This is my first attempt to build a HF beacon. The output power is about 0.9w on 28.230 Mhz. I wanted to build a beacon with a DDS module but when i found in my stuff a 28.224Mhz crystal i decided to build a classic colpitts oscillator. To increase the power i have used a 2N4401 transistor as a driver and a 2N3866 as final amp. At the end exists a 3rd order low pass filter.
For the keyer, was used one of my first microcontroller PIC16F84A at 4Mhz. The PIC16F84A can control the CW key, the output tone and 5 Led. The two of these flashes the Dih and the Dah, and the other three the current WPM. The WPM change is done by a push button, the other push button just exists for the future. The WPM has preset at 10, 15, 20. Also there is a switch to set On or Off the Buzzer.
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Tx Unit |
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Pic16F84A |
The antenna that i use is a Diamond KV5. My plan is to build an inverted V dipole with a 1:1 balun. The current frequency is 28.230 Mhz.
The time has passed and i was decide to transfer the project to PCB.
The new circuit and PCB with some modifications is here.
Print this side for toner transfer method.
Soon i upload photos of the Project.
I have replay the 2N3866 transistor with 2SC5739. The PCB support the two types.
The PCB shield is to protect the MCU from RF.
And complete.
You can download the Hex file here.
The time has passed and i was decide to transfer the project to PCB.
The new circuit and PCB with some modifications is here.
Print this side for toner transfer method.
Soon i upload photos of the Project.
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| PSU and MCU |
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| Oscillator(2N3904) and 2st Stage(2n4401) |
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| Complete Beacon |
I have replay the 2N3866 transistor with 2SC5739. The PCB support the two types.
The PCB shield is to protect the MCU from RF.
And complete.
You can download the Hex file here.
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