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Thursday, April 23, 2020

WA7SKT's Al Fresco DSB Rigs

Loren WA7SKT wrote: 

Got the balanced modulator and first RF power amp board mounted today for my 20 meter DSB transmitter (above). Still have to build carrier oscillator and final RF power amp boards yet. Coax with BNC connector is carrier osc input to bal mod. As is puts out 8.5mw into 50 ohm load.

Audio in through 2N3904 emitter follower to SBL-1 balanced modulator. Rf out to a 2N4401 Class A RF amp. Will have a final RF power amp stage and to the lowpass filter. Targetting 250mw output max for WSPR. Will add the 2N3904 Colpitts oscillator with tuned collector for carrier oscillator. Power supply will be 9 volts and 12 volts.

This is part of my fun in eventually building a 20 meter SSB transceiver. I am not interested in anything multi-band. This is my second DSB transmitter. First is larger and uses Si5351 for carrier oscillator.

I also plan on building a WSPR transmitter using an Arduino and Si5351 synthesizer so I dont need my PC.  There is a frequency shift program for Arduino to control Si5351. I use Si5351 now for VFO’s. My first WSPR transmitter uses one just for carrier oscillator.

Loren's First DSB Rig

I like Loren's self description on Twitter: 


  1. That looks really good. A great way to have some homebrew fun as we sit out COVID-19.

    Charlie ZL2CTM

  2. Hi Gang!
    My COVID Quarantine project is progressing nicely. Check it out here:


  3. Fine looking build!

    Enjoy the journey.


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