. Crane to feed your audio to the Procaster.

I don't think he's saying that Rich.

@rugster I am in Canada. We have considerably more field strength than FCC.
You can cover a small neighbourhood with a good receiver. Also we have two categories of unlicensed broadcasting BETS-1 which allows broadcasting to the general public and RSS-210 which doesn't. The Procaster made in and certified for Canada is certified RSS-210 and therefore not for broadcasting to the general public, e.g. neighbourhood station. The Decade MS-100 is BETS and can be used for a broadcasting "undertaking". You can advertise you are there.
AM has it's disadvantages. Yes you may go much farther and some claim miles but that is outside to a car radio, mostly fringe, not inside buildings or houses and add all the noise drowning it out on top of that. I never hear of anyone getting miles range and getting listeners. What good is all that distance you can achieve with a very elaborate set up needing your own property to do it if you are broadcasting to the trees.  Also, Carl has been wanting to figure out how to not loose all your range at night. With FM the range doesn't change day or night. FM also isn't obstructed like AM and wiped out by noise in buildings and houses. Also any home that has metal siding of any kind kills all AM reception but FM gets through. Also buildings with steel grid structure blocks AM getting in or out.
The Canadian rules are explained in the "about us" section as written by Artisan, and at the top of rules in other countries. It's a good summary.
Personally I want listeners and AM is a hard sell.
I know all these forums are USA based on the FCC but the FCC isn't the whole universe. No, Canada isn't like New Zealand but it's better than FCC.

AM......Not easy to get listeners when they turn on AM and hear this. AM was never like this growing up in the 60s and 70s.

@mark - I knew that the Canadian regulations regarding the FM band were a little more tolerant than the US ones, but I didn't realize by how much. I just checked the BETS regulations and am quite envious! 250µV/m at 30 meters is significantly more generous than 250µV/m at just 3 meters, given how field strength drops off in proportion to the square of the distance. It seems to be generally accepted that adherence to the US regulations results in coverage in open air, of 75-200 feet radius, with 200 feet an absolute maximum. I'm wondering how much of a coverage radius can be achieved in Canada? That sounds quite encouraging. If I lived in Canada (I did have the opportunity to do so once) I'd be a lot more enthusiastic about unlicensed legal broadcasting on the FM band than I currently am.

Agreed re: your comments being that the FCC isn't the whole universe. I imagine it's a bit frustrating/annoying at times being in forums that are US-centric. It's just seems to be a fact that there are so many of us Americans and simply by virtue of sheer numbers, we tend to dominate the narrative in a lot of online spaces. If it's any help, I am British, having grown up in the UK 🙂 On the downside, I have almost completely assimilated as an American, for which I can only apologize 😀 

@rugster You don't need to apologize. Our FM field strength is 100uV/m@30 meters, 250 uV/m@30meters is for AM(BETS-1).  But 100uV/m @ 30 meters is still considerately better than FCC.
RSS-210, not for broadcasting to the general public is the same for AM and FM as FCC.

@richardpowers  Rugster is right, I did not say that I was using a C.Crane FM Transmitter as an STL to feed the Procaster. The C.Crane FM1 is 'On the Air' for my own choice of hearing KDX on FM or AM. However, I do have a wireless means of providing audio to the Procaster. A TP-Wireless TP-WT02 Transmitter/Receiver sends the audio on the 2.4GHz Wi-Fi Band (not Bluetooth) on 2477.775 GHz. (just above Wi-Fi Channel 11).

@rugster  I also have an EDM FM Transmitter and think it's a wonderful device. For now, however, it is out-of-service with a blown final RF amp transistor caused by static discharge from lightning.

Thank you for the correction @mark.

@carl-blare - how do you distribute the same audio signal to both transmitters? Do you have a simple splitter cable, or something a bit more elaborate? I'm sorry to hear about your EDM transmitter. I'm on my way out the door in a few minutes, but now you have me wondering whether the final is an easy replacement, and what transistor is being used. I'll open mine up this evening and have a look.

I think that EDM is no longer in business