Created 23 June 2017

See plenty of project pictures below!

This post is about a Double Side Band (DSB) transceiver kit I built from OzQRP called the MDT which stands for Minimalist Double Sideband Transceiver. I spent two evenings and an afternoon putting it together. I wasn’t in any particular rush and there were plenty of interruptions. You can see the OzQRP website here, where you will find the MDT and other available kits. It was around AUD93.00, inclusive of shipping. This post mostly just contains some photos of the construction process and the final completed radio. I will add some more comments in due course. It was a great project! Well put together by OzQRP and a lot of fun to construct.

First, a little background on my interest in radio. I am a licensed amateur radio operator (ham radio) and have been since 2006, holding operating licences in the United States, Australia and Hong Kong, with Morse Code proficiency. I received my first ‘radio’ licence around the early 1990s as a CB operator when a licence was then required. I’ve repaired a few ‘boat anchor’ radios. These are large and often heavy vintage radios, like the Murphy B40, the National HRO-500 and the Racal RA-17L among others. My first amateur radio was an ICOM IC-718 for the HF/shortwave bands.

About 8 years ago I started to construct a small Single Side Band (SSB) receiver from small modules that made up the various building blocks of a receiver: low pass filter (LPF), RF amplifier stage, band pass filter, mixer, variable frequency oscillator (VFO), IF amplifier etc. This project has been put on the shelf for many years but the radio works and I will feature it in a seperate post as some stage when I get back to working on it.

Now back to the MDT. I won’t go into much detail about my experience building the kit here. I have only used it to receive so far. After construction, I did go back and perform a simple modification described by Peter Parker, VK3YE, on his YouTube channel which about doubled the frequency range of this 40m (7MHz) band radio. I highly recommend you check out Peter’s YouTube channel where you will find videos reviewing the MDT and describing the modification. Search for the OzQRP MDT on YouTube and see what other’s have posted.

I will update this post once I get a chance to try the radio out on air over the next few weeks back in Germany with a wire antenna and a Ventenna HFp portable vertical antenna. The microphone came from an old taxi mobile data terminal. I had to rewire the PTT switch in the microphone to suit the MDT’s microphone socket. For now, I will post some photos of the construction, the modification and the final product.

 

The completed project

Note the toggle switch on the top right in the picture below. This is the band segment selection switch. Also note that the tuning knob in the finished radio is larger. This was a suggestion from Peter Parker’s YouTube video to make it easier to tune the radio. I will update this post later with some comments about these modifications.