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7 MHz SSB Transceiver

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Power Supply Variable Frequency Oscillator Carrier Oscillator Audio Amplifier
Mic Amplifier Receiver Front End MC1496 Ladder filter
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Circuit - Part 1 Circuit - Part 2 Antenna Conclusion


Ladder Filter used in 7MHz SSB Ham Radio Transceiver.

The circuit uses ladder filter builds around 4.43 MHz crystals. I selected 4.43 MHz crystals for the filter because they are cheap and easily available.

By terminating input and output with a 1000E resistor, pass band ripple can be reduced. For R = 1000E and F = 4.43 MHz, the value of C0, C1, C2 are given below.

C0 = 101 PF (use 100 PF)
C1 = 65 PF (use 68 PF)
C2 = 14 PF (use 15 PF)

Ladder filter is assembled on a small PCB. The metal enclosures of all crystals are connected to ground through thick copper wire. For ladder filter you need four crystals and one crystal for carrier oscillator. Collect all crystals of same make and with same serial number.

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