Saturday, June 19, 2021

ATS-20 Si4732 receiver firmware update

I recently purchased a nifty shortwave and FM receiver from AliExpress built around an Arduino Nano and Si4732.

I pulled mine apart to try to see if there was a label that would provide a clue about which version to write it it - there isn't. A tip: you can just undo the top screws front and back to get the lid off. Watch the speaker connected by short wires

On power on, it displayed V1.1.5 of the library by PU2CLR. After upgrade it now shows 3.04.

I followed the instructions on swling.com but used Arduino 1.8.13 on macOS just fine.

Basically the steps are:

  • Select Arduino Nano
  • Select ATMega 328P (Old boot loader)
  • Install libraries:
    • SI4735
    • Tiny4kOLED
    • TinyOLED-Fonts (it's a dependent)
As well as plugging in to the Nano I had to power on the radio to program it.

The source code is available here. For my hardware, I found the version titled "SI473X_ALL_IN_ONE_OLED_RDS_CHINESE_V3" was the one that matched the buttons on my front panel.

In the source code of the sketch there are some settings to adjust if you like such as default volume.

Before upgrade here's the splash screen:


After the update it looks like this:


The display in operation is a bit different too.


It's quite a sensitive receiver and sideband works pretty well. Here's an example.



There is no bandpass filtering on the input so it would probably be overloaded if connected to a broadband antenna. It's wonderful to have the source code to play with - all credit to PU2CLR.

Thursday, June 17, 2021

My first SOTA - cold and wet but not disappointing

Paul, VK3HN, kindly invited me along to a Summits On The Air (SOTA) activation today at Mount Disappointment close to Melbourne.  

The weather did not look promising but we decided to risk it and while it was rather damp and cool, it could have been worse. 

David, VK3KR, generously drove and Owen, VK3EAR cleverly opted not to come and stayed at home to monitor.

I took a loop antenna and an IC-705 with external battery. Paul had two home brew rigs and used an end fed antenna. David was on 2m with a home built beam.

Paul has created a video that captures the day very well:


Here is Paul's latest home brew rig. It is a crystal locked CW transceiver. I really admire his construction and recommend his video about how he hand makes printed circuit boards.


The mountain was beautiful but there was intermittent rain and the temperature fell to about 7C. We were all soaked through by the end of the outing.


SOTA is a great idea in that it encourages bush walks to mountain peaks with a bit of ham radio activity. David was the most successful and even had a contact with Peter, VK3YE on 2m.

Things I learned:
  • Use pencil for the log - my ink ran in the rain
  • Less weight is good - even though the loop was pretty light an end fed wire would be better
  • Don't take a chair - I thought I was being clever by bringing a folding chair but it turned out that there was a picnic table there anyway so that was unwanted extra weight to carry.
I'm looking forward to trying this again in better conditions.

Monday, June 14, 2021

Games on Netflix? My comments on ABC Download this show

Topics on ABC Marc Fennell's Download This Show were the Apple Developer Conference announcements, Facebook's ban on Trump, paying for extra Twitter features and the prospect of renting games on Netflix. Here's a video segment:


The full radio version of the show is available here. I enjoyed meeting Dr Emily van der Nagel who has done some very interesting research into social media platforms.

A book I mentioned in the radio show is Influence by Robert Cialdini.