WA3TFS SDR Upverter Design

Features

SDR up-converter/receiver shifts HF (0-30 MHz) frequencies up by 100 MHz. Used to listen to HF frequencies on an inexpensive RTL-SDR module.

• $55
  • Purchased at W3PIE hamfest
  • Can be ordered as PCB, Kit, or assembled
• SBL-1 Level 7 mixer
• 100 MHz can oscillator
• Low pass filter
  • 35 MHz
• 1 kHz to 1.7 GHz SDR Receiver - WA3TFS Design
  • QST Article
  • SDR wiring diagram
  • Parts List
  • Layout

Schematic

Pass Filter

• 9 turns on FT37-2 = 0.3 uH

• LTSpice Simulation
  • 1-100 MHz

• LTSpice Simulation
  • 1MHz-1GHz

Software

• RTL-SDR
• HDSDR - Easier to use
• SDR Sharp - Crashier

Build

• Nice silver mica caps for the band pass filter
  • My kit was missing the center cap of the band pass filter (150 pF)
  • I used a junk box ceramic disc cap
• 30pF cap installed in J_A to J_B marked 300
• Build was too tough due to very small pads on the PCB
  • Particularly tough to solder ground pads
  • Pad shapes were not round so less area to set soldering iron
• Is LO drive more than 7 dBm?
• Pin 1 orientations on the mixer and oscillator "backwards" from other board legends
  • Pin 1 shown in red circle

RTL-SDR

• Has SMA connector

Wiring

• SPDT switch
  • One switch pole powers the card (turns off 12V)
  • Other switch pole switched in/out the Upverter
  • Could just move the cable

Enclosure

• Board fits perfectly in
  • Extruded Aluminum Enclosure Box - 94mm x 83mm x 30mm
  • Card just perfectly matches