FM Transmitter

Well that’s kinda cool! What’s the plan? Sometimes plans hatched in the wee hours can be pretty brilliant (or not).
 
Nice! Some interesting comments regarding FCC compliance at the link. I think I'll get one and broadcast polka music* at the same freq as Red Sox games, my neighbors will like that :)

*Substitute suitable irritant if polka music is your thang.
 
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Atta boy! Stick it to The Man! Wish I was in range.

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Been running a transmitter for years. Only about 10mW, but I end up streaming to it and listening most of the time on tuners. Also comes in handy when A/B'ing two different tuners. Been looking at more power and moving to the second floor to get better coverage.
 
Some years ago I used my Sound Tech 1000a and 1200 to transmit music while I mowed the lawn to Awia am/fm headphones, today AirPods. It is amazing how uncompressed FM can sound.
 
Not unless you have a FCC license for a translator station, LPFM (FCC Type Certified) or higher, and you have the technical skillset, the money. and want to get a real FM station legally (including paying ASCAP/BMI/SESAC royalties at minimum) and you needed to do so 3 or more years ago. Streaming is cheaper. easier (though you have to pay SoundExchange for the performance royalties to do so).
 
When I was a teenager I bought a small kit that transmitted on fm with 1 watt of power. My friend a few houses down could pick it up on his dads receiver. I'm thinking pirate radio with that little gem you bought. 15 watts just a bit of potential there.
 
Some general information.

The FCC is somewhat sporadic in their enforcement. Last November they went after 10 unlicensed stations that exceeded the signal strength limit of 250 microvolts per meter at 3 meters. One was only about 100 microvolts over the legal limit.

15 watts of RF power at 50 Ohms is almost 30 volts of signal, a fair amount higher than the legal limit (measured in millionths of a volt).

The location of the transmitter relative to others that might want to receive a weaker station can play a part.

Not all of these imported transmitters (they are likely not FCC type accepted) have the cleanest RF output. If one is within a mile or two of an airport, it would not be a bad idea to use caution.

Radio Locator has a function to help one find possible empty frequencies, likely a good idea.


Some additional information. A top of my head calculation indicates that the above 15 watt transmitter at full power and the antenna on a ground plane in the open (on the roof a car for example)...

Will produce a field strength in the ball park of about 9 million microvolts (9 volts) per meter a 3 meters.

It might not be a bad idea to pay attention to the location of the transmitter antenna with respect to any of your receiving antennas.

Even with 15 feet of separation, the field strength could still be several million microvolts per meter. This much signal might not make some receivers happy.

It is not a bad idea to start at the lowest power level and increase the power level only if needed.
 
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Some general information.

The FCC is somewhat sporadic in their enforcement. Last November they went after 10 unlicensed stations that exceeded the signal strength limit of 250 microvolts per meter at 3 meters. One was only about 100 microvolts over the legal limit.

15 watts of RF power at 50 Ohms is almost 30 volts of signal, a fair amount higher than the legal limit (measured in millionths of a volt).

The location of the transmitter relative to others that might want to receive a weaker station can play a part.

Not all of these imported transmitters (they are likely not FCC type accepted) have the cleanest RF output. If one is within a mile or two of an airport, it would not be a bad idea to use caution.

Radio Locator has a function to help one find possible empty frequencies, likely a good idea.


Some additional information. A top of my head calculation indicates that the above 15 watt transmitter at full power and the antenna on a ground plane in the open (on the roof a car for example)...

Will produce a field strength in the ball park of about 9 million microvolts (9 volts) per meter a 3 meters.

It might not be a bad idea to pay attention to the location of the transmitter antenna with respect to any of your receiving antennas.

Even with 15 feet of separation, the field strength could still be several million microvolts per meter. This much signal might not make some receivers happy.

It is not a bad idea to start at the lowest power level and increase the power level only if needed.

Yes, I am aware of all those issues. Been reading about it for months. I intend to use it low, inside a brick home. And I've had a couple of FM locator type sites in my Favorites for years, and AM, too. So choosing a broadcast frequency is easy. I also understand that the FCC usually sends a desist letter first if they catch a stronger-than-legal signal. I have a couple neighbors who may try to tune in occasionally.

I've read about the pirates, and found it interesting. Some have get-away drills. They warn that getting caught is not a matter of if, but when. And they run. My getaway would be awfully slow.

"Grab him boys! He's headed your way with a walker with tennis balls on the legs! He's about twenty feet away from you around the corner, probably be there in about 7 or 8 minutes!" amid laughter.

As bad as my FM reception is in this house, I doubt I'll be bothering anyone. At lowest setting, signals probably won't leak out much better than they do in.
 
"Grab him boys! He's headed your way with a walker with tennis balls on the legs! He's about twenty feet away from you around the corner, probably be there in about 7 or 8 minutes!" amid laughter.

That would be me...

Only I have one of the walkers with 4 wheels and hand brakes...And a nice little basket on the front.

I understand. That is why I made the comments about the FCC as general comments for others that might read this thread.

The part about RF field strength is just a heads up that transmitters in this power range may overload some receivers if the antennas are somewhat close, such as even 15 to 25 feet. Again, just some general information.




How are you coming with your self supporting dipole?
 
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