You all know I have been broadcasting on Fm for quite a while now.
You all know I have been broadcasting on Fm for quite a while now.
I have loved every minute of it, but with all the recent Nouo’s issued nearly every month I am re-thinking my broadcasting options.
My choice to use Fm for my part 15 operations was basically out of necessity and convenience. The main reasons : Fm is plug n play, the antenna if you use any at all is easier to setup and just about every listener out there prefers FM over Am.
I actually like both am & fm, heck i like silly sideband too. USB or LSB it does not matter to me. Anyways, back to the subject at hand.
FM is getting way too much bad publicity lately, mostly with the FCC.
As we all know most of the NOUO’s issued have been for FM operators running anywhere from 1 mW to 100’s of watts.
The 1 mW NOUO is a shocker to me, but hey there it is in black and white.
My funds are squeezed to the point my wallet looks like it was run over by a Steamroller, so a fine or NOUO just won’t do. Even if i had thousand’s of dollars in the bank, i still would not want trouble with the fcc.
So to avoid taking anymore risks I will be working on switching out the SStran fed into reversed coax for a bottom loaded antenna and placing the fm on the reversed coax or just shortening the whip antenna that came with my Ramsey FM 25b.
I have had trouble with one of the Talking House transmitters so I am thinking about placing the SSTran in a watertight tupperware container and using the motor driven ferrite coils from the old TH to help tune the antenna to my frequency.
This should eliminate any chance of a NOUO etc.
Limiting the FM to the house and just a few feet from my Faraday cage home should do the trick nicely. I could have used the Scosche transmitter for FM, but unfortunetly it doesn’t have any open frequencies I could transmit on and replacing the batteries every other day is a real pain in the neck.
At any rate, I will keep everyone posted on my progress.
Until then, Keep Rockin’
Two Thoughts
I understand your caution, rock95seven, and have also kept things “on the low down” to avoid attracting unwanted notice.
Two questions popped into the head after reading your message:
1.) What is “reverse coax?”
2.) Do we have a way of knowing what kind of transmitters were used by NOUO victems? Has anyone ever been cited for a Ramsey FM25 or other common-to-part 15 transmitter?
Good Questions
Hi Carl,
To answer your questions , ill start with question no. 2 first.
“2.) Do we have a way of knowing what kind of transmitters were used by NOUO victems? Has anyone ever been cited for a Ramsey FM25 or other common-to-part 15 transmitter?”
Not that i can tell, since the f.c.c usually does not include the type of transmitters used in the NOUO, which is unfortunate for us but works to the f.c.c.’s advantage i suppose. From what i understand the Ramsey FM 25b can generate somewhere in the neighborhood of 18 mW or more?
And test’s conducted here at my place with two different antennas has yielded different signal patterns with the same results in range.
With the rf power turned all the way up and fed into a dipole 5 1/2 feet off of the ground i was able to cover 1/4 or more but it was directional. On the Frank N Tenna I just built recently, and again with the rf turned all the way up, i was able to cover 1/4 to 1/2 mile in most directions with the exception of the Northwest where a hill blocks the signal reducing coverage in that direction to 900 feet.
There were drop outs from obstructions between my car and the antenna here at home and it was much worse with a Sony Walkman.
With the power turned all the way down, the Ramsey FM 25b covers most of the mobile home park with the ground plane antenna at 9 1/2 feet from the ground. Which is still over 200 feet.
There are 150+ mobile homes here and part of the park is lower in elevation than the rest of the park, i am on the upper end.
To answer question no.1
1.) What is “reverse coax?”
Basically i have the SStran fed into the shield of a 8 foot section of rg-6 75 ohm coax. Using the cable in this fashion gives the effect of leaky coax. But a lot cheaper. The cable was pinned up in a corner vertically. Range was limited to inside of the mobile home and about 8 feet outside.
Aversion to NOUO
Barry,
Your thoughts regarding receiving a NOUO are reasonable but you may be a bit over conservative on your approach to this. It appears that the NOUOs result from complaint driven inspections. If you run a clean operation, don’t cause trouble, and try to maintain technical compliance the chances of a complaint are minimal.
Having a transmitter which is capable of tens of milliwatts RF output (my Ramsey 25A can produce around 50 mW) does not by itself create a problem. I had a car with a 380 HP engine but never was arrested because I used it responsibly. Same for my FM tx. It is capable of producing 50 mW but I keep the antenna short enough so the field strength is not indicative of a full 50 mW power radiation. Because of the mismatch very little power is radiated. The 200 foot approximate range (speed limit) I get is not a guarantee of compliance but it should be close enough.
I have been playing with part 15 AM for over 50 years and part 15 FM for about 20 and have never had a problem from the FCC or anyone else. This is, in part, probably due to me not pushing the limits regarding range or programming. Will I ever get a visit or NOUO? Probably not but if I do I will comply with the directive and get on with my life.
You need to decide what you are comfortable with but I am comfortable with doing what I can to be compliant and not worrying about it.
Neil
Neil Made Me Think
Neil, your comments made me think of another point that I think some of us tend to forget. Is it not true that the first move on the part of the fcc is to send a letter? Then, if you fix whatever the letter mentions, they go away. The inspectors do not actually knock until AFTER a letter is ignored. Is this correct?
That is my impression
That is my impression Carl,
They leave you alone if you are cooperative and polite.
I have never been in trouble with the F.c.c. and would like to keep it that way. While it is true, i may not always agree with some of their decision making (rule making too) but if there was ever a problem with my station i would fix it and inform the F.c.c the problem was solved.
Of course if they want to inspect i would not reject the request.
Neil made some good points too. If you do your best to stay as close to compliance then there really shouldn’t be a problem.
Awhile back my wife made a good point that echos the comments for this thread, how many people really know who to call if there is a problem such as interference? If i don’t play anything offensive then there shouldn’t be a problem at all. I have rejected several services that cater to part 15 stations because the content they offer truly was not safe for broadcast.
If i hear one F-Bomb while reviewing their content i immediately reject their offer and go on about my business.
As for part 15 fm, i could reduce my coverage drastically by using a map from Google Earth like this one : http://radiodizzy.webs.com/200radius_fm.jpg which hopefully would put my station well within the 200 foot range expected in the rules.
Using the ruler function and place marks in Google Earth i was able to map out 200 feet or rather just under 200 feet as i had a hard time getting the ruler to measure exactly 200 feet so i settled with 199.40 or so. As you can see in the map, that should in theory keep my fm station as close to compliant as possible.
So the only thing to do now is adjust the whip antenna just as Neil has done to the point where my signal is close to what the map says is compliant. There is no way to predict what the weather or metal objects will do to this signal. I wouldn’t be surprised if some days the signal covers more than just 20 homes in my map. Then again my signal may only be good for the homes closest to me and anyone who might tune in to it while they drive through the park.
So maybe i am being too cautious but i still want to go ahead with building a bottom loaded antenna for the sstran. Now if it would just stop raining and being so darned hot. lol
I am actually listening to the sstran on 800 khz using the ferrite coils out of a TH 4.2 and 9 feet of copper wire, sounds great all through the house too.
FCC Visits and Other Stuff
Carl, I don’t know first hand how the FCC operates but from reading several NOUOs it appears that if they decide to issue a NOUO then they attempt to speak with the person at the time of the measurement probably to ensure that the NOUO was received. OTOH from reading some posts on the radio boards sometimes they talk to the station owner and resolve the difficulty without a NOUO. Again, I only speculate about this.
Barry, your approach with the map seems reasonable but don’t get too hung up on the distance being exactly 200 feet. As you know many things affect the range and even the 200 foot guideline from the FCC doesn’t mention what receiver is used. It is just a guide such as “put a pinch of salt in the stew”. That being said I have chosen to err on the conservative side for my FM range. It seems that even with this short range at your housing site you can reach many folks with a legal signal.
Knowing that your signal is such that someone nearby may be listening is part of the fun even if you don’t intend this. Your investment in a good antenna for the SSTRAN is worth the effort in my view because compliance is much easier to achieve realistically on AM than we can do with FM short of a certified and unmodified FM transmitter.
Play by the rules as best you can and have fun.
Neil
Another Good Thread
Good threads pop up all the time here at part15.us and this is one of them.
What gets me stunned is the talk of reaching 200-feet or several houses. My FM attempts, admitting that the transmitters are indoors, are hard to get in rooms of the house and nearly gone outdoors. Does that mean that everyone else puts their FM transmitters outdoors?
Fm is inside
Carl,
My FM Tx is inside the house feeding the antenna on the front porch with 75 ohm coax, or rather it was. But when i first got back into part 15 broadcasting 3 years ago i was using the telescopic whip antenna that was supplied with the Ramsey Fm 25b. It didn’t do too bad considering i had the transmitter sitting on my desk with the whip fully extended.
With the rf output turned to the maximum i was reaching out of my mobile home as far as 600 feet and more in some directions.
On cloudy days i could just barely hear it on a factory car stereo as far as 0.41 miles or 2,142 feet in the Supercenter parking lot behind my house. The transmitter is always set to mono to squeeze out a little more range.
I am a bit reluctant to place my sstran outside, this subject has come up at least once on Part15.us, my concern is theft.
About a week ago the vanity hub cap was stolen off of our minivan, not two or four, just …. one. Odd huh? The police have stepped up patrols in this neighborhood since there has been other thefts in the area as well as other crimes. So you can see why i would have second thoughts about placing my sstran outside.
I just don’t think it would do as well if the antenna was inside this metal cage. As i have been responding to your posts i have also been enjoying the smooth sounds of Amplitude Modulation courtesy of Sstran.
That is truly an amazing rig and i have yet to listen to the station outside so i have no clue how well it is doing beyond the inside of the house. I chose 800 khz for testing but will probably have to switch up to a higher frequency when i am ready for a more permanent install. At night here, 800 CKLW (one of many stations i grew up listening to) does manage to make it into Kentucky but it is not nearly as loud as it was when i lived in Ohio. So even if i chose 800 khz it would only do well as a very local signal and probably would not be of any use at night beyond my yard.
But to answer your question, I have heard that some have their fm transmitter outside placed in some kind of a waterproof container while others have the transmitters on the second floor in front of a window. I think KRQO has their C.Crane fm tx sitting in a window while some one whose name escapes me at this time had put their part 15 fm transmitter on their roof.
Most likely to over come obstructions that might reduce their coverage.
ERP
Maybe some of the fear about noui’s stems from a misunderstanding of the difference with how the medium wave vs the vhf part 15 power’s are measured. On AM (or actually medium wave) if you build the transmitter yourself (apparently applies to kits) you can measure the power input to the final amplifier and as long as you can show 100 mw or less input and the antenna and ground are less than 3 meters long then you have a legal setup. Notice I said input power, not output power. There is no restriction on the ERP (effective radiated power) or the range. Anyway discussing input power and getting the most effeciency from your transmitter and antenna/ground are reasonable discussions for such a setup on the AM band. Theoretically if somehow your station could be made and located in such a location that it rivalled the AM stations in range it would be legal unless someone complained of interference and then it would still be legal but you would have to shut it down anyway. FM is completly different in how the FCC looks at it. Discussions about input or output power are completly irrelevant. You can purchase a 10,000 watt commercial FM transmitter and operate it perfectly legally. The FCC only looks at ERP (what power effect your setup has) You would have to locate the transmitter in a shielded room and have a resistor bank to run the output through and finally deliver what’s left of the power to an antenna that when measured in any direction from the antenna the power does not exceed 250uv/meter or .01 millionths of a watt ERP ( I just got those numbers from wikipedia so I didn’t check the FCC site but it’s not very much.. Anyway AM (medium wave (You could run FM on medium wave and AM on VHF and the restrictions follow the frequency not the mode))) is a lot safer from a legal standpoint. Just locate your 100mw input homebuilt transmitter at ground level and make sure your antenna is less than 3 meters. Those of us that elevate our antennas or use loaded antennas are pushing the limits of what is allowed as proven recently by the issued citations. Using the car analogy someone mentioned earlier, On FM you can run a top fuel dragster with many thousands of horsepower but you are only allowed to go 5 mph. On AM you can go any speed you want but you have to do it with 2 horsepower!! 🙂
NOUOs with really low power
First of all, Dave. that’s the best analogy
I’ve ever heard, regarding what you can do
with AM and FM Part 15, and comparing it
to cars and horsepower and speed.
I know there have been some discussions
about NOUOs for FM operations that were
running a milliwatt or less. Does anybody
know any details about what happened in
these cases? Or – where do I go to read
about them myself?
Best Wishes!
Bruce, MICRO1690/1700
Staying Low-Key
Bruce,
I am not real sure whether or not there was a NOUO issued for more or less than 1 mw but i have seen a few stations that looked as though they might have been trying to stay legal but were just above 250 uV/m.
Here are 2 examples:
http://www.fcc.gov/eb/FieldNotices/2003/DOC-292262A1.html (323 uV)
http://www.fcc.gov/eb/FieldNotices/2003/DOC-297158A1.html (352 uV)
These NOUOs were just above the limit but look at the distance which is probably what was the deciding factor when the fcc issued the notices.
My mind has changed a bit after reading the recent enforcement actions. Just to be safe, i have reduced the power on the Ramsey to the point that it is noisy on the other end of the house. That is, i have turned the rf output to the point it is actually noisy on a Sony Walkman set to “local” and received at a distance of 60 feet.
I believe my home is a 16 x 70 3 bedroom.
The whip antenna is only half way extended and it takes some fiddling with a radio on the other end of the house just to get clear reception.
Next i will be making a coil for the sstran and mount it under a 9 foot whip on the front porch. As of right now, the sstran with a ferrite coil and 9 feet of copper wire, i can hear my station just about 6 feet out from my house with a little noise. After 6 feet, forget it, noise takes over and my AM station is no longer there.
I still have not chosen a frequency for the AM just yet but it will more than likely be in the x-band.
Before i go i want to mention that I read a NOV which was issued for a company here in London,Ky dated for 10-21-09, seems like if there was any question whether my station was causing intereference or was out of compliance then i would have received a knock on the door or issued a nouo while the fcc was dealing with this pager co.
http://www.fcc.gov/eb/FieldNotices/2003/DOC-294237A1.html
So i tend to agree with the statement that most nouo’s are complaint driven and if there was interference caused by my station, the fcc has had the opportunity to deal with it if they were in town issuing a nov.
Hold everything 🙂
Yes, the distance is the factor, without question. 352 uV/M @ 100 Meters is a completely different thing than 250 uV/M @ 3 Meters
IIRC, power would change exponentially with distance so 350 uV/M indicates far, far more power than that permitted at the 250 uV/M @ 3 Meter level.
Just sayin…
In Perspective
scwis put this in perspective with his comment. Further math shows that 350 uV/m @ 100 meters suggests an intensity of 11,666 uV/m @ 3 meters, 47 times the limit.
It also suggests that with a receiver with a 10 uV sensitivity and a decent antenna (car antenna) and a line of sight path that the range of this system would be about 3500 meters which is 11,480 feet.
EIRP formula
To calculate EIRP from the FCC field strength reading, the formula is
EIRP = [(E^2)(d^2)]/3(10^13) , where
EIRP is the effective radiated power in watts with respect to an isotropic radiator,
E is the field strength in uV/m, and
d is the distance from the antenna in meters.
For example, if the field strength is 323 uV/m at 60.8 m,
EIRP = [(323^2)(60.8^2)]/3(10^13) = 1.286(10^-5) W = 12.86 uW.
This is the EIRP for the Schubert NOUO linked by rock95seven. The Iglesia Vida Cambiada NOUO corresponds to an EIRP of 51.8 uV.