Andrew Mitz
LoopTune.inoAutomatic tuning program as of Oct 2019. Working.ino - 31.95 kB - 06/15/2020 at 19:19 |
|
|
ESP32 and RF circuits - small.jpgESP32 mounted on prototyping board with SparkFun Motor Controller. Blue circuit board of the Adafruit clock generator board. It's output connects to my 5-pole low pass filter (about 19 MHz). The output of the filter drives the coupling loop (link). The vertical SMT prototype board has a AD8307AN log amplifier to measure the sampled RF.JPEG Image - 183.05 kB - 09/10/2019 at 15:57 |
|
|
Motorized capacitor and coil - small.jpgThe loop antenna main loop is modeled with a copper coil wound on a custom 3D printed form. The exciter loop is modeled with a 50 ohm link coupling (green wire). A toroid transformer is used to sample signals from the tuned circuit.JPEG Image - 192.86 kB - 09/10/2019 at 15:48 |
|
|
Tuning box fixed and variable capacitors 3.jpgClose up of tuning and fixed capacitors. High current doorknob (RF) caps are 25pf and 50pf NPO. Variable cap is 2 section, 100 pf per section.JPEG Image - 535.81 kB - 08/08/2019 at 16:28 |
|
|
Tuning box fixed and variable capacitors 2.jpgOverview of tuning box. Variable cap has insulated shaft coupling and vernier reduction drive. Other end goes to radio knob to act as a pointer.JPEG Image - 165.51 kB - 08/08/2019 at 16:28 |
|
|
3-D printed clamp design.jpgAn 11 foot telescoping lighting pole is the support. 3-D printed clamps mount each component to the pole. Different clamps fit different sections of the pole.JPEG Image - 100.96 kB - 07/26/2019 at 16:53 |
|
|
Choice of range capcitors.pdfThis design uses a high voltage air variable capacitor. Fixed RF doorknob capacitors set the range over which the variable capacitor is used to tune. This graphic shows each potential tuning range.Adobe Portable Document Format - 39.97 kB - 07/26/2019 at 16:42 |
|
|
Loop size and capacitances.xlsxSpreadsheet and graphs of the different capacitances that would be needed depending upon the loop size.sheet - 18.53 kB - 07/26/2019 at 16:41 |
|
|
Basic HF Short loop antenna and some design notes
A portable loop antenna that works well on 40 through 10 meters. This basic design is advanced in my other projects.