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|7 MHz Transceiver||Advice for beginers||Winding Coils||Test Equipments|
|Power Supply||Variable Frequency Oscillator||Carrier Oscillator||Audio Amplifier|
|Mic Amplifier||Receiver Front End||MC1496||Ladder filter|
|IF Amplifier||Linear Amplifier||Power Amplifier||Block Diagram|
|Circuit - Part 1||Circuit - Part 2||Antenna||Conclusion|
The transceiver described here is remarkably simple based on popular communication building block MC1496. It is fairly simple to build because most of the functions are performed by MC1496. The emphasis during the design of the project was on repeatability, minimum number of switching and ability to modify for multi band operation.
In the beginning I would like to say that none of these circuit ideas are totally original and are taken from various books and magazines.
The circuit uses easily available components. Most of the coils are wound on low cost balun core. The circuit uses ladder filter. Filter is build around four numbers of 4.43 MHz crystals. I used ladder filter because it is cheap and getting reasonably good reports.
The circuit uses two numbers of MC1496. First MC1496 functions as receiver mixer cum balanced modulator. Second MC1496 works as product detector cum transmit mixer. The block diagram of the transceiver is given below.
Presently the circuit is only for 7 MHz SSB operation. It can be modified for other bands by suitably changing VFO, transmit band pass filter and receiver band pass filter. I had avoided CW and AM provision for simplicity. CW and AM can be implemented by making some carrier to leak through balanced modulator. This can be done by offsetting balanced modulator by applying some external voltage to pin 4 of MC1496.
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