Ham Radio - Fox Hunt Transmitter Keyer

[last updated: 2023-02-08]
ham radio home page
attenuators
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• This project uses an Arduino to send periodic messages (initially morse code) to a Baofeng UV-5R mic input.
  I will be using 2m, 145.6 MHz, a frequency in the "miscellaneous and experimental" band plan.
• Customary freq is 146.565 in California (Del Norte club)

• The first rev is based on a create.arduino project (https://create.arduino.cc/projecthub/nfarrier/auto-keyer-for-radio-fox-h...).
  It uses an arduino programmed to activate transmission via the radio's PTT control, and send a message.
  The arduino program energizes a relay (replaced with a transistor in my circuit) to close the PTT contacts
  (PTT line on Baofeng must be grounded to activate transmit).

• What gets transmitted:
  • Note: the protocol/syntax of the transmitted message is arbitrary, but must include your call sign.
    It should include something identifying it as a transmission from a fox.
  • send a CW message identifying your ham call sign and text "FOX" to identify the transmission,
    the tone is produced by Arduino and is input to the mic input on the Baofeng.
  • a 7-sec or so, 1000 Hz tone,
  • wait for a time (with PTT still closed),
  • release PTT,
  • wait for a time,
  • repeat.
  
  

  from arduino.cc project
  
  

  from my earPiece plug
  
  

  from Operation Manual
• Hardware: I pulled apart a Baofeng ear piece to get at the wires and map them. OMG they are tiny. Each "wire" (4 total - see diagram above) has maybe 10 strands of thread-like wires, wrapped with smaller threads of probably nylon.
  It was a tedious job (under a magnifier/microscope) to separate the nylon to allow twisting together the thread-wires.
  Each of them appeared to have a (colored) enamel insulation. After removing the nylon and twisting the wires together, I used high soldering iron heat to melt through the enamel to tin the ends.

• The first breadboard circuit, using a Nano r3, worked as designed. Volume/signal-strength at receiving Baofeng was OK, with tone good and clear.
  Arduino code - foxHuntKeyer-06.ino

• Next version used a microduino board. Some pinouts were changed from -06 program.
  Arduino code - foxHuntKeyer-07-microduino.ino

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• Links:
  • (link to:) Byonics micro-fox transmitters
  • (link to:) Amazon 1w VHF transceiver
  • (link to:) APRS tracker review
  • (link to:) VK3YNG Foxhunting equipment and info links
  • (link to:) RB­MX146 2m transmitter module for APRS
  • (link to:) FoxTTL DIY transmitter
  • (link to:) Arduino DTMF generator on github by dilshan
  • (link to:) Arduino DTMF generator by LloydM
  • (link to:) Arduino DTMF generator by dilshan - project page
  • (link to:) The Test Call - debug site
  • (link to:) Arduino DTMF generator by dilshan - arduino.cc page
  • (link to:) byonics
  • (link to:) wcar.ca
  • (link to:) Instructables - fox w/ Uno & sound board
  • (link to:) arduino.cc project
  • (link to:) Hackaday - project using sdr

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