My homebrew SDR rig

sdr display

The construction of my own Software Defined Radio (SDR) based rig started near the end of 2011.  I was very excited when I initially read some articles on SDR technology.  So, it became clear to me that I had to invest some time (and funds) to build my own system and learn from the experience.

In this section I will try to give a complete picture of my system.  I will comment on the construction adventures, and finally I will present my own measurements and comment on the performance of the system.

Deciding on the rig’s features

My first homebuilt SDR was a SoftRock RXTX.  This kit introduced me to the realm of I/Q sampling and to a few software options that exist for operating such a rig.  I had some very enjoyable QRP contacts (1W PEP output) and also built a 10W linear amplifier for it.

The SoftRock was built for the 40m,30m and 20m bands.  It was then that I realized that I wanted an all band SDR radio.  I then started putting together a list of features

Homebrew SDR rig’s features

Frequency coverage (RX and TX):  160m to 70cm

TX power for the HF range:  10 to 20watts PEP

RX MDS figure for the HF range: better than -110db

TX power for the 2m band: 5w PEP should be enough

RX MDS figure for the 2m band: better than -110db

Good linearity for all amplifiers, so that I can work digital modes

Capability to work voice modes without Virtual Audio Cables. (to avoid loading the PC’s CPU)

Support for CW operation (iambic keyer and straight key support)

Initially it should work with PowerSDR-IQ and then on Linux.

Abstract block diagram of the SDR rig

The following block diagram briefly presents the system, hiding most of the unnecessary details.

I will present more details while talking about individual subsystems

sdr block

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