Venturing into the world of AllStarLink

We’ve recently added a new room to the Matrix HAM Radio Space for Digital Voice modes as this was an area of interest that didn’t really fit into any of the other rooms.

The new Digital Voice room has attracted a lot of attention from members, with a lot of the focus being on the AllStarLink system. Michael, DK1MI built an AllStarLink node in the cloud for us all to use for Matrix Nets and so I decided I had to get in on the fun.

The Jumbospot SHARI SA818 Amateur Radio AllStarLink Radio Interface was originally designed by N8AR and implements a RaspberryPi 2/3/4 hosted AllStarLink node using a NiceRF SA818 embedded VHF/UHF radio module and sound card.

The two USB connectors on the SHARI device are position such that they plug into two of the available 4 USB ports on the RaspberryPi without the need for cables. This keeps the whole solution together in one neat package.

Before you start you will need to obtain a node number and secret (password) from the AllStarLink Portal. To get this you will need to provide proof to the AllStarLink administrators that you are a licensed Amateur Radio (HAM) operator. This is done by uploading a copy of the first page of your HAM licence to the website for the admin team to check. This can take 24hrs to be completed so make sure you get this all done before trying to build your node. You cannot build a node successfully without a node number and secret.

Of course you will also need a transceiver that can operate on the 438.800Mhz frequency or other frequency of your choice on the 2m or 70cm HAM band.

You will also need to open port 4569 on your internet router and setup port forwarding to the IP Address that you will be using on your RaspberryPi node. It’s important to use a static IP Address on your RaspberryPi.

There are quite a few different Linux based operating system (O/S) images that are available for the RaspberryPi devices that have been specifically tailored for the AllStarLink node and include all the necessary software and library packages out the box.

I decided to use the Raspbian GNU/Linux 10 (buster) based distribution as it is based on the very stable and reliable Debian Linux distro. You can download the exact version I am using from the Raspbian link above or directly from my website here.

Once downloaded you need to burn the ISO image onto a suitable SD card for your RaspberryPi. I use BalenaEtcher as it’s extremely quick and reliable at burning ISO images to SD cards.

Of course if you are a hardline Linux command line junkie you can always use dd to create the SD card.

Once you’ve got your O/S onto your SD card, slot it into your RaspberryPi making sure your SHARI device is connected to the two USB ports and then power it up. Make sure you have a good PSU for the RaspberryPi as the two devices together draw around 3A of current during the transmit cycle. (I use a 3.6A PSU from Amazon).

The default login for the Raspbian O/S is shown below. Login via SSH and configure your RaspberryPi for your local network. It’s important to use a static IP Address configured either directly on the RaspberryPi or via DHCP in your router.

Login: repeater
Passsword: allstarlink
SSH port: 22

Once you have your RaspberryPi connected to your LAN you are ready to start configuring it for AllStarLink.

The first thing you need to do is login to the raspi via SSH and then become root user using sudo as shown below:

sudo su -

Once you are root user, you need to add the AllStarLink repo to the sources file and update the operating system using the following command:

curl -s http://apt.allstarlink.org/repos/repo_signing.key | apt-key add
apt update --allow-releaseinfo-change
apt dist-upgrade

Copy and paste each line one at a time into your terminal. Once the last command finishes, the system is up to date and can be rebooted as follows:

reboot

Once the raspi has rebooted, login again via SSH as user repeater and then become root user again.

You now need to install a couple of Python components that are required by the system to function. Use the commands below as user root:

apt-get install python3-dev python3-pip
pip3 install pyserial

Next you need to change directory into the asterisk config file directory using the command shown below:

cd /etc/asterisk

In this directory you will find all the default config files that come as part of the distro. For this build we’re not going to use them and so we need to move them out of the way ready for a set of config files that have already been configured correctly.

Using the following commands create a new directory, move into that new directory and then move all the unwanted configuration files into it:

mkdir ORIGINAL-CONF-FILES
cd ./ORIGINAL-CONF-FILES
mv ../*.conf ./
ls -la
cd ../

You should now be back in the /etc/asterisk directory which will now be empty apart from the custom directory which we left in place.

You now need to copy the correctly configured configuration files into the /etc/asterisk directory. Start by downloading the zip file containing the new configuration files

Once downloaded, copy the .zip file into the repeater users home directory (/home/repeater) using either scp on the Linux command line or if using Windows you can use the FileZilla Client in SFTP mode using the login details above.

Once you have the .zip file in the repeater user’s home directory you need to copy the file into the /etc/asterisk directory as user root:

cp /home/repeater/AllStarLink-Config-v3.zip /etc/asterisk/

Next as user root, change directory into the /etc/asterisk directory and unzip the .zip file:

cd /etc/asterisk
unzip ./AllStarLink-Config-v3.zip

Once the file is unzipped you need to move a couple of files into the repeater users home directory using the following commands:

mv ./SA818-running.py /home/repeater
mv ./gpio /home/repeater

Once the files have been moved you need to set the correct ownership and privileges on the files using the following commands:

chown -R root:root /etc/asterisk/*.conf
chown repeater:repeater /home/repeater/gpio
chown repeater:repeater /home/repeater/SA818-running.py
chmod 755 /home/repeater/gpio
chmod 755 /home/repeater/SA818-running.py

The gpio BASH script and configuration details were supplied by Mark, G1INU in the Digital Voice room on the Matrix. It adds the COS light functionality to the setup. The COS light will now light every time the SA818 hears RF on the input.

The next thing you need to do is configure the SA818 radio device in the SHARI. The script I used was originally from https://wiki.fm-funknetz.de/doku.php?id=fm-funknetz:technik:shari-sa818 all I’ve done is change the entries to switch off CTCSS and changed the frequency to 438.800Mhz. Configuring the SA818 is done by running the SA818-running.py Python programme that you moved into the repeater user home directory. Making sure you are still user root, run the following commands:

cd /home/repeater
./SA818-running.py

At this point your SHARI SA818 device will be configured to operate on 438.800Mhz and CTCSS will be disabled.

If you want to change the frequency or enable and set a CTCSS tone to access the node you will need to edit the Python programme using your favourite text editor and change the entries accordingly. Once changed rerun the program as shown above and your SHARI will be reconfigured to your new settings.

Next you need to move the allmon.ini.php file into the correct directory so that it enables access to the Allstar Monitor web page on the device so that you can manage connecting/disconnecting nodes. Use the following commands as user root to achieve this:

cd /etc/asterisk
mv ./allmon.ini.php /var/www/html/allmon2/
chown root:root /var/www/html/allmon2/allmon.ini.php
chmod 644 /var/www/html/allmon2/allmon.ini.php

The allmon.ini.php file needs to have your node name entered into it for it to work correctly. As user root, change directory and edit the file using your favourite editor.

cd /var/www/html

Using your text editor, search for the line starting [XXXXX] and change the XXXXX to your node number. Save the change and exit the file.

At this point you are almost complete, all that is left to do is add your node number and node secret into the appropriate configuration files in the /etc/asterisk directory.

Since I am a Linux command line junkie I use vi to edit all the configuration files on the command line as user root, but you can use any editor of your choice.

cd /etc/asterisk

Start with the extensions.conf file. Search for the line starting with NODE = and delete the XXXXX entry and insert your node number. Save the file and edit it.

Next you need to edit the iax.conf file. This time search for the line starting with
register= and change the XXXXX for your node number and the YYYYYYYYYYYY for your node secret. Be careful not to accidentally delete any other characters in the lines otherwise it will corrupt the configuration file.

In the same file search for the two lines that start with secret = and change the YYYYYYYYYYYY for your node secret. Once you have changed both of the secret entries, save and exit the file.

The final file to edit is the rpt.conf file. Once again open the file using your favourite editor and search for the line starting with XXXXX = radio@127.0.0.1:4569/XXXXX, change the XXXXX entries for your node number making sure not to delete any other characters next to the XXXXX entries.

Further down in the same file there is a line that starts with [XXXXX], once again change the XXXXX for your node number making sure to keep the square brackets at each end of the node number as you edit it.

Finally move down to the very bottom of the file and find the two lines that start with /home/repeater/gpio, once again change the XXXXX entries for your node number.

Once this is done, save and exit the file. At this point your node should be fully configured and will only require a reboot to get it working.

As user root, reboot your raspi using the reboot command.

reboot

Once your raspi comes back online, login using SSH as user repeater and then become root user using the sudo command detailed above.

You now need to create the admin user password for the Allstar Monitor web page on the device. This is done using the following commands as user root:

cd /var/www/html/
htpasswd -c .htpasswd admin

You will be asked to enter a password twice for the admin user, make sure you make a note of this password as you will need it to login to the web page.

Once this is done your configuration is complete, logout from the terminal session by entering exit twice (once to logout as user root and another to logout as user repeater).

Using your favourite web browser enter the IP Address of your raspi into the URL bar as shown below:

http://<Your-Raspi-IP>/allmon2

Note: remove the <> from the URL once you have entered the required information.

Once this is done you should be presented with your node control panel as shown below.

First visit to the AllStar Monitor Web Page
First visit to the AllStar Monitor Web Page

Login using Admin and the password you set above and you are now ready to start using your node.

It’s a good idea to connect to node 55553 which is a parrot test node to check your audio levels. you can do this by entering the node into the field at the top left and pressing the connect button.

M0AWS AllStarLink Node 61928 connected to 55553 Parrot
M0AWS AllStarLink Node 61928 connected to 55553 Parrot

Once connected, tune your radio to 438.800Mhz FM and transmit a test message using your callsign and test123, or something similar. The parrot will then play your recording back to you so that you can hear how you sound. It will also comment on your audio level as to whether it is OK or not.

You are now connected to AllStarLink network and have the world at your finger tips. Below is a small list of nodes in the UK, Australia and America to get you started chatting with other HAMs via your node.

55553	ASL Parrot for testing
41522	M0HOY HUBNet Manchester, UK
60349	VK6CIA 439.275 Perth, Western Australia
51077	VK6SEG South West Hub B Albany WA
2167	M0JKT FreeSTAR UK HUB 2 freestar.network
53573	NWAG NW AllStar Group Lancashire, UK
27339	East Coast Hub Wilmington NC USA
M0AWS AllStarLink Node 61928 sitting on the equipment rack
M0AWS AllStarLink Node 61928 sitting on the equipment rack

Thanks to Michael, DK1MI for building and hosting the Matrix HAM Radio Space AllStarLink Node (57881) and getting us all kicked off into the world of AllStarLink!

We hope to be having regular Matrix Net’s on the node soon for all Matrix members and visitors. We’ll organise days/times via the Digital Voice room.

More soon …

Retevis RT85 antenna SWR

Since purchasing my Retevis RT85 2m/70cm handheld radio I’ve noticed that it seems rather deaf when using the antenna that came with the radio and isn’t as strong into the local repeaters as I imagined it would be.

Considering the local 2m and 70cm repeater isn’t that far from my QTH and there is pretty much a clear line of site view in the direction of the repeater I was somewhat surprised that on 70cm the repeater never breaks the squelch, even if it is set on it’s lowest setting of zero.

M0AWS Retevis RT85 dual band VHF/UHF Handheld Radio
M0AWS Retevis RT85 dual band VHF/UHF Handheld Radio

Connecting my home made end fed dual band vertical dipole at 10m above ground the performance of the radio improves drastically as one would expect.

Having recently purchased a JNCRadio VNA 3G antenna analyser I decided to connect the Retevis supplied antenna to the analyser and see what the resonance was like on the two bands.

The antenna is labelled as 136-174Mhz and 400-470Mhz. This is an extremely wide frequency range for such a small antenna and clearly isn’t going to perform that well over such a wide bandwidth.

Connecting the antenna to the VNA and setting the stimulus frequency range to 144-148Mhz I found that the SWR curve of the antenna wasn’t particularly good.

M0AWS Retevis RT85 Antenna SWR Curve 2m
M0AWS Retevis RT85 Antenna SWR Curve 2m

As shown above the SWR curve on the 2m Band is pretty poor. At 144.0Mhz it’s just over 3:1, at 145.496 (closest I could get to the 145.500 calling channel) the SWR is still 2.1:1. The antenna doesn’t really get close to resonance until 148Mhz where the SWR is 1.46:1.

With an SWR this high the radio will almost certainly be reducing the O/P power considerably to protect the PA stage from over heating due to so much power be reflected back into the transmitter. This explains the poor performance when using 2m repeaters locally and the somewhat limited range when using the OEM supplied antenna.

Looking at the SWR curve on the 70cm band, the antenna is much closer to resonance than it is on the 2m band but, it’s still not perfect.

M0AWS Retevis RT85 Antenna SWR Curve 70cm
M0AWS Retevis RT85 Antenna SWR Curve 70cm

At 430Mhz the SWR is 1.56:1, at 435Mhz 1.63:1 and 440Mhz 1.72:1. Since the antenna is much closer to resonance on the 70cm band I would expect it to perform better than it does.

Looking at the SWR curves over the entire supported frequency range of 136-174Mhz and 400-470Mhz, there is only one point of resonance on VHF around 148Mhz and on UHF around 400Mhz.

With such disappointing performance on both VHF and UHF I’ve decided to investigate making my own 2m/70cm antenna for the handheld to see if I can improve both the SWR on each band and the overall performance of the radio.

More soon …

70cm Band Eggbeater Satellite Antenna

Following on from my 2m Band Eggbeater Satellite Antenna here’s the design for the 70cm Band version that will enable duplex satellite operation.

The design is basically the same as the 2m antenna but, with smaller dimensions. All modelling has been done with the antenna at 5m AGL.

70cm Band Eggbeater Satellite Antenna

Each of the Eggbeater loops has a conductor size of 5mm and a circumference of 73.5cm with the radials exactly 5cm below the bottom of the loops. The 8 radials are exactly 34.15cm long each. The distance between the bottom of the eggbeater loops and the radials must be 5cm to get the best radiation pattern from the antenna.

With these dimensions the antenna has an SWR of <1.5:1 across the whole 70cm band making it ideal for both satellite and general repeater/SSB working.

70cm Band Eggbeater Satellite Antenna 3D Far Field Plot

The 3D far field plot shows that the antenna has a good mix of high and low angle radiation that makes it ideal for working satellites at all elevation angles.

70cm Band Eggbeater Satellite Antenna 2D Far Field Plot

The 2D far field plot shows that the antenna has the following high gain lobes:

6.43dBi @10 Deg
5.15dBi @40 Deg
3.4dBi @60 Deg
4.83dBi @80 Deg

The null at the top of the antenna isn’t as pronounced as on the 2m model and so this antenna should perform better when the satellite is directly above. Just like on the 2m band version, this antenna must also have a feed phase angle of 90 degrees between the two eggbeater elements. It’s very important that the phasing harness is built accurately as it can impact the radiation pattern of the antenna if the phase angle isn’t correct.

ON6WG has written an excellent article on how to create the phasing harness using 2 pieces of coax cable, this is an ideal solution for this antenna.

More soon …

Dual Band VHF/UHF End Fed Vertical Dipole

Since purchasing my Icom IC-705 radio I’ve only used it on the HF bands. Since the IC-705 is a “shack-in-a-box” I thought it was about time I ventured up onto the VHF/UHF bands and add another string to my bow.

Since I don’t have an antenna for these two bands I’d need to build something. I’m not really interested in DXing on the VHF/UHF bands as I’d need a yagi or two, a rotator and would need to get the entire setup up high on the chimney on the house.

We’re very fortunate in that there are a good many repeaters on VHF/UHF in East Anglia with quite a few being well within range of my QTH.

So I decided to go with a simple vertical antenna of some sort that I could easily attach to the top of a 10m spider pole and pop up in the garden without too much hassle.

The simplest of all antennas to build for any band is an end fed vertical dipole. It’s made purely from a piece of coax cable, you can’t get much simpler.

Using some dimensions I found online I unrolled a length of RG58U and set about cutting it to resonance for the two bands.

To start I measured out 910mm of RG58U and put a piece of tape around the cable at the 910mm point. I then stripped the top 460mm of the outer and braid from the coax so that the inner wire and plastic insulation was exposed. This then left 450mm of coax with the braid still in place to make up the 2nd half of the vertical dipole.

At the 910mm marker I wound the coax 9 times around a 27mm former to create a choke balun. I taped the coil up to ensure it kept it’s shape, removed it from the former and then used a few zip ties to hold it in place.

VHF/UHF End Fed Vertical Dipole Diagram

The diagram above aids in visualisation of the make up of the antenna that is made from a single piece of RG58U coax cable.

Choke Balun made from 9 turns of RG58U on a 27mm former

I next wound some electrical tape around the point on the antenna where the outer insulation and braid ended so that it would stop moisture getting into the rest of the coax and causing problems in the future. I also put a bit of electrical tape across the top of the end of the wire to stop moisture getting into the inner wire and then a piece of electrical tape around the wire to ensure it was fully sealed.

Electrical tape wound around the point where the outer braid finishes

At this point the antenna was complete! It literally took a few minutes to make. I could now either cut the coax a few centimetres from the bottom of the coil and fit a PL259 or just continue the coaxial cable back into the shack and fit a PL259 on the end. I decided to go with the latter as it’s one less connection to make.

VHF/UHF End Fed Vertical Dipole taped to the top of a 10m spiderpole

Once complete, I taped the antenna to the top of a 10m spider pole and then ran the rest of the coax back into the shack and soldered on a PL259 connector.

Raising the spider pole up to its maximum length put the antenna some 10m up above the ground. Hopefully this will give me a relatively clear path to the local repeaters.

Plugging the antenna into the IC-705 and checking the SWR I found it was <1.2:1 across the entire 2m band and <1.5:1 across most of the 70cm band. It was perfect for what I wanted!

VHF/UHF End Fed Vertical Dipole up 10m on a Spiderpole

I configured the local repeaters into the the IC-705 memories so that I could easily switch from one repeater to the next with all the appropriate tone and duplex frequency shifts set at the touch of a button.

My local 2m repeater GB3PO comes in at 5/9+10dB without any preamp and the local 70cm repeater GB3IH comes in at 5/9+5dB without any preamp. I was really pleased with the results and set about having a chat with other local HAMs on the local repeaters. It’s been a while since I’ve used the mic on this radio and it made a nice change!

To my surprise I found I could get into far more repeaters than I ever imagined. GB3NB in Norwich is 5/8 as are a number of repeaters down in Essex. This gives me quite a scope for chatting on the VHF/UHF bands via the repeater network.

To my surprise I can also hear ON0WV in Brugge Belgium, unfortunately it’s on the same frequency as the local 2m GB3PO repeater and so often gets drowned out completely but, it’s good to know that when there’s a lift in propagation I should be able to get into the near continent without too much hassle.

If you’re looking to build a simple but, effective 2m/70cm vertical for local repeater access then I highly recommend making an end fed vertical dipole. It only takes a few minutes to cut the cable to length, remove the outer sheath and braid and wind the choke balun, it really couldn’t be any easier.

More soon …