FM Transmitter

Discussion in 'Tuners' started by musichal, Jun 18, 2018.

  1. musichal

    musichal poet emeritus Subscriber

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    Inserted between antenna and transmitter, I guess?

    I see it attenuates from 15w to 1.5w. Does it then attenuate 1.9w to 0.19w? The transmitter offers output adjustment in 1.9 increments. 3.8 becomes 0.38? 5.7, 0.57? & etc?

    If so, that could be a very helpful circuit to dial in just the right low-power setting needed.
     

     

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  2. I LIKE MUSIC

    I LIKE MUSIC Super Member

    Yes, that is correct.

    Yes, that is correct.

    And you can built the attenuator for more attenuation (less power to the antenna) if you so desire.
     
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  3. Bob@FM

    Bob@FM Active Member

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    here's the web page for that power calculator
    https://a29.veron.nl/hams/pa1b/pa1b-power-attenuator-calculator/

    Note one thing that most of us know about resistor power ratings -
    As previous, also be careful to NOT use typical cement type or wire wound resistors, who have significant inductance at RF frequencies. Carbon or specifically "non-inductive" resistors are OK.
     
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  4. musichal

    musichal poet emeritus Subscriber

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    Be danged if the transmitter didn't just show up on the doorstep. I'll be trying it out again later, and let you know how it goes... maybe ask some questions. So the stage is set for Round 2.
     
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  5. Bill Ferris

    Bill Ferris Super Member

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    :thumbsup:
     
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  6. RickB

    RickB On the Road to Find Out

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    :lurk:

    .
     
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  7. I LIKE MUSIC

    I LIKE MUSIC Super Member

    Musichal, you might be interested in the article linked in this thread.

    From the article.

    Ajit Pai chairman of the F.C.C., promised to “take aggressive action” to stamp out pirates. In early May, the Preventing Illegal Radio Abuse Through Enforcement, or PIRATE, Act was introduced in Congress; it would increase fines from a maximum of a hundred and forty-four thousand dollars to two million dollars.

    It is interesting that this bill would give state and local governments the ability to impose civil and criminal penalties, although the FCC would be the last word in determining piracy.


    We will be passing the hat for you.:eek::D
     
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  8. dewdude

    dewdude I fix stuff.

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    So let me say this....regardless of how much you attenuate the output and comply with the field level for Part 15.....that transmitter is illegal.

    In a finished form...the device MUST be certified for Part 15 compliance. That will NEVER happen with this device due to the fact it has an antenna jack and external antenna. For that reason alone....any certification it has is likely counterfeit and it would never get certified.

    This is why you'll see "kits" for transmitters more than you'll see a ready to go product. You don't need certification to legally sell it...that would be up to the builder to ensure compliance. But if you sell "part 15" transmitters without full certification you're breaking the law.

    Now the confusing thing. ItsI not illegal to posess this thing...mere poesssion is ok. That's why these things are kind of a grey area. From the seller's aspect I'm not 100% sure what the rules are. With the FCC it's a lot about literal marketing. Market it as a low power transmitter itsi fine...sell it to normal people as a legal device and they have problems.

    So what's the danger in using this? Technically it's a violation of federal law. Don't forget FCC regulations are part of US Code. But the FCC is mostly enforcement...and like on an empty desert road...if there's no one to enforce how will anyone know. They don't go looking like some think...they mostly act on complaints. Most of the pirates spoken about in the previous post are the people putting serious power on the FM band...operating as an unlicensed wide coverage station...and usually wind up interfering with a license holder. It's from complaints they take action...and it's a difficult process.

    If they were to send you a NOV (notice of violation) over it....they usually give you a chance to rectify the problem before they start additional proceedings.

    I still wouldnt have such a thing in my house.
     
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  9. musichal

    musichal poet emeritus Subscriber

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    Call me an anarchist. But I'm not. However, there are several laws that I don't agree with, and think are past due needing changed but I'll not stray into politics here. Fact is, I don't give a damn that the device is illegal - or rather, can be used illegally. My intended use is not apt to result in any complaints, but if I did receive such a notification, I certainly would change what I was doing. My target piracy realm is a very limited one. If this new one sounds no better than the previous, I won't be using it at all. Technically (your modifier), how many laws per day does an average fellow break, I wonder?
     
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  10. dewdude

    dewdude I fix stuff.

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    "In Jersey anything is legal as long as you don't get caught."

    Same is true for a lot of stuff.

    Me 4 years ago would have been all "screw it! let's go till we get caught". These days...due to the fact I have FCC issued radio licenses...I put more on the line. They show no mercy to a licensed individual caught doing pirate activities.
     
  11. Retrovert

    Retrovert AK Subscriber Subscriber

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    Hmmm. You ever live in Jersey? Because only someone in Jersey could truly appreciate that logic. (NB: I grew up in NJ, but was eventually deemed ready to rejoin society and allowed to emmigrate.)

    The FCC, furthermore, has a policy that anyone found responsible for operating an illegal transmitter cannot obtain an amateur radio license.

    Hams can triangulate an illegal transmitter faster than you can say "Radio Direction Finding".
     
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  12. evsentry3

    evsentry3 Well-Known Member

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    It's fun when somebody in my area gets one of those transmitters. Takes minutes to find them and report it.

    These days, there is so many low power and translator stations crowding the band that there really is no place on the dial that an illegal isn't stepping on somebody's toes. And often several toes. I can't imagine in more congested areas how stacked up it's getting. And here is the bad thing...receivers that can separate out the signals are getting fewer and fewer. And yet we have more and more signals being jammed in. That's why these "I didn't mean to cause anybody any harm" signals are such a problem. Why would those that enjoy the listening want to cause further harm?

    It's also easy to tell when it's one of those really junky units as not only is the spectrum it transmits is bad, but as experience already in this thread, the audio of generally pretty bad too. When you try to condense a whole big boxed expensive unit down to a single chip, something...a lot actually...has to give.

    EV3
     
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  13. musichal

    musichal poet emeritus Subscriber

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    Fun, huh?

    That's a thread-killer.
     
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  14. barefootbrew

    barefootbrew AK Subscriber Subscriber

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    That's a bummer.....
     
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  15. Harvestor

    Harvestor Super Member

    Movie:
    Pump up the volume
    With Christian Slater

    If you have a message that just must get out past all the censorship like "THE CHAIR IS AGAINST THE WALL ------JOHN HAS A LONG MUSTACHE----" to Quote another movie
    ..
    Then keep moving like Mr Slater
     
  16. audiotemp

    audiotemp Well-Known Member

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    The sound quality of even a single-chip FM transmitter can be quite decent. At least some of the little devices that are (or, at this point perhaps, were) sold to play a portable music player through a car FM radio have SQ that is quite acceptible...as long as they are not over-modulated.
     
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  17. dewdude

    dewdude I fix stuff.

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    Thankfully no. "But I did spend a week there one afternoon."

    I was actually quoting Bob Dylan from The Traveling Wilburys.

    Joke's on you. A lot of hams don't know how to direction find... nor do they have an FM yagi available. They'd have to make one.

    You'd also have to be causing them direct harm for them to even care most of the time. "Oh..the guy next door is running an illegal transmitter? Well it hasn't QRMd me so I didn't know."
     
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  18. Retrovert

    Retrovert AK Subscriber Subscriber

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    My point was that direction finding is easily done by amateurs, and the FCC has ample ability to find such transmitters, as do the locals. I live in a major metropolitan area where such transmitters are readily found.

    I can't speak for the hams under forty, but the ones I know over forty can certainly direction find with ease. An FM yagi takes about an hour to make, including the trip to the hardware store for the tubing and the fiberglass rod.

    Relying on the incompetence of law enforcement only gets one so far. Assuming anyone in a position of authority actually cares, the amount of resource which can be brought to bear is prodigious.
     
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  19. hjames

    hjames dancing madly backwards ... Staff Member Moderator Subscriber

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    Seems an awkward argument at best.
    In College in the 70s, I worked with a campus radio station that used Carrier Current to transmit on campus. 25 watt transmitters tied to the building wiring, used the power wires in the wall as very localized antenna. Generally, you could hear it in Campus buildings but the signal dropped fast as you got any distance outside the walls. One weekend, for grins, we took one of the 25 watt transmitters to the roof of the student union building and terminated it into a light bulb. We got calls from the nearby Army base that they loved our music (typical rock/prog faire) ... We pulled the bulb REAL FAST - even tho the nearest FCC office was a state away in Atlanta GA, it was nothing to fool around with.
    And that was the 70s - so much easier to track stray signals in this day and age!

    Suggest you stop discussing Pirate radio as any kind of possibility.
     
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  20. dewdude

    dewdude I fix stuff.

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    I know...part of my comment about hams was meant as a joke. Most of the guys I know...who are well over 40...could make a FM yagi for direction finding with just the junk they've got lying around. But, at least where I live; pirate FM transmitters aren't an issue. We actually have a larger issue with pirate HT operators. I realize it's a huge issue in large metro areas.

    Carrier current is fun. You probably had an advantage of a less crowded AM band back then. I swear I could pick up the 66 watt nighttime signal from WKCW in Warrenton if it wasn't for all the other 1420khz signals skywaving in.

    Most of direction finding is still the old-fashioned "point a yagi till it gets loud"; the only thing that's really helped is GPS plotting and being able to zap that information among people on smartphones. The auto direction-finding systems that use doppler analysis from an antenna array help, but to really pinpoint it you still have to get out and take an azimuth from various points.
     
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