Automated Antenna Switch
Fabrication and installation of a network controlled antenna switch. Allows for 2 inputs with up to 6 outputs.
After putting up multiple antennas at my QTH, it was frustrating having to manually switch between antennas. There are plans to add SO2R (Single Operator, 2 Radio) operation and have the option to use the station remotely in the future. I needed some type of automated antenna switch.
Goal is to have an automated antenna switch that can be controlled over the network and/or the internet. In a SO2R or 2O2R (2 operators, 2 radios) environment using two computers, I’d would like each computer to know what antenna the other is using.
After doing some research, there were a couple options.
Commercial Options
4O3A Antenna Genius – Ranko makes some quality products for the serious contester. The ‘Antenna Genius’ has everything I want in an antenna switch. However, it’s quite expensive at around $875USD and that’s just the switch itself. This is way out of my budget.
Team-XCR 4 Way Remote Switch – When I was initially researching switches, I’ve heard about this project but it was still in development. As of writing this article, it appears they are in production.
I wasn’t interested in this project at the time because it was being developed as a 1X4. One antenna input, 4 outputs. I’m looking for a 2X6 configuration and SO2R support
However, it’s very promising. It’s controlled by Wifi (ESP32 Module) with a web interface and uses the coax to power the relays using a Bias-T circuit. For around $250USD (switch + bias T) that’s not bad at all. There is also development being made for a 2X6 which is promising. I’ll be watching this project for sure.
Snaptekk, Remoterigs, DXEngineering and others. – There are many options of automated/remote switching out there but either it didn’t support automated switching what I wanted or the price was just too much
Do It Yourself
It’s possible to do an automated antenna switch yourself but that depends on you value your time. Since I didn’t have much knowledge in creating a RF friendly PCB and don’t know how to create the code for an Arduino or Raspberry Pi project, I looked for people that already done to the work.
I found it’s possible to create a 2X6 automated switch that can be networked controlled if you combine two projects.
KK1L 2X6 Kit
First was the KK1L 2X6 PCB Kit. This has been on my mind for years. I’m aware of many people who have purchased it and use it in their shack without much issue. Ron only sells the PC boards but he does provide a really nice mouser list that you can import into your shopping cart. Makes it very easy.
However, I wasn’t really a fan of his controller and held off purchasing the 2X6 because of it. Nothing against the design. It’s not what I wanted. During my research I was unaware there can be multiple ways to control the relay board.
FreqEZ II By K8UT
While researching another project (MORRTY) and from a suggestion from a fellow ham on IRC, I came across the FreqEZ II by Larry, K8UT (Will call it FEZ2 from now on) I didn’t think much at first until I clicked on the link. It had everything I wanted in a controller. It utilizes a Raspberry Pi (RPi) and to top it off, he developed hardware that uses the RPi’s GPIO pins. For $50USD, the price was worth it. I had a few Raspberry Pis laying around from other projects (ADSB, RTLSDR).
Larry also developed software for Windows that could take data from BCD, UDP broadcasts from certain logging software (N1MM, DXlabs) to automatically switch antennas and you can also control it manually through the software.
Will They Work Together?
Yes they will!
Even Ron (KK1L) was interested in the FEZ2 and was implementing it into his station. Larry (K8UT) also assured me that it could work but at the time wasn’t sure about preventing the hardware and/or software from having both radios choose the same antenna.
Ron assured me that even if something happened with the software/controller, it won’t be able to connect both radios (inputs) to the same antenna (output) as designed by the hardware.
Larry (K8UT, FEZ2 dev) was currently developing features such as constraints to also prevent multiple radios from choosing the same antenna. For anyone planning to follow along, The FreqEZII wasn’t developed FOR the KK1L 2X6. It was developed for all sorts of hardware and applications.
The Goals
I have two goals in mind for this project. One is for a 2A (2 Station) field day option and the other is for home.
Field Day Option With 2X IC-705, 2 PCs, Router/Switch, KK1L 2X6 w/ FreqEZ, BPFs, Triplexor and Antennas (Goal 1)
I help out with a small (private) field day operation. It started as a simple 2 station effort with wires in the trees. Of course we complicate things over the years by adding a tower with a beam and multiple antennas. With the station and antennas optimized to our liking, only issue we had was switching antennas. My goal for 2022 was to automate the process
Option 2: This would be my “dream” setup
The above “option 2” diagram shows my dream setup. Dream is the 6600 with PGXL. However, it might end up being my current flex 6400, used HF solid state rig and possibly 2 amplifiers or something from SPE.
For now this project will be focused on Option 1 which is for Field Day use since it’s needed and promised. We’re going to focus on building the 2X6 relay board and getting it to work with the FEZ2
KK1L 2X6 Build
Ron had boards in stock and thankfully mouser had all the parts in stock as well. Ron provides a list on his website that you can import to your mouser shopping cart. Be careful because he does list optional parts and he recommends an enclosure that may or may not work with this exact project.
Ron and Mouser shipped very fast and received both items within a week. Ron has included assembly instructions but I prefer the ones from his website.
If you follow the instructions, the build is quite straight forward. Be sure to follow it carefully as components have to clear other components. Only thing I did different was fabricated spacers for the SO-239 mounts instead of using nuts that he specified.
1/8″ spacers made for the KK1L
Completed 2X6
FreqEZII Build
The build itself was easy. I purchased the FEZ2 hat that installs on any raspberry pi that has a 40pin connector. Well worth the money if you ask me. Just plug the hat onto the Raspberry Pi. Getting it to work with the pi is where all focus will be.
Larry suggests using a Pi4 or a Pi3 and provided detailed instructions. However at the time of starting this project, Raspberry Pi’s are quite difficult to get. I personally have a few Raspberry PI 1 B+ units laying around. They have the 40pin connector and figured to give it a try. The Pi Zeros with 40pin headers could work as well.
His instructions are for those who don’t know their way around a Raspberry Pi, Linux or using a CLI (Command Line Interface). Due to the limited resources and limited CPU of the Pi 1, I didn’t want to install a full GUI (Graphical User Interface like with Windows). This is where I deviated from Larry’s instructions.
I strongly suggest if you are following along to use Larry’s instructions. I know enough about linux to get myself into trouble.
As of writing this article, Larry has been very active in updating the software and the older Pis may or may not work after a recent major update.
I’ll keep this article updated as I go along.
Putting It All Together
With the 2X6 built and the FEZ2 in working order, we can now put both of these projects together. This will mostly involve wiring. This might change depending on exactly what you want to do with your project.
The KK1L uses 12Vdc to power the relays. However, the RPi require 5Vdc. Since most shacks use 12-14Vdc, you’ll need to convert 12v to 5. You can do it yourself but I went to Amazon and found a converter made for the RPi.
Even though I was initially confused at first, wiring the relay board to the FEZ is very simple. The FEZ has 16 outputs split into two bays. You’ll only need 12. 6 for “Radio A” and 6 for “Radio B”. What I did was use the first 6 outputs from the FEZ to feed all the “A” ports on the 2X6 and used the 2nd bay to feed all the “B” ports on the 2×6. Below is a diagram showing what I did
Diagram showing how I wired the FreqEZ to the 2X6 relay board.
The KK1L 2X6 relays use 12v. The 12V+ from the PSU is going to both “C” (control) banks as they can be operated independently.
Wiring
You’ll see that I also wired the 12v-to-5v converted directly to the GPIO pins of the RPi. I did this because I purchase the wrong converter and had a different USB type end.
If you decide to solder 5v directly to the GPIO pins of the Pi, please confirm that you are soldering to the correct pins and take care to prevent shorts. Not pictured in my diagram is inline fuses.
I have one prior to the case and I added one on the 5v side to protect the pi.
As for the wire itself, I used CAT6 cable. The relays are not requiring a massive amount amperage. I used two “short” sections. One for antenna “A” and another for “B”.
FreqEZ2, Raspberry Pi and KK1L 2X6 Test Setup
Testing went okay. Loaded the FreqEZ2 windows software and was activating and de-activating relays to confirm operation. This allows me to stuff everything inside of a case and continuing setting up the software which I feel is the 2nd “battle” of this project.
Enclosure Fabrication
This is where you won’t be able to follow along. I did not purchase the enclosure that KK1L suggested as I wanted room for a raspberry pi and a divider hoping to keep RFI away from the Pi and hat. The enclosure in KK1L’s mouser BOM may or may not work with both the Rpi and Relay board in the same enclosure.
I can’t confirm this. Hammond MFG does make a larger enclosure that you can purchase on mouser.
I can’t confirm if it will work 100% as I went with a custom fabricated enclosure. For those who want to fabricate their own enclosure, KK1L provides drawings with the hole layouts on his site. The pi and relay board are in separate enclosures.
Enclosure without relay board showing RasPI and converter
Enclosure with RasPi covered up to help with any possible RFI reduction.
Trial By Fire
With everything together, it would be best to test things out independently within its own environment before implementing it into a station. Make sure everything is working properly and try everything possible to make it not work.
I’ve confirmed that the software and hardware worked. At first, There were some issues when it came to networked operations using multiple copies of the windows software. Larry and Ron were quick to help. Larry even updated his software because of some of the issues I’ve had.
With things appearing to work properly, I should have put RF through it and tested everything again but of course that wasn’t done. I decided to use ARRL Field Day 2022 to be the first real test.
If this works throughout the entire weekend then I considered it a major success considering the quick implementation. Worst case is we go back to manual switching. However, I don’t want that to happen.
There was one issue I had setting up. However, it wasn’t related to the switch itself . It was related to trying to use the switch on an established network and accidentally setting stricter firewall settings on the PCs controlling the switch.
First Run
Antenna Switch In Action
Started FD with the network and firewall settings issue but it didn’t really get in the way. After the first hour we finally figured out what was causing the issue. Ended up turning off the PC’s firewall. Next year we’ll make sure the PCs join the wifi network as a “Private Network”.
I configured the switch to work based off N1MM+ UDP broadcasts to automatically switch antennas. We’re using Icom 705’s that are also connected to N1MM for control and to pass data back and fourth. This allows the operators to focus on operating and don’t have to learn the FEZ control software.
After that minor issue cleared up, the FEZ and KK1L switch worked flawlessly throughout the entire weekend. Even during power cycles. The operators that were using the stations enjoyed not having to manually swap coax or remember which coax is which.
Overall Thoughts
Overall it was a success and it will be used for field days and other events to come. Also plan on building one for my shack. Larry and Ron were a pleasure to deal with and I think it’s an excellent combination. If you’re looking for a network/remote controllable 2X6 antenna switch and you are willing to put in the work, the FreqEZ and KK1L 2X6 is a perfect, cost savings project that you would be proud to use.
As I was typing this article, Larry (K8UT, FreqEZII developer) has came out with some exciting news. He moved the project to it’s own website and even developed another piece of hardware that makes use of the Pi ZERO. He is continually working on this project.
I’m also aware that Ron is in the process of developing PCBs that will implement FEZ.
Thank you for reading. 73 DE NT1K
Author
NT1K
Posted on May 9, 2023 May 10, 2023
Categories: Antennas
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