Last year I received the GB3KEU beacon for the first time. That time the feed from the Pluto to the Portsdown4/Langstone box was via a USB cable which was a bit restrictive. Today I used an ethernet connection.
This opens up the possibility of putting the Pluto in a box by the antenna and having a pre-amp for receive and a linear amp for transmission on the 6cm band. So there would be no coax cables carrying RF to and from the antenna box, just an ethernet twisted-pair cable carrying digital packets. All the analog/RF stuff would be in the antenna box.
The beacon Pluto is drifting, probably because it is running on its default internal crystal reference. The audio amplifier is picking up some computer noise from the Raspberry Pi 4.
The nominal frequency for GB3KEU is 5760.925 MHz, but that is not the frequency that the Pluto sees.
I had been looking for a VNA which would work outdoors and which could optionally be connected to a PC with software for bench work indoors. The VNA is built in a nice metal box with N connector sockets. The label on the back says 50k-3GHz, H/W version V2_2.
It came in a nice protective case & included a calibration kit.
I loaded the VNA-QT software onto my Ubuntu Linux PC. This allowed me to upgrade the firmware on the VNA.
Updating the firmware
The VNA had version 202001117 on it when it arrived. This seemed to be a bit buggy, so I looked for the latest version. I found Unofficial Hardware Variants , “V2.74” from blackmagic 2020-10-13 firmware download worked OK. 106kB loaded.
Fromgithub nanovna-v2/NanoVNA-QT, I downloaded NanoVNA_QT_GUI-x86_64.AppImage onto my Ubuntu Linux PC. Windows versions are available. I had to alter the permissions on this to allow it to execute. Executing gave a screen with the banner: VNA View.
Holding down the left-arrow button on the VNA (the button closest to PORT1) and switching on the VNA gave me a white, blank screen, indicating serial upgrade mode.
Wtih the VNA connected to the Linux PC, VNA View then allowed the VNA to be selected in the Device menu and have the new firmware flashed.
I have discovered today (2-April-2021) that the original developers have a dispute with Hugen/Zeenko. So having found what I took to be officially-supplied firmware for “Unofficial Hardware Variants”, I now see there may be really no support at all. This is a complicated world!
I connected the Linux PC to the Portsdown‘s RasPi4 by ethernet, booted Portsdown & ran a putty session in a terminal, chose Hostname (or IP address) as 192.168.1.51 (the address I’d specified in Portsdown), port 22 and then clicked Open.
In the putty window I logged in with:
User: pi
Password: raspberry
With the “3Dsound” dongle plugged in to the RasPi4 I checked the available devices by entering arecord -l. This produced the report as follows. Note the reference “Set“:
card1: Set [C-Media USB Headphone Set],device 0:USB Audio [USB Audio]
subdevices: 1/1
Subdevice #0: subdevice #0
I edited the file which specifies the audio output device for Portsdown:
cd ~/rpidatv/scripts
nano lmvlcff.sh
Line 57 was the then clause in a nested if statement:
if [ s? == 0]; then
AUDIO_DEVICE="hw:CARD=headphones,DEV=0"
I edited “headphones” to “Set” (for the “3D Sound” USB dongle) and saved the amended file. I left the Config setting Audio Out = RPiJack. On re-booting Langstone, I got sound through the USB dongle from LongMynd. So then both Langstone and Portsdown output sound via the “3D Sound” USBdongle.
I bought a power meter board over eBay. It has a plug-in display screen board which sits on top of it. It is rated up to 1mW, so needs good attenuators and/or a directional coupler. The soldered connections for the SMA connector needed re-soldering.
I cut a bit of polythene foam to support the floating edge of the display board:
I plugged the display board in:
I couldn’t find a source of ready-made extensions for the SMA buttons on the board, so I improvised by sticking a bit of plywood inside the lid and drilled holes in it for dowel pegs:
I had salvaged a button facia from an old mobile phone. I cut a piece of this for dowel covers & stuck it on with superglue:
It is a bit of a bodge, but it works! C toggles from add to subtract, CL toggles between Power Measurement and Attenuator Setting, OK alters the attenuator setting (adding or subtracting). Menu covers up a blemish on the case.
This is going to affect delivery of little packets of electronics from China and elsewhere:
The current VAT exemption for imports of goods in small consignment of a value of up to £15 into the UK will be abolished.
eBay will collect and remit VAT on consignments up to a value of £135 imported into the UK and sold to consumers.
In cases where the seller is a non-UK business and the goods are already in the UK, eBay will collect and remit VAT for supplies of goods sold to consumers within the UK.
If the buyer is a UK VAT registered business and provides their valid UK VAT registration number, the responsibility to account for VAT will switch to the UK VAT registered business customer.
All sellers will have to provide a gross price and separate VAT rate on their UK listings, so that eBay can determine the correct amount of VAT to collect from consumers.
All prices will be displayed inclusive of UK VAT. Where eBay is responsible for collecting VAT, this amount will also be shown separately at checkout.
I want to try controlling the Pluto from Portsdown4 and Langstone via Ethernet rather than USB.
I obtained an Ethernet-to-USB 3.0 adapter and a short USB Micro male to USB female adapter lead. Here is the Ethernet-to-USB 3.0 adapter.
This is the USB Micro male to USB female adapter lead:
The USB Micro male plugs into the Pluto, the USB female connects to the Ethernet-to-USB 3.0 adapter.
With the Pluto connected to the Linux PC directly via the usual USB cable, I opened the Pluto mass storage “drive” on the PC. I edited the config.txt file with gedit.
I edited ipaddr_eth to be my chosen IP address for the Pluto and gateway_eth to the address of my router. Note: it is not advised to have the Pluto on the same sub-net as the internet connection, so I intend to change this later.
I removed the USB cable and connected the Ethernet-to-USB 3.0 adapter USB to the Pluto. The adapter uses an RTL8153 chip. I connected the Ethernet-to-USB 3.0 adapter to the network with an Ethernet cable (the yellow cable in the picture) with RJ45 plugs. The Pluto also had a Power Supply feeding it.
I was then able to ping and also browse the Pluto at 192.168.1.52, so the Pluto’s Ethernet connection seemed to be working.
On the Linux PC, putty connected to the Pluto fine. So all looked well. However…
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Update 14-April-2021: the above cabling proved unreliable. It stopped working. In case I had blown the ethernet adapter, I tried another, RTL8154 based, adapter. This worked and then didn’t. It too was unreliable.
I had found Matthias DD1US’s post about connecting an ethernet adapter to the Pluto using a Y cable. The article didn’t really explain why a Y cable might be necessary.
I had thought that the Pluto would easily supply the 40mA or so of DC to the ethernet adapter and it did do this, but I found that most of the time, the Pluto ignored the ethernet adapter.
After seeking advice on the BATC forum, Mike M0MJW suggested I should use a Y cable. It does seem to work. This below, is the arrangement I tried today. The white plug, bottom right, supplies the DC power. The DC is then fed via the Y cable to both the ethernet-USB adapter and to the Pluto via its USB port. The Pluto then finds the adapter. There is nothing plugged into the Pluto’s DC socket:
I was able to ping the Pluto at 192.168.1.52 from a PC on the network.
I tried Langstone and the software found the Pluto and showed a waterfall screen.
The PortsdownM2/Info screen showed its IP as 192.168.1.51 . I tried Portsdown transmitting a testcard and this produced RF power out from the Pluto. I could receive the picture across the bench on MinTtioune software.
So the more complicated arrangement with the Y cable works OK. My Y cable has USB3 A-type connectors and I had to add a USB A female to USB Micro female adapter so that I could plug in the power supply lead.
I moved the new Raspberry Pi 4 into the Portsdown box and used the Portsdown functions to upgrade both Portsdown and Langstone software versions to their latest versions. Via putty, I ran set_sound to select my “3D Sound” audio dongle. I fed the output to the speakers in the box via a little audio amplifier.
Conditions seemed pretty flat. Just as I was about to pack up I remembered that I had failed to raise Gordon GI6ATZ earlier. I messaged him on ON4KST and we worked in the last couple of minutes of the contest, Gordon on SSB and me on morse code/CW. He is good at decoding my morse.
