Improving 100mW FM Transmitter Design

[sophiecentaur]

One more comment. Was your transmitter bought or did you make it? It may just not be working optimally. You can make a vast difference to equipment, working at those frequencies by bending and tweaking coils and leads. You have the problem of not much available test gear, of course, which makes things doubly difficult.

 

[neeraj kaira]

One more comment. Was your transmitter bought or did you make it? It may just not be working optimally. You can make a vast difference to equipment, working at those frequencies by bending and tweaking coils and leads. You have the problem of not much available test gear, of course, which makes things doubly difficult.

I made it
This is the circuit diagram
What should i do please suggest some tips

 

[neeraj kaira]

Transmitter

 

[meBigGuy]

Is unlicensed fm transmission still limited to 100mW? I think it is.

The schmatic has been posted already in post 8.

I'd try making C2 a variable cap and see if it helps the antenna match.
What are you using for a transmit antenna?

Look at http://www.circuitstoday.com/2-km-fm-transmitter for a better design.

 

[neeraj kaira]

Is unlicensed fm transmission still limited to 100mW? I think it is.

The schmatic has been posted already in post 8.

I'd try making C2 a variable cap and see if it helps the antenna match.
What are you using for a transmit antenna?

Look at http://www.circuitstoday.com/2-km-fm-transmitter for a better design.

I'm using a wire as antenna

 

[sophiecentaur]

Is unlicensed fm transmission still limited to 100mW? I think it is.

The schmatic has been posted already in post 8.

I'd try making C2 a variable cap and see if it helps the antenna match.
What are you using for a transmit antenna?

Look at http://www.circuitstoday.com/2-km-fm-transmitter for a better design.

The problem with building circuits at 100MHz is that the way it's laid out is so important. Use of a ground plane and proper decoupling where it counts can make all the difference.
If neeraj kaira wants something that will just 'work for him' then he may not want to develop too much expertise as a result of 2nd and 3rd versions for laying out that circuit. That other schematic you provided is potentially better and more stable but it still needs to be soldered together with short lead lengths, disc ceramics in the right places, physically, etc.. The least he would need, I should say, would be a construction leaflet with a picture of a working model to work to - in addition to the schematic. You can often buy kits with a PCB which you just have to populate. That's the ideal way to get results, for starters.