With a 0.5 Watt amp into a quarter wave stub working against a ground plane, you will generate a usable signal to several kilometers, if your antenna is high enough above ground so that the line-of-sight signal isn't blocked by the curvature of the earth. This is quite illegal if you don't have a license, although little harm will come of it as long as you are not interfering with a licensed broadcaster. As long as there are no complaints, there won't be a problem.

emc_c

Yes good point I could have bought a 7W transmitter but talk about overkill! Where I live everyone is on cable so interference is not a problem and I bought the lowest power transmitter they had. I just want to cover my house with a strong clear signal and there is no FM reception in this area. Also 98 MHz is low in the band nothing there already checked. I also am surrounded by mountains and they call my tract home mountain view and FM does not like obstructions like mountains. There spec. said >300 M line of sight.

No FM and mountains don't mix but FM travels well on the water table too

Sorry I meant 100nW instead of 10nW. Thanks for all your expert suggestions on linear amps on the previous post.

You do not need a linear amplifier for an FM transmitter.

As I recall, one can have an unlicensed transmitter up to 10 watts and with certain antenna limitations; but stipulates that no interference to a licensed station is allowed. Review the FCC CFR for the regulations.

Then how come they sell them I have researched this see link:http://www.rfglobalnet.com/product.mvc/Model-NP-506-FM-Broadcast-Band-Amplifier-0003

Note that the specs include Amplitude Modulation.

It's a "one size fits all" item.

A great deal of equipment is available that it is illegal to use, or is only legal when licensed in certain countries. I manufacture a suitcase studio which optionally incorporates a mono 0.7W FM exciter. Used with an antenna this is enough power to cover a refugee camp or a small town or to provide an in-band studio to transmitter link (STL).

(A primary application for the suitcase studio is in disaster response broadcasting where communications networks have been knocked out, and we have one in use in Padang, Indonesia right now following the earthquake.)

Licensing regulations vary from country to country, but it would only be legal to broadcast in the UK with the right licence. It is however legal to own it without a licence, you just can't use it.

I will not sell it with the exciter option unless I am convinced it is for bona fide legal use, but many foreign manufacturers do not share these scruples.

I have run properly licensed temporary community radio stations in the UK using 1W transmitters. With the transmitter site on a hill, I could pick it up 15 miles away on a car radio although the range for indoor reception is much less. (Working in mono greatly extends the effective range).

7W could interfere with vehicle reception many miles away depending on terrain, up to 20 or 30 miles. I cannot believe that is legal in the USA. I am only aware of micro-power FM as a legal option for unlicensed broadcast and 7W is not micro-power. I think the limit is 100mW in the USA and there are other constraints as well.

Any links available for these spec's?

Thanks

FYI: This is the FM stereo transmitter I bought lowest power 0.5W. It is from China but I buy a lot of electronics from there and some of their stuff is high quality and the US can not compete. It is being shipped to me right now and is plug & play. Here is the link with the specs: http://www.elecsky.com/index.php?main_page=product_info&products_id=44

Nice transmitter except for the freq responce. toobad they cut the bass off so early. 100 HZ bottom, bummer!

Whats shipping costing ya?

Joe

$28 it is heavy. The total was $80 USD.

I think the antenna limit is 60 feet height and the watt limit 7...

Well I am on the air on a unused frequency of 98.5 MHz. It is high quality stereo FM and the bass response is excellent. The high frequency response is good but I will add some bullet tweeters to my other 5.1 systems. It sounds so good I actually though I was going direct into my 5.1 system that was next to the transmitter when I actually was in FM mode. No dropouts any where on my property or even my block. Went to 7/11 about 1/4 mile and reception was perfect. 1 mile away you here static. I changed the antenna to the one that came with the unit a China brand which are no good to see if I could reduce the power some. It works just as well inside but I have not driven down the street yet. The first Itune I played was the grateful dead "Touch of Grey" and at first I was over modulating so I backed of on the volume to find the best sound and then used the EQ and on some songs I get to much bass and the frequency response of this unit is 100-15000? The 100Hz must be a typo because my sub woofer is pounding out the bass. So all things look good a great project.

Contrary to popular belief good range of sub-woofer is between 80Hz & 150Hz

Thanks for that info but I also get excellent bass response in my truck no sub! Though I EQ the bass and treble. I know one thing I am getting a good bandwidth even though the spec says 100-15000 and I am a Audiophile. Very picky. So far no FCC but I am not stepping on any station or doing commercial broadcasting. I have been hunted by the FCC twice in my life. Once I had a 100 MW CB and they were trying to get me to talk so they could use their directional antenna, I gave them static. This was in the 60's when CB was very strict. The second time I put an antenna on the chimney that I built and did FM broadcasting. In less than a half hour I was in a dead spot and heard "we are almost there". I ran like **** to my house and pulled the plug on my station. I believe there was a FCC monitoring post close to me because one day I tried to talk to some one CQ and this strong signal with a man saying what is your call sign. I said I am a 100 MW transceiver and he said OK. LOL