Jameco’s eight tips for debugging circuits include:
Understand the circuit.
Do a visual inspection.
Use the right tools.
Check power supply and ground connections.
Consider signal tracing and analysis.
Conduct incremental testing and isolation.
Learn from documentation and community resources
Develop a methodical approach
For a more complete description, visit the Jameco website. My advice would include a combination of #2 and #4. After doing a visual inspection, the first thing I do is to check all the cables and connectors. It’s been my experience that bad cables and connections account for approximately 80% of electronics problems.
This article by K9YC is chock-full of information about RF chokes for HF antenna systems, including circuit theory and practical construction techniques. The introduction reads:
Common mode chokes are added as series elements to a transmission line to kill common mode current. The line may be a short one carrying audio or control signals between a computer and a radio, video between a computer and a monitor, noisy power wiring, or feedlines for antennas. This application note focuses on the use of chokes on the feedlines of high power transmitting antennas to suppress received noise, to minimize RF in the shack (and a neighbor’s living room) and to minimize crosstalk between stations in multi-transmitter environments.
Bluetooth multi-path distortion
I’ve started using a set of Bluetooth ear pods to listen to podcasts on my Android phone when walking around town. (I do a lot of walking.) I’ve noticed that when I’m walking around downtown, sometimes the sound will go out in one or both ear pods.
At first, I thought that might be because my hand or my body was shielding the Bluetooth signal when my phone was in my pocket. Thinking more about it, though, I’ve decided that I’m losing the signal due to reflections from buildings as I walk by them. It’s multipath distortion!
I should have realized this right off the bat, as I’ve been teaching this very thing in my one-day Tech classes for at least the last ten years.
In diesem Beitrag stellen wir euch den Nachfolger des BLE-BT-TNC vor und unterziehen ihm einen Test im Freien. Neulich haben wir euch in dem Beitrag TH-D74 mit aprs.fi auf dem iPhone koppeln eine Möglichkeit aufgezeigt, wie ihr euer Kenwood TH-D74 via Bluetooth mit eurem iPhone verbinden könnt, um es mit Anwendungen wie aprs.fi (iOS) oder … B.B.Link: Kenwood TH-D74/75 mit der aprs.fi App auf dem iPhone verbinden weiterlesen
Following on from my last article on improving the Heltec ESP32 v3 antennas I found during the installation of the 90 degree SMA connector that the device was very sensitive to stray capacitance from things around it. After reconnecting my VNA I found the SWR curve would change substantially depending on what the device was near and so I set about rectifying this.
I decided to remove all the insulation from the single radial inside the unit and then added two more radials to increase the ground for the antenna to tune against. I then removed the N type plug with the antenna connected to it and made a new antenna from a piece of 1.5mm solid core insulated mains wire connected directly to the N type socket, without using an N type plug. Tuning to resonance was much easier than before and I soon had the SWR down to 1.2:1. Moving the device around and placing near to other objects the SWR curve was now much more stable than before with only very slight changes in curve shape.
M0AWS Updated 868Mhz Antenna
Making this change to the 868Mhz antenna has shown an improvement in signal strength from my node-1 device of almost +0.5dB, every dB counts when you only have 100mW to play with!
The Bluetooth antenna update has made a massive improvement to the usability of the device via the iOS Meshtastic app. Being able to have a reliable, solid connection from anywhere in the house is great and I no longer lose messages because I’ve strayed outside the range of the Bluetooth connection.
I now have 2 new Heltec ESP32 v3 devices on the way to me and will be getting those configured and operational outside with external antennas in the hope of hearing some nodes locally to me.
So langsam verdichten sich die Gerüchte um den langersehnten Nachfolger des Mobilgerätes TM-D710G von Kenwood. In diesem Beitrag gehen wir den Gerüchten auf den Grund. Auf der Dayton Hamvention in den USA stellte Kenwood 2016 erstmalig ihr neues Handfunkgerät TH-D74 vor, welches neben analogem APRS auch erstmalig bei Kenwood D-Star und Bluetooth mit an Bord … KENWOOD – Neues VHF/UHF Mobilgerät mit D-Star, APRS und Bluetooth weiterlesen
Meshtastic is a relatively new thing in the internet of things (IOT) world and is gaining traction in the U.K. at the moment.
So what is Meshtastic?
Meshtastic is an open source, off-grid, decentralised mesh network built to run on affordable, low-power devices on the 868Mhz industrial, scientific, and medical (ISM) band. (Some devices can also run on the 433Mhz 70cm HAM band.)
The ISM band is licence free but, has limits on the RF power levels that can be used. The one plus over the HAM bands is that you can legally transfer encrypted messages over the ISM band making it secure.
The best way to think of Meshtastic is a radio version of the online decentralised Matrix chat system but, without the large server requirements and ever growing database!
Heltec ESP32 v3 Wifi, Bluetooth and 868Mhz device for Meshtastic
There are quite a few Meshtastic compatible devices on the market today with many costing around the £20 mark whilst others like the LillyGo T-Echo costing over £100 in the U.K. even though they are less than half the price in the USA.
Since I’m just starting out on my Meshtastic adventure I thought I’d start with a pair of Heltec ESP32 v3 devices that are normally readily available on Amazon but, due to the current push to build a U.K. wide mesh, they are currently out of stock pretty much everywhere.
Loading the Meshtastic firmware onto the devices is fairly straight forward and can be done using the web installer via either the Edge or Chromium web browsers. (Note: If using Windows O/S you will need to install some drivers from the Meshtastic website to be able to communicate with the devices)
Having neither of the two browsers and being a Linux command line junkie I decided to use the Python programme to load the firmware onto the two devices. It’s worth noting that you don’t need any drivers to be able to communicate with the devices if you’re using either Debian or one of the many Ubuntu flavours of Linux O/S.
Using the Python command line program sounds like a more complicated approach but, in reality it’s super simple, extremely reliable, quick and if like me you use a Linux PC in the radio shack then you most likely already have most of what you need to get the job done. Just follow the simple steps as laid out on the Meshtastic web site and you’ll have the firmware loaded in no time at all.
Installing the Meshtastic firmware onto my Heltec ESP32 v3 using the Python command line tool
The firmware takes less than a minute to copy across to the Heltec device and is automatically rebooted ready for configuration once the transfer has completed.
It is possible to configure the device via the command line tool however, since there is a nice GUI app for both Apple iOS and Android devices I decided to install the Meshtastic app on my iPad and connect to the device via Bluetooth to configure it.
Once you’ve got the Meshtastic app installed on your device and have connected via Bluetooth you’ll be ready to start configuring the device to join the mesh. The first thing you want to do is set the region. This is different in each country but, in the UK we use the EU_868 region settings. This will set the device to use the 868Mhz ISM band which is the band being used to build the U.K. wide mesh.
View of the Meshtastic app on iOS showing the configuration options for the Heltec ESP32 v3
There is a multitude of configuration options within the app which I will go into in greater detail in a series of articles at a later date.
Heltec ESP32 v3 running Meshtastic Firmware
For those of you that, like me aren’t near any other nodes you can connect the devices to the internet and use the Meshtastic MQTT server to communicate with other nodes. This of course isn’t off-grid but, it will get you started until the mesh grows into your local area at which point your device will automatically start communicating with the other nodes over radio.
Meshtastic MQTT connectivity
Once you are connected to either the MQTT server or other nodes via radio you will see the other node details appear in the Meshtastic app. It’s interesting to look at the information and see signal strengths and traffic levels etc for each node.
View of the Meshtastic app on iOS showing Nodes in the Mesh and Device Metrics for the M0AWS-1 Node
There are a multitude of cases available for the Heltec v3 devices, especially if you have access to a 3D printer. One of the nicest cases I have seen is the Bender from IKB3D (I know, it’s a strange name!) but, it really is a super little case for the Heltec series of devices.
Bender case for Heltec ESP32 v3 devices
You can either buy the 3D print files for £8.99 and print it yourself or just order a pre-printed and assembled case directly from the website although, due to demand there is a long lead time currently.
KENWOOD hat mittlerweile das Benutzerhandbuch in englischer Sprache sowie Software-Downloads für das KENWOOD TH-D75 online gestellt. Mehr darüber erfahrt ihr hier in diesem Beitrag. Jetzt dauert es nicht mehr lange, bis das KENWOOD TH-D75 auch hierzulande verfügbar sein wird. Wer schon jetzt einen Blick in das, wie von KENWOOD gewohnt, sehr umfangreiche und bebilderte Benutzerhandbuch … KENWOOD TH-D75 – User Manual und Software verfügbar weiterlesen
In diesem Artikel zeigen wir euch eine technische Lösung, wie ihr euer Kenwood TH-D74 via Bluetooth mit eurem iPhone oder iPad verbinden könnt, z.B. um empfangene APRS-Stationen auf einer Karte darzustellen. Wer sein KENWOOD TH-D74 für APRS nutzt, wird dessen großes Farbdisplay zur Darstellung der empfangenen Stationen mögen. Es werden u.a. die aktuelle Entfernung und … TH-D74 mit aprs.fi auf dem iPhone koppeln weiterlesen
If you followed my previous adventures with the Tinytrak 4 and Bluetooth you may know that I used HC05 modules which where RS232 levels capable. I bought these years ago and, as of today, they …
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Jameco’s eight tips for debugging circuits include:
