Ham Radio Projects Files

//========================================================================
// This directory contains modifications that KB1OIQ has done to his
// BITX40 QRP SSB transceiver.  This kit came from India and was created
// by Ashhar Farhan (VU2ESE).  Thank you, Farhan, for both creating
// the BITX40, and for making the schematics and software open.  None of
// these modifications would have been possible otherwise.
//========================================================================

bitx40_audio_mixer:
  * KB1OIQ found this circuit on the internet and modified it to
    meet the need.

bitx40_circuit_description.pdf:
  * Written by Ashhar (VU2ESE) Farhan, placed here for completeness

bitx40_exterior.png:
  * exterior view of KB1OIQ's BITX40

bitx40_interior.png:
  * interior view of KB1OIQ's BITX40

bitx40v3_circuit.png:
  * BITX40 circuit schematic by Ashhar (VU2ESE) Farhan

bitx40_wiring.pdf:
  * BITX40 wiring instructions by Ashhar (VU2ESE) Farhan

rf_gain modification:
  * Many thanks to Allison (KB1GMX) Parent for her help.

harmonic mod:
  * I did not create this mod, but implemented it successfully.
  * I *think* this mod came from Wayne (NB6M)
 
Protect_Q13_mod:
  * I did not create this mod, but implemented it successfully.

kb1oiq_v1dot26.ino:
  * This is an Arduino Nano source file for the BITX40, originally written
    by Ashhar (VU2ESE) Farhan and heavily modified by KB1OIQ.  DO NOT blindly
    download and install this file in your BITX40 - it WON'T work.  KB1OIQ
    performed several hardware modifications to his BITX40 that must be done
    in order for this code to work.  Those modifications include:

    * addition of a Sparkfun keypad
    * addition of a mic with up/dn buttons
    * addition of a fine tuning potentiometer
    * addition of voice synthesis code using the Talkie library
    * addition of an audio mixing circuit, so the Talkie voice can be
      "balanced" with the normal radio sounds in the same speaker

Unfortunately, I have not written up each of these mods in any detail.
I will attempt to do much better for the uBITX modifications.

The code and modifications are placed here as a way to give back to the
community.  Please peruse the code and use whatever parts of it you wish.

KB1OIQ BITX40 sketch features:
  * dual VFO, swap VFOs, make one VFO equal to another
  * MIC Up/Dn work to set frequency ranges for tuning
  * print help
  * calibration
  * specifically reduce display updates to reduce speaker clicks
  * diagnostic routines, including calibration
  * USB (for digital modes)
  * keypad functions
  * save/restore rig paramters to EEPROM
  * digital modes with custom cable
  * digital voice synthesis using Talkie library
  * many others, see the sketch

Digital Modes:
  * These work with my Rig Blaster Plug n' Play and a custom cable
    to plug into the MIC connector.  PTT works via rig control.
    The operator must set USB mode and the frequency manually.
    KB1OIQ made several FT8 contacts with his BITX40 in this way.

Things NOT implemented:
  * Split mode - requires PTT to be "hijacked" by the Arduino, in order
    to allow for the transmit frequency to settle before keying the
    transmitter.  (Interestingly, this is done in the uBITX.)

  * Rig control from a computer - not enough room in memory to implement,
    although uBITX is trying.

Most of all, have a LOT of fun, and 73,

Andy
KB1OIQ
04-March-2018