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Thread: What FM transmitters are being used?

  1. #21
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    Default Re: What FM transmitters are being used?

    Quote Originally Posted by Penfold View Post
    My .2 watt transmitter auction was closed down so I now have a 1watt transmitter coming my way. I know that it is illegal to broadcast more then 400ft (I believe it is that far). How could I get this transmitter running at a reduced broadcast range so I don't get the feds coming after me?

    Should I just put this transmitter back on ebay and get a belkin?
    Actually, it works out to about a maximum of 200 ft (radius). That was the old spec.
    Part 15 devices are now judged by received signal strength, but as few have field strength meters handy, the 200 ft rule will still work.
    Clearly the 1 watt units are way over the legal limit, and will easily broadcast a signal for several miles assuming a reasonably decent antenna, and no commercial stations on frequency.
    One class of low power licensed FM stations use 1 watt. Unfortunately licenses for such low power stations can not be obtained by individuals, which eliminates this as an option...
    Caveat emptor....
    Greg
    [URL="http://www.youngschristmas.com"]www.youngschristmas.com[/URL]

  2. #22
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    Default Re: What FM transmitters are being used?

    I've been using an FM-25B for two years with no problem (standard whip antenna.)

    This year I'm building an FM-100B (I just ordered it last week. ) The extra power and the microphone will be welcome additions.
    Thanks,
    Chuck

  3. #23
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    Default Re: What FM transmitters are being used?

    Would the use of attenuators bring down my broadcast range to around 200ft? If not then I think I will be better off putting this reciever up for sale and trying to get the 0.2watt transmitter.

  4. #24
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    Default Re: What FM transmitters are being used?

    I think an issue that some people may have with the eBay transmitter or the Ramsey is that they are not designed exceedingly well. The signal to noise ratio goes out acceptable capabilities of a FM receiver quickly (at least IMO....i'm not libel'ing here).

    Just as a precaution, I would recommend that anybody who is getting a transmitter over 10 mW is to at least go out and buy a signal strength meter that operates in the FM radio band. Keep attenuating the signal until you are within specs. If you no longer can hear the music clearly, that means you need a better transmitter with a higher SNR.

    Again...I'll keep people posted on the one I got from South Africa. If this does work out (i.e. about 200 feet with good SNR), this might be the ticket to keep people within FCC regulations.

    I don't like being a downer....but something about violating federal law does rub me the wrong way.
    Sincerely,
    Andrew Specht

    NOTE: No electrons were harmed during the creation of this thread. All threads are made with 100% recycled electrons. No electrons were discriminated against based upon race, age, religion, or direction of spin. The views in this thread may or may not reflect the views of DIYC or the views outside my window.

  5. #25
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    Default Re: What FM transmitters are being used?

    I hear that the reviews and tests on these FM transmitters from this particular vendor indicate that these units already have pretty bad "spurs" (out of band emmissions) at almost as much power as is being transmitted on the intended frequency when terminated correctly.
    How could i go about reducing or eliminating these unwanted spurs.

  6. #26
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    Default Re: What FM transmitters are being used?

    Quote Originally Posted by Penfold View Post
    I hear that the reviews and tests on these FM transmitters from this particular vendor indicate that these units already have pretty bad "spurs" (out of band emmissions) at almost as much power as is being transmitted on the intended frequency when terminated correctly.
    How could i go about reducing or eliminating these unwanted spurs.
    Put it back on eBay. You have to realize that the way AM/FM is, is because they wanted to make the receiver as dirt cheap as possible while putting all the cost into the transmitter. The transmitter, honestly, need to be very tightly tuned and controlled (especially in FM).

    The reason why the Ramsey is so expensive is because they have gone through the effort to make sure their design is within FCC regulations.
    Sincerely,
    Andrew Specht

    NOTE: No electrons were harmed during the creation of this thread. All threads are made with 100% recycled electrons. No electrons were discriminated against based upon race, age, religion, or direction of spin. The views in this thread may or may not reflect the views of DIYC or the views outside my window.

  7. #27
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    Default Re: What FM transmitters are being used?

    I found a site where the Ramsey transmitter is about $45 bucks cheaper for the FM25B and FM30B. Check it out.

    http://www.hobbytron.com/LowPowerFMTransmitters.html

  8. #28
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    Default Re: What FM transmitters are being used?

    Quote Originally Posted by Greg Young View Post
    Actually, it works out to about a maximum of 200 ft (radius). That was the old spec.
    Part 15 devices are now judged by received signal strength, but as few have field strength meters handy, the 200 ft rule will still work.
    Clearly the 1 watt units are way over the legal limit, and will easily broadcast a signal for several miles assuming a reasonably decent antenna, and no commercial stations on frequency.
    One class of low power licensed FM stations use 1 watt. Unfortunately licenses for such low power stations can not be obtained by individuals, which eliminates this as an option...
    Caveat emptor....
    Greg
    Hmmm.... Looks like I'll have to incorporate and file for station 'KDIYC' just to get my signal to the street.

    Quote Originally Posted by Trepidati0n View Post
    The reason why the Ramsey is so expensive is because they have gone through the effort to make sure their design is within FCC regulations.
    The stuff I've seen on the Ramsey advertises 1/8 mile transmit range. So which is it? 200 ft or 660 ft?
    Bob
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  9. #29
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    Default Re: What FM transmitters are being used?

    As far as I know the Feds only allow you a broadcast range of 200FT.

  10. #30
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    Default Re: What FM transmitters are being used?

    Quote Originally Posted by rlilly View Post
    Hmmm.... Looks like I'll have to incorporate and file for station 'KDIYC' just to get my signal to the street.



    The stuff I've seen on the Ramsey advertises 1/8 mile transmit range. So which is it? 200 ft or 660 ft?
    It isn't really feet but a "power @ distance" statement. It is still possible to clobber a radio station @ 2 miles if you are putting out a clean enough signal and the competing station is a 100 miles away trying to be received by somebody with a high gain antenna.

    http://www.ramseyelectronics.com/res...t.asp?page=fcc

    This explains it pretty clearly.
    Sincerely,
    Andrew Specht

    NOTE: No electrons were harmed during the creation of this thread. All threads are made with 100% recycled electrons. No electrons were discriminated against based upon race, age, religion, or direction of spin. The views in this thread may or may not reflect the views of DIYC or the views outside my window.

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