Total posts : 45366
That’s usin’ the ole knoggin Daniel! Learning how to work with what you have is half the battle.
I look at my RF signal using an old 10 mHz O’scope. I use a home-made coil and tuning capacitor coupled to a small sensing loop to pickup the signal. Kind-ol-like a crystal radio without the crystal. The test lead from the o’scope taps the signal off the coil. I can watch the actual RF signal and see if the audio is over or under modulating the signal. I prefer this method as it eliminates any distortion that would be added from the boombox itself, perhaps from overloading the receiver.
Some transmitters have a simple diode detector and low-pass filter at the antenna output which works to provide a point where you can monitor the audio right at the RF output. At that point you can either feed it to an amplifer to listen to it or feed it to your WinScope.
You could use a simple crystal radio and connect your WinScope in place of the earphone if the soundcard input impedance is high enough. The idea is to eliminate any other source of distortion to the signal to be viewed.
