Friday, September 30, 2022

QDX is an excellent digital modes transmitter (and very good on receive).

Recently I've been tinkering with antennas here and one of the resonant dipoles I put up is for 20m. I normally run digital modes on the IC-7300 which conveniently connects to a linux computer via a single USB cable but thought I'd get out the QDX again.

The QDX from QRP Labs is an excellent little transceiver for travel or portable operation. It's a bit hard to compare reception as conditions change so frequently but my impression is that it's almost (but not quite) as good as the IC-7300.

What is astonishing is how good the transmit is. On a single 2 minute transmit over just now on 20m I was spotted by 79 stations all over the world.

Here's the graph of spots over a 24 hour period.

The little triangles on the graph are transmit spots. This is a new feature of WSPR Watch that should be in the App Store (free) in a few days.

The reason that QDX transmissions are so well decoded is, I think, because it does direct frequency generation by measuring the audio frequency rather than mixing the audio up to RF. It's a very pure signal.

All over the world on a pocket sized transceiver.

I wrote a small review for the Macedon Ranges Radio club here by the way.

Tuesday, September 27, 2022

Solar K Index display from BOM using ESP32

There is significant solar activity at the moment. This activity changes radio propagation quite a bit for bad and good. One of the measures is called the K Index. I've been having good success with the little TTGO ESP32 + LCD boards and today created some code to fetch and display the K index.

This site has a good explanation which I reproduce here.

The K index is computed once every three hours (eight times a day) and the values can range from 0 to 9, with 0 being inactive, and 9 representing an extreme severe storm condition. The values are quadi-logarithmic.

K = 0 Inactive

K = 1 Very quiet

K = 2 Quiet

K = 3 Unsettled

K = 4 Active

K = 5 Minor storm

K = 6 Major storm

K = 7 Severe storm

K = 8 Very severe storm

K = 9 Extremely severe storm

Also, from here:

"The K-index, and by extension the Planetary K-index, are used to characterize the magnitude of geomagnetic storms. Kp is an excellent indicator of disturbances in the Earth's magnetic field and is used by SWPC to decide whether geomagnetic alerts and warnings need to be issued for users who are affected by these disturbances.

The principal users affected by geomagnetic storms are the electrical power grid, spacecraft operations, users of radio signals that reflect off of or pass through the ionosphere, and observers of the aurora."

To get the current value for Australia, in an easily machine readable form, I turned to our fantastic Space Weather Service of the Bureau of Meteorology. They have an API for this and other data documented here. Note that to use the API you must register with your email address and get an API key to use in requests.

There's not a lot to the code. It is built with the Arduino tool chain and uses the built-in esp32 http library and uses ArduinoJson to extract the figures. 

#include <WiFi.h>

#include <WiFiMulti.h>

#include <HTTPClient.h>

#include <ArduinoJson.h>

#include <ArduinoJson.hpp>

#include <TFT_eSPI.h>

#include <TFT_eWidget.h>

const char *kWifiNetwork = "SSID";

const char *kWifiPassword = "PASSWORD";

const char * API_KEY = "PUT YOUR API KEY HERE";

TFT_eSPI tft = TFT_eSPI();

WiFiMulti wifiMulti;

void setup() {


  while (!Serial) {

    ; // wait for serial port to connect. Needed for native USB port only



  wifiMulti.addAP(kWifiNetwork, kWifiPassword);




  tft.drawString("Starting", 10, 10, 4);


void loop() {  

// wait for WiFi connection

  if(( == WL_CONNECTED)) {


    tft.drawString("Connecting", 10, 10, 4);

      HTTPClient http;

      http.begin(""); //HTTP

      http.addHeader("Content-Type", "application/json");

      String payload = "{\"api_key\": \"" + String(API_KEY) + "\", \"options\": {\"location\": \"Australian region\"}}";


      int httpCode = http.POST(payload);


      // httpCode will be negative on error

      if(httpCode > 0) {

          // HTTP header has been send and Server response header has been handled

          // file found at server

          if(httpCode == HTTP_CODE_OK) {

              String payload = http.getString();


              DynamicJsonDocument doc(1024);

              DeserializationError error = deserializeJson(doc, payload);

              // Test if parsing succeeds.

              if (error) {

                Serial.print(F("deserializeJson() failed: "));




              Serial.println("Deserialised OK");


              long k_index = doc["data"][0]["index"];

              const char*  analysis_time = doc["data"][0]["analysis_time"];

              Serial.printf("K Index = %ld\n", k_index);

              Serial.printf("analysis time = %s\n", analysis_time);

              Serial.println("Serial print OK");


              tft.drawString("K Index", 10, 10, 4);

              tft.drawString(String(k_index), 90, 30, 8);

              tft.drawString(analysis_time, 5, 120, 2);

            if (error) {

              Serial.printf("Json error");



          } else {


            tft.drawString("Http error", 10, 10, 4);

            Serial.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str());







It varies during the day and I believe if K hits 5 things start getting serious.

All credit to the good folks at the BOM for making this easy and free to access.

Thursday, September 22, 2022

You can't beat a resonant dipole antenna

I'm a big fan of the Off Centre Fed Dipole. With a 4:1 balun and two lengths of wire you get multiple bands with good resonance. Recently I put up a dipole cut for 40m and could switch between the OCFD and the 40m dipole and it was clear that the dipole performed better.

The weather has been cold here but spring has arrived and I took down the OCFD and replaced it with a dipole cut for 80m. Resonance looks pretty good, if a bit narrow.

I used this dipole on the weekly Macedon Ranges Amateur Radio club net and other stations commented on how good, and improved, my signal was.

The antenna support tree has lots of space to hang baluns so I've now put up dipoles cut for 40m and 20m.

It's quite an effort tuning these antennas. Hoisting up, measuring, trimming, hoisting... but in the end I've got each of the antennas resonant in their bands. 

I use plastic egg insulators and fold the wire ends back and hold them in place with cable ties. This makes it easy to adjust the lengths as required for tuning.

The dead tree is a very handy support.

Getting lines over high branches can be a challenge. Dallas, VK3EB, was a great help with his big squid pole. I've also used a drone and most recently an arborist's throw weight.

Tonight I'm trying out 20m by running WSPR and performance seems excellent.

So far my antennas are all facing East-West and I think the next step is to have some dipoles facing North-South.

I was talking with Stephen, VK2BLQ, about all this and he said "you can't beat a resonant dipole".

Saturday, September 17, 2022

mcHF transceiver shown by David VK3DKR

David, VK3DKR, brought along the compact home built mcHF transceiver to the latest Macedon Ranges Amateur Radio club meeting today.

The radio is impressive and David reports excellent receiver performance and good reports of the transmissions when used on SOTA activations. Here's a brief snippet:

The amazingly good reception with just a clip lead antenna can be explained...

I used a HackRF to record a slab of the 40m band during the recent RD contest on my home antenna and then played back that recording into a whip antenna for David to receive.


hackrf_transfer -r capture  -f 7037000 -l 40


hackrf_transfer -t capture -f 7037000 -x 47 -R

On playback, the -x turns up the transmit power and the -R makes it loop when it reaches the end of the IQ recording. Note that the files get big quickly and my recording was over 3GB.

This is a terrific way to demonstrate a receiver when there isn't a good antenna available. 

Incidentally, my sincere thanks to David for thoughtfully bringing along a few J310 FETs which I mentioned on our club net I was waiting for. Very kind of you!

After 90 years who needs the ABC?

My view is that in this age of people getting their news from sites that optimise for engagement over facts, a source like the ABC is more vital than ever as part of a healthy democracy.

It was my pleasure to say a few words about the role of ABC Alumni at an event at Ballarat organised by ABC Friends Victoria.

We cut a beautiful cake, sang happy (90th) birthday and then heard from Matthew Ricketson the co-author if the excellent new book "Who needs the ABC?".

The ABC is under constant attack from the hard right, who think that the free market is the answer to everything and from some commercial media who think that the ABC prevents them from making larger profits.

Ricketson and Mullins' new book is a well researched defence of the ABC that knocks many of the oft-repeated arguments on the head with simple data and logic.

ABC Friends Victoria is a fantastic branch of ABC Friends. It is my pleasure to help them in any way I can.

Sunday, September 11, 2022

Dr Duino Explorer Arduino review

For prototyping new projects where an Arduino is to be connected with common peripherals, the Dr Duino Explorer board looks very useful. It's a good board with lots of useful components but the documentation is infuriating and there are attempts to up sell the purchaser at every step.

As you can see, there's LEDs, buttons, potentiometers, a light dependent resistor, a 128x64 OLED display, a bluetooth interface board, an ultrasonic range sensor (off board) and a row of eight NeoPixel RGB LEDs. Also there's a variable output power regulator.

In contrast to most other Arduino related products, visiting the DrDuino web site does not give you access to the construction or user manual. There is a link called Downloads but it tells you to go back and look in your spam folder for the instructions on how to log in to the site.

To get this basic information you must log in to the "exclusive" portal. Everything is strangely slow. Have you ever seen this on a modern web site?

I had to log in twice and it turns out that the site (Powered by KARTRA) is not compatible with the standard settings in modern browsers including Chrome and Safari. They suggest changing the default settings to re-enable third party cookies.

To be fair, the instructions are very detailed. What I found frustrating is that you have to step through them on the web site, one screen at a time. You are prevented from, for example, accessing the schematic until you've gone through every page up to that point.

In the end I visited each page and copied the content into a document which I could read on a tablet while constructing.

At several points during the construction DrDuino tries to sell you things such as PCB holder and side cutters with:

And... because you're a Dr.Duino customer, NO FULL PRICE FOR YOU!

There is a library to go with the board but I couldn't find it. It's not in the downloads area. Dr Duino happily uses libraries made by Adafruit but declines to share any work they've done with others. This seems counter to the norms of open source.

Anyhow, I don't want to be too negative. The board is good quality and has handy features on it. Construction went well for me and the OLED display and NeoPixel strip worked with the Adafruit libraries' examples unmodified.

Incidentally, I notice that despite all the security theatre, the link to the schematic seems to work even if you aren't logged in. Duh. 

Nuts and Volts has a good review that is quite informative - better in fact that Dr Duino's own documentation.

Guido, if you're listening, here are my suggestions to improve this product:

  • Make a single document manual that people can freely download. 
  • Put your "library" code up on GitHub (I'm pretty sure open source licenses you're using require this anyhow).
  • Sack Kartra unless they can get their authentication to work with default settings in Chrome and Safari.
  • Sack Kartra for stuffing up basic security on things like access to the schematic.
  • Don't assume users are running Microsoft Windows.
  • Tone down the "NO FULL PRICE FOR YOU" stuff.
  • The Arduino UNO clone supplied does not work out of the box on Ubuntu 22.04 by the way but there are solutions out there to fix this. (The serial chip collides with a brail device).

Saturday, September 03, 2022

WTF Adobe - so many processes!

My wife had to install Adobe Acrobat on a shared Mac for her Uni work and I'm astonished at all of the processes this has added to the system. 

Adobe CEF Helper (GPU)

Adobe CEF Helper (Renderer)






Adobe Desktop Service

Adobe CEF Helper (Renderer)

Adobe CEF Helper


Adobe Desktop Service Networking



Creative Cloud

Creative Cloud Helper

Creative Cloud Helper

Creative Cloud Helper Networking

Creative Cloud Networking

Creative Cloud Helper Networking

Core Sync

Core Sync Helper

My guess is that there's even more that I didn't recognise in Activity Monitor. The processes seem mostly idle but it's hard to understand why they are all required for something that just views and does some proprietary editing of PDF documents.

Most annoying is that in my account I now have a menubar button (no, it's not a menu) that if clicked asks me to log in to Creative Cloud. I hate you Adobe.

Friday, September 02, 2022

ESP32 with 2.8 inch LCD display

I wrote recently about a little ESP32 board with a tiny LCD display from Lilygo that worked "out of the box" for me.

Another board from AliExpress, with a larger 2.8 inch display, gave me a lot of trouble before I got it going.

Described as "ESP32 Arduino LVGL WIFI&Bluetooth Development Board 2.8" 240*320 Smart Display Screen 2.8inch LCD TFT Module With Touch WROOM"

The board has an ILI9341 display board bonded to the PCB and connected via an SPI interface.

After trying all sorts of combinations of pins for the SPI interface, and having the screen remain dark, I shone a torch obliquely at the screen and found that it was working fine but without the backlight was not visible.

Switching to MicroPython makes experimenting a bit easier. I used this ili9341 python library and with the generous help of the author rdagger, figured out that the backlight is connected to GPIO pin 21.

Here's how I set it up for drawing:

from ili9341 import Display

from machine import Pin, SPI

Pin(21, Pin.OUT).on()

spi = SPI(1, baudrate=40000000, sck=Pin(14), mosi=Pin(13))

display = Display(spi, dc=Pin(2), cs=Pin(15), rst=Pin(12))

display.draw_text8x8(0, 0, 'Built-in', color565(255, 0, 255))

As mentioned in other posts, I'm currently using these things to monitor solar power generation so I can time the use of high energy appliances with the sun hitting the panels here. A device like this, that can use internet services has all sorts of applications and a larger screen could be handy.