- April 11, 2019 at 7:22 am #110860
The Rolls website says that the HR70 has a transmitter output power of 40 milliwatts, antenna impedance of 75 ohms, and 150 milliamps of current.
Can any of that data be used to determine if the field strength of this transmitter is under 250 microvolts per meter?
- April 11, 2019 at 7:39 am #110861
The transmitter output power, antenna impedance, and the current it uses has nothing to do with the field strength or whether it is legal.
- April 11, 2019 at 10:52 am #110864
Thanks for the info…just making sure it was too good to be true. I’ll stick with the cigarette adapter transmitters I’ve been using for FM. Those at least have FCCID numbers.
- April 11, 2019 at 2:07 pm #110866
@RFCCLebanon: The FCC agent I’ve been in contact with after he visited my house has offered me his Email and his contact number when I have a question about these transmitters. Recently I called to ask him about a Wireless Headphone set with transmitter which transmitted on 84.950 Mhz and an output of 50 mW and is there any legal rule that prevents me from giving out the frequency out on the Deltaville, VA Facebook page as a Radio station telling people to throw their Radio in Japanese mode.
His reaction was for me to try and get the model number picture of the device if I could and FCC ID number to verify it was not a fake FCC ID number or a faulty FM transmitter because he himself had to force Walmart to remove some of its part 15 devices from their store shelves after his tests revealed harmful interference issues.
If you publish the FCC ID of this illusive part 15 FM Transmitter I’ll check with him and see just what he tells me about it. He knows about New Radio Revolution and knows about my activities regarding my C-Quam AM Stereo campaign too.
Lets hope this thing is what they claim it is.
- April 11, 2019 at 2:44 pm #110868
RFCCLebanon, You can still use something better than a car FM transmitter that goes 10 ft.
Looked at that Rolls one and of course not certified for part 15 and connecting any BNC antenna to the jack at 40 mW will put you way over the limit but I noticed it has a variable RF control on the front. Probably with a rubber duck BNC antenna type and adjusting the output control to get no more than 200ft or so to a decent radio you could operate it within the limit. I don’t know how good it is, but I saw the frequency response is only to 12K. For the price, and it doesn’t look like junk, it should be better than that. Maybe thelegacy’s agent friends have some knowledge about this model.
Saw this is available in Canada also from recording gear online shops and is around $300.
For that price you can look at Broadcastvision which is good and certified in the USA for part 15.
To get the actual field strength you need a very expensive FIM meter.
- April 13, 2019 at 10:06 am #110875
Actually, the Scosche TuneIt and the Prime Audio I have both have a range of about 100 or so feet without fading and they fade out completely around 200 to 250 feet depending on the terrain, with no modifications. I’ve posted about them a while back. The Prime Audio can work off a 12V AC Wall Adapter, and the Scosche can work off any adapter that has a cigarette female to wall male connection. I just used the Scosche the other night for some softball games. The fields and press box are set up to where anyone with a decent radio can listen from the bleachers.
- April 13, 2019 at 2:20 pm #110877
Not all car mp3 players are under powered. In fact, the FCC pulled a number off the shelves years ago for not being Part 15 compliant. It sounds like the ones you’re using are OK.
Just to give you how much the Rolls is NOT compliant…
The amount of power required to meet the Part 15 FM rules is measured in nanowatts (around 20), not milliwatts. That’s into a matched antenna, of course. 40 milliwatts output into a matched antenna is over a MILLION times the power of a compliant transmitter. Given that the field strength is proportional to the square root of the power, you’re looking at around 1,000 times the field strength of a compliant transmitter, or 250,000 uv/m at 3 meters. Not even close to being within the rules.
Even with a mismatched antenna, I doubt you’ll get your field strength low enough.
Unfortunately, you’re either stuck using your current transmitters, or spending big bucks (hundreds of dollars) to get a decent, true Part 15 certified, transmitter, such as the Decade MS-100 or the Broadcastvision BV-3001 or its successor. You can usually find a used Broadcastvision 3001 on e-bay for anywhere between $50-150, but used Decades are expensive. Not sure its worth it, particularly since you seem to be operating close to the limits of the rules already.
- April 14, 2019 at 4:54 am #110881
I’d be leery of the Broadcastvision models.
While the last one I tested was about 2 1/2 years ago, it was WAY over the legal limit. See my test report at:
- April 14, 2019 at 5:25 am #110883
Yeah, there’s ZERO chance the Rolls HR70 is even legal for sale in the USA. It doesn’t seem to be certified, at least it’s not mentioned in any listings for it and a search of the FCC database has no mention of it. Most legit Part 15 certifications are readily searchable at the FCC.
Not surprising as it has several readily apparent issues that would prevent it from passing certification. For one, certification for Part 15 FM requires either a permanently affixed antenna — being the same one it was certified with, or a removable antenna that connects with a non-standard connector. A BNC connector is quite standard. And apparently no antenna is even supplied.
Also the FCC Part 15 compliance statement and ID number must be affixed to the transmitter.
Further, a certified unit must not be able to broadcast outside of the FM broadcast band in the USA. Operating abilities down to 87.5 would eliminate this from certification in the USA.
As previously mentioned 40mW output even into a crummy antenna would put output well over the legal limit.
I just read the manual. No mention of certification, and a lot of info on finding a good, preferably directional antenna for best results. This would only further put it over the limit.
This thing has been out for at least a couple years now. I’m amused that is states “Made in the USA” but the word “Transmitter” on the front is spelled wrong.
And it has pretty crummy frequency response as well.
I say avoid at all costs.
- April 14, 2019 at 6:00 am #110885
I’m also amused that this is a “digital transmitter”. It does not accept any digital form of audio, it has analog inputs only, and it does not transmit any digital data, as well. No digital audio, not even RDS. It’s “digital” in the fact that the frequency used is read out digitally. LOL.
- April 14, 2019 at 7:40 am #110887
- April 16, 2019 at 5:29 pm #110898
Ok guys very good news could be under way. I found the model number and FCC ID for the Wireless headphones that are FCC certified and transmits on 84.922 Mhz at an output of 5mW.
I Emailed as well as a follow up call and I’m waiting for the green light. If I get it the USA well have its Hobby Broadcasting frequency of 84.922 Mhz FM Stereo.
The Legacy will have truly paved the way for us to get real listeners. People in Deltaville, VA will be informed how to receive us on America`s true Hobby Broadcasy frequency. I cannot wait.
- April 16, 2019 at 7:22 pm #110900
But no radio goes below 87.5, at least for the N America market. And 84.922 isn’t a designated frequency that a digital tuner would go to, especially a selective one. You would be detuned. The only radios that would receive it properly would be an analog tuning radio that goes from 76-108 or an older radio with TV VHF audio and wouldn’t have the sensitivity of .9uV you say you need.
Not trying to put a damper on your enthusiasum but don’t be expecting this to work as good as you think.
- April 17, 2019 at 9:41 am #110902
More Experimenting needed at $20-30 for each wireless headphone set and for the agent to check on his analyzer.
If I get approval for this Mark has a few concerns but does point out those VHF TV sound Radios that were analog. It also occurs to me maybe we can order Radios or get Mitsubishi car Radios that will tune in Japanese mode. We need to play around and see. My Broadcast engineer is trying to find me such a Radio.
- April 17, 2019 at 10:27 am #110904
Now we have our National Hobby Broadcast frequency 84.922 Mhz @ 50 me as the agent told me the Wireless headphone made by ONN is 100% legal and if I wanted to experiment and post it on the Deltaville VA Facebook page I could.
He is saying that not everyone will get the same range but being that I’m near water you’re in Deltaville it may cause the signal to carry out pretty far to a very sensitive radio and there’s nothing bend the rules that prevent me fromm telling whoever I want my frequency and the fact that I’m transmitting there you.
These headphones are quite affordable and I think it could be the resolution that will stop FM piracy as I have explained to the agent and told him I am very excited to let everyone know about this. He sort of laughed but he also says to be careful that there is not a Channel 6 to close to you that you might interfere with but that’s easily to find out about. He did say that most Channel 6 has that are operating at low power will be off the air in 2020 and that the frequency should be blank for everybody. This means hobby Broadcasting on that frequency.
Thanks to everyone that brought this to my attention the new radio Revolution has now done everyone a great favor bye making this loophole as the agent says and very legal a way that we can broadcast without getting into trouble. So the Legacy will be promoting radios that will go down there. I suspect the makers of these headphones are going to be getting tons of orders now. I’m also going to spread this all over the internet this is going to be the national hobby broadcast frequency
- April 17, 2019 at 1:34 pm #110907
I already posted this string of random comments in the FB Part 15 group, but for others:
Well, there are several comments I have here. First of all which name/model headphones? There are many “ONN Wireless Headphones”. Second of all, what did he have to green light? Thousands and thousands of people have purchased these and used them to transmit music from their audio systems and computers to their headphones. How is that any different than running your station into them? I know an awful lot of radio pros working in studios using wireless headphones in the studio while on the air, which means they are “broadcasting” their radio station on 84.922 as well as whatever their commercial broadcast frequency might be. How do these avoid interference if, say, your neighbor or guy down the block decides to use wireless headphones? It’s not an official “Hobby Broadcast” frequency. It’s just broadcasting your hobby station on an already available frequency already being used for transmitting music. Now, I own probably 200 FM radios, from portables to receivers, newer and vintage. I don’t believe I own ONE that has a way to simply “throw it into Japan mode”. And neither will the typical man on the street. I do own one Sony, from Japan, which has the expanded FM band, slide rule tuning, and even though it’s a smaller mono radio I think it has stereo headphone output. Can people get it on their clock radios? In their cars? I see some limited use here. All that being said, I’d love to do some range and field strength tests once I know what the exact model is. It appears several brands of wireless headphones use this frequency. I do see one potential good use not mentioned — as a studio/transmitter link for AM. I also like the suggestion of using old radios with TV Band audio reception. I own several of these. All are mono, but always had good sound. But they had analog slide rule tuning and would have no trouble tuning in the somewhat odd frequency. Experimentation to begin. The Sony radio I have with the expanded band is a Sony “2Band Radio” ICF-801. It has the expanded Japanese Fm band, slide rule tuning, runs on batteries or A/C power with a power cord, NOT a wall wart power supply! The sound is excellent. They seem to have gotten rather expensive however. But great little radio with great speaker sound.
- April 17, 2019 at 2:36 pm #110909
ONN FM Wireless Headphones ONA14AA011
FCC ID 2ABV4-ONA14AA011
Tim I’d love you to do some tests with these. The agent did tell me down on part 15:236 its Power so you don’t have to worry about the field strength. In the agents tests it actually put 50 mW and as he told me the Range will be funny but if I could get my transmitter high and near water it may go further. It was why the gentleman who posted about his experience and going all the way out on a lake with his boat and still hearing the Headphone transmitter loud and clear.
Most Wireless headphones I came across were on 900 Mhz but what I like is these do transmit down on the Japanese FM and TV sound bands where people may be able to get a good TV sound Radio next to nothing or pay a bit for a highly sensitive Radio. Some did have good Mono sound and I think some Album Rockers would listen. I’ve heard Mono on some good Sony Radios and I didn’t mind that too much. To me it still sounded way better than mono AM.
I want to give my listeners a choice between C-Quam AM Stereo and this way to listen and since the headphone transmitter transmits Stereo an analog Stereo tuner would get it. Maybe a Stereo Radio with TV Sound could be modified to receive FM Stereo in the TV sound band on VHF Low. I’m excited to find out.
- April 17, 2019 at 3:27 pm #110911
Yes that Sony ICF-801 is still available on Ebay new but used to be under $100 + shipping but now for some reason the price is around $250-$300. Amazon has none. Whole page of them on Ebay.
But can you convince potential listeners to get one of these?
- This reply was modified 7 months, 3 weeks ago by Mark.
- April 17, 2019 at 4:02 pm #110915
Well, that’s just one of many radio options. I bought mine a couple years ago and they were less expensive.
But as was mentioned, there are thousands of radios with TV audio band in them that would work quite well. I have several multi band portable radios from the 70’s and 80’s with great sound that would work.
Still easier to find a suitable receiving radio than trying to come up with a readily available C-Quam AM receiver I’d say.
I must say, I still vote “skeptical” on this transmitter idea, but time and some experimenting will tell more.
I did just read the complete certification report at the FCC site, and as was mentioned, for this frequency the limitation is power output, not field strength. The limit is 50 mW, however the test report and the FCC specifications clearly show the output of this transmitter to be 5.50 mW. That’s 5 point five, or just above 1/10 of the limit.
I have ordered one to play around with. They’re practically free.
- April 17, 2019 at 8:03 pm #110917
Let us know which TV receiver or radio that receives this frequency has the best sensitivity. I think that’s going to be the key.
I saw the test report too and I thought it said five milliwatts but the agent was saying Tumi 50 microvolts. He did say there are other models that will go down there too that transmit audio. So if this one doesn’t do it we should look for the one that gives you the full 50 mW and has the certification on it.
I saw one similar model where the transmitter only would run on batteries and I saw a different one where it will do electric or battery. If it’s the case maybe what’s happening is the one that runs on electric is using that ground wire as an antenna which means plug it in and it’s acting sort of like neutral injection carrier current. And since there’s no field strength rule as long as you don’t modify that unit and you’re running it as instructed it’s making you get out further than the batteries will. That could be where the 1-mile reception happened from the person that was on a boat.
We definitely have a play toy.
- April 17, 2019 at 8:25 pm #110919
Looked up the certification and saw this complies with Part74 and states this item is for NON- BROADCASTING. Also saw the word licensed with part 74.
Just going by the non- broadcasting it means the intent can’t be getting out to the general public. This is similar to the Canadian definition of broadcasting and non-broadcasting. It was certified to get to you as the user with headphones, not to broadcast to a radio for the general public.
This certification that Tim posted is definitely not in accordance with part 15-239, which, is the section in question when this subject started.
Not trying to sound like Rich but this may not be the big loophole to get lots of power on FM that it seems. I still am skeptical till I see how thelegacy does with it and I think thelegacy should check again with his agents and show them this certification. And if the agents say it’s OK, get it in writing.
Canada has a section in RSS-210 on wireless mics also and it also says max 50mW on the VHF frequencies below the FM band but like I said, until I see different I don’t think it is a way to get a license free broadcast station on FM with a lot more power.
- This reply was modified 7 months, 3 weeks ago by Mark.
- April 18, 2019 at 1:22 pm #110926
If you read the full report you will see it is ALSO compliant for 15.236 and in fact has a FCC ID issued for part 15 certification.
I was a bit concerned about a couple other details — the rule states:
“(b)Operation under this section is limited to wireless microphones as defined in this section.”
And the definition in this section states:
“(1)Wireless Microphone. An intentional radiator that converts sound into electrical audio signals that are transmitted using radio signals to a receiver which converts the radio signals back into audio signals that are sent through a sound recording or amplifying system. Wireless microphones may be used for cue and control communications and synchronization of TV camera signals as defined in § 74.801 of this chapter. Wireless microphones do not include auditory assistance devices as defined in § 15.3(a) of this part.”
Which doesn’t include broadcasting.
But on the other hand, there are an awful lot of wireless headphones offered on this frequency, and everyone using them would in effect be ‘broadcasting”.
- April 17, 2019 at 11:34 pm #110922
When a complaint is sent to the Enforcement bureau David Dombrowski is the one who sends this agent to shut down those who violated the rules. David and I too have spoke on the phone a few times when I called to talk to the agent that visited me and he is aware of my correspondence. Technically part 15 section 236 was Not meant for broadcasting but as the agent said no NOUO will be issued to me so long as I use a certified non modified headphone or Wireless Audio sender I asked about posting 84.922 Mhz doing my Album Rock show promote where to buy the special Radios (That is the loopwhole) to receive my Hobby Broadcast.
Knowing how the FCC listens to my station on the net (They told me they do) they are Well Aware I was gonna post it. Timinbovey ordered his for testing so we will see.
The agent laughed at my idea in a good way and he knows if people want to listen bad enough they will buy the Radios. It’s the best its gonna for a close replica to New Zealand. I’m sure agents are laughing at how I figured this out. I’m a real Radio geek having fun.
- April 18, 2019 at 6:12 pm #110928
I don’t know why Michelle Bradley could not find the report for 15:236 on this device? So is there another similar one with 15:236 certification just in case there is an issue so I don’t get busted? (I doubt it) but lets cover our bases.
- April 18, 2019 at 6:30 pm #110931
Whitespace devices have been around a while, and the issue has always been whether broadcasting was an acceptable use. It appears, at least from this one agent’s comment, that it would be OK, as long as all the other provisions of the Whitespace rules are followed.
In my opinion, broadcasting is problematic in any event as the onus is up to the unlicensed user of these devices to continuously check the Whitespace Database to ensure that they will not be causing interference to those that have registered. Presumably on a daily basis, if not more frequently.
The other issue is, of course, the radio one. You need a radio that will receive Whitespace frequencies to receive a broadcast on those frequencies. You’re going to need really loyal listeners for that.
On a side note, Mister Wonderful (the Webmaster at another website) is at it again. A day or so ago I saw some disparaging comments about ‘pirates’ posting on other (maybe this one) sites about operating on the Whitespace frequencies, including 87.9. He talks about how this frequency is off limits for Part 15 (presumably 15.239) broadcasters. Of course he’s right, but then, these whitespace devices are NOT operating under Part 15.239. As long as they are certified under the correct Part 15 rules for their frequencies, then the only real issue is whether the FCC would consider broadcasting acceptable use.
I don’t see why not, but then, I’m not an FCC agent.
I know in Canada, the Whitespace frequencies are governed under RSS210, which does not allow broadcasting to the general public. However, broadcasting within a confined area is not considered broadcasting (RSS123 is a licensed version of this) so you COULD, theoretically, broadcast wihin a mall, or arena or similar area using a certified wireless microphone.
- April 19, 2019 at 11:49 am #110862John SeesParticipant
Total posts : 41
Perhaps you could use it under 15.236 as a wirelesss microphone on 87.9? It looks like it tunes down that far and the 40 milliwatts output is under the 50 allowed for wireless mics. The 15.236 definition of wireless mics is pretty loose and I don’t see any restrictions as to uesage, transmitted content nor intended audience…
- April 19, 2019 at 3:06 pm #110943
I believe “Mr. Wonderful” is right that these are not applicable for 15.239 use. However, they ARE available for use under 15.236. This is clearly spelled out in the FCC’s “Wireless Microphones Rules Update” of 11/1/2017.
It states 76 – 88 mHz can operate under 15.236, unlicensed, with a maximum power of 50 mW EIRP. And also operate under Part 74 Subpart H, licensed, with the same maximum power of 50 mW EIRP.
Again, every bit of documentation I can find for test and certification results for the transmitter discussed here, the output is stated at 5.5 mW, far under the legal limit. And with the tiny antenna enclosed in the case (you can see this in their certification paperwork) I would not be surprised if range is similar to a legal Part 15 FM band transmitter.
I think when we come down to discussing if this can be used for “broadcasting” consider — likely tens of thousands of consumers purchased these to enjoy headphones connected to their stereo, computer, TV or whatever with the convenience of wireless connectivity. If they listed to their favorite radio station or TV station are they then not for all intents and purposes broadcasting? I mentioned before, I have known several radio announcers at commercial stations who use wireless headphones while doing their airshafts, so they may move about the studio, music library, etc without removing their headphones and dealing with the cord. Hence, their entire show is being “broadcast” on the frequency of their wireless headphones.
Certainly the use of these headphones is legal for their intended purpose of broadcasting sound to listen to wirelessly. They have all sorts of documented certification and lab tests, and are certified for use under two different classes. Whether you decide if they are legal for “broadcasting” I think, is a bit of a matter of interpretation.
Anyway, the one I ordered has been shipped. I’ll give it my usual FM Transmitter tests. RF output, field strength at 3 meters (just so we can compare it to a 15.239 unit), modulation capabilities, and some rather unscientific range testing.
Couple oddities. I note it also includes a built in FM radio. And It also states that if you are trying to listen to your audio being transmitted from it’s base and experience static or interference you need to press a button to “select a different frequency”. There’s more than one?
We’ll see once it arrives.
- April 19, 2019 at 4:51 pm #110946
Mr. Wonderful was calling users of such devices pirates. At best he was being disingenuous, at worst deliberately misleading. It doesn’t appear that there’s anything wrong with using these Part 15(.236) certified devices, unlicensed, on the frequencies between 76-88 Mhz, as long as you don’t cause interference with other licensed users, or unlicensed users that have registered in the Whitespace Database.
- April 19, 2019 at 7:00 pm #110952
There is a Zimtown Wireless headphone that transmits on 86 Mhz but I can’t find any FCC certificatation for it. A lot are on 85 Mhz. Station8 found this but its way too expensive @ 300 dollars but does have full 50 mW output but has a bandwidth for the FM modulation of 90 Khz for the deviation. I know standard FM is +- 75 Khz for deviation so that is not cool even if I could afford it. It transmits from 76-88 Mhz.
The Rolls transmitter may be usable but does it come with FCC certification? Does it come with an antenna? I gave away my ground plane to a Ham after I got visited because I didn’t know about this holy grail and after I mentioned that the agent told me He didn’t say I could never use FM just have to use certified equipment. But the Rolls (if certified) I’m sure may have issues with a ground plane. Telescopic antenna maybe. But the agent said down there its not a field strength issue its a Power issue. The ground plane I had was 3db gain.
I think having an FM antenna too close to my AM transmitter is not good either. If the rolls is certified I could use a telescopic antenna for it and call it a day.
- April 19, 2019 at 7:03 pm #110953
Oh there was a dude on Facebook that also called the FCC and told them what I was doing. The other agent also told him the same thing. I’m sure David Dombrowski is having a cow now that I discovered this but never got the call on the phone from the FCC telling me to cut it out and stop posting it.
- April 20, 2019 at 3:23 am #110954
Well, I certainly doubt the use of these wireless headphones, as they come from the store is illegal or “pirate”. The only possible discussion would be if “broadcasting” with them is outside of the realm of their legal use. In which case we need a legal definition of broadcasting.
Now, I don’t know where you’re finding the review of the guy who gets one mile to his boat with this ONN transmitter. But I have no trouble finding a slew of reviews that complain it won’t go ten feet, and complain that they barely work, with static and interference, and dropouts, etc. Then again, those reviews are from people who used them as wireless headphones and weren’t trying to receive them on a radio. Perhaps the receivers in the headphones themselves are horrible. This is likely.
Also this whole “it’s not the field strength it’s the power”, as I explained above is not really correct. The FCC specification for certification and use under 15.236 and under Part 74 clearly states 50 mW EIRP, which is NOT a measurement of the output power of the transmitter. It is a measurement of the output of the transmitter, plus the gain of the antenna. The gain of the antenna with this transmitter is probably zero, or more likely less than zero. Certainly connecting any other sort of antenna would cancel the certification. Is it legal to use something under 15.236 that is not certified? If so, are you prepared to determine the output computing actual output power times accurately computed antenna gain, to determine legality? Will anyone care?
As for the Rolls transmitter, as I explained somewhere, it can’t possibly be certified. Just it’s physical characteristics make it an unsuitable candidate for certification. Further, specs indicate audio response only to 12.5k. Typical is to at least 20k. It wouldn’t sound much better than AM radio.
And we need to remember, when we say something is Part 15 certified, that just doesn’t refer to our AM and FM band transmitters. There is a practically uncountable number of devices out there that aren’t on the broadcast bands that are certified under Part 15 and legal for use by consumers. Your cordless phones are Part 15. Your wifi is Part 15. Your baby monitor is Part 15. Your cordless outdoor thermometer is Part 15. Your kids walkie talkies are Part 15. Heck, when I was a kid I used awake talkies to do a “show” and play records and announce them to my sister who listened on the other walkie-talkie. I was probably 10. This was I’m sure “broadcasting” by definition. But I’ve never seen walkie talkies that say you can’t “broadcast” with them. Or course these were on the CB band, and 100 mW, and sold to kids with no manual on what you could legally transmit. Heck, just bought my grandson a pair of these. They were “Spiderman” walkie-talkies. Are they limited only to crime fighting communications? That’s what a kid might think. As a curious adult I read the instructions completely. No mention of what you could transmit. I imagine a guy could rig up a cordless phone to an audio source and pump music into it. Is it legal? Hard to say. But I bet plenty of people have help up a phone to a speaker and said “Listen to this!” Do the instructions for these wireless headphones come with a list of things you can’t do with them?
We’ll know more once mine arrives.
Random food for thought.
- April 20, 2019 at 8:29 am #110955
The Rolls would still sound better than AM as AM tops out at 5K with the 10 klz bandwidth. FM tops out at 15K so any quality FM transmitter should be pretty flat from 30Hz-15Klz. That it only gets to 12.5K, and probably with drop out at that, tells me it’s not that good an item.
- April 20, 2019 at 10:00 am #110956
I’m sure the receiver in those ONN headphones suck. I think those also can be wired.
I’m thinking we can find a better device but these are just to start our efforts. I’m talking about this on Facebook quite a bit and also promoting The New Radio Revolution’s site as a Hobby Broadcast set of frequencies is what we wanted to petition the FCC for. Now we may not have to unless by the agent telling me this and my posting it and starting a swarm of hobby broadcasters ordering the ONN headphones may cause the FCC to finally allow makers of FM transmitters like the Whole House FM Transmitter and C. Crane to start pushing this. The NAB should be jumping for joy now that I’m promoting this and getting the Pirates to think about this. I’ll go to some Pirate sites I know and post it too if we can find some great devices.
I even had some folks who work in Radio congrats me but if it weren’t for some folks daring me to call the FCC agent that visited me maybe it would not. Call me crazy but it was a temptation that did pay off.
- April 22, 2019 at 2:19 pm #110963
Just heard back from one of the sellers of a Rolls HR70. He reports that it has no FCC certification numbers, no required FCC compliance sticker or label, and near as he can tell has no connection with the FCC in any way.
I suspected as much as neither the FCC nor Part 15 was mentioned anywhere in it’s advertising or the manual.
Conclusion: Not legal for sale in the USA. Period.
Not that this stops anyone from selling illegal transmitters. But for those of you wondering. It’s a big no from me.
- April 22, 2019 at 6:11 pm #110966radio8zSenior Moderator
Total posts : 232
Thank you for replacing opinion, hearsay, and speculation with the facts you posted.
- April 22, 2019 at 10:08 pm #110968
Thanks Tim I definitely won’t be getting that thing. Now we know the real deal.
- July 19, 2019 at 3:00 pm #111936RobertSParticipant
Total posts : 3
I’m new to the forums, but not new to Part 15 FM. I’ve been running Part 15 Low Power FM since 2001. Jolly Roger radio FM in Minnesota. I’ve had EDM, Ramsey 25b, 35b, and 100, a whole house and a CCrane. Loved those Ramsey transmitters, but all good things come to end. One by one my beloved Ramsey xmitters failed. I bought a Rolls HR70 and here is my review. The station is stable, sounds good, and REALLY reminds me of Ramsey 25B both for sound and signal strength. The setup is a little touchy, you really got to tweak it a bit, but not too bad. I understand my 25b was 25 milliwatts the Rolls is supposedly 40 milliwatts. My range with the Rolls is exactly the same. I’m not an electronics guy. I cant give you any real technical differences, only my experience. I always go out in my car and listen to the car radio, along with a boombox on the passenger seat. EXACTLY the same as my 25b for range with both using the telescoping antenna. If I attach a custom made Dipole using a coax cable to the antenna port. I get out a little further, but again, exactly the same range for the two transmitters. I have to say I like my Rolls so far. I know the some may get excited about range. But, I’ve been doing this for 18 years, and never had an issue. There is a professional AM station three blocks from my house. I know the owner well. He knows about Jolly Roger FM and he always asks how it’s going. I even did an interview at his station about it. I was just careful not to give away too much info. Just talked about Part 15. But I digress. The Rolls seems to be the closest thing I’ve found to an EDM or Ramsey transmitter replacement. Well that’s my 200 cents.
- July 19, 2019 at 3:33 pm #112079
Like how you said the Ramsey’s one by one conked out! That is because the output chip they all used was the GAL-5 that was very susceptable to any electrical shocks from your finger if touching it or going near it with static electricity. Whether it was on or off! I had a Ramsey 25B way back when I started doing this(didn’t know it wasn’t legal at the time) in Canada and I had to get from Ebay a large supply of GAL-5s from China and I got tired of having to replace them and they are tiny surface mounts and not too easy!
Later I found out that a 2.2uH coil across the antenna to ground will protect the output on these transmitters.
- July 19, 2019 at 6:21 pm #112081
As it was stated previously in this thread, the Rolls transmitter is not legal for use in the U.S. (or Canada). It is highly unlikely that 40mw output, even to a bad antenna, will produce a legal field strength.
BETS-1 certified transmitters in Canada are allowed much more field strength than the U.S. (100uv/m at 30 meters, as opposed to 250uv/m at 3 meters), and they generally have around 1 microwatt output (about 40,000 times less than the Rolls).
I also note the poster giving the review was careful not to give out details on the range he was getting. It it is significantly more than 200 feet to a portable radio, and it would be with that kind of power, then it’s not legal.
Given that the transmitter isn’t certified, and doesn’t even pretend to be Part 15 compliant, I think that users of said transmitter would be in a whole lot of trouble if the FCC comes a knocking (regardless of who else tolerates it). It would be difficult to convince an inspector that you were attempting to be legal, and just made a mistake, when using a non-certified transmitter.
- July 29, 2019 at 1:58 am #112123
It been along time since I have been up here with Carl and Neil.
Anyways lets get down to the rules that are for broadcasting on the FM Radio band.
Ok part 15.239 states the opperation of frequencies of 88-108 Mhz.
Now go to subpart C of 15.239
It states The field strength of any emissions radiated on any frequency outside of the specified 200khz band shall not exceed the general radiated emissions limits in 15.209
If you look under 15.209
You will see 30-88mhz is aloud 100 uv@3 meters but there a special notes for the frequencies from 76-88mhz and it refers you to 15.231
Part 15.231 periodic operation in the bands 40.66-40.70 Mhz and above 70 Mhz
(a) The provisions of this section are restricted to the transmissions of a control signal such as those used with alarm systems, door openers, remote switches, etc.. Radio control of toys is not permitted. Continues transmission, such as voice or video, and data transmissions are not permitted.
This kills any transmitter like the decade or any other legal part 15.239 transmitter being aloud to transmit below 88mhz and almost every part 15.239 transmitter will only go down to 88.1 Mhz.
If you look at any transmitter that falls under the 15.236 rule will never transmit up in the 88-108 Mhz range. I am hoping with Most channel 6 tV stations moving into digital transmissions that they will expand the frequency down to 87.9Mhz but realize that they only reserve that frequency for non commercial education broadcast radio station and I only know of 2 stations in the entire country that can operate on 87.9 mhz. They are very low power stations running around 10 to 25 watts of power at that.
Channel 6 TV stations are being moved in to the UHF frequencies for better digital streaming their signals over the air. I have been an electronic engineer for more than 47 years and work in broadcasting as well. Along with working for Raytheon and NASA.
Which all these jobs require me to get a license to work on transmitters. Also been a Ham radio operator for 43 years.
The FCC knows you are going to broadcast with part 15.239 transmitters but the headphones they probably think most will just listen to their favorite programs from a TV or radio . Now even an Ipod or phone. Anyways Not sure if everyone has seen the distance chart that Ramsey use to post if you used the 250uv@3meters.
It showed distances greater than 200ft but you would have to have a very sensitive receiver to achieve these distances.
I hope this will help out with distance under part 15.239 and 250uv@3meters.
These are expected field strengths at these measured distances.
Wow all my really old post must of went away because I have been on this site
for more than 14 or 15 years.
- July 29, 2019 at 3:46 am #112129RichParticipant
Total posts : 188
RE: Not sure if everyone has seen the distance chart that Ramsey use to post if you used the 250uv@3meters. … I hope this will help out with distance under part 15.239 and 250uv@3meters. These are expected field strengths at these measured distances.
A caveat: that table shows the fields that would exist in free space. However the fields radiated from an antenna near the earth will produce reflections from the earth, as well as from other nearby reflecting objects and surfaces such as wires, metal buildings/roofs, signs etc. Those reflections can either reduce, or increase the field at each given location, and can/may result in a field that exceeds what is produced under free space conditions.
FCC field agents measure the fields radiated from Part 15 systems at locations near the surface of the earth, which will include the effects of all its reflections. Those fields could be larger than expected when using the Ramsey table as a reference.
- July 29, 2019 at 9:44 am #112130
- July 29, 2019 at 9:51 am #112132
I am thinking that these measurements were done in a wide open space what most people do not have.
I was just posting them to show that a more sensitive FM receiver with a possible
elevated antenna could maybe receive a part 15 transmission more than 200 ft away.
This was to show you may be able to set up your FM transmitter outside in a weather proof box at a height above your roof top of your home. Then a neighbor down the street maybe able to place an outdoor FM antenna on their roof with a very sensitive receiver and get your signal. Which would be better than the standard portable FM Receiver .This is the only reason why I place the table up there. Not for measuring your transmitter but to show possibilities of your signal being pick up further than 200ft away. I know that I have tried out various receivers and found some to be far more sensitive than others. Most receivers did cut off around 200ft at 250 so week hard to hear.
The strangest thing I have discovered was that the Realistic DX 360 is very sensitive on FM that it was picking up my FM signal past the 200FT mark while almost every other radio I had just stop around that 200 ft mark. I know some very sensitive car radios have been reported to pick up part 15 radio signals 600 ft away. The chart could be used to reference the sensitivity of a receiver you want to purchase. A lot of receivers will give their sensitivity in the specifications part and you could use this to compare to the chart what the signal may be like at that range.
If you wanted the best range of all by a receiver. Then you could check and see if the receiver has the sensitivity of .5uv with a s/n ratio of 20db
This is just an example but it just a way to get a possible range found on the chart but if it does not it still may get you closer to a distance you want. People with indoor stereos with an antenna on their roof will have a better chance of picking your station up on FM.
Anyways it was only to be used as a reference to choosing a very sensitive receiver.
hope this clears things up a little bit. I am going to let everyone get back to talking about part 15.236 and the new transmitters being made under that rule.
- This reply was modified 4 months, 1 week ago by Seankw40.
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