You can not drive the power amplifier (MFR101A ) directly with the output of the AD831 mixer. 10dBm power ist not enough. So I did design a 14dB voltage gain amplifier to get the needed power to fully get the final 50W output from the power amp.

Here are some experiments with a simple first IIR filter implemented on a STM32F4. After some theory the design and implementation is presented. Enjoy!

We look at the basic concepts of active filters, design a 2nd order lowpass with TI’s filterdesign tool and then build a filter and measure the filter performance on the lab bench. Maybe you want to watch the introduction to electronics filters first, since I do reference to that video so what.

This series of videos give you an overview/introduction on electronic filters. basic introduction to electronics filters analog / passiv filters crystal filters active filters digital filters This first video talks about filter specifications, filter types, basic RC filter discussion and shrot discussion on s-parameters. Here you can find more videos about “electronic filters”:

This video discusses theory, active and passive mixers, simulation with LTSpice and GNU radio. Watch the video here:

This is how I did design the bandpass and lowpass filters.

See how I approached the design of a 8 pole crystal ladder filter for SSB @9MHz and with a bandwidth of 2.4 kHz.

Check out how the antenna amplifier got designed, simulated and tested.

I did choose to build a super-heterodyne type of receiver. What alternatives do we have?