Wide Frequency Receiver TR105

Retekess Technology Co., Ltd.; Shenzhen

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  • Year
  • 2019 ?
  • Category
  • Broadcast Receiver - or past WW2 Tuner
  • Radiomuseum.org ID
  • 349716

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

 Technical Specifications

  • Number of Transistors
  • 5
  • Semiconductors
  • Main principle
  • DSP, Digital Signal Processor
  • Wave bands
  • Broadcast, more than 2 SW bands plus FM or UHF.
  • Power type and voltage
  • Batteries / addl. power jack / LiPo 3.7 / USB 5 Volt
  • Loudspeaker
  • Permanent Magnet Dynamic (PDyn) Loudspeaker (moving coil) / Ø 4 cm = 1.6 inch
  • Power out
  • 0.2 W (max.)
  • Material
  • Plastics (no bakelite or catalin)
  • from Radiomuseum.org
  • Model: Wide Frequency Receiver TR105 - Retekess Technology Co., Ltd.;
  • Shape
  • Very small Portable or Pocket-Set (Handheld) < 8 inch.
  • Notes

  • The Retekess TR05 pocket radio features FM, VHF, MW, SW, CB, and AIR bands. It offers clock and Alarm.

    Main features

    • FM:  87.5 - 108 MHz (100 kHz steps)
      • Sensitivity: 2 µV
    • VHF: 30 - 223 MHz (2.5 kHz steps)
      • FM-N or FM-W, selectable
      • Sensitivity: 2 µV
    • MW: 520 - 1720 kHz (10 kHz steps), 522 -1720 kHz (9 kHz steps), selectable
      • Sensitivity:3 mV/m
    • SW: 2.3 - 30 MHz   (5 kHz steps) continuous scan
      • 13 bands for easier tuning
      • Sensitivity: 4.0 dBµV (1.6 µV)
    • CB: 25 - 28 MHz (5 kHZ steps)
      • Squelch: OFF/ON (1 µV single level)
      • Sensitivity: 1 uV
    • AIR: 118 - 138 MHz (5 or 25 kHz steps, selectable)
      • Squelch: OFF/ON (1 µV single level)
      • Sensitivity: 2 uV
    • Manual and ATS tuning (50 presets per band)
    • Built-in 700 mAh Li-Po battery charged from the USB port
    • 3.5mm stereo jack for earphones (recommended 32 Ohm impedance)

    Brief technical description

    The PCB reference is "BY-737A  V2.1  2019.9.10".

    The design is based around a AKC6955 FM/TV/MW/SW/LW DSP receiver IC. 

    All RF bands are handled by the DSP IC with exception of the Air band that requires AM mode not available in the DSP chip. Therefore an Air band front-end was added. A 150.000 MHZ TCXO and a 2SC3356-R25 NPN transistor generates the 1st local oscilllator, while another 2SC3356-R25  mixer converts the signal down to the 1st IF that will then be handed to the DSP chip.

    Another FM/VHF/SW front-end uses a third 2SC3356-R25 NPN transistor and adequate RLC networks for each band. 

    Five 74LVC1G3157DCK3-C5J 340 MHz SPDT analog switches are used to select band/filters as required.

    The radio management is handled by a A31G112CLN Cortex 32KB Flash MCU, using a 32.768 kHz crystal that also synchronously drive the OscIn pin of the DSP IC.

    The built-in speaker is driven by a YX4871 class-AB power amplifier IC, while the stereo earphones are driven by the DSP IC built-in audio amplifier.

    The power supply uses two A1sHB (SI2301B) P-MOSFET as switches; one applies +Vbatt to the VBAT pin of the DSP chip; the other applies +Vbatt to the TCXO. The charger circuit uses just one 1R0 resistor in series with a S4 (B5819WS) diode, between the USB port and the 902040 LiPo Battery, while the charging management is handled by the battery integrated protection PCB.

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

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