Let's Build Something SSB Transceiver

The Lets Build Something Transceiver project currently has two transceivers on the air and we know of several that are in various stages of the build. It is imperative that the Part I Direct Conversion Receiver be built first as this accomplishes two things: 1) it builds critical units that will be used in Part II and 2) for the "newbie" builder promotes the development of the necessary skills needed to successfully complete Part II.

The authors have received numerous emails where because of the information published on this reference page, some builders forged ahead and built the Part II boards without completing Part I. The problems encountered were obvious -- Part I must be built and the Part II article has not been published as yet. Without the benefit of the Part II article it is a very difficult task to simply take schematics and expect a working project. The Part II article will appear in the next issue of QRP Quarterly. So step one is to join QRPARCI so that you will receive the next article.

This project is a springboard where many enhancements and expansion opportunities abound. The goal was to literally build all of the circuit elements from scratch. Performance improvements in the form of using surplus commercial crystal filters is readily accomplished. For instance two choices would be the filters out of the Heathkit HW/SB 100, 101 or 102. These are superb filters many of which can be found for $10 and operate at 3.395 MHz. The filters from the Yaesu FT-101 series are another candidate as they operate at 3.180 MHz. These are two particularly excellent choices for use on 17 Meters. [See the Yaesu Page here.]

Another variant which was used was the 9.0 MHz crystal filter available from the GQRP Club. The connections are the same as for the Yaesu FT-101 (500 Ohm Impedance). Three number changes in the software and the same software is useable with the GQRP Filter. Here is the sketch for the 9.0 MHz Filter.

Often the filters can be found but are missing the matching crystals, which also means a chance to bargain since without the matching USB/LSB/CW crystals the filters are kind of useless. But that is no longer an issue since the Si5351 can generate the needed crystal frequencies. The Bilateral matching transformer design would need a turns ratio adjustment to go from 50 Ohms to 2K Ohms for the Heathkit and the Yeasu would need a 50 to 500 Ohm match. Placing the VFO on the correct frequency to accommodate the filters and/or different bands is but a couple of lines of changing numbers in the Arduino Sketch. It's software not hardware!

Another improvement would be to use the SBL-1 Double balanced mixers in place of the homebrew mixers built for project. Some of the emails we received about problems with building the DBMs relate to not watching the three you tube videos on how to build the DBM's. It is difficult at best to build DBM's that match units built to exacting specifications on a manufacturing line. That said those built for the LBS are "Good Enough".

When one of the authors mentions he is using a homebrew transceiver, the most frequent question is "Which Kit Is It?" There is no kit and like the early days of radio this is a home built radio transceiver!

A real side benefit of the LBS is that it is a platform for experimentation such as was done with the installation of the various filters.

In case there are any concerns -- 5 Watts works! Stations in Washington, Idaho, Oregon, and Montana have been worked from Southern California running 5 Watts and which proves this is a viable transceiver project.

KK6FUT & N6QW