Sorry - I should have clarified some points in my earlier posting.
Soundcard Oscilloscope is free software that turns your PC and Soundcard into an audio frequency Oscilloscope, Spectrum Analyser and Signal Generator.
With this software running you have all the components of an audio lab without having to buy any hardware.
Most PC and Laptop soundcards use 3.5mm (1/8th inch) stereo jacks for audio in and out. You only need to makeup a simple adaptor cable to connect between your microphone and soundcard microphone input. It's at least as easy (if not easier) as making up a dedicated test box with a built-in amplifier.
A general note to all readers - If you haven't ever experimented with your PC soundcard connected to your radio - I'd strongly recommend trying it - there is a lot of very good free software available that allow you to do all sorts of amazing stuff.
Martin - G8JNJwww.g8jnj.webs.com