- June 7, 2019 at 8:59 am #110812
Well, I’m new around here and I see there’s been talk before about low power broadcasting on or about 13.56 mhz. I’ve been messing around with low power broadcasting since I was twelve years old when I bought one of those Knight Kit tube type transmitters for the am broadcast band. The idea of doing this on one of the short wave bands really intrigues me. But, it looks to me like the actual radiated power on 13.56 under the current rules can be but a few milliwatts. My experience on the 20 meter ham band was generally bad if using less than 100 watts SSB. So, my question is: Is anyone here actually broadcasting around 13.56 and getting any results?
All comments much appreciated.
John/W9LWAJune 7, 2019 at 11:18 am #111398
Well, I was a lot newer around here back when I posted that, but I’m still wondering if anyone is making LPSW work…
W9LWAJune 7, 2019 at 3:48 pm #111409ArtisanRadioParticipant
Total posts : 566
There have been a few people in the past who have used the ISM frequency at 13.56 and have posted about it. If I recall correctly, range was similar to Part 15 AM stations that they had run, but that’s all I can remember (1/2 to 1 mile).
It’s important to note that on the ISM frequency you’re not limited by output power, but by field strength – to achieve that field strength you can use whatever output power and antenna you want.
I believe that calculations were done here to determine that with an ideal monopole antenna, you could have an output of a few milliwatts. You are not allowed a field strength over 10uv/m at 1600 meters (that comes directly from Part 18.305).
Part 15.219 is not limited by field strength. Even so, there are theoretical limits to the maximum field strength you can achieve with 100 milliwatts input to the final stage of a transmitter (even if that final stage is an ATU, as with the certified Talking House) and a 10 foot antenna/ground wire.
I suspect that background noise levels, as well as the type of receiver and receiving antenna would determine which had better range – there are probably more sensitive and selective receivers that can receive 13.56, and antenna systems would be smaller and easier to construct (and install). There’s also probably lower noise levels, particularly in non urban areas, so the theoretical maximum on 13.56 would be greater.
My guess would be that for ordinary, run of the mill receivers and transmitter installations, both would have similar ranges.June 7, 2019 at 5:17 pm #111416BrooceParticipant
Total posts : 49
I built a 13.560 MHz transmitter and that in itself was fun.
It was a long time ago. A couple of different people did it. I can come back with more tech info later — I can’t stay on here too long right now.
The XMTR has a few mW of power in the output. I still have it.
Amplitude modulated, of course.
Great fun. It’s signal traveled many many blocks down the street to a Sony ICF-2010.
You won’t hear the AM signal skip off the ionosphere, as we know. I don’t think any kind of
receiver/antenna combination, no matter how good, could do that. There are experimenters getting VERY long distances with the digital modes. But that’s another story.
Gotta go. Hope there are no misprints here.
Brooce, ConnecticutJune 8, 2019 at 9:30 am #111428
I think it would be interesting to broadcast on shortwave, but it doesn’t sound very practical in the US. Licensed sw broadcasting here is limited to transmitters 50kw and over which puts it out of range of almost everyone. It sounds like Part 15 restricts the power so much that it’s not practical, either. I posted the original question hoping I’m wrong about that.
The solution would be to allow unlicensed sw broadcasting of a few watts or maybe allow it if one were a licensed ham operator. Unfortunately, after all the flak about LPFM, I don’t see the FCC allowing LPAM or LPSW anytime soon, no matter how empty the bands otherwise become.
W9LWAJune 9, 2019 at 10:49 am #111435
W9LWA I saw you on The Initiative (The New Radio Revolution) and sent you the secret Elite Pasword so you can see some of the previous rough draft petitions we were working on.
At first it was FM but after finding this would never fly we switched gears to AM (Since its a dying band) and Short Wave looking for 2 miles at 40 dbuV to a Tecsun PL-380 or something that measures dbuV.
No you should NOT be required a Ham license to broadcast and on as little as 10 Watts AM it will cover 3 miles easily to most acceptable Radio’s that perform as they should. Since there has been little or no interference complaints with 10 Watts I believe we need to start there.
Please take note as a rebuttal against the entities who will try and kill this before it even hits the FCC’s table for viewing because they’ll say that this is just another way to legitimize Pirate Radio and as a rebuttal we need to think fast. One way is to promote this is New Zealands GURL General User Radio License very easy similar to signing your name and they don’t have issues with Pirates as this curbed this activity. Australia allows a whopping 400 Watts on medium Wave and we’re not asking anything near this power.
The Legacy was started as an Album Rock station playing the genre that was cut off Radio after 1984 when Earth, Wind, and Fire was not played on MTV due to it didn’t meat the Album Rock status and they were sued for discrimination (Yea Right). Many stations were afraid to stick to their guns to this format in fear of financial and bodily harm. The Legacy and others like us should be allowed to exist and serve a niche format that is otherwise in danger of extinction. Low Power Hobby AM and Short Wave can help with this.
Hobby Broadcasters can offer emergency weather alerts by using a weather Radio and a VOX circuit or converting a CAR Stereo which many new car stereo’s have EAS and Bluetooth capability. Simply use a Bluetooth audio sender to the car Radio and connect the car Radio to your audio processor and you have a cheap, effective EAS system as my broadcast engineer friend found his car Stereo does this. You can find wreaked cars with perfectly good Radios like the Kenwood that has EAS built in. This rebuttal can be used as I’m sure the enemies will try and use this to stop us we have to think FAST don’t give any bullet holes to kill us.
I gave you my number in a PM on The Initiative and this is where we need to do talks about such a service as this website is dedicated to this very activity. It was something I tried since June 5, 2015 but due to the lack of an attorney we could not get anyone to take the website, nor any of this seriously and the idea was often laughed at.
Now our dream can come true if we unite and make this stand as Hobby Broadcasters who want to make this change to make Radio more diverse and the dying band of AM is the place. I also strongly propose that C-Quam AM Stereo be a mandate for this service since an FM Pirate becomes an FM Pirate due to the Stereo ability. Forcing manufacturers like Procaster, Rangemaster, Talking House to make all of the Hobby Broadcaster service transmitters C-Quam AM Stereo will show ex pirates that this service meets their needs and no more need to use an FM transmitter that often causes interference with the Aircraft band and other services. The FCC is concerned with interference so make this service and C-Quam AM Stereo and you’ve killed the need to Pirate. Lets get this done 4 years in the making.June 9, 2019 at 2:21 pm #111437
Thanks, Legacy. I saw your message there and will give you a call. I agree a ham license shouldn’t be necessary for any of this. I just thought adding some non-ham sw frequencies to the ham allocations for broadcast transmissions only might have a better chance for low power sw. The way the federal government has this thing about pirate broadcasting these days, requiring a ham license might let them feel less like they’re giving in to pirates by expanding low-power broadcasting of any kind. (No, it doesn’t make much sense, but politics rarely does.)
Around here, the FM band is getting pretty full so I expect AM is going to have to be the way to go for a local audience. I think the fellow from Kentucky proposed something like 30 or 35 watts with roughly a thirty foot tower. I suppose that would work and it would be a great addition to a town like mine where the local AM has been off the air for quite a while. I guess I don’t know what happened to that prior AM petition. From my usual sources it looks like it was filed but nothing ever happened. Perhaps you know more than I do about that.
But, that’s not really Part 15, is it? I wouldn’t mind seeing an increase in allowable Part 15 power on bands like AM and SW that are being abandoned by commercial and NFP stations. Probably less restrictions on antennas and ground wiring, too.
I think it’s worth a shot.
W9LWAJune 9, 2019 at 2:41 pm #111440radio8zSenior Moderator
Total posts : 247
Please try to keep to the original topic when replying, especially to questions pertaining to a specific topic. Though TheLegacy’s post is interesting and deserves a read it did not address the question posed and could have been better presented in a new thread.
NeilJune 9, 2019 at 3:07 pm #111442
Low power SW does work and a few Watts or 100 mW can surely travel under good conditons.June 9, 2019 at 3:22 pm #111444radio8zSenior Moderator
Total posts : 247
And you know this how?
NeilJune 9, 2019 at 3:36 pm #111446
Here is proof of my statement courtesy of another follower on a forum and on my radio stations Facebook page who presented me this video. I hope everybody will like.
https://lm.facebook.com/l.php?u=https%3A%2F%2Fyoutu.be%2FpwXCiuRfIY8%3Ffbclid%3DIwAR2wdgvXSaq1hTGY-GG7jjFmNeWFGhPe4ZOLtOPfKVdf3htXi-L4-pIhYHQ&h=AT3U7VwLu1Z3UZjQ9Mf3NeSUlOiWfKq3AnYwLqUWQ3zaYCp5V6bLp7DXwMi6xsrwwfvXSEPnhkbxiFUSCkbUsXKDXIBe0RMa2VjWbSqcDf4HMS6-Z0MyTsQL0ty3iWDT7wM0June 9, 2019 at 4:56 pm #111448
Indeed, there are plenty of stories of hams working the world with less than a watt. Ok, lots of times that was with CW and appreciative listeners willing to tough it out with a poor signal in order to get the qrp contact. But, in SW broadcasting we shouldn’t have to deal with the pile-ups hams do with two way communications. Working the world with less than a watt is great except when there’s a guy with a kilowatt and a beam on top of us. Avoiding that should make a huge difference in getting the signal out with SW Part 15.
I think SW would be a great addition to any AM or FM Part 15 station and share our local programs with a potential world-wide audience.
W9LWAJune 9, 2019 at 9:04 pm #111450ArtisanRadioParticipant
Total posts : 566
Amateur radio communication at the mw level is almost always narrow band type modes, such as CW. Beacons are essentially a narrow, CW pulse. It’s very difficult to communicate with SSB at those power levels, never mind AM, which requires a much greater bandwidth.
Mind you, it might be worthwhile attempting to use SSB on 13.56, just to see the kind of range you would get. I don’t think there’s any restriction on modes, just frequency and field strength.
There are reasons hams use SSB. Even some shortwave pirates use SSB, as it’s a much more reliable mode of communication at lower power levels.
I’ve communicated thousands of miles (from Vancouver, BC to northern Florida, and up and down the U.S. East Coast) using SSB on 10 meters with only 5 watts and a pretty suspect antenna (a quad band mobile clamped to a metal plant holder on an apartment balcony) – the actual output power from the antenna was probably under a watt). So you never know.June 9, 2019 at 9:21 pm #111452
I have had a good time listening to Russia on 40 meter ham around 7147. I heard it the other day my Tecsun Pl-365 and I will tell you that today is digital processing the side band does not have that weird sound of the drift of the clarifier. Once you get it locked in it stays locked in and sounds real good. On Side Band a lot of the noise that you would normally hear on AM is gone. That’s why C-Quam AM stereo sound so good as one day by accident I forgot to turn off the side band on my radio when I switch back to my station on 1640 and I was on the Lower Side Band and lo and behold I turned it in and got the Left Channel. I went to the upper side man to that end and I got the right Channel. I figured A-ha C-Quam is using the middle part of the carrier for the L + r and the upper side it’s just for the + r the Lower Side is for the minus l for the Left Channel.
That is why I think we have a good chance of being able to get out with low power anywhere between 5 to 10 watts.
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