TinySA

TinySA - Spectrum Analyzer

• Maximum input level
  • 0 dBm = 1 mW
  • dBm = 10*LOG(milliwatts)
  • -10 dBm = 0.1 mW
  • +10dBm = 10 mW
  • +20dBm = 1000 mW
• 3.3V at 50 Ohm = 0.2178W
  • 217.8 mW = 23.4 dBm
• tinySA wiki

Attenuators

30 dB Attenuator

• Pi Attenuator Calculator

• Built
  • Standard 5% resistor values
  • R1 = 820 in parallel with 22K = 790.6 ohms
  • R2 = 2 paralleled 120 Ohm 1/4W resistors paralleled with 470 ohms = 53.2 ohms
  • Flat from 0-30 MHz
  • Measured attenuation is flat
    • -30.01dB at 1 MHz
    • -30.24dB at 30 MHz
  • Input Impedance - 53.1 ohms, 21.3nF
  • SWR 1.06
  • 1/2W max (5VDC max, 0 ohm source)
• LTSPICE Simulation

20 dB Attenuator

• Build
  • Standard 5% resistor values
  • R1 = 510 in parallel with 8.2K = 247.3 ohms
  • R2 = 2 paralleled 150 Ohm 1/2W resistors paralleled with 330 ohms = 61.11 ohms
  • Flat from 0-30 MHz
  • Measured attenuation is flat
    • -tbd dB at 1 MHz
    • -tbd dB at 30 MHz
  • Input Impedance - tbd ohms, tbd nF
  • SWR tbd
  • 1W max (8.6 V max, 0 ohm source)
• LTSPICE Simulation