- 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
Total posts : 429
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 1 day, 2 hours 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 21 hours, 56 minutes 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
Total posts : 429
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.
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