gc75067 Posted April 25, 2013 Share Posted April 25, 2013 i dont want to deal with any problems with the FCC. will the EDM be legal or not in the US? ive seen on other forums with people getting nasty letters from the FCC for using other devices that were "non compliant" and want to avoid receiving one of my own. Link to comment Share on other sites More sharing options...
gmac Posted April 25, 2013 Share Posted April 25, 2013 Almost all the ones you see for $59-$89 arn't FCC compliant from the standpoint of infringing into some emergency frequencies bands and some just blast way too much power.......Lets face it why would we want to blast our songs more that a few houses away when they can't see the lights anyway and take a chance of being fined (IMO) ......Transmitters like the EDM and the Ramsey FM30 (I have this one) may cost more but you would be FCC more compliant and put out a much better sound almost as good as commercial broadcasts. Link to comment Share on other sites More sharing options...
Steven Posted April 25, 2013 Share Posted April 25, 2013 The EDM can be legal or illegal depending on what antenna you use and how high you turn up the output power adjustment. As gmac said, one big advantage of the EDM (and Ramsey) is they have "clean" output, so even if you are running more than legal power, you probably won't get into trouble because you won't be inteferring with something on a different frequency. The only transmitters that are guaranteed to transmit at legal levels are ones that are FCC certified, and these must all have built-in antennas. They typically don't give satisfactory results. To keep yourself out of trouble, get a "clean" transmitter (like an EDM or a Ramsey), make sure there is no other station on the same frequency (that anyone close to you will be listening to), make sure your signal sounds as good as a commercial station (Your volume will be a little less, since the commercial stations have expensive audio equipment to make the audio sound louder), and make sure your signal fades out when you are far enough so you can't see the lights. Link to comment Share on other sites More sharing options...
gc75067 Posted April 25, 2013 Author Share Posted April 25, 2013 good info guys. another question. Steven, you mention that it could depend on the antenna that you use. which types would be used to remain "compliant"? Link to comment Share on other sites More sharing options...
bobschm Posted April 25, 2013 Share Posted April 25, 2013 Those cheap FCC certified transmitters generally have a just a short piece of wire hanging out for an antenna. You can lengthen the wire and get more power, but then you're not technically legal anymore. "A friend" did that and ran it last two years with good results. No men in black have showed up yet. Link to comment Share on other sites More sharing options...
LORisAwesome Posted April 25, 2013 Share Posted April 25, 2013 Don't mess with the length of the antenna, unless you know what you are doing. The length of the antenna affects the SWR (Signal to Wave Ratio I think...). If the SWR is too far out of whack, it can ruin the transmitter. If you ever used a CB radio, you may have noticed the length of the CB antenna can be adjusted, this to set the SWR. You need something called a SWR meter to make the adjustment. Again if the SWR is too far out, it can ruin the CB transmitter... Max Paul can probably explain this much better than I can. Maybe he will chime in here. Jerry Link to comment Share on other sites More sharing options...
gc75067 Posted April 25, 2013 Author Share Posted April 25, 2013 Don't mess with the length of the antenna, unless you know what you are doing. The length of the antenna affects the SWR (Signal to Wave Ratio I think...). If the SWR is too far out of whack, it can ruin the transmitter. If you ever used a CB radio, you may have noticed the length of the CB antenna can be adjusted, this to set the SWR. You need something called a SWR meter to make the adjustment. Again if the SWR is too far out, it can ruin the CB transmitter... Max Paul can probably explain this much better than I can. Maybe he will chime in here. Jerrynot sure im getting your point. i havent seen anything or anyone mentioning anything about changing the length of an antenna. there are many choices of antenna out there. my question is - is one more compliant than another.. one i see a lot of talk about is a j-pole antenna. my only goal is to keep the feds from sending me mail or knocking on my door Link to comment Share on other sites More sharing options...
Steven Posted April 25, 2013 Share Posted April 25, 2013 Steven, you mention that it could depend on the antenna that you use. which types would be used to remain "compliant"?There is no answer to this question. The technical, legal answer is found in Part 15, paragraph 15.239, which says:The field strength of any emissions within the permitted 200 kHz band shall not exceed 250 microvolts/meter at 3 meters. The emission limit in this paragraph is based on measurement instrumentation employing an average detector. However, very few of us have a field strength meter that is sensitive and/or accurate enough to make such a measurement at that frequency, so we have to guess. A good rule of thumb is that the signal should fade when you get to the next house, but that depends on how much noise and interference is present at the receiver. ... the SWR (Signal to Wave Ratio I think...). Actually Standing Wave Ratio. When the impedance of the antenna is not the same as that of the transmission line, the signal voltage will not be the same throughout the line. The SWR is the ratio of a high point to a low point. If the SWR is too far out of whack, it can ruin the transmitter. A high SWR means that a high ratio of transmission energy is being reflected back to the transmitter, as opposed to being radiated by the antenna. That energy can destroy the transmitter, although it's usually not a concern for us because our transmitters are very low power. The transmitter in a CB radio is typically 100 to 1000 times more powerful than the FM transmitters we use. Link to comment Share on other sites More sharing options...
LORisAwesome Posted April 25, 2013 Share Posted April 25, 2013 not sure im getting your point. i havent seen anything or anyone mentioning anything about changing the length of an antenna. there are many choices of antenna out there. my question is - is one more compliant than another.. one i see a lot of talk about is a j-pole antenna. my only goal is to keep the feds from sending me mail or knocking on my doorThe post just before mine mentions lengthening the wire to get more power. I assumed that he was talking about the antenna. I was warning against that. Link to comment Share on other sites More sharing options...
gmac Posted April 25, 2013 Share Posted April 25, 2013 not sure im getting your point. i havent seen anything or anyone mentioning anything about changing the length of an antenna. there are many choices of antenna out there. my question is - is one more compliant than another.. one i see a lot of talk about is a j-pole antenna. my only goal is to keep the feds from sending me mail or knocking on my doorTo keep it simple I think the other post was speaking of adding a piece of wire to the antenna thats attached to the transmitter....a J-Pole or 5/8-3/4 wave antennas are the types you would put outside say on your roof to increase the distance, BTW the FCC does frown on people like us using them. If I were you I would purchase a EDM or Ramsey and see if your FM signal is OK for 3-4 houses from yours and if it is your in good shape.if not then you could purchase a external antenna and then adjusting the power to stay FCC compliant. Like Steven Stated in his previous post FOLLOW: A good rule of thumb is that the signal should fade when you get to the next house Link to comment Share on other sites More sharing options...
gc75067 Posted April 25, 2013 Author Share Posted April 25, 2013 To keep it simple I think the other post was speaking of adding a piece of wire to the antenna thats attached to the transmitter....a J-Pole or 5/8-3/4 wave antennas are the types you would put outside say on your roof to increase the distance, BTW the FCC does frown on people like us using them. If I were you I would purchase a EDM or Ramsey and see if your FM signal is OK for 3-4 houses from yours and if it is your in good shape.if not then you could purchase a external antenna and then adjusting the power to stay FCC compliant. Like Steven Stated in his previous post FOLLOW: A good rule of thumb is that the signal should fade when you get to the next house missed that part of lengthining the wire antenna. im buying a retired setup and not sure if what i am getting comes with the original or not. thats why im wondering.. if i dont get an antenna then what is safe for me to buy Link to comment Share on other sites More sharing options...
gmac Posted April 25, 2013 Share Posted April 25, 2013 I assume your speaking of the original antenna. Not 100% sure on the EDM but most units like that come with a BNC connector to attach a antenna and if it does you can pick one up at Radio Shack or any local electronics store ( even if the connector is different there are adaptors to BNC that you can get)....some people call them rubber duckie antennas and those would do the job. Link to comment Share on other sites More sharing options...
Steven Posted April 25, 2013 Share Posted April 25, 2013 Here's my antenna: Link to comment Share on other sites More sharing options...
Max-Paul Posted April 26, 2013 Share Posted April 26, 2013 Steven your antenna would be considered over kill for our purpose. Ok as for putting a different antenna on the transmitter other than what might have came with it. When it was type approved by the FCC is was done so with a certain length of coax and antenna, be it a wire or telescoping type on the back of the unit. If you install say a J-pole and it was not certified with this J-pole, it is no longer FCC certified. Now what I am about to say will NOT get you out of jail free, but it is the voice of reason, or I should say I would like to think it is. And you basicly have already heard it from others. Use only enough power or radiation to have a good solid signal in front of your display. Now this might mean you can still hear it a few blocks away, but it better be getting static in it. Lets just say you want to be like a soldier in a trench warfare, keep your head down. So, only transmitter as far as you need to, to insure that those in front of your house get a good static free signal. Each house that receives your signal is a potential complainer. So minimize the number of houses that receive your signal. Broadcast for miles and risk pissing someone off cause they cant listen to their favorite FM station cause your interfering and you run the risk of a visit. Being a HAM radio op, I have heard of stories of illegal broadcast stations and how the FCC fines are very costly along with loss of equipment. The choice is yours. You have been given good advice by not only me but several above post. Link to comment Share on other sites More sharing options...
PMC Posted April 26, 2013 Share Posted April 26, 2013 (edited) +1 Edited April 26, 2013 by PMC Link to comment Share on other sites More sharing options...
bobschm Posted April 26, 2013 Share Posted April 26, 2013 I was talking About a tiny FM transmitter whose antenna is a six inch piece of wire sticking out the side of the case. The instructions advised attaching more wire to get more distance out of the transmitter, but warned that you might exceed FCC standards. This thing hasn't got enough power to blow its nose no matter what the swr. Link to comment Share on other sites More sharing options...
LORisAwesome Posted April 26, 2013 Share Posted April 26, 2013 The EDM FM transmitter works great. I just use the test antenna that comes with it and use the low power setting. Jerry Link to comment Share on other sites More sharing options...
travis p Posted April 27, 2013 Share Posted April 27, 2013 the edm transmitter will handle swr loads of up to 19.0to 1 with out damage to its finals i got my swr ratio down to 1.2 to 1 with an antenna like Stevens having some radio experience i did not wish to see magic smoke from a new edm so i got one of those over kill 1/4 wave tunable jobs and an swr meter and went to work edm set on low power low swr clear signal =800 feet Link to comment Share on other sites More sharing options...
Steven Posted April 30, 2013 Share Posted April 30, 2013 Steven your antenna would be considered over kill for our purpose.Yes, overkill, but inexpensive. I used an SO-239, some brass rods, PVC pipe, plenty of caulking, and black paint. It's connected to the transmitter with 50 feet of cheap coax. (I don't worry about the loss in the coax because I don't need that much power.) The reason I don't have the antenna next to the transmitter is the metal garage door and the metal roof created nulls in the front of the display. Link to comment Share on other sites More sharing options...
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