Portsdown 4 plus Langstone transciever construction

Langstone is basically a combination of a Raspberry Pi 4 and an Analogue Devices ADALM-Pluto. Potentially it should cover 4m, 2m, 70cm plus the microwave bands up to 6cm and possibly beyond via harmonics. It will need appropriate filters and amplifiers. It can be combined with Portsdown 4 for DATV.

There doesn’t seem to be one site for Langstone, so here are the links I have gathered so far:

I ordered a RasPi4 with 7″ touchscreen, PSU, heatsink and 16GB SD card from PiHut and a Pluto from DigiKey UK.

The RasPi4 came with various connectors and leads. After some digging about for information, I connected the jumper leads to the screen connections:

  • Red: 5V
  • Green: SDA
  • Yellow: SDL
  • Black: GND

And at the RasPi GPIO connector end:

  • Red: pin 2
  • Black: pin 6
  • Green: pin 3
  • Yellow: pin 5

Note which way round the ribbon cable goes (white with blue marked ends). The conducting contacts are on the reverse side of the blue. They must mate with the conducting contacts on the boards. Pull out the plastic wedges just enough to slide the ribbon end in, then click the wedges in again to clamp the end of the ribbon, so it looks like this:

Above shows the RasPi4 board screwed in place. I attached the PSU lead & plugged it in:

A pink LED lit up (lower left on the RasPi). The SD card came with a system on it. Turning the boards over showed this display:

I wanted to integrate Portsdown 4 for DATV, so I started at the Portsdown 4 Wiki. This said: “You MUST start with a fresh build of Raspios Buster (NOT Raspbian) on an SD Card of 8 GB or greater”.

Back to Colin’s site, I followed the instruction to download Raspbios Buster Lite. He has instructions for downloading to a Windows PC, but I downloaded to my Ubuntu Linux PC and then installed Raspberry Pi Imager for Ubuntu. I extracted the image from the zip file. I ran the imager & selected the image via the Custom option and the SD card (from the RasPi4 in a USB adapter) and clicked Image. The image seemed to transfer OK. Remounting the SD card on the Ubuntu Linux PC I got two drive icons: rootfs and boot. In boot, I right-clicked and used New Document>Empty File to create a new file: ssh (as instructed in Portsdown 4 Wiki).

I moved the SD card back to the RasPi4 and powered it up. It flashed up a message resizing something on the screen and then went through the usual boot stream of messages, ending in Raspbian GNU/Linux 10 raspberrypi tty1 and a login prompt.

I cut the power to the RasPi4 and remounted the SD card back in my Linux PC. I launched a terminal window and entered the command sudo gedit and selected /rootfs/etc/dhcpcd.conf file on the SD card.

With my router at 192.168.1.1 and 192.168.1.51 the address I’d chosen for the RasPi4, I edited the static ip configuration lines to read:

interface eth0
static ip_address=192.168.1.51
static routers=192.168.1.1
static domain_name_servers=192.168.1.1

With the SD card back in the RasPi4 and an ethernet cable connecting to the local network I applied power to reboot. The RasPi4 start-up message sequence included:

  • Started Hostname
  • dhcpcd on all interfaces
  • Reached target network

In a terminal window on my PC I typed ping 192.168.1.41. Packets arrived OK. I typed putty and in the putty session I entered 192.168.1.41 in the Host Name (orIP address) field. I got the message connection refused.

I realised I had the address wrong. I pinged 192.168.1.51. Packets arrived. I unplugged the RasPi4 from the network. Packets stopped arriving. I had the right address!

My internet router is on the 192.168.1 subnet, so altering the RasPi4 IP address above means that the necessary internet access is there to install Portsdown 4 and install Langstone. On my Linux PC I entered 192.168.1.51 in putty. I got a login prompt. I logged in as user pi with password raspberry. Paste didn’t work, so I typed in three commands (slide the scroll bar right to get all of the long command):

wget https://raw.githubusercontent.com/BritishAmateurTelevisionClub/portsdown4/master/install_portsdown.sh
chmod +x install_portsdown.sh
./install_portsdown.sh

I got: Installing BATC production version of Portsdown 4

As instructed, I went for a cup of tea. When I got back, the Portsdown 4 menu was displayed.

I entered the Langstone Options submenu via menu M2.

I touched Install Langstone. It said Installing Langstone Software, Please Wait for Reboot.

A short while later, it re-booted and the Portsdown 4 menu returned.

I plugged the Pluto into the RasPi4 via its USB lead. The Ready LED lit and LED1 flashed. In M2 I touched Switch to Langstone.

I got the Langstone screen with the message: Lang_RX.py not responding.

I ordered the recommended audio USB device. While I waited for that to arrive, I searched the junk box. I found a “3D Sound” USB dongle. It wouldn’t fit against the other USB plugs, so I took its covers off. I added a mouse and also plugged in Minitiouner, fed from my Es’Hail2 satellite dish.

Re-booting and running Portsdown4 on receive, I got a lovely decode of the Es’Hail2 beacon, using the Play with ffmpeg VLC option, with sound from the RasPi jack socket.

Colin G4EML has provided some useful diagnostic programs. I set the putty session going again and entered:

cd ~/Langstone
./stop
./HW_Test

HW_test let me check the screen touch and also verified the mouse buttons and wheel were working.

./Pluto_Test

This verified the throughput, 1919, in my case was close to the expected 1900.

./Sound_Test

Sound_Test is now superseded by set_sound. Sound_Test found my audio dongle giving the details:

Unable to find the default sound device
hw:CARD=Headphones,DEV=0
hw:CARD=Set.DEV=0

I amended Lang_RX.py and Lang_TX.py as suggested and restarted Langstone. Running Sound_Test again via putty, it still said “Unable to find the default sound device“. However when I restarted Langstone it did not complain about a missing sound card. I still got the message: Lang_RX.py not responding.

Then I noticed Colin had updated Langstone to include a new utility, set_sound. I updated Langstone on the RasPi4 by entering the following commands in the putty session on my Linux PC:

cd ~/Langstone
./stop
./update
./run

set_sound found only one device, the 3D Sound dongle. I selected 1 and it edited the Lang_RX.py and Lang_TX.py for me. Neat!

I also made sure all the USB plugs were properly seated in the RasPi4 sockets and that the Pluto and MiniTiouner plugs (with the thick black leads in the picture below) were in the USB3 (blue) sockets.

Restarting Langstone gave me a waterfall for the first time. Plugging headphones in the 3D Sound dongle gave noise, so that looked and sounded promising.

I connected the Pluto to the 70cm pre-amp & yagi & pointed the yagi at GB3FNY:

My first reception on Langstone! The horizonal stripes are probably OTH radar swipes. Unfortunately the display freezes after a few minutes and Langstone seems to crash and the Portsdown4 menu comes back up. Clicking on Switch to Langstone goes back to the Langstone scteen, but there is no waterfall or reception. It needs a full reboot of Linux to get Langstone running again. I don’t understand why Langstone should crash? Power supply?

I plugged the Pluto USB cable into my Linux PC. I edited config.txt as below (leaving the original lines as # comments), saved it & ejected the Pluto “drive”.

[NETWORK]
hostname = pluto
#ipaddr = 192.168.2.1
ipaddr = 192.168.1.41
#ipaddr_host = 192.168.2.10
ipaddr_host = 192.168.1.52
netmask = 255.255.255.0

Although putty on my Linux PC linked fine to the RasPi4, I failed to get it to link to the serial port on the Pluto, so I decided to try kermit. In a terminal session, I executed: sudo apt install ckermit

I knew ttyACM0 was the serial device for Pluto. In terminal I ran:

kermit -l /dev/ttyACM0 -b 115200
C-Kermit 9.0.302 OPEN SOURCE:, 20 Aug 2011, for Linux+SSL+KRB5 (64-bit)
Copyright (C) 1985, 2011,
Trustees of Columbia University in the City of New York.
Type ? or HELP for help.
(/home/gray/) C-Kermit>

At the C-Kermit> prompt I entered c for connect and later root and analog for the Pluto login name and password respectively:

(/home/gray/) C-Kermit>c
Connecting to /dev/ttyACM0, speed 115200
Escape character: Ctrl-\ (ASCII 28, FS): enabled
Type the escape character followed by C to get back,
or followed by ? to see other options.
Welcome to Pluto
pluto login: root
Password: analog
Welcome to:
_ _ _ __________
| _ \ | | | / | _ \ \
| |/ / | | |
\ --.| | | | |_/ / | __/| | | | | __/ _ \--. \ | | | / | | | | || | || () /_/ / |/ /| |\ \
_| ||_,|____/____/|_/ _| _|
v0.30
http://wiki.analog.com/university/tools/pluto
^C

I entered the following commands (shown in bold) and got the following responses:

fw_printenv attr_name
Error: "attr_name" not defined
fw_printenv attr_val
Error: "attr_val" not defined
fw_setenv attr_name compatible
fw_setenv attr_val ad9364
reboot

Communications disconnect (Back at Lab)
(/home/gray/) C-Kermit>exit
Closing /dev/ttyACM0…OK

Barry G8AGN referred me too a youtube video which set a third parameter, maxcpus, on the Pluto. I checked the first two parameters and added the third:

fw_printenv attr_name
attr_name=compatible
fw_printenv attr_val
attr_val=ad9364
fw_setenv maxcpus
reboot

I copied pluto.frm file dated 21-Aug-2020 into the Pluto “drive”. I ejected the Pluto drive. LED1 flashed rapidly. Eventually the Ready light came on again and LED1 flashed slowly as usual.

I’ve noticed the config.txt file on the Pluto had reverted its IP addresses back to the original. I don’t know what has done this; possibly the firmware update?

I browsed 192.168.2.1 and got Welcome to the ADALM-PLUTO QO-100/DATV custom firmware:

Misc scribbles:

[I installed libiio on my Ubuntu 18.04 Linux PC by executing this command in a terminal session: sudo apt install libiio-utils]

from youtube video:

Pluto tools: SDRangel

325 MHz to 3.8 GHz

In putty session:

fw_setenv attr_name compatible
fw_setenv attr_val ad9364
fw_setenv maxcpus
reboot

Unplug Pluto and plug it back in again.

46.875 MHz to 6GHz

To reset Pluto to original spec:

fw_setenv attr_name
fw_setenv attr_val
fw_setenv maxcpus 1

Hack Green SDR’s aerials

I’ve been using Hack Green SDR as a way of evaluating my experimental G7FEK aerial.

Tony G1HMO has let me know the aerial configuration:

The VHF and UHF SDR antennas are folded dipoles at about 40m up the tower. They both have bandpass filters and tower-mounted amplifiers at about. They are then fed down the tower using LDF-450 Heliax cable.

The 70MHz receiver is a folded dipole at about 25m, fed with LDF-250 cable.

The 10m receiver is fed from the HF SDR antenna multicoupler, the antenna is a double sized G5RV at about 30m one end, and 10m the other end. The antenna is connected to an 8 output multicoupler designed and built by G7CKX. This gives just enough gain to overcome the loss of the splitter and lots of isolation between the 8 ports.

I still need to find a way of evaluating the G7FEK antenna on 30m.

I’ve mainly made comparisons on 20m, but, as it stands, my version of the G7FEK aerial, when feeding the K3 does not show signals as better than Hack Green SDR (HGS). The signals are often as good on signal strength as HGS. An obvious problem is that I have an S-point or so of extra noise, so generally, the signal-to-noise ratio using the G7FEK is not as good as HGS.

Portsdown 2020: Unable to connect to GitHub – specifying network gateway address

When I tried to upgrade the Portsdown software I was getting: “Unable to connect to GitHub to check the latest version“.

In console mode, I went to the Linux command line.

route -n showed no gateway address. I could ping my router on at 192.168.2.1 so the connection to my local private network was working, but pinging google at 172.217.169.3 failed.

I found a suggestion from Arpit Agarwal who suggested route add default gw 192.168.2.1 eth0. I found sudo route add default gw 192.168.2.1 eth0 worked. route -n showed the gateway address. I tried a Portsdown software update & it worked fine.

So that gave me a work-around.

My problem is that the gateway address is lost again after a reboot. I’ve tried modifying the ip= command in the cmdline.txt file (see viewtopic.php?f=103&t=6742) to specify a gateway address, but I didn’t get it to work.

How can I make my gateway address persist?

I tried removing my ip= command from /boot/cmdline.txt , in case it was overriding your commands, but still no joy.

Dave G4FRE helped me out on the BATC forum.

I edited /etc/dhcpcd.conf so that it had the commands:

interface eth0
static ip_address 192.168.2.47
static routers=192.168.2.1
static domain_name_servers=192.168.2.1


route -n now shows I have a gateway!

Portsdown 2020: Specifying IP address in cmdline.txt in situ

I had boxed up the RasPi and then discovered that in order to try OBS that I needed to specify an IP address on a file on the SD card buried in the box. https://wiki.batc.org.uk/OBS_-_Open_Broadcast_Studio
I wanted to avoid dismanteling it so I experimented and found the following approach using console mode seemed to work. I used a remote device, a PC running Linux in my case, to run console mode.

In menu M2, use the Info button and make a note of the IP address. Make sure you have a network connection between the RasPi and your remote device.

Start a putty session on the remote device. In PuTTY Configuration, enter your noted IP address in Host Name (or IP address) and click Open.
Login as: pi
password: raspberry

You should see Portsdown DATV TX etc.
Select Shutdown and reboot options.
Select Exit menu to command prompt. You should get a Linux prompt like pi@raspberrypi:~$. Enter:
cd /boot – the prompt will change to /boot $
dir – this should list cmdline.txt as one of the files.
sudo nano cmdline.txt – opens a text editor. You should see a big long line of text with commands in it. Use the arrow keys to navigate towards the end of the line and just after rootwait type in ip=192.168.2.47 (substituting the IP address that you want to allocate instead of 192.168.2.47). Space it like the other commands. Enter ctrl-O to Write Out and save the amended file, then ctrl-X to exit the nano editor. Enter exit to quit the putty session.

When you reboot Portsdown, M2/Info should show the new IP address.

I don’t know my way round the Portsdown system & I’m not a Linux expert, but I am sharing this in case it helps.

Minitioune and Portsdown UDP streaming to VLC on a PC

I had Portsdown, the Win10 PC and the target PC all on the same wired network and each allocated a fixed IP address in the range 192.168.2.n

VLC

In VLC on the target PC I selected Media/Open Network Stream, in the Network Protocol box I entered Network URL as udp://@:1234

MiniTioune to VLC (on target PC)

In the minitiouneConfig file I edited TS_AdrUDP=192.168.2.41, the address of the target PC on my local network. Also I amended TS_Port=1234

Selecting a DATV signal I clicked the UDP switch. VLC on the target PC displayed the video stream.

Sometimes VLC lost sync & then I reselected Network URL as above.

Portsdown to VLC (on target PC)

On Portsdown, via the RX/Config menu, I set UDP IP (the target PC) and UDP Port similarly. With a DATV signal frequency & Symbol Rate selected I tapped UDP Output.

I received Dave G8GKQ:

200702_Dave_G8GKQ_testcard_F

DATV reception from Es’Hail2 QO100

I had installed the Minitioune software on Win10, but I was struggling to decode signals via Minitiouner hardware. I improved my bias T. (The capacitor was rather high at 100nF.  I wondered if it was coming close to a self-resonance. I had 1nF to hand, so I used that instead. It is probably still a bit high. 100 pF should be fine).

Some while back, I bought a cheap Rocket LNB in order to take the lens for the dual-band feed. I decided to try the Rocket LNB on the dish, just running without any external reference oscillator. This improved the signal-to-noise ratio a few more dB as seen on my GQRX SDR software via the RTL dongle.

Sure enough, MT now decoded the WB beacon and other stations. The only problem is that the LNB’s local oscillator runs about 0.5 GHz high and drifts somewhat. As long as I tune the beacon first & store the LO frequency, it works better than with the Octagon with external locking.

I had assembled a Portsdown transciever using a Raspberry Pi version 3 and a 7″ screen bought from Pi Hut.

IMG_20200513_101527

Here’s the back of the screen:

IMG_20200513_101433

This morning I used Portsdown on receive to decode DATV signals with VLC doing the decoding. It was quick at deriving the FEC and measuring MER.

MiniTiouner hardware plus MiniTioune software

MiniTiouner hardware

I thought the MiniTioune  (developed by Jean-Pierre F6DZP) would be a good lock-down/self-shielding project. I had never tried Digital Amateur TV (DATV).

You need to be a member of the British Amateur Television Club (BATC) in order to use their online shop.  I bought:

MiniTiouner version 2 blank PCB

MCP1826 1 volt regulator

Serit FTS-4334LU NIM / tuner module

MiniTiouner USB interface module

These items came to less than 60 GBP.

There is a list of parts and a schematic contained in Mike Willis G0MJW’s Notes on building the BATC v2 MiniTiouner. I recommend you follow his advice.

Also see Adrian M0NWK’s professional-looking article with excellent hints and tips.

The Hammond 1455 series 103x120x53mm enclosure came from rapidonline (eBay).

The DC-DC Converter (MP1584 Adjustable 3A Step-Down Buck Voltage regulator came from alltopnotch (eBay).

The 7HC10 chip came from vila restor (eBay).

I made a couple of substitutions:

I didn’t find the ferrite bead chokes 28C0236-0JW-10, so I used Wurth 1.8 uH 20% Ferrite Rod Core Inductor, 5A Idc, 6mohm Rdc, WE SD from RS Components. These mount horizontally, but there is plenty of room for them on the board. Probably RS has a direct equivalent if you search for it.

I didn’t find the 3.3V regulators MCP1826S-3302EAB so I bought MCP1827S-3302EAB (rated 1.5A max). I found the specified 6’s right after I ordered the 7’s!

I didn’t find a small board-mount fuse holder, so I adapted one out of the junk box.

That added another 40GBP to the bill, so 100GBP so far.

I found some nice Panasonic 22uF capacitors with ESR < 0.25 ohm. Some similar Nichicon capacitors had ESR < 0.55 ohm so these should do fine too.

Most of the other components came from the junk box.

I was delighted to find that the MiniTiouner version 2 blank PCB from the BATC is a top quality board, easy to solder and hard to damage.

I set up the DC-DC converter separately on the bench. The tiddly pre-set pot is fiddly to set. I set the output to 3.8V as measured on a digital voltmeter. Surprisingly, another DVM agreed!

Following Mike’s guidance,  I attached the components to the board & soldered them in, but not yet attaching the Serit or the USB daughter-board. With a 13.8V feed, checking the regulator outputs I got 3.25V, 3.23 V and 1.13 V, so all OK. The DC-DC regulator still read 3.8V out.

IMG_20200515_144234

I added a 10K resistor to the FT2232H daughter-board.

IMG_20200519_115636

MiniTioune Software and PC set-up

I struggled to find the MiniTioune software, but I eventually found the Telechargement / Download Section and downloaded the MiniTioune V0.9.9.1 .zip file. I had to set up a Windows 10 PC (Win10) especially for this software. Oh for a Linux version!

The MiniTioune Software page says: “run the test programs found in the directory where you extracted MiniTiouner to”. I tried the first one I noticed.

I launched Test My Minitiouner Version 2.3. Windows Defender didn’t like this! I clicked Run Anyway.
It detected NIM Tuner B and NIM Tuner A. I didn’t know the difference between MiniTiouner V2 and MiniTiouner V2+ so I clicked on the button MiniTiouner V2 as it says V2 on the board. The test program launched. I clicked I2C Master init (NIM). The journal said:

NIM I2C controller init OK. OK MPSSE is empty. Init MPSSE NIM I2C done!

This felt positive. It awarded a green light!I clicked Test NIM. The journal gave a spiel of read/write tests, but counted no errors. Another green light, but only 26% on the I2C performance scale.I clicked Test Digole Master.

Digole Master Init is not OK.

Digole Master was not happy! Digole Master 2.6 wasn’t happy either.I tried Test OLED1 Master:

Pb with OLED1_master SSD1306 init! NOT OK

I ticked led TS1 OK and led TS2 OK and clicked Read TS leds state:

TS1 led is ON. TS2 led is ON.

I quit that test application & launched Check MiniTiouner Driver and Filters V0.4A. I clicked USB Tuner. A long spiel included:

SeritPro NIM detected. initialising STV0910. STV0910 init OK.Synthesizer Detection, Synthesizer found, value $75. STV 6120 init OK.

5 green lights! I clicked Directshow:

Cannot find the “Universal Source” filter. Cannot add “Universal Source” filter.

It couldn’t find LAV filters either, so 3 green lights, but 2 red lights. The play buttons were greyed out so I clicked Network: 2 green lights!The MiniTiouner Softwage page said “All tests should pass – if it fails the USRC filter test try running the install_usrc_ax_winXP.exe file in the directory and run the test again”. I ran install_usrc_ax_winXP which finished with the message: DllRegisterServer in usrc.ax succeeded which sounded positive. I re-launched: Check MiniTiouner Driver and Filters V0.4A and clicked USB tuner.

FT2232H has bad device parameters. use FTprog to reprogram it

So install_usrc_ax_winXP might have scrambled the USB card? Time for a cup of tea… MiniTiouner hardware Version 2 says “If you obtained your module from elsewhere or you need to reprogram it it follow the instructions here“. Following the instructions there, I downloaded: FTDI CDM driverThe FTprog software and NIM tuner template.I ran CDM21218_Setup and followed the installation wizard. It installed two drivers:

FTDI CDM Driver package – Bus/D2XX Driver (06/16/2016 2.12.18) andFTDI CDM Driver package -VCP Driver (06/16/2016 2.12.18)

Next I ran FT_Prog_v3.2.76.375 Installer. A wizard launched. I left the boxes ticked for FT_Prog executable, Create Desktop Shortcut and Templates. It installed & I closed the wizard. I ran FTProg from the desktop icon. It found no FT devices. I tried a better-looking USB cable, re-booted windows & switched the MiniTiouner off & on. One or any of these actions may have helped.

I re-ran Check MiniTiouner Driver and Filters V0.4A. It gave 5 green lights for USB Tuner and Directshow had a green light for usrc filter. So it looks like install_usrc_ax_winXP did do something useful. Maybe a better lead has helped? There was still a red light for LAV filters. I re-tried FTProg with the poorer-looking lead. It found device information. I don’t know what is going on!

I re-tried FTProg with the better-looking lead, intending to proceed on the safe side. It found device information. I right-clicked device 0, selected Apply Template and From File and chose the using NIM tuner XML file. It applied the template. The device 0 Product description says: USB <-> Nim tuner.
I selected DEVICES and Program, clicked the Program button and closed the programmer. Checking settings:

Device 0/Hardware Specific/Port A/Hardware = RS232 UARTDevice 0/Hardware Specific/Port A/Driver = D2XX direct
Device 0/Hardware Specific/Port B/Hardware = 245 FIFO
Device 0/Hardware Specific/Port B/Driver = D2XX direct

After an internet search I found some CODECS from Cole Williams Software Ltd which I downloaded and installed. This gave me all green lights for the USB Tuner and Directshow tests, so the LAV was now flushed with success! However none of the Play… button video clips worked.

I suspected the NVdia on-board graphics controller was not doing the job when driven by the Basic MS graphics driver. I couldn’t find a Win10 driver for the on-board graphics controller. I installed another old graphics card: ATI Radeon 2400 and routed the monitor to this instead. Somewhere in all this, Win10 decided to update itself for a couple of hours, so I had a lunch break. When it finally finished (and reallocated various file types to MS products and demoted my Firefox browser without asking me – I was reminded why I generally avoid Windows!) I found in Device Manager/Properties/Driver that Win10 had allocated an AMD driver 13/01/2015 version 8.970.100.9001 to the ATI Radeon 2400Display Adapter“.

Re-running the MT Drivers & Filters test gave me all green lights. The video clips ran fine. Yay!

So the on-board NVidia graphics adapter in my HP Pavilion Slimline‘s motherboard did not work with MiniTiounter (MT), perhaps because Win10 didn’t find a manufacturer’s driver for it and loaded a Basic MS Graphics Driver instead. I was lucky that Win10 found a manufacturer’s driver for the equally old ATI Radeon 2400. The reasonably-priced current graphics adapter might be a Radeon 1310, needing only 30W; In the end I didn’t need to try this.

I found a bigger monitor so that I could run 1280x??? pixels.

I tried running MiniTiounter (MT) in Win10 user mode. Windows Defender objected to MT; I clicked Run Anyway. Then MT needed permissions to “make changes on my device”. I gave it Administrator permissions. Win10 Defender Firewall needed permissions too.

Thurs-21-May-2020. I connected the feeder from the 23cm antenna to the top F connector of the MiniTiouner. I left off the jumper LNB-A2 so that the MiniTiouner didn’t try to feed DC up to the yagi.

I aimed the 44el 23cm Wimo yagi at Lincoln cathedral. I set MT to 1400 kS/s, 1310,000 kHz, 0 offset. Nothing received. Finally I realised that in moving the coax cable that I had disconnected the DC supply to the pre-amp from its usual bias T;  I had forgotten the pre-amp altogether! I put that right. The repeater output came in at -68dB on the  RF Power meter, which seemed good to me. I was delighted to see a picture!

G0KOO accessed the repeater from near Boston. His were the first DATV signals I’d ever received from a radio amateur.

200521-1930_G0KOO

Here is one of the GB3VL Lincoln Repeater images:

200521-2051_GB3VL_flypast

The hardest part with MT has been setting up the PC with it’s graphics card, driver and CODECS. But thank you Jean-Paul for making it all possible.

A dish for Es’Hail-2, QO100

Last year I experimented with using a 13cm band yagi for the up-link and an LNB strapped alongside my horn on the dish I use for terrestrial work for the down-link.

I’ve now put a dish up for the Qataris’ Es’Hail-2 satellite. It is a 1.1m off-set PrimeSat dish.

Prior to putting it up,  I had bodged a bit of aluminium  box tube to take the dual-band feed. I checked the dish’s focus with a few stick-on mirrors and the sun as an light source. There did seem to be a bit of distortion in the dish, though it looked in excellent condition, with no visible damage. I may be able to squeeze out this distortion using the braces for the LNB arm.

Bearing in mind how windy it gets here I’ve used belt and braces in mounting the dish. I decided not to get the larger 1.3m dish. I felt the 1.1m dish would be easier to manoeuvre  up to the roof and also it would be less affected by wind. I’ve used two steel chimney lashings to hold two brackets. I decided the usual aluminium pole might not be up to the job, so I set a section of steel scaffold pole in the brackets. The dish’s two clamps are fixed to the bottom of the pole. In case of the dish clamps somehow working free, there is a third clamp at the bottom of the pole to stop the dish dropping off.

I’ve fitted braces to the LNB arm to hold the arm steady in the wind.

Being low down on the chimney and on the easterly side of the house, the dish is in the lee of the strong westerlies and south-westerlies.

IMG_20200429_124932

The 13cm patch antenna in the bigger plastic box is not really working as circularly polarised. It is more like linear, effectively from a dipole, but the return loss is quite good. The patch is fed with a shortish length of Ecoflex 10.

The LNB has a bit of “satellite” coax taking the signal back into the station. I found the connectors on my thin “WiFi” coax were very poorly fitted. I use this to carry the 27 MHz reference oscillator signal to the LNB. I soldered a proper SMA connector on the LNB end of the cable. An LNB lens takes the signal from the dish which is then piped along a short length of copper waveguide (22mm domestic copper pipe) into the LNB. The waveguide is held by pipe clips mounted on short lengths of stainless steel studding. The LNB has a bit of a twist on it in an attempt to optimise the match to the polarisation from the satellite.

I sealed all the connections with self-amalgamating tape.

See Dual Band Feed construction.

Note: I had originally mounted the N-type socket for the patch feed with the socket mounting flange inside the plastic box, but this meant the N-plug did not mate reliably, so I re-mounted the socket on the outside of the box.