Step 1: Gather Supplies
-A crystal oscillator (will talk about which kind in the next step)
-A 9 pin serial jack (D-SUB9)
-A little bit of wire
-Something to use as an antenna
-A male to male audio jack (unless you know morse code)
Step 2: Which Oscillator?
Regular AM/FM radio - We will be using only the AM part. The numbers on the dial are frequencies in KHz. Most oscillators are marked in MHz. You will probally want something in the .3MHz(300KHz)-1.5MHz(1500KHz) range.
Shortwave radio - Go with whatever frequency your SW radio can play. My radio has 3 bands. One is a KC (KHz or AM) band and the others are MC (MHz). I use a 20MHz oscillator.
Step 3: Wire Some Stuff Up
You will also need to solder a (black) wire to pin 5 of the serial jack.
Step 4: Wire Up the Oscillator
Step 5: Add Antenna
Step 6: Send Some Morse Code
Connect the serial jack into your computer.
Type some stuff in.
Click the radio menu on the top.
-You may have to choose a different COM port from the "Com Port" menu.
-If your using a SW radio you can select the CW setting by clicking the radio menu and selecting CW
Your radio is now transmitting.
Step 7: Receive Some Morse Code
-Learn morse code
-Use a computer: Find a radio.Tune to your freqency. Use a male to male headphone plug to connect the headphones part of the radio to the microphone jack in the computer. Download and install cwget.zip. When running it SHOULD (doesn't work well for me) start to decifer the morse code. Read the manual to figure out how.
Step 8: Congrats
A few tips:
-Get a good antenna. I heard about someone who did this with a 24.3MHz oscillator and a 10 meter antenna and sent his signal from California to Texas. I haven't tried testing mine outside my house yet, but it works pretty well here.
-Get a higher frequency oscillator if possible. If you have a SW radio then you can to this, otherwise stick with AM. If you use AM though be warned that your messages won't be private. Anyone can pick up an AM signal.
-Check your frequency. If your frequency is in an amatuer radio range then you will need a licence to run it. If it is in an AM range, you can only send your signal a few blocks (I think it's a mile) without a licence.
Hope you can use this to send secret messages to far away friends.