Si5351A 160m-17m VFO Kit for the QRPGuys DSB Digital Transceivers


    Si5351A 160-17m VFO Kit – $30



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Add this module for either our original “Rev. B” transceiver or the new II transceiver for additional digital modes and bands without sourcing crystals!


We asked Steve Weber (KD1JV) to design a PLL synthesized VFO kit (160m-17m) for our DSB Digital Transceiver kits. His design utilizes the Si5351A PLL clock generator chip, with a single chip Atmega328P µP for control, featuring a five digit LED frequency readout to 10Hz resolution. You simply set the band and frequency with the onboard push buttons. No need to source crystals for additional frequencies or modes. This kit contains all the components and hardware for the VFO to mount onto either digital transceiver pcb, or if desired, using the four corner holes, mount remotely in your custom chassis. The Si5351A clock chip is the only SMD component, all others are through hole.

The pcb is 3.95″ (74.8mm) x 1.60″ (40.7mm), and mounts directly on either transceiver board, using the included hardware, still retaining access for the band modules. Power required 9-14V @40mA. With the addition of the VFO, you disable the crystal on your current band modules, but retain the needed low pass filter components. For the original Rev.B transceiver, connect the minimal power needed for the module, and output of the Si5351A via pads on the main board. For the new Rev. II transceiver, the VFO plugs directly into the pcb for power and signal.

As a starting point, the VFO defaults to the FT8 frequency for 160m-17m. Specific frequencies for other modes can be easily entered. To use, simply power up and set the digital readout to the specific frequency for your mode. The firmware is written with the Arduino IDE and is open source, allowing for the user to modify the sketch to add functions. On a scale of 1 to 5, 5 being the most difficult, this is rated as a 3-4 due to the SMD chip. The normal tools required are a soldering iron with a small tip, rosin core solder, small side cutters, small phillips screwdriver, and some Solder Wick® if needed. Allow a couple of hours to build, depending on your experience.


Click here for the VFO assembly manual


Click here for the Arduino sketch for customizing