May 11 2007
Improving the signal strength of FM transmitters
One problem I always have with MP3 players is getting these things to play in the car. It’s like if your car is in the technological limbo between a tape deck and MP3 player compatibility you’re stuck - most likely you have a CD player with no where to plug in your ipod at all.
That means you’re stuck with an FM transmitter. I’ve had several of these things, and all have been pretty bad. Some are constantly staticy, while others go in and out of dead zones.
I was researching this online, and actually it’s not a problem with the manufacturer of these things, it’s a problem with the FCC. They only allow FM transmitters to transmit to a certain range, and this limitation results in lower signal strength and poor quality audio.
How to fix this? You can actually open up these transmitters and attach a longer antenna, thereby improving signal strength. There are a bunch of tutorials online, and I’ll try to provide a basic one here as well.
I just got a cheap FM transmitter off ebay - these things are close to $10 now. This model is a belkin, but it seems like most of these things have a similar design.
First, you open up the transmitter. In this case, you remove a sticker in the battery compartment that exposes a screw (picture 1). Next, you pry the case open and remove the other screw that holds down the circuitry (pic 2).
The next part can be kind of difficult, depending on your transmitter. You have to identify the antenna wire (pic 3). In my case, this was easy - the wire was labeled (the blue one in the picture) - but this is not always the case. If it’s not labeled, you basically have to guess, but most likely the antenna wire will look different from the others, and be placed a bit farther away from the others. It should be pretty obvious if you look at the placement of the wires.
As you can see, the antenna wire goes up to the 3.5mm jack along with the audio wires. This is why reception is so bad on these things, the antenna is only a few inches long!
Next you solder on your new antenna (pic 4). Basically you can use any wire, just make sure it’s pretty long (mine was 6 feet). You just detach the antenna wire, and then solder the new one in it’s place. This can be kind of tough, because everything is pretty close together, but if you go slow it shouldn’t be a problem.
After you attach the new antenna, all you have to do is close things up and find a way for the antenna to exit the case. In the case of my belkin transmitter, there is an open hole (pic 5). You should also secure the wire so you don’t accidentally pull it and detach it from the circuit board. I used double stick tape with one side not sticky, because that’s all i had.
In any case, this is a good way to take a cheap $10 transmitter and turn it into something that actually works. The new transmitter sounds much better and doesn’t cut in and out as much. But at the end of the day, it’s still an FM transmitter, and the sound is crap compared to a direct connection. But this way at least you don’t go crazy with the static.





