At $12 from Walmart I am amazed that anyone is complaining about this little transmitter. Adding a simple wire to this transmitter gives about 50 to 70 feet of good stereo sound around my building. My friend has achieved considerably more distance with a quick knock up antenna and plenty of height. I have found that the best use for mine is part of my setup for watching movies online, and listening on my hifi. It's probably the cheapest way to surround sound anywhere. In a back-to-back comparison it outperforms my Talking House. It's definitely a good choice for 'audio' in a laptop to TV movie setup, if you plan on trying that out.
If my friends claims are to be believed (and he doesn't usually mess around) then it can even perform better than the TH in distance (under certain conditions naturally). It's a good transmitter to experiment with. I've already rehoused one and made it more suited to sitting on a table top with a better antenna and switchable mic. Using it mostly for my OTR.
Other things I plan to do with this is a transmitter (radio-mic if you like) for my guitar, needs better jack. For it's actual purpose it performs very well in a car. Why waste $70 on a C.Crane just to do that? Wire a mic to it and it's also got the makings of a pretty good baby monitor (or room bug) which should easily cover a house. If some people are experiencing something else, then maybe it's your receiver that is to blame? I've found that best effect comes from keeping the volume of your source well under half way. eg. I am listening to Pandora right now the volume control is about 40% of it's way. Interested to hear of any other ideas people have of how to adapt it for other uses.
Some folks like the Scosche, some don't - it probably depends on expectations and use. I have one set up as a transmitter and I used a second one this summer so I could retransmit TV audio out to my little apartment sundeck. I like to watch TV from the deck in the hot weather however while I could see the TV from the deck, I couldn't hear it without the Scosche.
For those who might have missed it, more Scosche info here:
http://part15.us/node/2006
http://part15.us/node/2015
After some tweaking i managed to get a 62 house coverage range with the C Crane. I had to turn up that resistor and add a 3 1/2 foot Dipole to it. so at my Freq that's about a half wave length. and at 300 feet or so that still legal under part 15 rules!
I'm not sure if this is kosher to post this here or not, but I'm auctioning some of my surplus Part 15 equipment (after deciding on using the Decade MS-100 for FM, and Rangemaster 1000 for AM). I just listed a BroadcastVision FM3001 (fully Part 15 certified) and will be listing others (including several Panaxis ACC-100 stereo units, again fully Part 15 certified) over the next few days - I'm putting the links to the auctions in the For Sale section of the Forum.
The equipment we decided to use for Artisan Radio is considerably better, in my opinion, than that we are selling, but also considerably more expensive! Part 15 FM was also problematic for us, since we're located in Canada, where we're allowed a considerably greater field strength than in the U.S. (so Part 15 certification is actually a negative). I was quite impressed by the sound quality of the Panaxis ACC-100 for the money, and it becomes even better when you use a decent, regulated power supply. But again, if you're going for distance, stereo is actually a negative (not so if you just want to broadcast over your house).
I don't know what your level is for "doesn't cost a fortune", but I STRONGLY recommend the EDM FM transmitter. This is a real gem. It's built like a rock and has a frequency display that is tunable over the whole band. Mine sits on a shelf in the basement with the short wire hanging down. It covers the whole house clearly on the 10 mW setting. It will easily cover your yard. You can go to the 100 mW setting if necessary. If the range is beyond the FCC Part 15 requirements you can cut to 10 mW or adjust the antenna length until you comply. Audio and stereo separation is superb.
http://www.edmdesign.com/index.html
I looked at the EDM. Perhaps it was just my unit, but I could hear the signal splattering off into adjacent frequencies, where that was not the case with certified Part 15 (or more expensive) transmitters. Plus it will only do stereo transmission - if you want mono, you have to order a custom chip and replace the existing one, which may be an impediment for some. Finally, you need a REALLY good, well regulated power supply or you will get hum, as there is no filtering inside the unit itself.
It did sound nice once the hum was eliminated.
The other thing to consider is that if complaints are made to the FCC (and Canada's regulatory arm, Industry Canada), it goes a long way to be running a certified transmitter. There are other things these guys look for than field strength levels.
The previous post is absolutly correct, and this is why even EDM recommends against treating that unit as a plug and play. The circuit board definitely needs proper power supply, proper case, proper filter and a carefully matched and attenuated antenna to be a useful item.
Certified is a much better way to go for those not willing to take on the compliance responsibility themselves.
I have no experience with the EDM unit but as an interested observer it seems that according to what I have read it is a well performing unit.
SCWIS posted "The circuit board definitely needs proper power supply, proper case, proper filter and a carefully matched and attenuated antenna to be a useful item." and this raises some questions which some experienced folks could address.
What is meant by a "proper filter"? RF filter?
What is the need for an "attenuated antenna"?
How does one set up a compliant system using this unit? Any suggestions from those who have been there and done that?
The reason I ask is that I am considering adding a second housecaster on part 15 FM. My unit is tied up serving my only listener (wife) who is not hesitant to let me know when the "transmitter is off". The EDM is price competitive with the Ramsey FM25 series so it is on the table for consideration here. I have found that my FM 25 needed a proper power supply, proper enclosure, and even a compressor to work well. It would appear that similar considerations apply to the EDM.
Neil
If a unit isn't certified, and you want to be legal, I would certainly look at the output with a spectrum analyzer to measure the purity of the signal. Filtering the output to make it compliant with Part 15 is probably well above the technical means of most.
Keeping an EDM in the basement with a minimal antenna, as the other poster suggests, is one way to attenuate the signal at a distance, unless the FCC or Industry Canada decide to measure the field strength (if it gets that far) in open space from the unit (there's no way even at the 1mw level that you'll meet Part 15 requirements in open space, even with that small wire antenna).
But this all seems to be a lot of effort when you can purchase a certified transmitter that sounds just as good or better for not much more than the EDM (I recently saw a Decade MS-100 go for $200 on e-bay).
Proper power supply: Filtered and regulated to prevent hum
Proper case: an RF snug enclosure that will prevent extraneous environmental RF from getting into the audio and rf sections, and to prevent spurrious signals from getting out
Proper filter: A low pass filter that rolls off at about 110 MHz to prevent spurrious signals
A carefully matched and attenuated antenna: To help the trasnmitter work properly an antenna length matched to the fequency is ideal, but ideal can far exceed Part15 guidelines, so each user will need to look at that for themselves.
I have the old 10 mW version, so if I attach a frequency matched dipole I'll get out far too far to be considered compliant - around 3000 feet. The newest version has a variable power output from .01 mW up to around 100 mW, so there can be some adjustments made with the newer units. For the fixed value versions the best bet is a very short, poorly matched antenna or an attenuator from one of our advertisers, like these:
Which one to use? That's up to you!
Certified FM units are certified with the antenna in place and changing that loses the certification.
Either way, the user will need to configure the antenna so that the field strength doesn't widly exceed the requirements of legal operation. Since there is absolutely no affordable way to do that with any certainty, you'll need to guess and assume some risk - it's experimental broadcasting, after all. The standard wisdom is a range of around 200' on a good portable radio, somewhat farther on a car radio but the "standard wisdom" is no response to an NOUO, you'll just have to shut it off if you are asked to.
The good news is that the NOUOs you'll see at the enforcement bureau are usually for tens of thousands of uV/meter, so keep your range at a reasonable facimile of the standard wisdom and your operation will be less likely to be scrutinized.
How does one set up a compliant system using this unit?
Very carefully 🙂 Folks seeking an absolute guarantee of legality should stick to certified transmitters like those mentioned or like the certified FM links sold for car radios.
For anyone who might be wondering, I once had a leaky cable FM operation that turned out to radiate pretty far past the uV/Meter limits due to my error in making th leaky cable terminating resistor and I did get a visit from the FCC because of that. They told me to turn it off, I did what they said, end of story 🙂
Because of some practical reasons, a certified transmitter is likely to have significantly lower field strength than the FCC limit of 250 uV/m @ 3 m.
Part 15 FM transmitter certification testing is likely to be done by a lab independent of the manufacturer. This is because few companies have the equipment and the full-time staff needed for compliance testing. Some larger companies have the equipment and staff for pre-compliance testing, but contract with an independent lab for the final compliance tests.
The consequence of using an independent lab for compliance testing is that the results are not only honest, but probably also very conservative. The manufacturer's management can't pressure the lab personnel to come up with the results that are desired.
In order to avoid reflections, Part 15 FM transmitter certification testing is likely to be done in an open-area test site. First, broadcast stations have to be identified so that they can be removed from the final results. On a typical test site, the accuracy of the field strength measurements is quite low. It is usually +/- 4 dB. If cost were no object, the test site might be calibrated for field strength accuracy of +/- 1 dB; but cost definitely is an object. The services of a test laboratory are very expensive, and trying to get better than standard accuracy would be economically unfeasible.
To guarantee that the FCC field strength limit of 250 uV/m @ 3 m is met, the measured field strength must be at least 4 dB less than the limit, which is not more than 158 uV/m @ 3 m. The true field strength may also be 4 dB less than the measured field strength. This would be 99.7 uV/m @ 3 m. With an additional safety margin, the measured field strength limit would be set even lower than this.
I looked up the C. Crane transmitter certification test report on the FCC web site, but the measured field strength was excluded from the data available to the public. Manufacturers have the right to hide sensitive marketing information from the public, and the measured field strength is probably under the category of sensitive marketing information.
Here are a couple of certified Part 15 FM evaluations:
http://hobbybroadcaster.net/reviews/Decade_MS-800s_8_2009_P01.html
http://hobbybroadcaster.net/reviews/CCrane_FMT_08_03_2008_P01.html
Hope this helps.
The Decade review was interesting (although not a surprise, since Artisan Radio uses one, but a mono version).
I can't emphasize enough the need to broadcast in FM MONO to get the maximum range out of your transmitter, Part 15 certified or otherwise. Just take a look at the specifications of any FM receiver - typically, for a good car radio, you'll be able to receive a 2uv +- a bit mono signal with some quieting, while it generally takes a 20uv stereo signal to get the same quieting. Home stereos are not as sensitive, but maintain a similar difference between mono and stereo signals. It takes a lot of power to maintain that stereo separation (and you're pushing a lot more signal through the airwaves).
Remember, a good mono signal will beat a crap stereo signal any day.
You said, "Remember, a good mono signal will beat a crap stereo signal any day."
I said, You're Right!