QRPGuys 40/30/20m DSB Digital Transceiver II Kit


This kit is discontinued. Please visit here for the new QRPGuys AFP-FSK Digital Transceiver III kit, complete with VFO kit, and 40/30/20m band modules.


The new QRPGuys DSB Digital Transceiver II is a low cost, multiband, DSB transceiver kit, with three easy plug-in modules for 40/30/20m, (additional module pcb’s available). Changes that Steve Weber (KD1JV) have included are, a high pass filter to help with BCB interference in troubled environments, replaced the relay with solid state switching, added a zener diode for atmospheric surge suppression, and designed a multi-band 160m-17m VFO as an easy plug-in option. The transceiver output remains the same at an approximate 2.5 watts on 40m, over 1.5 watts on 30m, and over 1 watt on 20m. The receiver sensitivity was measured at .4uV (-115dBm). The board is the same size, and all the components are included for the transceiver (3.0″ x 3.12″) and three band modules, for 40/30/20m.

You can see the optional new Si5351A VFO here, designed for our original transceiver and the new II transceiver to allow different modes and bands from 160m – 17m.  No more sourcing crystals!

The transceiver runs the popular free WSJT-X software (Windows, Linux, or macOS) that requires an accurate time synchronization program, such as Dimension 4, or many of the other free ones available. Users will need two generic 3.5mm stereo jumpers to your computer or tablet microphone/speaker jacks on the sound card.

The T/R relay is replaced by a transistor switch with the VOX circuit sensing the signal from the software on the pc or tablet speaker jack. The optional VFO plugs into and mounts directly on the pcb. The connections to the transceiver are BNC for the antenna, 3.5mm stereo jumpers to the computer audio jacks, and 12-14 VDC for the pcb mounted 2.1mm pin coaxial power jack. Power consumption is about RX-15mA / TX-350mA. The total weight w/three band modules is 3oz. (85gm). The normal tools required are a soldering iron with a small tip, rosin core solder, and small side cutters. The transceiver can be built in an evening. On a difficulty scale of 1 to 5, 5 being the most difficult, this is rated at 3 to 4 depending on your experience.

Early October 2020 we changed to the smd mixer because of the shrinking domestic availability of the dip8 version of the popular mixer and to keep the kit low priced. Performance of both versions is identical. Both assembly instructions are shown next.


Click here for the v.II assembly manual with dip8 mixer.


Click here for the v.II assembly manual with smd mixer.


Excellent FT8 Users Guide by ZL2IFB


Reference URLS:

https://physics.princeton.edu/pulsar/K1JT/wsjtx.html Latest WSJT-X program

Dimension4  download  – Coordinates computer time

https://time.is/ – Checks time accuracy of the computer time