3 Watt FM Transmitter


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Rae XL Tkacik 290,472 9 81
This is the schematic for an FM transmitter with 3 to 3.5 W output power that can be used between 90 and 110 MHz. Although the stability isn't so bad, a PLL can be used on this circuit.

This is a circuit that I've build a few years ago for a friend, who used it in combination with the BLY88 amplifier to obtain 20 W output power. From the notes that I made at the original schematic, it worked fine with a SWR of 1 : 1.05 (quite normal at my place with my antenna).

Schematic


This is the schematic of the 3W FM Transmitter

Parts

Part
Total Qty.
Description
Substitutions
R1,R4,R14,R15410K 1/4W Resistor
R2,R3222K 1/4W Resistor
R5,R1323.9K 1/4W Resistor
R6,R112680 Ohm 1/4W Resistor
R71150 Ohm 1/4W Resistor
R8,R122100 Ohm 1/4W Resistor
R9168 Ohm 1/4W Resistor
R1016.8K 1/4W Resistor
C114.7pF Ceramic Disc Capacitor
C2,C3,C4,C5,C7,C11,C127100nF Ceramic Disc Capacitor
C6,C9,C10310nF Ceramic Disc Capacitor
C8,C14260pF Trimmer Capacitor
C13182pF Ceramic Disc Capacitor
C15127pF Ceramic Disc Capacitor
C16122pF Ceramic Disc Capacitor
C17110uF 25V Electrolytic Capacitor
C18133pF Ceramic Disc Capacitor
C19118pF Ceramic Disc Capacitor
C20112pF Ceramic Disc Capacitor
C21,C22,C23,C24440pF Trimmer Capacitor
C2515pF Ceramic Disc Capacitor
L115 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L2,L3,L5,L7,L956-hole Ferroxcube Wide band HF Choke (5 WDG)
L4,L6,L831.5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L1018 WDG, Dia 5 mm, 1 mm CuAg, Space 1 mm
D11BB405BB102 or equal (most varicaps with C = 2-20 pF [approx.] will do)
Q112N3866
Q2,Q422N2219A
Q31BF115
Q512N3553
U117810 Regulator
MIC1Electret Microphone
MISC1PC Board, Wire For Antenna, Heatsinks

Notes

  1. Email Rae XL Tkacik with questions, comments, etc.
  2. The circuit has been tested on a normal RF-testing breadboard (with one side copper). Make some connections between the two sides. Build the transmitter in a RF-proof casing, use good connectors and cable, make a shielding between the different stages, and be aware of all the other RF rules of building.
  3. Q1 and Q5 should be cooled with a heat sink. The case-pin of Q4 should be grounded.
  4. C24 is for the frequency adjustment. The other trimmers must be adjusted to maximum output power with minimum SWR and input current.
  5. Local laws in some states, provinces or countries may prohibit the operation of this transmitter. Check with the local authorities.

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Comments

Add A Comment

mehedi
3 Watt FM Transmitter
Thursday, February 26, 2015 3:23:00 PM
hello sir how r u? thanks for fm circuit. plz tell me more about L2,L3,L5,L7,L9 6-hole Ferroxcube Wide band HF Choke (5 WDG) is it available in market? if yes then whats its name plz tell me in details sir thanks i m waiting ur answer sir thanks again
anonymous
3 Watt FM Transmitter
Saturday, March 15, 2014 4:50:30 AM
i did not found BF115??
anonymous
3 Watt FM Transmitter
Saturday, March 08, 2014 2:01:20 AM
i make this.. but i have a problem i could not found bb405 varicap.. so can i use BB109 with BB405?? PLEASE HELP ME? ITS URGENT.
Venkateswaran
3 Watt FM Transmitter
Wednesday, March 05, 2014 11:07:41 PM
Sir... Can you please explain what are the different parts in this circuit ??
hitz
3 Watt FM Transmitter
Monday, April 29, 2013 5:28:55 AM
This is an awsome transmitter. that i had ever seen in my life with an unbelievable range of 8 miles . thank u very much sir. its amazing!!!!!!!!!!
anonymous
3 Watt FM Transmitter
Tuesday, October 30, 2012 7:34:26 PM
What the hell is wrong with all those lazy people? Why can't they just try putting together the circuits themselves instead of having to be spoon-fed the whole building process. Even weirder is, that some of them are claiming to be studying electronics related subjects and needing these circuits for their graduation project. If that's true, than how can't you understand these fairly simple diagrams, and what does that say about the intelligence of students or colleges/universities? It's mind boggling when you think about it.

(Editor's notes: I agree 100%.)

Radio Pirate
3 Watt FM Transmitter
Friday, March 02, 2012 10:09:19 PM
Stop begging please. This is an easy schematic, so it shouldn't take you long to create a pcb layout from it. If you can't then you shouldn't start with this project. If you don't know how to make the coils/inductors, go start with a simple transmitter, google for "FM BUG". With these small transmitters yo ucan gain a lot of experience, then you can start with bigger projects. Stop asking about teh range, because the range depends on many factors, how you build the transmitter, your swr, and the quality of the coax etc. All passive components are available on the market, except for the 2N3866 and 2N3553 but you still can buy them from e-bay (watch out for fakes), well some companies still make them but you'll need to find it out yourself, I'm not going to post any links here. If you want any other transistors you need to checkout the datasheets of them and compare them with available transistors. For BF115 you can use a BF199. 7810 is a voltage regulator, you can buy this component it's really cheap (yes even for Indians). Look for 7810 or 78L10, they're available in a TO-92 and a TO-220 package. And people don't forget to use a dummyload when you're configurating the stages and power. If you don't use a dummyload you will burnout the final transistor. For the stability, you need to cool your transistors with good heatsinks, use the proper shielding for every stage, and build a good metal case around your transmitters pcb. The ferroxcube thingy is a simple wide band choke with 6 holes in it. If you don't know what it is google it (image's), you can get this part everywhere. And my final words are; don't use this crappy transmitter for serious businness! Because it will interfere on the whole RF band, it will jam important frequencies (air traffic, emergency etc)! I will build this transmitter this month with a fifteen watt amplifier. Imma going to check this page often.
carristers
3 Watt FM Transmitter
Thursday, February 24, 2011 10:14:41 AM
this transmitter with a home made broadcast centre can do wonders.try it with multireplier and communication within 3 miles using a modulated mike in specific radios will do wonders.i made it why not you!
PRAKASH SHARMA
3 Watt FM Transmitter
Friday, January 21, 2011 10:56:37 AM
I made it but not working why? plz send me a circuit with easy way.
indx 14
3 Watt FM Transmitter
Saturday, November 27, 2010 2:32:42 PM
Well to those who are having trouble, it may help to a) try building an simple(r) FM transmitter (google search) or b) try building an AM transmitter, unless FM is necessary. Also, looking up what each individual component is, and what it's job is in this project may also help. (slightly simpler) ones (for casual learning/fun): http://www.pira.cz/entx1.htm
anonymous
3 Watt FM Transmitter
Wednesday, April 14, 2010 4:03:51 PM
Have any questions been answered yet? This is a test question to see if any one monitoring this site. What happens if I poop on the transmitter?

(Editor's notes: Questions aren't answer here, hence why these are called "Comments". If you want your question answers, post to the forum as it says above the comments section.)

darren
3 Watt FM Transmitter
Monday, April 05, 2010 9:39:49 AM
the transmitter design is just basic. it will give 3-4 watts with the output device with ease. but the oscillator is not pll so it may not be stable in frequency operation. add a pll (phase locked loop) to the oscillator and youre on to a good start. my design that i made uses a similar layout and i added a pll to it and its now giving out about 7 watts into 50ohms.
KXRN 93.5
3 Watt FM Transmitter
Friday, April 02, 2010 6:34:30 PM
We are a licensed LP FM radio station that has to duce our max output of 100 watts down to 50 watts because of our proximity (Within 100 miles) to the California/Mexico border.. ok now that we establish a transmitter site we are required to reduce our 50 watts down to 3 watts because of the position on top of a hill, otherwise known as the line of sight over the community. Is it worth it to have an LPFM in my community if i cant get maximum coverage or wattage..?
anonymous
3 Watt FM Transmitter
Thursday, September 10, 2009 1:59:38 PM
A semi-professional stereo coder to complete this transmitter can be found at http://homepage.univie.ac.at/johann.doblhofer/sender/sesmanl.html although the description is in German
anonymous
3 Watt FM Transmitter
Friday, July 24, 2009 10:48:30 AM
Will using a longer antenner provide greater range.?
Cthulhu
3 Watt FM Transmitter
Sunday, May 10, 2009 12:12:14 AM
Hey, cool it boy; it just so happens that there are a few of us out here who are not conversant with all the jargon of electronics! Perhaps if you should explain just what the items named actually are, we would all be a lot happier, especially the fellow who is asking! An inductor, for example, is a wire coil, wound according to a certain criteria, and soldered into place. Now you have a go!
Anon
3 Watt FM Transmitter
Wednesday, February 04, 2009 3:45:05 PM
You're a jerk. People like you make our planet a nasty place to live.
anonymous
3 Watt FM Transmitter
Sunday, November 02, 2008 2:15:58 PM
WTF??? If you don't know what a regulator is, or how to make an inductor, or how to work out how far a 3watt transmitter will propergate then you SHOULDN'T BE TRYING TO BUILD ONE!!! Try simpler things fist, like water alarms. Then move on to FM transmitter kits (google search that). You definately shouldn't be worrying about 20/30/50/100watt outputs yet. Besides, this ciruit is non PLL (free running), high power ios completely pointless!! The frequency will be all over the place!! Don't keep embarrasing yourselves with silly questions, DO YOUR RESEARCH!!
DIGME ROBERT
3 Watt FM Transmitter
Monday, October 06, 2008 12:03:40 PM
Well I would like to build this transmitter my self but I dont know how far it is going to cover, it also seems it will be transmitting MONO. Is there a way I can go about it to make it STEREO. Please let me know, and weather I can change the Watts and also what about the frequency? is it adjustable. Thank you
slim
3 Watt FM Transmitter
Monday, August 11, 2008 5:31:02 PM
i wanna run a radio station w/ at least 1 mile distance just want to open up the box plug it in and start i been resarchin on buildin one but i cant get a hold all those electronics where can i buy a package to start my underground radio station or a list of where i can find one sutibule for my needs i can put it together thats not a prob. can u help
francisco
3 Watt FM Transmitter
Wednesday, July 30, 2008 2:30:22 PM
please ! could you explain me more about 8 WDG, Dia 5 mm, 1 mm CuAg, Space 1 mm and how could I mount the coil in pracitce Vy Kindest Rgrds francisco
ehsan
3 Watt FM Transmitter
Saturday, June 21, 2008 4:12:44 PM
What is the u1?
Mansoor
3 Watt FM Transmitter
Thursday, June 19, 2008 11:28:45 PM
Can I make it a 30 watt-100watt by connecting its output to amplifier then to antena,or somehow?? Can I use my remote controlled car,wireless headphones, old radio or somehow just take out a receiver out of something and alter it to work for me. I need to run a radio station for atleast 1miles radius.
freab demissie
fm trasmitter that covers 1km square
Monday, March 17, 2008 8:59:12 AM
it helps me to the final project .so that i want schematic diagram and discription of each components and ratings.
Dumidan
3 Watt FM Transmitter
Tuesday, March 11, 2008 4:44:29 AM
U1 7810 = LM 7810 or equivalent voltage regulator, out=10V
Shelton
3 Watt FM Transmitter
Saturday, March 08, 2008 7:11:39 AM
I think you can change the frequency of transmission by adjusting C14. Regards
George
3 Watt FM Transmitter HELP....
Saturday, March 01, 2008 12:55:17 AM
The circuit seems very useful.But it will be very helpful if you clarify my following things 1. What is its working range or how to set the frequency range. 2.Will it depend on the antenna height. 3.What is the use of 7810 Regulator.
JASEEM
3 Watt FM Transmitter
Saturday, March 01, 2008 12:40:40 AM
1.WILL YOU TELL ME ABOUT "U1 7810 REGUTATOR". USE AND OPERATION 2.WHAT WILL BE THE RANGE ? 3.HOW TO SET THE FREQUENCY? THANK YOU
Dipen Sen
3 Watt FM Transmitter
Friday, February 22, 2008 9:17:57 AM
i want to know the range of this transmitter.
v.vinoth
3 Watt FM Transmitter
Thursday, February 21, 2008 5:32:05 AM
it will be allowed are not for project and how long distance it will work?
hellbend
100 Watts FM Transmitter
Tuesday, February 19, 2008 1:48:15 PM
i want to build a 100 watts or greater transmitter, what i'm trying to do is to learn how to build a land mobile radio, mostly like the ones made by Midland or Vertex, is there anyone that can direct me to any informations. thank you
OMAR HAMIDU HASSAN
3 Watt FM Transmitter
Wednesday, February 13, 2008 5:15:01 PM
I wish to build 3 Watt FM Transmitter as my project, please guide me on the schematic diagram and send more detail in respect of the circuit diagram through my email omarhassan2323@yahoo.com
Gan
FM Transmitter
Tuesday, January 29, 2008 7:26:13 AM
can you send to me FM Transmitter schematic and proposal to me as fast as possible.thx.....
Ali
3 Watt FM Transmitter
Thursday, January 24, 2008 1:16:33 AM
I wanna plan 100 watt transmitter or more , can any body help me how to build it and the cost, I really appreciate any help...
BISWAJIT
making a ground connection in a circuit board
Wednesday, January 23, 2008 6:38:40 AM
hello, i'm new to soldering electronic circuits on a circuit board.so,i don't know how to make a ground connection will somebody help me please ?? regards biswajit
satbir
3 Watt FM Transmitter
Saturday, January 12, 2008 9:22:26 AM
can u send me the more clear pcb design..............please... & how much cost this project......... thnx...
Godfrey E. Wade
3 Watt FM Transmitter
Tuesday, January 08, 2008 3:39:35 AM
Sir, can you send me a clear PCB design of the circuit, and the detail construction of the RFC tsok? thanks if u respond my request, God bless.
OLORUNFEMI ABIODUN
100 watts audio amplifier
Sunday, January 06, 2008 2:43:55 PM
I wish to build a 100 watts Audio amplifier as my project. can anyone give me circuit and guidelines on how to go about that? I will so much appreciate this. If anyone want to help, please contact me via abbey4evera@yahoo.com
habibullahkhan
3 Watt FM Transmitter
Saturday, January 05, 2008 5:12:08 AM
i want to build fm radio transmitter please guide me and sme me schemetic diagrams

(Editor's notes: Scroll up 6 inches.)

skystars
50 Watt FM Transmitter
Wednesday, December 19, 2007 2:18:59 AM
I want to make a 50 watt stereo transmitter. Anybody pls tell how i can do this & how much will it cost? Pls mail me at my yahoo id. I will be very thankful if anybody could help me.
Waldo Pulanco
3 Watt FM Transmitter
Saturday, December 15, 2007 7:11:43 PM
sir can you please send me a schematic at foil pattern of 3 watts fm transmitter
Sudip
3 Watt FM Transmitter
Thursday, December 13, 2007 10:12:30 AM
I didn't understand how to make those inductors... :$. Can someone pls help me?
ato
4Watt FM Transmitter & frequency 35MHZ.
Wednesday, November 21, 2007 4:00:16 AM
Hi can u send me the details of how to make a 4watt fm transmmiter of frequency 35Mhz. thank you
Prim
3 Watt FM Transmitter
Friday, November 16, 2007 12:33:06 AM
Is it possible to make with AWG wire these 6-hole ferroxcube wide band HF choke. Please tell me how to make such fabrication.
Kripanshu
FM Transmitter
Tuesday, November 13, 2007 2:08:26 AM
I want some basic info about radio transmitter of any type of band.
mithun patra
3 Watt FM Transmitter
Monday, November 12, 2007 3:21:19 AM
can use this in our coll? how can i play song? how much cost for this project will spend?
Bob Almazora
3 Watt FM Transmitter
Saturday, November 10, 2007 8:37:10 PM
Please include pictorial view of coils use like L2, L3, L5, L7, L9 and the whole project assembly to get the details of the parts and project assembly.
makanjuola sulaimon
3 Watt FM Transmitter
Monday, November 05, 2007 12:35:17 PM
sir, with due respect, we are final year physics student of a nigerian university. our final year project is the construction of a mini fm radio transmitter(50meter radius). sir kindly help, we need a literature review of the device, including circuit diagrams.
vinit.c
3 Watt FM Transmitter
Tuesday, October 30, 2007 6:49:51 AM
Sir, I had tried lot to get 6-hole ferroxcube wide band HF chocke(5WDG). Please give substitute nos. of same.
weebe
3 Watt FM Transmitter
Sunday, October 28, 2007 8:19:29 AM
I need more scema for more hi fm transmitter power,maybe up to 15 - 30 watts power completly...n i have trouble with pcb layout...can you send it? thanks before..bye
sanjeevonymous
3 Watt FM Transmitter
Friday, October 26, 2007 8:55:38 AM
how to avoid hum noise at the receing end when using a power supply.............please explain
rahul shrivastava
3 Watt FM Transmitter
Sunday, October 07, 2007 9:38:22 PM
It is a really well workable Transmeter.which is in the easiest circuit diagram.
Neetya
3 Watt FM Transmitter
Saturday, October 06, 2007 6:28:31 AM
Hi, can u send me the details of how this circuit of 3W FM transmitter works and what should be done to increase the coverage area of transmitter. Thank you
atthot
3 Watt FM Transmitter
Tuesday, September 25, 2007 1:58:56 PM
Hi!I want to know more about the values and idea of making the coil of MW and FM transmitter circuit. Would u kindly write about the receiver circuit also? How can I increase the range of fm transmitter some thing upto 1 or 2 kilo mitters around. thanks a lot
anonymousgeetika adlakha
3 Watt FM Transmitter
Thursday, August 23, 2007 8:23:54 PM
can u plz tell me da layout diagram of 3 watt fm transmitter
anonymous
digital FM stereo receiver
Monday, August 20, 2007 3:25:18 AM
can you provide me the circuit for digital FM stereo receiver. i am not able to find this ckt anywhere............. hope you do get me
MOSES.S
3 Watt FM Transmitter
Thursday, August 16, 2007 7:14:58 AM
sir i am in rural area .so i want get a component&pcb for this circuit.how can i approach to you for receive component&pcb
anonymous
3 Watt FM Transmitter
Monday, August 06, 2007 12:22:48 AM
I am concerned with the legality of this transmitter, since it has the potential to cause harmful interference with aircraft navigational systems. Use caution as you may have Industry Canada or the FCC down your neck.
Er Sukhwant Singh
3 Watt FM Transmitter
Saturday, July 28, 2007 10:37:46 AM
hello sir how r u? thanks for fm circuit. plz tell me more about L2,L3,L5,L7,L9 6-hole Ferroxcube Wide band HF Choke (5 WDG) is it available in market? if yes then whats its name plz tell me in details sir thanks i m waiting ur answer sir thanks again
Kaas
3 Watt FM Transmitter
Thursday, July 26, 2007 6:32:39 AM
3 Watt should be able to get about 2/3 miles of range or about 4/5 KM
vipul
3 Watt FM Transmitter
Wednesday, July 18, 2007 12:57:46 AM
sir, i m a student of 5 th sem e.c eng. i want to know more details about f.m 3 watt transmiter.
Sunny Bhalerao
3 Watt FM Transmitter
Tuesday, July 17, 2007 2:57:36 AM
What is the range of this fm transmitter
anonymous
3 Watt FM Transmitter
Wednesday, June 27, 2007 12:40:11 AM
Can this be adjusted to transmit in stereo.

(Editor's notes: No.)

Mosaku David
3 Watt FM Transmitter
Thursday, June 21, 2007 8:35:58 AM
Please I woould like to know how many kilometers this transamitter can go . Thanks for ur assistance
Donu Gameli
3 Watt FM Transmitter
Wednesday, June 13, 2007 7:18:06 AM
How does fm modukator work
FRank
3 Watt FM Transmitter
Monday, June 04, 2007 8:21:39 PM
Anyone have an idea of where I can find a u7810 in the USA?
anonymous
3 Watt FM Transmitter
Tuesday, May 29, 2007 10:31:59 AM
you have to add how it works, and what's the range, thanks
Rene Aduviri
3 Watt FM Transmitter
Monday, May 28, 2007 3:12:54 PM
Can you put signal voltage levels in each stage?? Output in BF115, Output in 2N2219....... The circuit is very interesting. Best regards
Moon
3 Watt FM Transmitter
Wednesday, May 23, 2007 8:17:52 AM
The u7810 is a REGULATED POWER SUPPLY IC. It has 3 probe. First input, second ground, and last is output. Thanks
carlo
3 Watt FM Transmitter
Monday, May 21, 2007 10:23:01 AM
do you have circuit, 10w-25w? thanx!
a chinese ham.
thorey of this?
Monday, May 14, 2007 9:40:49 AM
please tell me how it is work in detail?
kunle
3 Watt FM Transmitter
Friday, May 11, 2007 7:17:11 AM
The transmitter is cool in its design but can the output be modified into a dc pushpull for greater power output?
sreedhar
3 Watt FM Transmitter
Wednesday, May 09, 2007 6:21:50 AM
this is very useful
Raid Salha
3 Watt FM Transmitter
Saturday, May 05, 2007 5:09:09 AM
I wanna to ask about the transistor , what we can use instead of 2N3553 , because i didin't found it
the
3 Watt FM Transmitter
Thursday, May 03, 2007 5:19:00 AM
works?
anonymous
3 Watt FM Transmitter
Wednesday, May 02, 2007 7:57:55 AM
what is the range of this transmitter
Kiran
3 Watt FM Transmitter
Sunday, April 29, 2007 7:45:35 AM
How much distance will it cover ..since i am using an dipole antenna.....
zulfi
3 Watt FM Transmitter
Monday, April 16, 2007 10:55:15 AM
it's good, but where is the PCB?
anonymous
3 Watt FM Transmitter
Saturday, March 31, 2007 11:16:01 AM
what is u7810 regulator?
aadish bahati
3 Watt FM Transmitter
Tuesday, March 20, 2007 11:29:13 PM
wud ny1 plz provide me the layout of the pcb for this circuit .........................
MANI
3 Watt FM Transmitter
Wednesday, February 28, 2007 3:10:06 PM
WILL YOU TELL ME ABOUT "U1 7810 REGUTATOR". USE AND OPERATION
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