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500mW FM transmitter - is it FCC compliant?

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anhtuanb

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Hi guys,

I just recently bought a HLLY 500mW FM transmitter. It seems to have good specs on it and it's relative affordable. It comes with a basic antenna and 12V power supply.

I have read some post on here about running these types of transmitter with a FCC warning for non-licensed operator. ke5frf seems to know a lot about this topic.

I live in US and want to know if this transmitter power is FCC compliant. I ran a quick test and I got about a mile radius.

If I reduce the input DC power, will it help reduce the radio output to FCC legal level? Or do I need a dummy load using a resistor in the 50ohm coax?

Thanks.
 
HLLY's website does not open properly so I could not see the specs of the 0.5W FM transmitter.
It is much too powerful and if there is a complaint about it causing interference then the FCC will remove it and anything connected to it, shoot you and chop your head off. Maybe if you are in the middle of a desert or mountains then nobody will have interference and the FCC will not know your transmitter is too powerful.
 
It's not April fool yet. :)

ke5frf has help someone to reduce 5W transmitter down to 500mW to make it legal. I am thinking about doing with the resistor to bring it down further if necessary.

I also don't run on other's people frequency. I scan and look up vacant frequencies in my area and use them.
 
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I live in the suburb of the biggest city in Canada with many FM radio stations. Nearby are many cities with many FM radio stations. USA is not far with many FM radio stations so there is no vacant station frequency in my area.
I used the frequency of a low power foreign language FM radio station on the other side of my city for one hour testing the range of my FM transmitter and I did not get caught. I don't know how many people heard me instead of their radio station.
 
Operating in on an open channel doesn't make it legal.
 
So for the more obvious question what are you intending to use it for?

Operating in on an open channel doesn't make it legal.

True but its not like the FCC runs a fleet of black mystery vans around every single street and road 24 hours a day scanning every single frequency to make sure that no one is on one illegally.

Unless you piss off enough people the odds are they will never find you let alone have reason to do a dedicated search to locate you anyway.;)
 
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After I posted the schematic of my 20mW FM transmitter another member near me said he copied it and saw the RF cops going down his street looking for me?.

You need a licence to use a FM radio transmitter unless it is certified and made to transmit a small distance of 1m or 2m to a radio.
The licence specifies that a certified transmitter must be used with the power specified at the frequency specified with the type of program specified. Or they will shoot you and chop off your head.
 
I have to ask what does an "RF cop" vehicle look like any way? :confused:

Sure its not the local telecoms or business band guys out servicing equipment that is legal on a different frequency? ;)

If they are that fussy over a 20 mw transmitter how do they find it in the loads of wide band hash that all the CFL's and other arc tube based lighting plus the thousands upon thousands of SMPS's that emit RF noise into every frequency known to man?

Just asking?
 
With all that said, I think it's better to have it legal than non-legal and try to evade FCC by broadcasting on vacant channels.

My next question would be, how can I reduce the output of my .5W transmitter? I know input power has some effect on the output power. What about installing an resistor in the coax line for the antenna?

Thanks.
 
The van of an RF cop has a multi-frequency Yagi antenna with a rotor on the roof. It is very obvious. The scanning receiver can detect any frequency.
The RF cop has a big machine gun or shot gun and an axe or machete.

They caught me when I was a teenager with a badly sparking fan motor. It caused radio and TV interference to hundreds of people.
I am glad the RF cops didn't shoot me and chop off my head.
 
I think unless someone complains, they will not bother to go down the street everyday and scan for a milliwatt transmitter running on a 9V battery, unless they have nothing better to do or have to meet their quota ;) Especially here in Singapore, with public housing having so many units inside one block, will they pay someone to go and knock and every door checking for a small transmitter? I bet not. And they need a search warrant to search your house to find the transmitter. So unless your transmitter is very powerful or causes disturbance with other radio stations, you'll most likely be fine.
 
RF cops catch illegal transmitters that cause interference to real radio stations. People complain when they get interference on their favouite station.
Some harmonics of illegal transmitters are heard on ambulance, fire department, aircraft and police radios then there are many complaints.
 
Different countries have different RF power laws. Some countries have no laws. You do not say where you are. I think the limit is 25mW in North America and most of Europe.
The transmitter is probably made for a pirate ship off the coast of a large city but in international waters. The Engrish translation is pretty bad.
I did not know that Rohm made it and I think Rohm do not make that IC anymore.
 
I think Rohm do not make that IC anymore.
I contacted directly to Rohm once and they said they already stopped to manufacture the transmitter ICs like BH1417 etc. Some distributors have listed the IC in their stock. I never got one around me. It would be so nice toy!!
 
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