Good Part15 FM transmitter

I hate to be the one to tell you, but there is no such thing as a "good range FM transmitter that is legal".  FM transmitters for Part 15 are limited to 250 uV/m field strength. No matter what transmitter you buy that amount of power will only go so far.  Maybe 250-300 feet in any given direction and can be influenced by about a million things.   If you read of people with FM transmitters with range beyond that I can assure you they are not legal. 

I did testing of several FM transmitters over this past fall and summer, including both the C. Crane FM 2 and the Whole House 3.0. The WH 3.0 was in no way even close to being legal.  The C. Crane was well under the legal limit.

I won't go into all the details here, all my Part FM transmitter tests are posted on this site. If you have a hard time finding them I can send you to a link where I have them all posted together. 

There are a lot of places advertising great range FM transmitters, and quite a few people talking about their amazing range, but 250 uV/m will only go so far. It's just basic physics. 

TIB

If you get that with indoor set up and a wire near the window stay with that. No FM transmitter operating near legal....even in Canada....will get you that far even on car radio.

Mark

@timinbovey

I found your post about the Whole House FM 3.0 and it seems all odd. How come the FCC approved it when it was over the limit? I am guessing they lied about it and make a under powered one then on the units they sold they made them have more power.

@Mark

I dont have plans for it to go a mile or two. I mainly would like a FM for the christmas music. The max range that will make me happy is across the street so people can pick it up in there cars. As long as it sounds clean and good I will be happy. I would use the AM but the AM transmitter does not go far at night. I just goes down my driveway before it is overlapped by all the noise out there at night. 

Again this is why you should participate in the thread called I believe in

Im sure there are some power control issues with some part 15 transmitters but i dont count on 75% of the folks owning a Whole lot of NOUO's.

Don't know how much you can spend.

The Wholehouse is certified and will do that and get down the street from the second floor of a house.

The Broadcastvision is certified and works very well out of the box with great sound quality and on board compression/limiting that works.

Decades...CM-10, MS100 which Artisan is selling right now is great also.

The C Crane is underpowered as Tim's tests showed and won't do as well as the others mentioned.

Mark

Interesting thing -- the FCC never even looks at a Part 15 transmitter for approval.  The work is all done by independent labs all over the world. They submit the paperwork, and the FCC approves it.  Only in very rare instances does the FCC actually request an actual transmitter to have a look at it.  There is lots of room for fraud in this system. 

Further it seems there is quite a large swing in quality control of many of these transmitters. You can easily have three of the same transmitter, purchased at the same time, and have three widely varying outputs. 

Virtually any of the popular FM approved Part 15 transmitters are going to work "across the street" to car radios.  And although of the ones I tested I didn't do any scientific testing of audio quality, they all sounded good.  Especially if you're going to car radios playing Christmas music. 

TIB

Here with Industry Canada there are two choices...I can have a transmitter and have the tests done for compliance by a qualified technician and then it can be approved and officially certified and if I know someone like you for example at not much cost to me.

But if not I can send to Industry Canada and at big cost have them do it.

This is probably why companies have their own labs do it and submit results to the FCC.

But that's what we, the consumers have to go by.

Mark

I bet i could buy 50 C. crane FM2 transmitters and test each one on 96.3 Mhz and no two transmitters will have the same range.  The Whole House. 3.0 i bet is the same hence Fra,kenmuth,Michigan and 1/4 mile range in STEREO.

Back when the FCC started certifying computing (digital) devices, they requested samples of everything. They were flooded with so much equipment they had no place to store it.  Not to mention that the staff of 4 or 5 people in the lab to do the tests could not handle the workload. This was a bigger mess than the FCC anticipated, especially with stuff coming in from the far east. 

I have a C Crane FM2.

I live in a 1 story rancher with brick on the outside.  With the C Crane in a front room near the window at table height I had good coverage of my front yard with a useful range of at least 90 feet (through a layer of brick) to a Sangean DT-400W pocket radio.  In the back yard, with the signal going through 30’ of house and a layer of brick, the range on the same radio was about 70 feet.  I was using a channel that had a co channel station about 50 miles away and HD radio noise on the adjacent channels from local stations.

At one point I had the C crane FM in my dining room.  It struggled to get signal to a under cabinet mounted radio 12 feet away through one wall; however the C crane’s antenna was vertical and the under the cabinet radio’s antenna was horizontal so most of the signal was lost from non-matching polarization.

There is a thread on this forum where the field strength from a FM2 was measured.  The C crane was reviewed at hobby broadcaster.  There are better FM transmitters for more money, but the C Crane FM2 is certified and the company seems to stand behind their product.

If your goal is to get music to passing cars, put the FM2 in an enclosure outside with the clearest line of sight to where the cars will be.  You can spend more and tweak things to try and get more range but short of getting a transmitter that is right at 250uv/m@3m, installing it as high as possible, and having 3 perfectly quiet adjacent channels the range on FM is limited.

Also keep in mind that as part of the AM radio improvement effort there are going to be 2 rounds of translators moving and 2 filing windows for translators for AM stations.  I would not spend much money on a FM transmitter when any holes on the dial near you may have a 250W translator occupying them.  (I am guessing if there is any holes left on the dial after the AM stations have their chop at the FM band, the FCC will open a general translator window and that will pack the FM dial everywhere.)

Ok so I found another transmitter that is at a similar price. It is called the Signstek 0.2W Portable Stereo FM Transmitter. Now the people on amazon are saying it is FCC compliant but a post on New Egg says its not. So I want to know is this transmitter legal to use?

Thanks 🙂

0.2 watts is 200 milliwatts.  JUst to give you an idea of what kind of power a compliant transmitter would have, using a dipole antenna you would only need 11 NANOWATTS (thats 11 billionths of a watt) to generate a field of 250uv/m at 3 meters.  The only way for that transmitter to be compliant would be to greatly attenuate the signal, and I doubt that is likely out of the box.

You need to stick with a certified FM transmitter, and even there, unless you're using the C Crane, it's been shown that most of them still exceed the legal field strength.  I would use a transmitter from a reputable manufacturer, such as a Decade CM-10 or MS-100. unless you have the necessary equipment to measure field strength.  At least then you can argue (if an FCC inspector shows up) that you've made every effort to be compliant within reason (you're not going to go out and spend thousands of dollars on measurement equipment for a several hundred dollar transmitter).

Has to have a certifiction # on transmitter to be really FCC certified.

Add the Broadcastvision AXS-FMTD to the recomended ones.

Mark