Category: Electronics

Pi PoE

Still sorting the shack out today, hopefully two more days and it’s done. Today’s task was to fit PoE HATs to the two Raspberry Pi systems that run things like Pi-Star, the ADSB grabber and HamClock. These were both Pi 3B’s which do not have the pins for PoE – the 3B+ or the 4 does.

So, first off, strip the cards out of the box. Not too bad. The first Pi 4 and its HAT was easy but the Pi Star one has the RF board. Installing the PoE HAT does not leave any of the Pi 4’s pins protruding. Fortunately I had a small stock of extenders, in fact, just enough. Not the neatest of constructions but it works.

One thing caught me out though. The Pi Star Pi gets a static IP address via DHCP. When it booted up it would not let me connect or get to the web interface. A scan of the network found it and only then did I remember that, of course changing the card means a new MAC address! Anyway, both cards now have their MAC addresses in pi-hole (even though the IP is static doing it that way makes pi-hole record their activity against the names) and the Pi Star one has been reconfigured with a static IP rather than DHCP.

Tiger tiger burning bright…

So I need 28V at 15A for a 2.4GHz linear so I can finally do DATV via QO100. Meanwell do a 27V PSU that is sufficiently adjustable to get the 28V needed and they have a good reputation. I finally got round to ordering one from one of the suppliers I use.

I was rather surprised to be told they cannot sell it to me because of the CE / UKCA business caused by good old Brexit. I would need to be a VAT registered business and be purchasing for business use.

Drat.

I found the same PSU from a UK supplier but again I cannot buy from them as I do not have a business account.

Double drat.

Ok… they (the UK supplier) have a PSU from a different manufacturer, Tiger, which has the same rating as the Meanwell one. I am hoping that this is of similar quality to Meanwell, has EMC components (rather than just a space where they would be!) and holds up under load. Time will tell.

These Brexit benefits just keep on coming…

Zigbee

I have finally removed the remaining X10 controllers having replaced the outside light controllers two days ago and the main room lighting dimmers today. Time will tell if any of these suffer from interference being 2.4GHz Zigbee but so far, so good. All of the X10 stuff is destined to go on eBay but it doesn’t seem to sell well – I guess I waited far too long to update everything here.

It’s not a major setup, one Zigbee controller / hub or whatever it’s called – USB and currently stuck in the front port of the server, two dimmers, two bulbs, and three relays.

The setup is Mosquitto and Zigbee2mqtt on the server and Homebridge on a Pi. The server is due to be replaced by another Pi shortly to save space and watts. So now Siri rules our lighting – well some of it! Be nice to Siri…

Zigbee

I have always dabbled in home automation, pretty much since before it even became a thing. Most of the control was, and mostly still is via X10 devices and controllers which use mains signalling. This is rather old fashioned now and, being mains signalling is susceptible to interference. At one stage the outdoor light, which are controlled via an X10 appliance module in the workshop were very intermittent, until I discovered the wall-wart on one of the internal cameras was injecting awful noise that caused a scanner AM to buzz wildly when held near any mains outlet in the house!

Anyway, that isn’t radio related, but this is… enter Zigbee. I have not read very far into this yet but it uses 2.4GHz among other frequencies for its signalling and there are lots of modules available. I plan to change our two dimmers to Zigbee and it will be pretty much plug and play. Apart from removing the mains signalling path the modules communicate both ways, so the controller can see their status as well as control them. Some of the newer X10 modules do this but very few of them and none of the ones I have.

The current setup here is a Raspberry Pi running Homebridge which appears in the Apple Home app and can respond to commands via Siri. The X10 lighting controllers are handled via shell scripts which are called by a Homebridge plugin. But with no status return, if the lights are switched on by a switch or, in the case of the garden and outdoor lights via a script which calculates dusk and dawn the Home app has no clue as to their state. With Zigbee it will.

There is a little way to go yet but everything appears to work. The Homebridge software has a plugin that communicates with software on the server which in turn works via a Zigbee 2.4GHz USB dongle. Basically, with very little work new devices feed their names all the way back to the Home app. All I need now is some more!

FT817 upgrade

I plan to use the FT817 portable but also for VHF and UHF FT8 and other digimodes, so I wanted to upgrade the standard oscillator to the TCXO version (Yaesu’s TCXO-9). But these are scarce, at least in the UK. I’ve searched for a while and got nowhere so I ended up buying one from Wimo in Germany as they had them in stock.

The original TC1 unit (left) and the TCXO-9 (right) are, of course identical in size and sit on 7 pins. There are at least two variants of the TCXO-9 and I guess this one is the newer of the two.

The unit is easy to install. Obviously – or it should be! – disconnect the battery, wear an anti-static bracelet or take appropriate measures, then the old unit simply pulls off of the 7 pin connections and the new unit presses in to replaced it. With the set back together and given a little time to warm up, and set up for CW it holds steady just 2 hertz high. That should be good enough for data modes!

Projects…

I seem to have a lot of stalled projects currently. And then I got a kit of parts to build another Minitiouner… so I did that, and still have the same number of stalled projects! Oh well…

The build went as well as the first one I constructed, very easy to put together and test. When connected to the Windows PC the test software all runs fine. This will go into the box I had for the previous Minitiouner the board of which is now inside the (stalled!) Portsdown.

Portsdown / Langstone progress

Slowly coming together. Yesterday I decided to attack the front panel with a drill and mount the rotary encoder, switches and the little Arduino board which I programmed earlier. This is for tuning the Langstone. For some reason my drill press insists on making triangular holes – if I wanted a triangular hole I’d never manage of course. So I’ve resorted to making a smaller hole and using a round file. Anyway, everything went into place, although the Arduino board has no mounting holes so I’ve tie-wrapped a piece of plastic under it as an insulator and used a decent (hopefully!) sticky pad to secure the board inside the front panel.

So far, so good. Here it is receiving the Allstar microHub…

I need to sort the microphone out. The USB audio dongles seem to be constructed for stereo input so I wired the same to the front panel. Plugging the headset in gives no audio, presumably its all shorting out. I can make it work by ‘adjusting’ the plug (pulling it out until it works!) so I need to re-wire or make a little adapter.

There are a couple of fans in the case and so far it seems to be keeping nice and cool. Next steps include making the GPIO breakout board and possibly the band switching stuff.

Edit: of course I have a mono to stereo adapter plug, I just never looked in the junk box! Mic input now working fine…

Spectrum analysers

I’ve been looking for some time for an affordable (i.e. used) and useful ranged (i.e. not cheap!) spectrum analyser. Obviously I want DC to light but don’t need it and don’t want to sell the house for a bit of test gear. I have a TinySA which is good to 960MHz but I will need a higher frequency range as I fiddle more with microwaves.

The ultimate, e.g. a Rigol or Siglent LCD type device is just far too expensive. Nice to have yes but something one would need to be using all the time in order to justify it. Then I came across Satsagen – http://www.albfer.com/en/2020/02/21/satsagen-2/

Satsagen runs under Windows and by default uses an Adalm Pluto as its interface to the real world. The software even does the necessary to upgrade the Pluto to the ‘full’ range of 70MHz to 6GHz (you can do this easily by hand but it’s nice of the software to do it anyway). The software has three basic function too – spectrum analyser, spectrum analyser with tracking, and generator. So, one PC, one Pluto, Satsagen and you get a pretty decent 70MHz to 6GHz spectrum analyser, tracking generator and signal generator.

I have not yet delved into all the functionality and only carried out a couple of quick tests on a handheld and on my 70MHz transverter, plus a very quick test of a FPV transmitter (TS832) up at 5.6GHz.

It will work with other devices such as the HackRF and the RTL dongle but it seems so useful I purchased a Pluto just for it (yeah, ok, I can use it for other stuff too but hey)

PiBox progress…

The PiBox is almost completed. It’s taken far too long due to all sorts of silly things like having to get fans because a dry run indicated the poor little boards were getting a bit hot, having to get bolts for the fans because I had none long enough, and having to get a connector for the 1-wire (actually 3 wires!) lead from the central heating sensors.

So, there is is. Two fans on the left, 5V PSU bottom right, gigabit Ethernet switch above that, then the Pi’s: top is the PiStar with the DVMega board which has coax to the rear panel and then a dummy load, middle is the ASD-B and central heating monitor Pi, and the bottom is a general purpose one with various bits on such as rtl_tcp. The lower two boards have USB-A sockets on the rear of the case for the two SDR sticks, one for the ADS-B antenna and one to attach to a Discone for general use.

But there is an issue. I had originally intended this to sit in the shack but those fans are just too annoying. Not loud, but constant. I suspect the box will end up in the loft. Or maybe a re-think. I may fiddle with running the fans from one (or two) of the Pi’s and set up some temperature control to turn them on and off. It may even be that I am rather too ‘sensitive’ to the temperature range as others seem happy running their boards a lot hotter than I do mine.

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