The Nashua Area Radio Society will be using our portable Satellite Station this year at Summer Field Day. A number of members got together recently to assemble and test our Computer-Controlled Portable Satellite Station for Field Day. Here are some pictures of our Field Day Satellite Station Test…
Several members of the Nashua Area Radio Society got together to set up and test our Portable Satellite Station for Field Day 2021. Our station is a computer-controlled one and enables us to work FM and Linear Satellites using phone mode and CW.
You can see how the portable station goes together in the article above. You can learn more about the design and construction of our Portable Sation from the series of articles that begins here. We hope to work some of our readers on the birds during Field Day this year!
Many Hams (including this one) have problems with RF Interference (RFI) at their stations. Many RFI sources typically come from inside our own homes. Symptoms include birdies at single frequencies, interference that moves around across the Amateur Radio Bands, and high noise floors. We have had all of these problems here.
We recently built an improved EME station for the 2m Band. We noticed a higher-than-ideal noise floor when operating 2m EME during the initial testing of the new station. We decided to do some additional testing to see if we could isolate the source of the noise levels. One test we did was to shut down much of the ethernet network and associated devices here at our QTH. To our surprise, this lowered our noise floor on 2m by some 6 dB, and eliminated many birdies in the EME section of the 2m Band!
Our network mostly uses wired Ethernet running throughout our home on Cat 5e and Cat 6 unshielded ethernet cables. Many of the devices in our home use Power Over Ethernet (PoE) connections to power them through the ethernet cables.
We decided to solve our noise problems via a pretty major upgrade to our home network. The upgrade included:
Installing OM4 multimode fiber optic cables to replace all of the non-PoE wired Ethernet connections to the rooms in our home. The fiber cables were chosen to support 1 GbE and 10 GbE connections now and to be upgradable to 100 GbE connections in the future.
Installing a shielded rack enclosure to house the switches and management devices for our upgraded Network
Installing new Cat 6A Shielded Ethernet cables to PoE devices that we wanted to remotely shut down when we are operating using weak-signal modes on 6m and above
Upgrading portions of our network to 10 Gbs Ethernet speeds to improve the efficiency of Video Editing and Backups
The project began with the installation of a Shielded Rack Enclosure in our basement. The Rack is wall-mounted and fully shielded and grounded. It also includes cooling fans that move air vertically through the Rack to keep the gear inside cool.
Core Network in Rack
Next, we mounted all of the gear for our upgraded core network in the Rack. The main components include (from bottom to top):
Two rackmount shelves that hold a NAS-based Media Server that stores all of the entertainment content for the media system in our home.
PDU Web Interface for Network Control and Management
We are going to power down most of our IP Cameras and the WiFi AP devices around our home when we are operating on 6m and above. We implemented this capability using an IP-Controlled Power Distribution Unit (PDU) that allows us to remotely turn network devices in our network on and off via a web browser from anywhere in our home.
IP Camera PoE Switches
The PDU controls a pair of Netgear PoE Edge Switches that power most of the IP Cameras in our home via PoE connections. Shutting down these switches via the PDU removes power from the associated IP Cameras which eliminates a great deal of noise and other RFI.
WiFi Acess Point Control via PoE Edge Switch
We also installed a VLAN-capable Netgear PoE Edge Switch and connected it to the PDU. This switch enables us to shut down other devices on our network such as WiFi Access Points which are also significant sources of RFI. This switch uses a pair of optical interfaces that connect it to our core network
OM4 Fiber Cable with LC Connectors Installed
A large part of the work associated with our network upgrade project involved running OM4 Multi-mode Fiber Optic cables to all of the rooms in our home. We ran 12-fiber cables to locations that would likely benefit from upgrades to 100 GbE in the future (ex. our shack, home offices, media-equipped rooms, and servers/NAS devices) and 6-fiber cables were used elsewhere. All of our fiber cables use LC connectors with two fibers for each Ethernet connection (one for Tx and one for Rx). We used a mix of pre-terminated cable assemblies and unterminated cables to complete the room installations.
Fiber Prep using a Fiber Cleaver
Field terminating fiber optic cables is not difficult but it does require some special tools and careful attention to detail. The ends of each fiber must be prepared to precise specifications and be very clean before the LC connectors can be installed. The image above shows a Fiber Cleaver which is used to “cleave” the end of each fiber to form a square, low-reflection/low-loss connection to a field-installable LC connector. Proper use of a high-quality Fiber Cleaver is important if you are to achieve low-loss, low-dispersion field terminations.
Verifying an LC Connector Installation using a Visual Fault Locator
A Visual Fault Locator (VFL) with an LC Connector Adapter is used to confirm the proper installation of each LC connector. The tool shines a bright red laser light through the LC connector and fiber cable. The field installable LC connectors include a window that indicates laser dispersion at the fiber/connector junction. Too much light in the window due to dispersion indicates a poor connection. The VFL tool is also very useful for checking end-to-end optical transmission and continuity of the completed fiber cable installations.
Fiber Wall Outlet and Patch Cables
The fibers were terminated in wall outlets in the rooms of our home. The outlet plates accept standard keystone jacks. We used LC Keystone Couplers with our wall jack plates. This approach ensures that the ends of fragile fiber optic cables running to the rooms will not be damaged or broken when connecting the fibers to ethernet switches and other devices.
Fiber LC Interconnect Enclosure
The other end of each fiber cable is terminated in a Fiber LC Patch Enclosure Tray in our Rack. The enclosures provide a test point and LC patch cable interconnect point for the fiber cables. The advantage of using enclosures such as these is that they protect the ends of the fiber cables running to the rooms from damage. A total of three trays terminate a total of 72 OM4 fiber pairs that we installed in our home.
Optical Fiber Connector Cleaner
It is very important to keep all of the fiber connections clean. Standard practice should be to ALWAYS clean the ends of each LC connector with an Optical Fiber Connector Cleaner each time before an LC connector is installed in a jack. It is also important to keep the supplied caps that come with LC connectors installed when they are not connected to a jack or optical SFP.
10GBase-SR SFP+ Transceiver
The fibers in the core rack and in the rooms are connected to switches, computers, and NAS devices via SFP or SFP+ Transceivers. An example of an SFP+ Transceiver is shown above. These devices convert the laser signals carried on the multimode OM4 fibers to a standard electrical format that can be handled by the core and edge switches in our network.
Core Network Components
The connections between the Fiber Termination and Patch Enclosures and the SFPs and SFP+s in the Core Switches in our rack are made using OM4 LC Patch Cables (the aqua cables shown in the image above).
Fiber Wall Outlet and Patch Cables
Similar patch cables are run from the Wall Jacks to the Ethernet Edge switches in each room to complete the connections to the core network. Most of our Edge Switches in the rooms in our home use two pairs of fibers in a LAG configuration. This increases the bandwidth capacity of the connections and also increases reliability. Should one of the fiber pairs experience a failure, the other pair continues to carry the traffic until the problem can be repaired.
Shielded CAT6A Ethernet Terminations
Some devices in our network such as the PoE IP Cameras on our Towers and a portion of our WiFi Access Points cannot be shut down without significantly compromising the operation and functionality of our Network. We controlled the noise and RFI contribution from these devices by installing new, Cat 6A Shield Ethernet cabling to connect them. The Cat 6A cables must be terminated using a grounded, fully shielded ethernet panel. This device is 10 Gbps Ethernet capable and properly terminates the shielded Cat 6A cables in our Rack.
So how did all of this workout? We are seeing a 6 – 7 dB improvement in the noise floor on 2m. This is a huge improvement for our EME station! We are also seeing about 1 dB in noise floor improvement on 6m. We are also seeing a significant reduction in birdies on all the bands. Finally, many of our computers and most of our NAS drives have been upgraded to 10 Gbps Ethernet which enables us to move large files around our network much more quickly. We are also seeing some improvement in the actual measured throughput of our 1 Gbs/400 Mbps Fiber Internet connection.
I hope that our readers find our Fiber Optic and 10 Gbps Networking project interesting.
We’ve been wanting to try a Loop Fed Array (LFA) Yagi on the 6m Band. The Nashua Area Radio Society’s 2021 Field Day operation presented us with a good opportunity to do this. We choose a lightweight 3-Element LFA Yagi from InnoVAntennas and used a fiberglass mast to get it up 25 ft (about 8 meters).
The LFA Yagi performed very well! You can read more about this antenna’s performance and our upgraded portable station via the link above.
February 2021 Tech Night – Understanding and Using Radio Propagation to Work The World
Anita, AB1QB, recently did a Tech Night Program on Radio Propagation as part of the Nashua Area Radio Society’s Tech Night program. I wanted to share the presentation and video from this Tech Night so that our readers might learn a little more about propagation and how to use it to facilitate contacts.
Anita, AB1QB provides a comprehensive overview of HF and VHF/UHF propagation and how to use it to Work the World. Topics include the many online tools to help one determine and measure propagation conditions. VHF+ modes such as Meteor Scatter, Tropo, EME, and Satellite paths are also covered.
EME II Tech Night – Station Construction and Operation
We recently did a second Tech Night Program on EME as part of the Nashua Area Radio Society’s Tech Night program. I wanted to share the presentation and video from this Tech Night so that our readers might learn a little more about how to build and operate an EME station for the 2m band.
January 2021 Tech Night – EME II: Station Construction and Operation
A key part of optimizing our EME Station was to reduce RFI from the network in our home. You can read about the installation of Fiber Optic Networking to reduce RFI and improve our EME station’s performance here.
We’ve been making good use of our Satellite Ground Station. Our existing 2MCP14 and 436CP30 antennas have enabled us to make over 2,000 satellite contacts; working 49 of the 50 U.S. States, 290+ Grid Squares, and 31 DXCCs. Our station is also an ARISS Ground Station which enables us to help Schools around the world talk to astronauts on the ISS.
As you can tell, we are pretty active on Satellites so we decided to take our station up a level by upgrading our antennas. We choose the 2MCP22 and 436CP42UG antennas from M2 Antenna Systems with optional remote polarity switches. These are larger yagis with booms over 18+ ft in length. The upgrade required us to improve the mechanical aspects of our Satellite Antenna System as well.
Antenna Assembly
2MCP22 Parts Inventory
The first step in the project was to unpack and carefully inventory all of the parts for each antenna. This included carefully presorting and marking each element as we did during the assembly of our EME antennas.
2MCP22 Completed Antenna
The new antennas are quite large and they took most of the available space in our workshop during assembly. Getting good results from any antenna is all about attention to the details. Small things like turning the boom sections to get a good alignment of the elements, using NOALOX on the boom sections and hardware to prevent corrosion and galling, carefully measuring and centering the elements, etc. are all good things to do.
2MCP22 Feedpoint Assembly including Polarity Switch Upgrade
The feedpoint system on these circular polarized antennas requires careful attention during assembly. It’s important to install drive element blocks, shorting bars, polarity switches, feedpoint splitters, and all phasing lines EXACTLY as shown in the antenna assembly manual. Failure to do these steps will likely results in SWR problems down the road.
436CP42UG Feedpoint Assembly
The images above show the feedpoint assemblies for both of our new antennas.
New Satellite Yagis Ready For Installation
A rough SWR measurement with the antennas on the ground was performed to check for assembly errors. It’s a good idea to use a 12V battery to test the antenna SWR’s in both RHCP and LHCP. These tests checked out fine and we are ready to begin installing the antennas on our Tower.
Old Antenna Takedown and Work Stand
Old Antenna Assembly Takedown Using Boom Lift
The next step in the installation was to take down our existing antennas. We rented a 50 ft Boom Lift for the project. The lift makes the work much easier and safer.
Old Antennas on Test Stand
We have a ground tower that we use for portable satellite operations. It was fitted with a longer mast to create clearance for our larger antennas. We lowered the existing antenna system onto the ground tower for disassembly, installation, and testing of our new antennas.
It’s important to fully test a complex antenna system like this on the ground prior to installation on a Tower. We have routinely found and corrected problems this way. This approach also enabled us to properly adjust our cross boom and antenna support trusses and balance the final assembly properly. All of the required adjustments are MUCH easier with the antennas on the ground.
We also run our rotators under computer control for at least one full day before installing the completed assembly on our Tower. We have consistently found and corrected problems with cabling and balance this way.
Antenna Mounting and Trussing
2MCP22 Boom Truss
The new antennas have very long booms (approximately 18 ft) and they have a tendency to sag. Add the ice and snow load that we experience here in New England and you end up with quite a bit of stress on the booms over time. Robert at M2 Antenna Systems came up with a custom truss assembly for our installation to address this problem. It’s important to minimize any metal in a setup like this to avoid distortion of the antenna patterns. The trusses use a solid fiberglass rod and small turnbuckles to support the ends of each antenna boom. There is much more weight on the rear of the booms due to the weight of the attached coax cables and polarity switches. For this reason, we located the truss anchor point for the rear of the boom such that it creates a sharper angle for the truss ropes at that end of the truss. This reduces the compression load on the rear of the boom and enables the truss to better carry the weight at the back of the antenna.
436CP42UG Boom Truss
Installing a truss on the 70cm yagi is much trickier due to the tight pattern of this antenna. We minimized the added metal components by drilling the antenna boom to mount the truss plate directly to the boom via bolts.
We relocated the boom support plates on both antennas as far to the rear of the largest boom sections as possible to improve overall antenna balance. The clamps were also adjusted to change the orientation of the elements from vertical/horizontal to a 45-degree X arrangement. This maximizes the separation between the element tips and other metal components like the cross boom and truss plates.
Tubing Drill Guide
All of this required drilling some new holes in our antenna booms. We used a Tubing Drill Guide and C-clamps to perform the required drilling operations accurately.
Satellite Antenna Boom Assembly
The photo above shows the new antennas mounted on our cross boom. The modifications worked out great resulting in well supported and aligned antennas on the cross boom.
Balancing The Array
Cross Boom Counterweight and Trusses
It’s very important to properly balance any antenna assembly that is used with an elevation rotator. Failure to do this will usually result in the failure of your elevation rotator in a short period of time. We initially had some pretty major balance problems with our new antennas. This is due, in part, to the weight of coax cables that run from the antenna feed points along the L-Brace Assemblies. The added weight of the Polarity Switches near the rear of the booms was also a significant contributor to this problem.
We created a counterweight by replacing one of our cross boom truss tubes with a metal section of pipe about 4 ft long. The pipe acts as a counterweight to the weight of the coaxes, etc.
Wheel Weights Used for Balancing
Next, we added 4 1/2 pounds of weights to the front on the metal pipe. We used several layers of Wheel Weights built up in multiple layers to get the necessary counterweight. A heavy layer of electrical tape and some large cable ties were used to ensure that the weights say in place.
This got us close to a good balance but the boom of the 2MCP22 was still significantly out of balance. Matt at XX-Towers came up with a good solution to this problem. We added a few strips of wheel weights inside the very front of the boom of the 2MCP22 to finally get the antennas balanced. A combination of the adhesive tape on the weights and two small machine screws through the boom ensures that the weights remain in place and do not short the elements to the boom.
Finally, we adjusted our Green Heron RT-21 Az/El Rotator Controller to slow down the ramps for the rotator. Final testing indicated the smooth operation of the rotator at slow speeds.
SWR Testing and Baseline
2MCP22 Installed SWR
A final check and baseline of all of our antennas were made on the ground. Both RCHP and LHCP modes were checked and recorded for future reference.
432CP42UG Installed SWR
We found that some fine-tuning of the locations and routing of the phasing lines on our 436CP42UG improved the SWR curves. This is a common situation and it’s well worth the time to make small adjustments while carefully observing how they impact your SWR readings. The phasing cables are firmly secured to the antenna boom after the fine-tuning is complete.
New Antenna Installation and Integration on Tower
Upgraded Antennas Going On Tower
The next step in our project was to install the updated antenna assembly back on our Tower. We had to push the lower rotator and mast up about 4 ft to accommodate the larger antennas. We removed our 6M7JHVHD Yagi and temporarily fastened it to the side of our tower to make these steps easier. We also took the opportunity to work on our 6M7JHVHD Antenna to adjust the length of the Driven Element for better SWR performance in the FT8 and MSK144 section of the 6m band.
Satellite Tower Infrastructure and Accessories
There is quite a bit of feed line and control cabling involved in a complex antenna system such as ours. The next step in the project was to reconnect all of the cables and coax feedlines.
Control Cable Junction Box at the Base of VHF Tower
We use small junction boxes on our tower and a larger one at our tower base to make it easy to remove and reinstall all of the required control cables. Our approach was to hook up and test the rotators first to ensure that we did not have any new mechanical or balance problems. This step checked out fine. The stiffer chrome molly mast and its added length actually resulted in smoother operation of rotators than we saw during ground testing.
The final step was to work through the other control cables and feed line connections; testing each connection as we went. The Boom Lift makes this work much easier to do.
We took advantage of the availability of the Boom Lift and added some additional enhancements to our VHF Tower. Previously. changing the battery in our Weather Station involved climbing our main tower to 50 ft. We moved the weather station to the 30 ft level on our VHF tower to make this maintenance step easier.
We also added an ADS-B antenna and feedline for the Raspberry Pi FlightAware tracker in our Shack. The parts that we used for the ADS-B antenna include:
Initial testing of our new antennas is showing some major improvements. The uplink power required to work LEO satellites has been reduced significantly. As an example, I have worked stations using the RS-44 Linear Satellite with just 0.4 watts of uplink power out of our Satellite IC-9700. The signal reports we’ve received have been excellent as well.
More About Our Ground Station
Here are links to some additional posts about our Satellite Ground Stations:
Our new 2m EME Antenna System has been performing very well. One area that we noticed that could use improvement was the alignment of our antennas as we move them in the Elevation plane. The problem is caused by the weight of the coax feedlines running from the antenna feed points to the power dividers on our H-Frame assembly. Our H-Frame assembly includes T-Braces to support the coax feedlines but the T-Braces tended to bend and distort the alignment of our antennas as the Elevation Rotator is moved.
Custom H-Frame Truss System
Matt at XX-Towers and Robert at M2 Antenna Systems helped us to come up with a very nice custom solution to solve these alignment problems. The solution consists of two additional truss cables on each of the H-Frame’s T-Brace assemblies. The truss cables are made from Phillystran Cable which is non-conductive and is adjusted via Turnbuckles that are anchored at the center of the H-Frame’s Vertical Risers. This approach minimizes any metal in locations that would affect the pattern of our antennas.
Cross Boom Extension
The first truss is mounted on a short custom extension on each end of our H-Frame’s Cross Boom and is run to an eye bolt in the center of each T-Brace Vertical Rod.
T-Brace Main Truss
These risers stabilize the tendency for the T-Brace Vertical Assembly to flex and move towards the center of the H-Frame when the full weight of the coax cables are bearing on them at various elevation angles. Careful adjustment of the combination of these new Truss Cables and the existing 45-degree T-Brace Horizontal Support Assemblies results in the rear of each antenna boom staying perfectly aligned as we rotate our antennas in elevation.
T-Brace Rear Truss
The other problem that our custom Truss Solution addresses is the tendency for the weight of the coax cables to bend the rear of the antenna booms down when the antennas are at 0-degrees in elevation. The bending is due to the weight of the coax cables on the T-brace being unsupported and bearing down on the rear of the antenna booms. This problem is solved by a second Phillystran truss cable that runs from the metal section of each Vertical Riser assembly to the junction between the rear of the bottom antenna booms and the associated junction of the Vertical T-Brace Assemblies.
We fastened the Phillystan cables directly to the junction point without the use of any metal hardware to ensure that the pattern of our antennas was not affected. These secondary Trusses now carry all of the weight of the coax cables on the T-brace as the antennas approach at 0-degrees in elevation and have eliminated the bending at the rear of our antenna booms.
With these modifications, our antennas remain perfectly aligned at any elevation angle. There is also noticeably less stress on the fiberglass sections of the Vertical Riser Assemblies since they are no longer carrying the load of the coax cables.
If you’d like to learn more about How To Get Started in EME, check out the Nashua Area Radio Society Tech Night on this topic. You can find the EME Tech Night here.
Software is a big part of most current EME stations. The JT65 Protocol, which was created by Joe Taylor, K1JT, has revolutionized EME operations. It has made it possible for modest single and two yagi stations to have lots of fun with EME.
Phase 1 of our 2m EME station software and hardware uses manual switching/selection of receive polarity. This Phase is about integrating all of the station components together and sorting out operational issues. After some experimentation, we have settled on a dual-decoder architecture for the First Phase of our 2m EME Station.
You can learn more about the Phase 1 EME hardware setup at our station here.
EME Software Environment
EME Station Block Diagram – Phase 1
The diagram above shows the current configuration of our 2m EME station. As explained in a previous article in this series, we are using a FUNCube Pro+ Dongle with the MAP65 application as our primary JT65b decoder and we are using our IC-9700 Transceiver along with WSJT-X as a secondary, averaging decoder. Using multiple decoders has proven to be a significant advantage. It is quite common for one of the two applications to decode a weak signal that the other does not.
We use two custom applications (WSJTBridge and Flex-Bridge) to capture the Moon Azimuth and Elevation data generated by the MAP65 application and use it to control the rotators for our EME Antenna Array.
We have been experimenting with Linrad as a front-end to MAP65 and WSJT-X. At present, we are using the NB/NR functions in MAP65 and in our IC-9700 as an alternative to Linrad. We expect the add Linrad into our setup when we add Adaptive Polarity capabilities in Phase 2.
EME Software Operating Environment (click for a larger view)
We use the DXLab Suite for logging and QSL’ing our contacts along with several web apps to find potential EME contacts and to determine the level of EME Degradation on any given day.
The screenshot above shows most of these apps running during a 2m EME operating session.
MAP65 Application – Primary Decoder and Operating Application
MAP65 Software
We are using MAP65 as our primary decoder. It also controls our IC-9700 Transceiver when transmitting JT65b messages. MAP65 used the I/Q data from our FUNCube Pro+ Dongle to detect and decode all of the signals in the 2m EME sub-band. A waterfall window displays all of the signals on the band as well as a zoomed-in view of the spectrum around the current QSO frequency. MAP65 also generates heading data for our rotators as well as estimates for the doppler shift between stations. The MAP65 application also provides windows that list all of the stations on the band as well as the messages that they are sending.
EME QSOs via MAP65
The screenshot above shows the main MAP65 window during a QSO with HB9Q. Round trip delay (DT) and signal strength information (dB) is shown for each message that is decoded. The MAP65 application along with a manual that explains how to set up and use the program for 2m EME can be downloaded here.
Moon Tracking and Rotator Control
Custom Rotator Control Apps (WSJT-Bridge and FlexBridge)
We developed an application we call FlexBridge some time back as part of our ongoing project to remote our Satellite Ground Station using our Flex-6700 based SDR Remote Operating Gateway. This application includes functionality to operate Az/El rotator controllers based upon UDP messages which contain tracking data. We wrote a second application that we call WSJT-Bridge which reads the Moon heading data that either MAP65 or WSJT-X and generates and sends UDP messages that enable FlexBridge to track the moon. The combination enables MAP65 to control tracking the moon in our setup.
Both of these applications are at an alpha stage and we will probably separate the rotator control functionality from FlexBridge and make it into a dedicated application.
Antennas On The Moon
One of the first steps in the integration process was to carefully calibrate our rotators to point precisely at the moon. We got the azimuth calibration close using the K1FO Beacon in CT. With this done, we made final adjustments visually until our antennas were centered on the moon on a clear night.
EME Tower Camera at Night
We recently installed an additional IP camera which gives us a view of our EME tower. This is a useful capability as it enables us to confirm the operation of our rotator from our shack.
WSJT-X – Secondary Decoder
WSJT-X Software
We also run WSJT-X as a second decoder using the receive audio stream from our IC-9700 Transceiver. WSJT-X has some more advanced decoding functions and can average several sequences of JT65b 50-second transmissions to improve decoding sensitivity. It only works on one specific frequency at a time so we use it to complement the broadband decoding capability that MAP65 provides.
We can also transmit using WSJT-X which enables us to use its Echo Test functionality to confirm that we can receive our own signals off the moon.
The WSJT-X application along with a manual that explains how to set up and use the program for EME can be downloaded here.
Finding Contacts and Logging
Finding Contacts and Logging
We use the DXLab Suite for logging and QSL’ing our contacts. DXLab’s Commander application provides the interface between WSJT-X and our IC-9700 Transceiver. This enables the DXLab Suite to determine the current QSO frequency and mode for logging purposes.
MAP65 Software and DXKeeper’s Capture Window
We keep DXKeeper’s Capture Window open on the screen where we run MAP65 so we can easily transfer QSO information to our log as we make contacts.
We also use several web apps to find potential EME contacts and to get an estimate of the level of EME Degradation on any given day:
LiveCQ – provides automated EME spots from stations running MAP65
We are working on interfacing our instance of MAP65 to LiveCQ so that we can contribute spots when we are operating. More on this to come in a future article in this series.
We are planning some enhancements to our H-Frame to enable better alignment of our antennas along with improved reliability and stability when rotator our antennas. We will cover these enhancements in the next article in this series.
You can read more about our EME station project via the links that follow:
If you’d like to learn more about How To Get Started in EME, check out the Nashua Area Radio Society Tech Night on this topic. You can find the EME Tech Night here.
A key part of optimizing our EME Station was to reduce RFI from the network in our home. You can read about the installation of Fiber Optic Networking to reduce RFI and improve our EME station’s performance here.
EME and Satellite Ground Station Hardware Components
Now that our 2m EME Antenna Array is fully installed, we have turned our attention to the setup of the equipment in our Shack. Our plan is to do a mix of JT65 Digital and CW operation with our 2m EME Station.
The image above shows the equipment that is dedicated to EME and Satellite operations in our station. We built some shelves to make room for all of the equipment as well as to create some space to move our Satellite Ground Station 4.0 to this same area. The components in our 2m EME station include (left to right):
Unfortunately, the LinkRF Receiver and Sound Card to enable a full MAP65 Adaptive Polarity installation are not currently available. As a result, we’ve created a Phase I Architecture that uses an SDR Dongle and manual selection of Receive Polarity via a switch. We also added a receive splitter and a Transmit/Receive relay in front of an Icom IC-9700 Transceiver which is dedicated to our EME setup to enable both the MAP65 and one of either the WSJT10 or WSJT-X Software Decoders to operate simultaneously.
This approach has some significant advantages when conditions are poor as one of either MAP65 or WSJT10/WSJT-X will often decode a marginal signal when the other will not. More on this in the next article in this series which will explain the software we are using more.
Transceiver, SDR Receiver, and Sequencing
IC-9700 Transceiver and Sequencer
A combination of an Icom IC-9700 Transceiver and M2 Antennas S2 Sequencer handle the Transmit side of our EME Station including the associated sequencing of the preamplifiers and Transmit/Receive Switching which is part of our Antenna System. The IC-9700’s receiver is also used with the WSJT10 Decoder in our setup.
IC-9700 Frequency Drift and Stability
Controlling IC-9700 Frequency Drift – Reference Injection Board Installed in IC-9700 (Leo Bodnar Website)
To ensure good frequency stability and limit IC-9700 frequency drift in our setup, we installed a Reference Injection Board from Leo Bodnar in our IC-9700. The Reference Injection Board uses Leo Bodnar’s Mini Precision GPS Reference Clock (the small device on top of our IC-9700 in the photo above) to lock the IC-9700 to a highly accurate GPS-sourced clock. The installation and configuration of the Reference Injection Board in our IC-9700 were simple and Leo Bodnar’s website covers the installation and setup procedure for these components.
FUNcube Dongle Pro+
We used a FUNcube Dongle Pro+ as a second Software Defined Radio (SDR) Receiver in our setup and as an I/Q source to drive the MAP65 Software. Good information on configuring the MAP65 software to work with this dongle can be found here.
EME Station RF Paths and Sequencing
The diagram above shows the RF Paths and associated sequencing in our Version 1 EME Station. A Manual Antenna Switch is used to select either Horizontal or Vertical polarity when in receive mode. The S2 Sequencer handles polarity selection during transmit. A splitter divides the Rx signal between the FUNcube Pro+ Dongle for MAP65 and a Transmit/Receive Switching Circuit in front of our IC-9700 Transceiver. The relay enables the IC-9700 to provide Transmit signals for both the MAP65 and WSJT10/WSJT-X Software applications. The IC-9700 drives a 1.2 Kw Amplifier during Transmit and the final Tx output is metered using a WaveNode WN-2 Wattmeter.
Completed T/R Relay Assembly
To enable both the receivers in our IC-9700 and the FUNcube Dongle to function simultaneously, we built a circuit using a CX800N DPDT RF Relay and a Mini-Circuits 2-Way RF Splitter. We also built a simple driver circuit for the relay using a Darlington Power Transistor and some protection diodes. The circuit enabled our S2 Sequencer to control the relay along with the rest of the sequencing required when changing our EME Station from Receive to Transmit and back.
Finally, we configured a 30mS transmit delay in our IC-9700 to ensure that the S2 Sequencer had some time to do its job as the station changed from Receive to Transmit. This delay coupled with the Transmit delays built into the MAP65 and WSJT10 software ensures that we will not hot switch the MAP65 Preamp System on our tower. One must be very careful to ensure that RF power is not applied before the sequencer can complete its transition to the Transmit state or damage to the Preamplifiers and/or relays at the tower will occur.
Amplifier and Rotator Controls
EME and Satellite Ground Station Hardware Components
The Elevation Rotator from our Antenna System was added to the Green Heron RT-21 Az/El Rotator Controller previously installed in our shack and both the Azimuth and Elevation Rotators were roughly calibrated. Our EME station requires quite a few USB connections to our Windows 10 Computer so we added a powered USB hub to our setup. Chokes were added to the USB cables which run to our IC-9700 Transceiver and our FUNcube Dongle to minimize digital noise from getting into our receivers.
Our 2M-1K2 Amplifier can produce about 1KW of power on 2m when operating in JT65 mode and this should be enough power for our planned EME wor. Our S2 Sequencer also controls the keying of our Amplifier as part of the T/R changeover sequence in our EME station.
WaveNode WN-2 Wattmeter
We added a 2m high power sensor to the output of our Amplifier and connected it to a free port on one of the WaveNode WN-2 Wattmeters in our station to provide output and SWR monitoring of the Transmit output of our EME station.
Supporting EME Station Infrastructure
VHF+ Antenna Switching Console
We had some work to do to configure the antenna, grounding, and DC power infrastructure in our station. We redid the manual switching in our VHF/UHF Antenna Switching consoles to accommodate our new EME Antenna System as well as to prepare for our Satellite Station to be moved into our shack in the near future. The console on the right provides Grounding of the Transmit and Receive sides of our EME Antenna System as well as the selection of the Antenna’s Horizontal or Vertical polarity for decoding.
We also expanded our station grounding system to provide a ground point directly behind all of our EME equipment. Our DC power system was also expanded to accommodate our EME equipment.
GPS NTP Server
Our station already has a GPS Controlled NTP Time Server installed and we’ll use it to ensure that the clock on the PC which will run the MAP65 and WSJT10 software will have very accurate clocks for JT65 decoding.
EME Tower CAM
We already have cameras that cover our Main and Satellite Towers. We’ve added a third camera to allow us to view our EME Tower’s operation from our shack. This ensures that we can visually confirm the operation of our antennas and detect any problems should they occur.
Next Steps
All of the new EME equipment has to be integrated and tested with the software components which provide digital operation, tracking of the moon, logging, and other functions in our station. The software setup as well as our initial experience with operating our new EME station will be covered in the next article in this series.
You can read more about our EME station project via the links that follow:
If you’d like to learn more about How To Get Started in EME, check out the Nashua Area Radio Society Tech Night on this topic. You can find the EME Tech Night here.
A key part of optimizing our EME Station was to reduce RFI from the network in our home. You can read about the installation of Fiber Optic Networking to reduce RFI and improve our EME station’s performance here.
After a year’s worth of planning and 10 months of construction, we have our new 2m EME Antenna System installed on our EME Tower and working! This stage of our project took about a week and included a lot of help from Matt and Andrew at XX Towers.
Final Preparations
Antenna Ground Test
The first step was to arrange the four 2MXP28 Yagis that we built on saw horses near our EME Tower and check each antenna’s vertical and horizontal SWR. Performing SWR measurements with the antennas close to the ground like this does not produce very accurate measurements. Doing this does allow one to spot potential problems if some of the measured SWR fail to show a resonance or are wildly different than the other antennas in the group. All of our antennas checked out as expected.
50 Ft Boom Lift, H-Frame Cross Boom Assembly On The Ground
We also rented a 50-ft Boom Lift and set it up near our EME Tower. A tool like this is almost essential to safely assemble and adjust a large, complex antenna system involving an H-Frame. It also speeds up the assembly and adjustment process considerably.
Elevation Rotator and H-Frame
Elevation Rotator Installation on Mast
The first step was to install the MT-3000A Elevation Rotator on the mast. We pre-installed the control cable for the elevation rotator before installing it on the tower. This enabled us to get it temporarily hooked up to the Rotator Controller in our shack so that we could adjust the elevation of the H-Frame and Antennas as we installed them.
With the H-Frame in place, we installed the upper 2MXP28 Yagi Antennas next. The image above shows the rigging of the boom trusses which was done on the Tower.
Lower Antenna Installation and Adjustments
Next came the lower 2MXP28 Yagis. We spent considerable time leveling and aligning all of the Antennas and H-Frame components at this stage.
Feedlines, Electronics, and Balancing
T-Braces and Feedlines
The T-Brace assemblies and Antenna Phasing Lines were installed next. Each Antenna requires two LMR-400 Phasing Lines and these coax cables add considerable weight to the backs of the Antennas. The T-Braces support these cables and help to align the Antennas on the H-Frame.
We replaced the Vertical H-Frame Boom Truss Pipe with a heavy section of Mast Pipe to act as a counter-weight and balance the final H-Frame and Antenna assembly. This step is critical to ensuring a long life for the Elevation Rotator’s drive system and chain.
Phasing Lines, Power Dividers, and Feedline Connections on Crossboom
The photo above shows the final installation of the Power Dividers, Antenna Phasing Lines (there are 8 in total), the MAP65 Preamp Housing, and the Feed and Control Cables that run down the Tower. We took the time to carefully make SWR measurements on each Antenna and check all of the connections to the MAP65 Housing at this stage.
Antenna Integration Details
Rotator Loop
The Rotator Loop contains the following cables and Coax Feedline connections from the H-Frame/Antenna assembly:
Vertical and Horizontal Rx Feedlines
Tx Feedline
Elevation Rotator Control Cable
MAP65 Housing Control Cable
All of these cables are bundled and securely fastened to the H-Frame Cross Boom and to the Tower. Andrew is a master at this sort of rigging!
Control Cable Connections at Tower Base
I took some time to finalize the Control Cable connections at the base of our tower. Time was spent with a voltmeter doing checks to ensure that everything was connected correctly and working. This effort resulted in the discovery and correction of some wiring errors and a faulty relay in the MAP65 housing. Had I not done these steps, we would have surely destroyed the Preamps in the MAP65 Housing when we transmitted for the first time.
Testing Our New Antenna System
Vertical Polarity Tx SWR at Shack
A series of SWR measurements were taken before sealing the coax cable connections on the tower. SWR measurements were checked and recorded for future reference at the following points in the feedline system:
At the ends of the phasing lines associated with each antenna
At the output of the two Power Dividers on the tower
At the shack entry ground block
Measurements were taken separately for both the Vertical and Horizontal elements of the final Antenna System. The image above shows a typical SWR measurement for our final Antenna System.
I did many final checks and adjustments while the Boom Lift was still here. These steps included:
Checking the oil level in the elevation rotator
Re-lubing the elevation rotator chain
Adjusting the limit switch stops on the Elevation Rotator to allow enough over-travel for future adjustments and maintenance
Checking all hardware for tightness
Sealing all coax cable connectors with Coax Wrap and Electrical Tape
Making some final adjustments to align the four 2MXP28 Antennas with each other and the H-Frame
If you’d like to learn more about How To Get Started in EME, check out the Nashua Area Radio Society Tech Night on this topic. You can find the EME Tech Night here.
