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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Thu 08, 2018 10:18 pm 
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Will the OP and anyone else owning this type of FM transmitter please post what their field strength measurements are, as required by the FCC rules that were shown on the previous page?

From the current FCC website on unlicensed home transmitters, both AM and FM:

Penalties for Operation Without A Permit or License
The Commission considers unauthorized broadcast operation to be a serious matter. Presently, the maximum penalty for operating an unlicensed or "pirate" broadcast station (one which is not permitted under Part 15 or is not a Carrier Current Station or Campus Radio Station) is set at $10,000 for a single violation or a single day of operation, up to a total maximum amount of $75,000.

Adjustments may be made upwards or downwards depending on the circumstances involved. Equipment used for an unauthorized operation may also be confiscated. There are also criminal penalties (fine and/or imprisonment) for "willfully and knowingly" operating a radio station without a license. DON'T DO IT!


Would hate to see anyone get fined or criminally charged due to ignorance of the rules, they don't accept that as an excuse.

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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Fri 09, 2018 12:18 am 
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Joined: Feb Mon 13, 2017 10:46 pm
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Location: Atlanta GA
How would one go about measuring the field strength? Of course I am tuning to a section of the FM band that does not have any competing FM broadcasts.


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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Fri 09, 2018 12:41 am 
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Location: USA
For something like this, I think it's sufficient to use a portable FM radio to see how far the transmitter is reaching.

If the unit is made by a reputable source, there should be a label on the unit or in the packaging where the manufacturer certifies the unit complies with FCC Part 15 requirements.

In this instance, the product description on Amazon says "Transmission distance more than 300 meters (In the line of sight, field, open land)." If true, the unit is not in compliance with FCC rules. I think you can switch to the low power mode (0.1W) to reduce the transmission distance.

https://www.amazon.com/Signstek-Broadca ... dpSrc=srch

https://apps.fcc.gov/edocs_public/attac ... 7510A1.pdf

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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Fri 09, 2018 2:18 am 
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Location: Dallas, TX
AJJ wrote:

If the unit is made by a reputable source, there should be a label on the unit or in the packaging where the manufacturer certifies the unit complies with FCC Part 15 requirements.



That is kind of what I was wondering about. I suppose the rules in China are less stringent.
Many years ago I was aware of some of the Part 15 rules, I was hoping there were some new exceptions.

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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Fri 09, 2018 4:36 am 
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Even 100mW will cover a fair distance - I think my little transmitter is micro-watts - goes about 25 yards up the road. The specs say 20mW for the chip but there's a low pass filter and an attenuator before the antenna.

I don't know if it's the same in the US but here we have a selection of frequencies that can be used for low power FM broadcast at the bottom and top of the band.

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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sat 10, 2018 4:45 pm 
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bluebellyyankee wrote:
How would one go about measuring the field strength?

By conducting a suitable series of field intensity measurements with a calibrated FM field intensity meter such as a Potomac Instruments FIM-71. I have done such measurements in the past with a rented FIM-71 (I do not own an FIM-71). An easier way to ensure compliance is to use a transmitter that has an FCC certification ID number. The transmitter in the first message of this topic is not FCC certified and is clearly in violation of FCC Rules & Regs.

Dale H. Cook, Radio Contract Engineer, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcityeng/index.html


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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sat 10, 2018 6:52 pm 
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Location: Atlanta GA
Will placing some type of cover over the antenna help cut the power of this transmitter? I just re-tested the range on thing when it is on low power. While driving around the neighborhood in my car I can definitley get a solid 500 foot range and in some spots it reaches 1000 feet. Between 500 and 1000 the reception starts to get weak. If I remove the antenna completely from the transmitter I can not pick up anything even if the radio is in the same room as the transmitter. So, would covering the antenna with something help?


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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sat 10, 2018 7:31 pm 
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Nothing will help if the transmitter has no FCC certification - using it without certification is a violation, unlike Part 15 AM transmitters.

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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sat 10, 2018 7:58 pm 
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Location: Utica, NY 13502 (USA)
I agree with what Dale said.

I am surprised that Amazon is selling these. I have seen the same kinds of transmitters in various forms and power levels offered on ebay by off-shore sellers but I would not expect Amazon to be selling and shipping these within the US since the fines for doing so are far greater than those imposed on a buyer who uses them.

The problem is not confined to interference within the FM band. More importantly, it is the possible interference caused to aircraft and emergency communications due to this transmitter's harmonic and spurious signal suppression which, according to its spec sheet, is only 40 db. These signals need to be reduced to a much greater degree in order to receive an FCC certification.

Dave


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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sat 10, 2018 8:56 pm 
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Location: Atlanta GA
The problem is not confined to interference within the FM band. More importantly, it is the possible interference caused to aircraft and emergency communications due to this transmitter's harmonic and spurious signal suppression which, according to its spec sheet, is only 40 db. These signals need to be reduced to a much greater degree in order to receive an FCC certification.


Dave,

What you brought up here is actually more of what I would be worried about. I cant imagine that my broadcast on an un-used frequency would really pan out to be a problem. There are about 30 homes inside this "footprint" around my home. I cant imagine one of them complaining about a broadcast that is only on one frequency that nobody listens to but what if this thing was giving off some other radio anomolies and causing problems that I am not aware of? In the meantime I found a friend who knows somebody with a field intensity meter that can take a measurement. We will see what that looks like.

BB


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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sat 10, 2018 9:07 pm 
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bluebellyyankee wrote:
I cant imagine that my broadcast on an un-used frequency would really pan out to be a problem.

Neither can I; wait'll one of your neighbors files a complaint with the FCC (I expect it'll be a loooong wait...). Of course first they'd have to know which house it was coming from.

Just relax and enjoy your setup.

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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sat 10, 2018 9:22 pm 
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Location: Virginia Beach Va
They do care about you using unused freq besides it causing air disasters .
According to the enforcement page,you are stealing ad dollars from one or more of the consolidaters controlling radio in your area. From FCC -"In addition, pirate stations compete unfairly with licensed broadcasters for advertising dollar".

Most of the enforcement these days is FM, since other frequencies and modes are on Death row


Last edited by davep on Mar Sat 10, 2018 9:31 pm, edited 1 time in total.

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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sat 10, 2018 9:30 pm 
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Joined: Feb Mon 13, 2017 10:46 pm
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Location: Atlanta GA
Here is another one from amazon:

https://www.amazon.com/Crane-FM2-Digita ... op?ie=UTF8

At least this one is supposed to be FCC compliant. It does not look to be as powerful as the one I have now but all I need is for my house to be covered. Reading some of the reviews it sounds like people have figured out how to crack open the unit to adjust some pot that will greatly increase the range.


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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sat 10, 2018 11:41 pm 
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bluebellyyankee wrote:
If I remove the antenna completely from the transmitter I can not pick up anything even if the radio is in the same room as the transmitter. So, would covering the antenna with something help?


Something like this would be the simplest solution. You can buy/make an RF attenuator and install it between the set and the antenna; or make a "dummy load" to put in place of the antenna. Someone more fluent in this type of gear may comment on how to do this.

Experiment: completely cover the antenna with plastic wrap, bag, or tape. Then wrap foil on top of that; ground the foil.

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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sun 11, 2018 4:35 am 
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AJJ wrote:
Someone more fluent in this type of gear may comment on how to do this.

I have held an FCC commercial license to work with broadcast transmitters for nearly 50 years so I will comment. That transmitter is illegal, period. There is nothing that can be done to make it legal.

Dale H. Cook, Radio Contract Engineer, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcityeng/index.html


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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sun 11, 2018 9:29 am 
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bluebellyyankee wrote:
Here is another one from amazon:

https://www.amazon.com/Crane-FM2-Digita ... op?ie=UTF8

At least this one is supposed to be FCC compliant. It does not look to be as powerful as the one I have now but all I need is for my house to be covered. Reading some of the reviews it sounds like people have figured out how to crack open the unit to adjust some pot that will greatly increase the range.

Oh hell, that's wimpy; this baby reportedly puts out over 7 watts. You could cover the neighborhood, maybe the whole damn town with a tall enough antenna; :wink:
https://www.amazon.com/Signstek-Transmi ... RW75J56GBY

davep wrote:

Most of the enforcement these days is FM, since other frequencies and modes are on Death row

That's ridiculous; what's your reference?

Dale H. Cook wrote:
I have held an FCC commercial license to work with broadcast transmitters for nearly 50 years so I will comment. That transmitter is illegal, period. There is nothing that can be done to make it legal.

So is spitting on the sidewalk in many cities, but unless someone complains, nothing will come of it.

As long as the "illegal" transmitter is broadcasting on an unused frequency in the band, what are the chances of a complaint? I would suggest zero.



Now with all that said, this site only promotes LEGAL activity (so pay my ramblings no mind :wink: )

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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sun 11, 2018 12:42 pm 
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FM /384. Low hanging fruit
AM/SW - 2

I don't think there's any doubt AM and Shortwave are in trouble


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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sun 11, 2018 3:34 pm 
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If I may, a little common sense here.

The FCC requirements for Part 15 transmitters allow for small signals on the two broadcast bands. Reasons for this include test equipment, certain wireless products (wireless phonographs, baby monitors, etc.), and hobby use. Any unlicensed transmitter IS legal as long as it conforms to the specs provided -- and does not interfere with neighbors' reception.

The specs for an AM transmitter include maximum antenna length, along with other technobabble that has been discussed at length here. There is even a spec that prohibits using a connector for the antenna! As for FM, it just says don't go over 200 feet. With either one, the intent here is to allow a signal that does not go further than a city block. As has been mentioned, they don't want interference with licensed stations, and they don't want to see competition; obviously it's not fair for a station to spend thousands to comply with the rules, only to have someone else run a similar station from his garage, with fewer commercials or none at all.

You can get a bunch of test equipment to measure your signal to ensure it falls within the specs, or you can simply listen in and determine how far it goes. If you don't create a problem, the FCC will never find out anyway and it doesn't matter. As for intent, if you want to listen to radios in your house, and maybe allow a neighbor or two, no problem, but if you want to feed the community it IS a problem. As for airplanes flying overhead, I'm not quite sure where some of you are going with this -- if they're fine with 15 licensed 10,000 watt stations in the city, why would something a tenth of a watt in the same frequency band be a problem?

I have an AMT-3000 transmitter connected to my computer. If I flick it on (when not used it's off), I'll get a good signal anywhere in the house. My next door neighbor can't get it -- he tried. Perfect! I have a Ramsey 100B FM transmitter, and I'll be the first to say it's a bit too much. I'll use it on occasion, but I keep the antenna at short length. It might get as far as across the street, but that's all. A couple of times I've raised the antenna enough to do my cul-de-sac, about maximum legal, so neighbors can hear, but really -- I have no desire to create a problem.

As for the FCC, they're understaffed in this department, and pirates out there can often go for years before anything happens. Assuming you DO create a problem with your little Part 15, most likely the first thing they'll do is knock on your door and ask you to turn it off. Complaint fixed, no problem. If you're deliberately turning it up and broadcasting to the town, I don't know how long it takes but heaven help you -- and you'd deserve it.

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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sun 11, 2018 8:07 pm 
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^ Good post, Gary (as usual).

davep wrote:
Fifties:

2017
FM /384. Low hanging fruit
AM/SW - 2

I don't think there's any doubt AM and Shortwave are in trouble

I would agree that S/W seems to be a dinosaur, thanks I would guess mainly to the internet, but AM? Tell that to the 4700 AM station owners across the country.

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 Post subject: Re: Using a FM transmitter for home
PostPosted: Mar Sun 11, 2018 8:50 pm 
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All I listen to is SW and AM , look what I did to the listening post. So for me it's completely viable . Its a huge subject that's been beaten here a few times I recall . I hope it lasts as long as I do.

The 50k and 5 and 10k stations seem to be doing ok, at least someone's there.
Would you buy a medium wave station right now as an investment if it came up?


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