5-Watt Transmitter

This is a very simple 5 watt CW TX based upon a TTL logic chip. There is just one "tricky" component and this is Cx. This component should have an impedance of about 10 - 50 ohms at the frequency of interest. If you wish to reduce the transmitter power, increase the value of Cx. It is Cx which causes the square wave from the output transistor to approximate a sine waveform.

• 1.8 MHz = 4.7nf
• 3.5 MHz = 2.2nf
• 7.0 MHz = 1.2nf
• 10 MHz = 820pf
• 14 MHz = 560pf
• 18 MHz = 470pf
• 24 MHz = 390pf
• 28 MHz = 330pf