Test and Adjustment:

Using an oscilloscope we will look at the wave produced by our transmitter. Then we will adjust the frequency by inserting an iron nail in the center of the coil.

Part 1 / Part 2 / Main Page

 

Step 1:

• Power up the transmitter. If you have an oscilloscope, look at the antenna tap on the tank coil, and you should observe a sign wave of about 5 Vpp at about 1 MHz frequency.

 

Step 2:

• Connect a 1 Vpp audio signal from any source to the input shown on the schematic. If you have an oscilloscope, you should see the height or amplitude of the AM signal begin to change in synchronization with the audio signal.

 

 

Step 3:

• Insert an iron nail into the transmitter tank soda straw coil form. It will lower the frequency. You can tune the transmitter by varying how far the slug is inserted.