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Howdy fellow part 15 ites. I’m a student at ITT Tech in Woburn MA and my group decided to do a project on Pirate Radio for our group dynamics class.
I must say I’ve been blown away by the possibilities of Part 15 AM. I done some research on a good transmitter. I was going to purchase a Ramseys AM25, but then saw that the general consesous is that the sstram AMT300 was the way to go. I have since ordered one and cant wait for it to arrive.
Howdy fellow part 15 ites. I’m a student at ITT Tech in Woburn MA and my group decided to do a project on Pirate Radio for our group dynamics class.
I must say I’ve been blown away by the possibilities of Part 15 AM. I done some research on a good transmitter. I was going to purchase a Ramseys AM25, but then saw that the general consesous is that the sstram AMT300 was the way to go. I have since ordered one and cant wait for it to arrive.
My question is this. I realise the AMT300 is built to put out 100mw. However does part 15 rules provide me a way to put out a more powerful signal if I’m using this on campus?
Total posts : 45366Hi,
I have both the AM-25 and the AMT-3000 and both work well. You will be happy with the AMT-3000, but with either of these units, don’t expect great range unless you build a legal coil loaded antenna with a good ground. Check out the other posts here for grounding information. The AMT-3000 has an advantage here because they post the antenna plans on their website. I don’t know if the SSTRAN antenna works with the Ramsey or not since it was specifically designed for the SSTRAN unit.
There are different part15 rules that can be applied for campus AM operations, but they are NOT based on power. They are based on measured field strength at the borders of the campus. Check out the part 15 rules. Let me know if you can’t find it and I can dig out the links and post a followup.
Unfortunately, FCC acceptable measurement of field strength is beyond the capabilities of most people and groups, so setting up a > 100 mW legal station on a campus can involve $$$ for someone qualified to come in and perform the measurements. I am not saying don’t do it, I am just giving you some idea of what is involved. You can always use the 100 mW. input (NOT output) and 3 meter antenna rule and be legal on or off campus.
I taught in an EET program and for one of our communication labs we would set up a AM-25, attach an antenna and CD player, check it with a spectrum analyser, and the students would tune in on their way home. Never got much range beyond the parking lots, but it was still fun. Just so you won’t be disappointed and know what to expect, the indoor range was lousy…could not hear it 20 feet down the hall. A 3 meter antenna out the window did get out much better.
Neil
Total posts : 45366Neil,
Could they use a Radio Systems or LPB transmitter with the antenna coupler and use the existing electrical system to run the AM station?
They are an institution and therefore would qualify to use 10-20 watts carrier current as long as part15.209 field strength was observed.
I used this at the high school I do a radio broadcast program in the past but I had to remove it because the signal bled into the audio/visual equipment of the school visual arts dept.
But if there is no such problem using this setup, I’d go with the carrier current transmitting.
Trust Neil, the SSTRAN AMT3000 transmitter is a much higher quality unit than the Ramsey, the sound is cleaner and more crisp, plus the added benefit of the base loaded coil, which can be built or bought ready made is a bonus…
Good luck…
Radiopilot
Total posts : 45366There are special provisions for campus radio, by the way.
And it all depends on what you have for “campus”. Stanford University’s campus extends all over Palo Alto, so it’s old campus radio used to extend throughout PA as well.
You can bcast to the boundries of your campus – where ever they may be.. now, if your campus is like a grade school – then you will be very limited on your creativity – but if your campus spans several locations… 🙂 You see where this could take you?
There is a fellow who has been operating a “campus radio” in Florida – his campus is the entire county because he has a school that teaches bcasting.. thats how he sells it to the FCC, and while the radio dogs will start barking over this being wrong, or not in the books, or illegal or whatever – it really is FCC and not the know-it-alls who have the final say …
Total posts : 45366I agree with you MLR, we have a college here in Savannah, Savannah State University, WHCJ-FM, and the signal is 6k watts, not bad for a non profit org.!
This college radio has been around for quite some time, but in this age where you have to jump through hoops just to get 10-100 watts for non profit types, it amazing they got away with 6k watts.
Savannah College of Arts and Design (SCAD) is similar, if they had a broadcast station, they too would cover the whole city of Savannah, as the student halls and buildings are scattered throughtout the city!
Going back to carrier current, it’s the way to go if all they want is a ‘local’ presence, but they could enhance it with the 100mw part15 AM’s to go along with it and transmit 1-3 miles in all directions, they have the audio setup already, just plug and play….
Radiopilot
Total posts : 45366Hi,
Good comments about campus carrier current stations, but I wonder if ITTPirateRadio (BTW I would rethink that “pirate” name) is intending to have a broadcast service on campus rather than just experiment with occasional transmitting. Perhaps he/she could elaborate.
The ITT campuses I have visited have been nonresident and consist of one or a few buildings. This is not too good a market for carrier current.
Some related, but a little off topic comments. For two years as a student, I was the chief and only engineer for a campus radio station This is a huge campus, and at the time, the studios were at the affiliated Conservatory of Music located about a mile from the main campus. This was a 24/7 operation with the CM students at the studio spinning and talking.
The system had a transmitter in each dormitory (if I recall, 5 at that time) linked by leased phone lines to the studio. It had good coverage in the dorms but very little outside the buildings. The transmitters were simple plate modulated class C 5 to 20 watt units which were matched to the power lines with L/C tunable output networks. Some were home built by engineering students. I built the 20 watt unit. The only complaint of interference while I was there resulted from someone on the production staff taking it upon himself to visit one of the transmitter sites and retune the matching network. The transmiter went into Barkenhausen mode and really messed up AM reception in the dorm. I was away for work section at the time and had to drive 60 miles to campus to fix this. We got a black eye from the licensed campus FM station because they were initially blamed for it. Folks heard the ID and thought it was them. The story goes that after I left someone connected a longwire antenna between the football field light poles and went on the air with one of the transmitters. A FCC monitoring station picked up the signal and paid a visit. This may just be hearsay, but considering the tuning experiment, it would not surprise me if it were true.
The staton had a good listenership in those days when FM was just getting started and produced some radio talent who went on to fame and fortune. Things can get frustrating in CC radio, but I must admit that it was a great experience and would encourage those who are interested to check it out.
Neil
Total posts : 45366As I’m just getting into this whole part 15 thing, please excuse me if I dong yet have all the lingo down. I’m not too shure what yall mean by carrier current. Anyway the purpose of this project is just to get the signal around our small campus. Maby when I get this thing home after this semester, I’ll see just how far I can take it.
I got alot of good ideas. Problem is, most of em suck.
George Carlin (WINO)
Total posts : 45366Hi,
The lingo does sometimes get in the way of things doesn’t it. Don’t be shy here. There are a lot of people here who will try to answer your questions and help you.
Carrier current (CC) AM radio is a system which the FCC rules permit for campus operation. Instead of broadcasting from an antenna as you will do with your SSTRAN, CC systems use building power lines and branch circuits to distribute the signal. The transmitter output is coupled to the plain old 120 volt AC line. The good news is that you can get really good signals inside the building, but the bad news is that power transformers block the signal. This makes covering large or multiple buildings complicated, either requiring multiple transmitters or networks which couple the signal across the transformers (dangerous and expensive). Don’t try this with your transmitter!
In my story in a previous post I mentioned we used leased non switched private phone lines. Back then campuses were not wired for a phone to every room nor did they have their own signal circuits which are so common today. Amost all of our engineering budget, which came from student fees, went to pay for these lines. That is why we built our own transmitters.
Based on your situation at campus as I understand it, CC is not the way to go. I would expect that with a good antenna you can cover your campus with a broadcast part15 legal signal. Start there and see if you are really interested in going further. You will learn a lot by using your transmitter at your home. I predict the first thing you will want to do is extend your range. That’s where the learning begins. Don’t give up because the range you get with a piece of wire antenna is not much. It can be a lot better, you just need to do your research and build a good antenna.
Your experiences and technical knowledge gained if you do this will make a great technical report or term paper.
Keep us posted on your progress.
Neil
Neil
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