maxparveen Posted January 2, 2007 Report Share Posted January 2, 2007 happy new year guys!please help me.i want to build a fm transmitter for radio transmission in my college campus and got so many schematics.but i m confused regarding their ranges.actually i need a stereo fm transmitter having a range of minimum 1 km (with in surrounding buildings ).frequency stability is also matters much.please send me a fine tested circuit . Quote Link to comment Share on other sites More sharing options...
maxparveen Posted January 4, 2007 Author Report Share Posted January 4, 2007 com on guys 2 days passed but no replyplease do it Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 4, 2007 Report Share Posted January 4, 2007 The circuit you want is illegal in most countries so people don't have it. It causes radio and TV interference.There are a few 1W FM transmitter kits available from Ramsey and Free Radio Berkley and are used by "radio pirates" who own ships at sea. A few of the newer kits are pretty good. Quote Link to comment Share on other sites More sharing options...
maxparveen Posted January 7, 2007 Author Report Share Posted January 7, 2007 i m having license up to 10 watt so no need to be afrraid of and i am having whole equipment to make own pcbs so i dont want to buy a kit.please forward me a schematic Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 7, 2007 Report Share Posted January 7, 2007 This Micromitter project is excellent and is used to transmit from an MP3 player to a car radio. I have seen them in stores. It has an attenuator on its output so remove it and make a 100MHz power amplifier for it. Quote Link to comment Share on other sites More sharing options...
D0T-C0M Posted January 26, 2007 Report Share Posted January 26, 2007 oh I just saw this post. I too would be interested in finding an amplifier for it so I can get at least 500ft range. I live in a rural area and I would like to boradcast my satelitte radio from my house to the garage. Quote Link to comment Share on other sites More sharing options...
AN920 Posted January 26, 2007 Report Share Posted January 26, 2007 The Micromitter has flea power. Only -10dBm out of the chip. To get 1W you will need to amplify at least 40dB and deal with the resulting harmonics! :) Quote Link to comment Share on other sites More sharing options...
D0T-C0M Posted January 26, 2007 Report Share Posted January 26, 2007 yeah but I was thinking that because the 1W amp needed 100mW to drive 1W out that with the 10mW or so that the micromitter has (without the attenuator) that I might be able to drive 100-200mW. Anyway i decided to return the micromitter kit and bought the EDM kit the is switchable between 10mW and 100mW which should be more than enough for what I need. From what I've read the signal quality is pretty decent. Quote Link to comment Share on other sites More sharing options...
AN920 Posted January 26, 2007 Report Share Posted January 26, 2007 The output of the Micromitter without the attenuator will be about 0.1mW and not 10mW Quote Link to comment Share on other sites More sharing options...
D0T-C0M Posted January 26, 2007 Report Share Posted January 26, 2007 ok you are probably right , I was only going by what I read on the diy site. They said it would put out 20mW but I read somewhere else someone posted that there must have been a typo and at most it would be 10mW. In any case I think I will be happy with the EDM-TX-110EP I ordered Have you heard of it? Quote Link to comment Share on other sites More sharing options...
AN920 Posted January 26, 2007 Report Share Posted January 26, 2007 I stumbled onto the EDM page while looking for info on the BH chips. I never bought one as I made my own circuit with a BH1417. I looked at their mod meter at one stage and was thinking of getting one but found a surplus meter on ebay. I have seen a lot of post on the EDM transmitter on various boards. Looks like a good tranmitter. You may want to read the reviews on part15us. This is a site dedicated to low power transmitters AM& FM http://www.part15.us/node/691 There is something on the EDM as well Quote Link to comment Share on other sites More sharing options...
D0T-C0M Posted January 26, 2007 Report Share Posted January 26, 2007 thanks for the heads up. i was quite concerned at first ordering something from south africa but apparently they have a subsiduary in california USA and they are paypal verified since 2001. Quote Link to comment Share on other sites More sharing options...
jaya000 Posted January 26, 2007 Report Share Posted January 26, 2007 Visit here to see more FM transmitters. http://www.electronics-diy.com/downloads_pdf.php?s=fm_transmittersHope this helps! Quote Link to comment Share on other sites More sharing options...
djdiler Posted February 8, 2007 Report Share Posted February 8, 2007 You have some good schematics on www.pira.cz ;) Quote Link to comment Share on other sites More sharing options...
AN920 Posted February 10, 2007 Report Share Posted February 10, 2007 yeah but I was thinking that because the 1W amp needed 100mW to drive 1W out that with the 10mW or so that the micromitter has (without the attenuator) that I might be able to drive 100-200mW. Anyway i decided to return the micromitter kit and bought the EDM kit the is switchable between 10mW and 100mW which should be more than enough for what I need. From what I've read the signal quality is pretty decent.Was wondering if you could give us a report when you receive this transmitter? Quote Link to comment Share on other sites More sharing options...
D0T-C0M Posted February 10, 2007 Report Share Posted February 10, 2007 Was wondering if you could give us a report when you receive this transmitter?I recieved my EDM transmitter last Wednesday. It is an awesome little unit. I am so impressed with the sound quality. It really sounds awesome especially when I connect my cd player to it. Sirius Sat Radio sounds alot better too. Seems to have a really great pre-emphasis stage in the input. The treble sounds better and the base sounds better too. What I like the most is it's separate L-R input level POTs so you can fine tune your inputs for better stereo balance and you can adjust MPX value manually so you are capable of using all the the 75Khz deviation band of the FM signal. Anyone who gets this Tx will not be disappointed. The workmanship is excellent and support so far has been really good. fast email responses. You can purchase them through paypal. Once you purchase a unit from EDM they give you access to a private yahoo group which has lots of great info on such as homemade attenuators, antennas etc...Anyone who wants more info , dont hesistate to contact me. Quote Link to comment Share on other sites More sharing options...
D0T-C0M Posted February 10, 2007 Report Share Posted February 10, 2007 using the stock whip antenna I did some preliminary range tests. The Tx was installed in the cab of my truck with the antenna running up and down the mirror which isn't the best placement for it but nevertheless I was very happy with the range I received. using a fairly good quality FM headset I walked down the road and the sound was crystal clear up to about 300 feet after that I started getting some static and the occasional blank spots. On high setting I got crystal clear sound up to 500-600 and after that a bit of static and the occasional blank spot. Keep in mind that the Tx was in the cab of my truck with alot of metal around it. I have made a custom 50Ohm coax and made a 1/4wave ground plane antenna and I expect the range to be better when I mount this antenna outside the cab of my truck. I've read that on high setting I can get about 1/8mile. Quote Link to comment Share on other sites More sharing options...
AN920 Posted February 10, 2007 Report Share Posted February 10, 2007 Sounds very promising. Please report again once you finished testing with your new antenna. BTW what other transmitters can you compare the unit against? Can you say which types you tried out before? Quote Link to comment Share on other sites More sharing options...
AN920 Posted February 10, 2007 Report Share Posted February 10, 2007 Have you tried any of the other stock names like Ramsey before? Quote Link to comment Share on other sites More sharing options...
D0T-C0M Posted February 11, 2007 Report Share Posted February 11, 2007 I researched the Ramsey model but they are about $60 more for a kit and about $100+ assembled. Second is the fact that EDM is also microprocessor controlled and has digital LED readout. If I can quote from their site This is the only Compact, Multi-Channel, Digital-Display, Fully-Synthesized, Microprocessor-Controlled, Stereo FM Transmitter kit that we know of for under $100 (including S/H)!!I found all the feedback I read on all the independant website was all positive. I was hard pressed to find anything negative about them. I also liked that EDM posted alot of their graphs and tests online. As a customer I felt re-assured that they were very open and honest by posting their specs online. This tell me that they have nothing to hide and not afraid to post their results publically.Full Band operation: (87.7 - 107.9MHz) in 0.2MHz increments, on LED displayFrequency Stability: < 0.0005% of set frequencyFrequency Accuracy: < 0.001% error from set frequency10mW (+10dBm) into a 50 Ohm load100mW (+20dBm) unit also availableRF output is reduced 20dB while tuning with PLL un-lockedVSWR: Withstand 20:1 without damage (both models)Low phase-noise-90dBc/Hz @ 10kHz-94dBc/Hz @ 20kHz-104dBc/Hz @ 100kHzLow spurious output: < - 50dBcLow Residual FM: < 25Hz rms (Measured in a 300-3kHz Bandwidth)Incidental AM: < 0.2%Frequency Response: 20Hz - 15kHzLevel: Line level input via RCA type sockets (level adjustment on module)Max Audio I/P sensitivity: < 100mVp-p (integrated limiter)Distortion (THD): 0.2% with 1kHz tone at 75kHz deviation level (mainly 2nd, 4th)Signal to Noise Ratio (SNR): > 60dBStereo Separation: Typical about 40dB Quote Link to comment Share on other sites More sharing options...
AN920 Posted February 11, 2007 Report Share Posted February 11, 2007 I must agree with you that I have never seen any worthwhile specifications published by Ramsey on their transmitters! Maybe because the final outcome relies on the builder builing it correct. But then they can do it for the export- fully assembled models. Quote Link to comment Share on other sites More sharing options...
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