Electronics 2000

Hi All,

I'm new to the forum and not particularly technical, but i can handle some (very) simple electronics. Whether or not this is a simple job, i don't know you decide...

Why would i want to add an external antenna to an mp3 player/radio which already uses the headphones as an antenna? i hear you ask.

Well, it's like this. I drive an old classic car, which only has LW/MW radio. I have managed to connect my mp3 player via a cassette adaptor to the tape deck which lets me play mp3 in the car, and i've routed the cable out the back of the car radio so you don't see the wire. Thing is, i really miss my local radio station on the drive to work. I bought a media player with FM radio built in, unfortunately the reception is pretty poor as the player uses the headphones as an antenna.

Is there any way i could use some sort of 3.5mm jack splitter, and route one side to the cassette adaptor and the other side to the car antenna? I don't want to go ahead and try this as i'm worried that i could damage the internals of the player so wanted to check with you guys whether or not you think this would work first.

Failing that, do you think the cassette adaptor lead may be doing a bad job as an antenna? Would i be better, again, using a splitter but plugging the headphones into the other side of the splitter, are these headphones specially designed as an antenna???

Any help on this would be very much appreciated.

Thanks in advance,

Gordon.

Car radios generally have pretty sensitive receivers but the same can not be said for the FM receiver built in to the typical MP3 player. As long as you don't set your expectations too high it could interesting to experiment with adding an external antenna. The following assumes that your suggestion that the headphone line is the antenna is correct.

You can take a male and female connector and make a short extension cord as the base for your splitter. Then connect your experimental antenna to the one the audio lines through a small capacitor. 470 pF will pass the FM signal and block the audio from the outside word. That value could be several times higher and still work well. There many antenna types you can try.

You can try different lengths of wire routed around the car in different places. You can try a loop of wire, in the neighborhood of 8 -10 feet, connect one side to the cap and the other to the common lead. The loop could formed into a T shape to emulate a folded dipole. You could even make a folded dipole from 300 ohm twin lead if you have some lying around.

There are many unknowns that keep this project from being an exact science but stranger things have worked before. Trial and error may lead to better reception, as long as you protect the audio line with the small cap there's not much risk to your MP3 player. Have fun.

pom901,

Thanx for your speedy reply, i went into the high street electronics store. The lad there was very helpful when i told him what you had recommended and agreed with your thinking. However, he said that what i should try first, is buy a splitter and use the headphones as an external antenna first as these may already have the capacitor built in and may work better than the cassette adaptor.

Failing that, i'll then try what you have suggested. According to him, there's no point jumping in and buying the capacitor first in case i don't need it (obviously not on comission, i like that )

I have bought my splitter, but not tried it yet, i'll keep you posted as soon as i do.

Thanks again for the help.

Gordon.