FM Transmitter - Help Please

G'day all,

I got around to modifying my FM Transmitter (Velleman-Kit K1771) so that it can accept an input from an audio source such as a CD player, sound card, etc. Now I have a different problem.

There is a constant background humming in the broadcast. This changes in volume and pitch depending on where the transmitter is situated, generally if it is near metal, the noise increases. From this I gather that I need to shield it, the question is how do I do this?

Circuit Diagram **broken link removed**

Cheers!
Grant

Hmm Interresting...

I think you need so make some thing that will block Maghetic power!

PS:
I have no idea how to block magnetism!

I considered that it could also be a problem with the power source. Since it runs for long periods, I am running it from a 240VAC -> 9VDC Plug-Pack. Could this be a problem? If so, is there a solution?

Try it with a 9V DC Battery, if the current rating is not enough, try to connect two batteries in parallel.