Dilshan R Jayakody’s Web Log

I found the ZZRX-40 receiver while going through some old issues of QEX magazine . Designed by Craig Johnson (AA0ZZ) , this is a very simple and easy-to-build 40m direct conversion receiver. Even though it is a simple circuit, it performs quite well for its size. Prototype version of extended ZZRX-40 receiver. For this project, I decided to make my own PCB design because I wanted to use components that I could easily find in our local shops. Since I couldn't find any PCB files online, I drew the schematic in KiCad and designed a custom board. If you are interested in building this, I have shared the Gerber files and KiCad project files here: https://github.com/dilshan/zzrx40-clone . Antenna connector and external VFO headers (JP101 and JP102). The heart of this receiver is the popular NE602 (or SA602 ) mixer chip. This single chip handles both the local oscillator and the product detector, which makes the whole circuit very compact. Although it is designed for the 40-mete...

In this project, we extend the shortwave superheterodyne receiver we developed a few years ago . Like the previous design, this receiver operates on the traditional superheterodyne principle.  In this upgrade, we enhanced the local oscillator with Si5351 clock generator module and Arduino control circuit. Compared to the old design, this new receiver uses an improved version of an intermediate frequency amplifier with 3 I.F transformers. In this new design, we divide this receiver into several blocks, which include, mixer with a detector, a local oscillator, and an I.F amplifier. The I.F amplifier builds into one PCB. The filter stage, mixer, and detector stages place in another PCB. Prototype version of 455kHz I.F amplifier. In this prototype build, the Si5351 clock generator drives using an Arduino Uno board. With the given sketch, the user can tune and switch the shortwave meter bands using a rotary encoder. The supplied sketch support clock generation from 5205kHz (tuner f...