• Country
• People's Republic of China

• Manufacturer / Brand
• Keduosheng Technology Co., Ltd. (Qodosen); Huizhou City

• Year
• 2023 ?

• Category
• Broadcast Receiver - or past WW2 Tuner

• Radiomuseum.org ID
• 356699

Click on the schematic thumbnail to request the schematic as a free document.

• Number of Transistors
• Semiconductors present.

• Semiconductors

• Main principle
• DSP, Digital Signal Processor

• Wave bands
• Broadcast, Long Wave, more than 2 x SW plus FM or UHF.

• Power type and voltage
• Batteries / addl. power jack / Li-Ion 3.7 / USB 5 Volt

• Loudspeaker
• Permanent Magnet Dynamic (PDyn) Loudspeaker (moving coil) / Ø 4 cm = 1.6 inch

• Power out
• 1 W (undistorted)

• Material
• Plastics (no bakelite or catalin)

• from Radiomuseum.org
• Model: FM Stereo/LW/MW/SW Multi-Band Radio SR-286 - Keduosheng Technology Co., Ltd

• Shape
• Very small Portable or Pocket-Set (Handheld) < 8 inch.

• Dimensions (WHD)
• 128 x 75.5 x 38 mm / 5 x 3 x 1.5 inch

• Notes

• The QODOSEN SR-286 portable receiver employs one advanced performance tuner chip from the automotive industry. It features FM-RDS Stereo and AM bands, squelch, clock/world clock, sleep timer and alarm.

  The SR-286 was followed by the DX-286. They share the same chassis and cabinet, but the DX version firmware was modified to feature different way to invoke some functions that requires two-key combination on the RS version.

  Main features

  • FM-R(B)DS: 64 - 108 MHz, 76 - 108 MHz, 87 - 108 MHz, 87.5 - 108 MHz (200, 100, 50, 10 kHz steps)
  • SW: 1711 - 27000 kHz (1 & 5 kHz steps)
  • MW: 522 - 1620 kHz (1 & 9 kHz steps), 520 - 1710 kHz (1 & 10 kHz)
  • LW: 144 - 519 kHz (1 & 3 kHz)
  • Sensitivity
    • On telescopic antenna:
      • FM: <= 0.5 µV (30 dB S/N)
      • SW, LW, MW: <= 10 µV (20 dB S/N)
    • On built-in magnetic antenna
      • LW: <= 2 mV/m (20 dB S/N)
      • MW: <= 1 mV/m (20 dB S/N)
  • Selectivity:  >= 60 dB
  • Bandwidth
    • FM: 17 bandwidths and Auto, selectable
    • AM: 3/4/6/8 kHz
  • Manual, direct, and automatic tuning with storage
  • 1000 memory presets
  • Built-in LNA, selectable
  • Built-in antenna attenuator
  • Audio output power: 1 Watt at 10% THD
  • Audio tone control
  • 3.5mm extenal antenna jack
  • 3.5mm Stereo 32 Ohm earphones jack
  • Power supply: Removable rechargeable 18650 Lithium Battery 
  • Micro-USB charger port, 5 V, 500 mA
  • Shutdown current: 150 µA
  • Quiescent current: 190 mA

  Brief technical details

  This unit features four PCB assemblies: PCB Antenna Socket "2023-6-15", PCB Receiver "SR-268V04 2023-8-18", PCB MCU/Audio/Display "SR1KV05 2023-8-10", and PCB KB/PWR "SR1AJV02 2023-6-1". Older PCB versions exists, like MCU/Audio/Display "SR1AJV03 2023-8-8" and Receiver "SR-268V02 2023-6-25"

  The RF tuner uses a F8605/TEF6686AHN by NXP chip. The speaker is driven by a 8002D chip, and the earphones by a LM4809 chip.

  The radio is managed by an non marked 80-pin chip and a 24C32A memory chip. Additional active components are used, like a 74HC595D shift register chip, a charger chip, a few LDO regulators, and control transistors.

• Net weight (2.2 lb = 1 kg)
• 0.2 kg / 0 lb 7 oz (0.441 lb)

• Author
• Model page created by Jose Mesquita. See "Data change" for further contributors.

• Other Models

• Here you find 1 models, 1 with images and 1 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Keduosheng Technology Co., Ltd. (Qodosen); Huizhou City