Repository for recent

Amateur Radio Projects


Adding an I/Q output to the Elecraft KX2

A mini writeup of an ill-conceived little project, adding a homemade option board to the Elecraft KX2 transceiver.

Last upd: 2017-02-13

Status: New - added 2017-02-13

Power and SWR Meter - Rev II

An update to the original Power and SWR Meter project.

TFT Graphics and Touch display

or alternately, a 20x4 LCD, like previous project

Last upd: 2020-06-21

  • Revision 1.03 of the TFT version. Maintenance update to accommodate changes in the ADC library.

  • Revision 1.02 of the TFT version. Bugfix, ADC had a kink around 1.67V. Added power level floor settings up to 10 mW

  • Revision 1.01 of the TFT version. A minor adjustment to keep it compatible with rev 1.36 of Teensyduino (updated ADC library)

  • Detailed instructions added for compilation of source code. Also added some info and pictures describing a slightly improved version of the Tandem Match Coupler and AD8307 bridge.

  • Revision 1.00 of the TFT version. Floor function added for the displayed power level, user settable at 1mW, 0.01mW, 1uW or no floor.

  • Revision 0.99 of the TFT version. Bugfix of Reverse Calibration feature.

  • Revision 0.98 of the TFT version. Added features

  • Revision 0.98 of the LCD version. Encoder bugfix

  • Revision 0.96 of the TFT version. Minor cleanup

  • Revision 0.97 of the LCD version. Minor cleanup

  • Revision 0.96 of the LCD version. Fixes a pin assignment discrepancy for the Enact switch.

  • 2016-09-05 Firmware version 0.95 uploaded, some minor improvements.

  • Project added 2016-06-12

Machine recognition of hand-sent morse code

Two easy to build microcontroller projects.

Last upd: 2016-03-20

To automatically tune a Magnetic Loop Antenna

Last upd: 2020-06-21

  • Firmware version 4.10.

    • Maintenance update to accommodate changes in HardwareSerial and ADC library.

  • Firmware version 4.09.

    • Bugfix for DRV8825 / A4988 stepper motor driver option. Had glitches when switching between full and fractional step modes.

  • New "BOM and Building Instructions" added for Rev3 / Rev4 printed circuit boards, which utilize the DRV8825 or A4988 Stepper Drivers

  • Firmware version 4.08.

    • Update to stay compatible with latest version of Arduino/Teensyduino.

    • Added two transceivers, Yaesu FT920 and Kenwood TS870 (neither has been tested yet)

  • Firmware version 4.05:

    • Added SWR Alarm output signal on pin/pad 33.

    • Backlash Compensation Select function changed to Backlash Compensation Adjust with an user (Menu) adjustable range of 0-400 steps

    • Bugfix: Some displays garbled when using the precompiled hex files with version 4.04

    • Bugfix: Endstop Option 2 had bugged logic around handling of upper endstop signal

  • Firmware version 4.04:

    • Pushbutton function rewritten, now no false readings.

    • Kenwood TS2000 "TX;" issue addressed.

    • Improvement for endstop features 2 and 3.

    • Switch-in/switch-out capacitor feature improvement.

  • Updated "Operation Instructions and Notes".

  • Updated "BOM and Building Instructions" , adding a detailed description of the Dual Antenna Changeover feature.

  • Firmware version 4.03. Main additions:

    • Pushbutton debounce improvement

    • Added USB commands for remote tune

    • Screensaver disable feature added

    • Further LCD handling improvements

    • USB commands made case insensitive and ';' added as USB command terminator.

  • Firmware version 4.01 Improved handling of certain OLED displays.

  • Firmware version 4.00. Main additions:

    • Triple Antenna change-over feature

    • Transceiver Profiles and tune power level management

    • Yaesu FT-1000 Mk-V, Kenwood TS-440/450

  • Firmware version 3.07. Added Yaesu FT-990, minor bug fixes.

  • Firmware version 3.06. Further Kenwood / Flex bug fixes.

  • Firmware version 3.05. Kenwood / Flex bug fixes.

  • Firmware version 3.04. ICOM bug fixes.

  • Firmware version 3.03 - capability to handle 3 additional transceivers added

  • Project added 2014-04-30

Power and SWR Meter with dual bargraphs, using 2x AD8307

microwatts to kilowatts, accurate SWR at 1mW.

Last upd: 2016-05-27

(see also updated project: Power and SWR Meter - Rev II)

  • A new version (rewrite) of the firmware, using the Arduino environment. Arduino sketch, v. 0.90.

  • Firmware v.0.75, yet another bug fix. Thanks ON6ZG

  • Firmware v.0.74, another bug fix, courtesy of M0KGV.

  • Firmware v.0.73, bug fix.

  • Firmware version 0.71, firmware bug cleanup.

  • Firmware version 0.70:

  • 12 bit ADC option added.

  • Some tweaks of USB commands

  • New and more stable USB-Serial stack

  • Major rewrite of description.

  • Project added 2013-09-29

Magnetic transmitting loop antenna excercises

Two magnetic transmitting loop antenna projects:

        • 0.5 x 0.5m loop using a manual stepper motor controller for tuning

        • 1 x 1m loop and an automatic microcontroller based stepper motor controller

Last upd: 2014-04-30

  • Automatic Controller and firmware now outdated.

  • See the more recent project: To automatically tune a Magnetic Loop Antenna

  • Rough description of two magloop projects added 2013-07-15, including a manual controller and a fully automatic controller for tuning of magnetic loop transmitting antennas

A very simple to build, menu driven RF Power Meter, based on the AD8307 log amp

(This project is also described in QEX Magazine, May/June 2013 Edition)

Last upd: 2014-04-30

AD8317 based Intelligent Attenuator/Power Meter for 0.2 to 500 MHz

A multipurpose RF lab instrument:

  1. RF power meter, 0.2 to 500MHz, input power -50 to +30dBm, 0.1dB resolution.

  2. Step Attenuator, 0 - 151.5dB in 0.5dB steps.

  3. "Intelligent Attenuator" or "Signal Level Generator" function, automatically adjusting to a preset output power.

Last upd: 2012-04-13

  • Bugfixes and new features

  • (Bargraph Power Display)

SDR Widget

A group project to develop the ideal sound card/controller for an SDR

Last upd: 2011-04-17

  • A full fledged sound card with superior performance, and Mobo style SDR control functions. HiFi Audio playback variants also developed. Development continues

Comparison of “conventional”, “DDC based” and “soundcard based” receivers

A rambling mini thesis on SDR performance

Last upd: 2010-07-28

Mobo 4.3 Application Programming Interface (API)

Here is the Mobo 4.3 Firmware API, as well as the complete AT90USB162 / ATmega32U2 sourcecode for download (see bottom of page).

The MoboControl GUI is available for download at the bottom of this page.

Last upd: 2017-01-20

  • Uploaded a new version 1.08 of the firmware source code. The new version can be compiled using Atmel Studio 7.

  • API and repository for the Mobo 4.3 firmware added on 2011-04-02

Mobo 4.3 Project - The continuing Saga of the SR 6.3 kit - Now becoming a deluxe HF Transceiver

This section includes description of a firmware development project, using the AT90USB162 microcontroller to provide Si570, and TRX control

(automatic BPF + LPF switching, PA bias, SWR measurement and protect, etc...)

Last upd: 2011-04-02

Softrock 6.3 Project - An all band HF Transceiver, based on the Softrock RXTX v6.3 kit

Including the following home brew projects:

Last upd: 2011-01-16

  • Added a picture from Alex, RN6LW, showing his very nice SDR transceiver, including the ATmega168 controller

  • Stable since 2009-09

A 4m tall, bottomfed, electrically fullsize halfwave vertical dipole for 20m (tuneable to other bands)

Last upd: 2009-03-01

Here is my own version of a disclaimer:

This is an Amateur Radio Techno Blog site. Everything on these webpages has been put here for my own benefit and enjoyment. If I happen to have included an inappropriate link, please notify me, lofturj (-at-) gmail (-dot-) com, and it will be promptly deleted. No responsibility whatsoever is taken for any material published on these webpages. Some projects described here may include an element of original thought, now this is unlikely but statistically possible, remember the monkeys and the typewriters. In such a wildly unlikely event, while I claim ownership, I also expressly grant license to use on a non-profit basis. To stretch this to the extremely silly; if anyone becomes filthy rich by implementing something based on an original thought found on this web page, then I want a 50% cut. So there.

This site is not set up to be esthetically beautiful. In fact, perverse pride is taken in its haphazard construction and top-heavy graphics. Project descriptions may and will appear and disappear without rhyme or reason.

(Page last updated 2020-06-21, Loftur E. Jonasson, TF3LJ / VE2AO)

(translated to new Google Sites 2022-10-10)

Original site content available here: