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
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
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
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:
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:
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.
Reference Injection Board Installed in IC-9700 (Leo Bodnar Website)
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 transitions 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 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.
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:
Fred’s New Hampshire First Place Finish in the ARRL June VHF Contest
I haven’t had the chance to work the ARRL June VHF Contest from our home station for several years. A combination of Nashua Area Radio Society activities and preparations for ARRL Field Day has taken a higher priority. ARRL June VHF is a great contest and I was looking forward to working it this year. A few days before the contest Anita and I were talking about the contest and she suggested that I do a 6m Digital Entry. E-skip has been pretty good on 6m this year and we wanted to sort out how we’d do digital and 6m for our upcoming 2020 Field Day Operation from our home so I decided to take Anita’s advice and focus on 6m Digital for June VHF. I entered the contest in the Low-Power Category.
June VHF Operating Setup
AB1OC Operating in 2020 June VHF
We built a Remote Operating Gateway that allows our station to be operated both over the Internet and from any room in our home via our Home Network. I decided to set up a 6m Digital Station upstairs in our dining room so I could be with Anita more during the contest. The setup consisted of a laptop PC with an outboard monitor and a Flex Maestro as the client for the Flex 6700 SDR in our shack.
The three antennas can be pointed in different directions and selected instantly via the computer. This provided to be an advantage during the contest. I kept one on Europe, one point due West, and the third pointed at the Tip of Florida and the Caribean during the contest.
Operating Setup – N1MM+ and WSJT-X
Having two monitors (the Laptop and an outboard one) allow me to arrange all of the N1MM+ Logger and WSJT-X windows for efficient operating. The image above shows a snapshot of the screen layout during the contest. N1MM+ has some nice features that integrated with WSJT-X to make it easy to spot new grids (Multipliers) and stations that have not yet been worked. The windows on the very right side allowed me to control antenna switching and monitor power and SWR while operating. I use the PSTRotator application (lower-left center to turn my antennas.
Band conditions on 6m were amazing from here in New England almost the entire contest period! The band was open right at the start of the contest on Saturday and remained open to 11 pm local time on Saturday evening. I was up early on Sunday and was working folks in the Northeastern Region right from the start. After being open all day on Sunday, the band shut down around 5 pm local time and I was afraid that the fun on 6m might be over. I ate some dinner and took a 45-minute nap and got back to my station at around 6:30 pm. About 15 minutes after I resumed, 6m opened again to most of the United States and I was able to work DM and DN grid squares in the Western States! The band stayed open right until the end of the contest at 11 pm local time.
What About the VUCC…
100 Grids Worked on 6m
Conditions on 6m were so good on Saturday that I almost worked a 6m VUCC by 11 pm on Saturday evening when the band closed. I had 93 grids worked on 6m in just 8 hours! The band opened again early on Sunday morning and I worked my 100th grid square before 10 am – working a 6m VUCC in less than 18 hours!
Final 6m Grids Worked
By the end of the contest, I had worked a total of 162 Grids! They ranged from the West Coast of the US to Western Europe and from Southern Canada to Northern South America.
6m Grids Worked During 2020 June VHF
The image above shows most of the 6m grids that I worked plotted on a world map (the EU grids are not shown).
Final Claimed Score
I was able to make a total of 402 unique contacts on 6m by the end of the contest with a final Claimed Score that was a bit over 65K. All of my 6m contacts during the contest were made using a combination of FT8 and FT4 modes on 6m.
New Ones on 6m for AB1OC
AB1OC Worldwide 6m Grid Map
I was hoping to work some all-time new Grids and June VHF did not disappoint. I worked a total of 11 new Grids and one new DXCC (Dominica) on 6m during the contest. The image above shows my worldwide grid coverage including the new ones worked during June VHF (my grids in Argentina and Uruguay are not shown above). I now have worked 432 grids on 6m and have confirmed 408 of them with 63 DXCC’s worked and 62 confirmed on the Magic Band.
Summing It All Up…
I must say that I had as much fun working 6m during June VHF this year as I have ever had in any contest! The band openings on 6m were really good and I was busy making new contacts for the entire time that I operated. The combination of the 6m Band and the contest certainly made some Magic for me!
I’ve had a chance to operate on the 6m DX this past week. We are approaching the prime time for the summer Es (E-Skip) season here in the Northeastern United States. As a result, I wanted to see how propagation on the 6m band might be unfolding during this spring Es season. I was fortunate to catch a typical limited DX opening on the 6m band between our location here in New England and Europe. I thought that it might be helpful for those who are relatively new to the 6m band to see what this was like.
A 6m DX Band Opening Begins – JTDX Software View
I spent some time on and off yesterday calling CQ and monitoring the 6m band using the JTDX software and FT8 mode. FT8 now dominates most of the activity on the 6m band. This is a result of a combination of FT8’s weak-signal performance and available reverse beacon tools such as PSKReporter. As you can see from the JTDX screenshot above, the 6m band was basically only open to the United States here until about 16:58z. At that point, I weakly decoded CT1ILT. This station faded almost immediately and I was unable to make a contact.
Approximately 4 minutes later, the 6m band opened solidly to Spain and France and quite a few stations in this area of Europe appeared with relatively strong signals.
6m DX Opening to Europe – Spotlight Area Propagation (PSKReporter)
As you can see from the PSKReporter screenshot above (taken near the end of the band opening), the probation on 6m was quite strong but limited to a very specific area and heading in Europe. This is typical of limited double-hop Es propagation. We most likely had two Es clouds aligning in such a way that a narrow path of propagation had been created on the 6m band.
A 6m DX Band Opening In Full Swing – JTDX Software View
The view above shows the 6m band opening in full swing. I was hearing 5-6 strong stations from France, Spain, and Italy almost immediately. These stations are all on a relatively narrow range of headings center at about 65 degrees from my QTH. I am scrambling to work the stations that represented new grid squares for me. I am using JTAlert as a bridge to my logger (DXLab Suite) and it is telling me that 2-3 of the station in the mix are in grid square that I have not yet worked on the 6m band.
A 6m DX Band Opening Comes to an End – JTDX Software View
Like all good things, the 6m DX opening had to come to an end. As you can see above, the 6m band closed as rapidly as it opened, leaving me calling CQ with no takers to work in Europe.
Contacts Made During the 6m DX Opening
The total duration of this opening was about 20 minutes. The contacts that I made during this period are shown above. During the brief opening, I was able to make a total of 11 contacts with a limited set of grid squares in Europe. Most of the signals were quite strong (see the Sent and Rcvd columns in my log above). During the opening, I worked 5 new grid squares that were centered around the border between France and Spain.
AB1OC 6m Grids Worked and Confirmed
By this morning, three of the five new grids that I worked had already confirmed on LoTW. Just for fun, I plotted my 6m grid progress on the Gridmapper website. I keep a copy of the Gridmapper view of my log by my operating area as a reference that I use in conjunction with PSK Reporter to help me identify 6m band openings that might provide opportunities to work new grids.
I hope that this article gives you some idea of the nature of 6m DX openings. The opening described here is pretty typical in that:
The band open (and closed) suddenly without much warning
The propagation was very good with many strong signals being decoded and worked at once
The opening was of short duration lasting only about 20 minutes
The band closed as rapidly as it opened
Monitoring the 6m Band at AB1OC
In order to work 6m DX, this experience emphasizes the need to monitor the 6m band for DX openings on a regular basis. This is most easily done using PSKReporter. The pattern of DX openings on 6m to Europe from here in New England is such that EU DX openings typically begin south of us and progress northward. I use our Remote Operating Gateway, a Flex-6700 SDR based setup, to monitor the 6m band for DX openings while I work here in my office. You can see the 6m FT8 setup here in my office running in the monitor-mode above.
FlexRadio Maestro Console
I use the Maestro here in my office as my SDR client.
I hope that this information has been useful to our readers. As you can see from this example, the 6m Band is called the Magic Bandfor good reason. It is very exciting to be able to catch and work a good DX opening on 6m. The FT8 mode has both increased the level of activity on the 6m band and made 6m available to many stations with simple antennas and 100W transceivers. You can learn more about how to get started with FT8 on 6m here.
As I sit here writing this, the 6m band just opened to Austria and Hungry! Have to go work some DX on the 6m band…
We’ve recently received our L24TX Transmit Converter from Down East Microwave. The unit is compact, simple, and produces up to 25W output in the satellite section of the 23 cm band (1260 MHz – 1270 MHz, actually 24 cm). The L24TX is a transmit-only device that is intended to enable L-band uplinks for Satellite use. This article is about our most recent project which involved integrating the L24TX into our Flex SDR Satellite System.
24 cm Tx Converter Rear Panel
Connecting the unit is straightforward. The unit requires an IF input, a 10 MHz reference oscillator, DC power, and a transmit keyline. The later two inputs are provided via a 7-pin connector and a DEM supplied cable. We ordered our unit with the following configuration options:
IF 28 Mhz = 1260 MHz output
Max IF Drive Level – +10 dBm
Fan and Case configured for mounting in the shack
Fortunately, our feedlines for the 23/24 cm band are hardline-based and relatively short. The unit is also available in a configuration that would enable it to be remotely mounted in an enclosure on a tower.
24 cm Tx Converter Installation in our Remote Gateway SDR Rack
The unit fits nicely into our Remote Gateway SDR Rack. The L24TX does not include a power output display so we used a 23/24 cm sensor and our WaveNode WN-2 Wattmeter to monitor output power from the unit. The unit does have leads that output a voltage that is proportional to output power. This could be used to build a power output bar display or meter. the front panel indicates display a power-on indication, lock to the 10 MHz clock input, and Tx when the unit is transmitting.
Overall Satellite SDR System Design
Integration into our Satellite SDR System was straightforward. Our system already included splitters for the 10 MHz GPSDO and the 28 MHz Transverter outputs from our Flex 6700 SDR. I had hoped to use one of the leads from the SmartSDR BITS cable we are using to key our 70 cm Transverter but the BITS cable did not have an adequate drive level to key the L24TX.
Remote SDR Gateway Tx Band Settings
Fortunately, the Flex 6700 has configurable TX1-TX3 outputs for keying devices like Transverters. The use of the TX2 output to key the L24TX was easily configured in the SmartSDR’s TX Band Settings.
23 cm Tx Converter Setup in SmartSDR
It is necessary to configure SmartSDR for the L24TX. The required settings are in the XVTR options tab. In addition to configuring the mapping between the Flex 6700’s XVTR IF frequency and the unit’s output Frequency, one needs to set the IF drive levels. We used the default drive level of 6.0 dBm and adjusted the IF Gain Control on the L24TX until the full output of 25W was reached while transmitting a tone. The correct adjustment is apparent when further gain increases do not provide a proportional increase in output power. The proper setting of the RF drive and gain will keep the L24TX’s output in its linear range of operation.
SDR Satellite System Remote Power Control via a RigRunner 4005i
The RigRunner is remotely accessible over the Internet and our network via a password-protected web interface. This enables us to easily power down or power cycle individual components in the Satellite SDR System remotely.
MacDoppler Tracking AO-91
With all of the hardware installation and calibration steps complete, we are turning our attention to the software side of the setup. We will be using MacDoppler for satellite tracking and VFO control of our Satellite SDR System. This creates a need to connect the MacDoppler program which runs on a Mac to SmartSDR and the Flex 6700 which is a Windows-based system. Fortunately, MacDoppler provides a UDP broadcast mode that transmits az/el antenna position information as well as data to control radio VFOs to adjust for Doppler shift.
FlexBridge Software Beta
We are working on a custom windows application called FlexBridge to enable MacDoppler to run our Flex SDR-based Satellite System. FlexBridge runs on a Windows PC. It receives and parses the UDP broadcast messages from MacDoppler and uses the FlexLib API to properly configure and control the Flex SDR’s VFOs.
SmartSDR Operating With AO-92 in L-V Mode
At present, FlexBridge can configure and control SmartSDR (or a Maestro Client) that is operating our SDR Satellite System. The screenshot above shows the MacDoppler, FlexBridge, SmartSDR combination operating with AO-92 in L/V mode. This software is still an in-progress development and we plan to add the ability for FlexBridge to connect to the radio via SmartLink as well as support for the Green Heron RT-21 Az/El Rotator Controller that we are using. We’ll be sharing more about FlexBridge here as the software development progresses.
The next step in our Satellite Station 4.0 Remote Gateway project will be to move our satellite antenna controls and feedlines into the shack and begin testing the complete setup using local control. Once this step is complete, we’ll focus on the final steps to enable remote operation of our satellite station via the Internet.
Here are links to some additional posts about our Satellite Station 4.0 Projects:
What goes into an 11A Field Day? Well, for starters, 13 stations! We got together at AB1OC/AB1QB’s QTH a couple of weekends ago to set up ALL of our Field Day stations at once and test them together. Here’s a rundown of our final Field Day Station Test…
The Nashua Area Radio Society does a pretty big Field Day Operation each year. We will be 11A for Field Day 2019 with 4 towers up. Did you ever wonder what goes into pulling off a Field Day this large? Well, it’s all about planning and preparation. Take a look at the article above to see some of the preparation that we are doing for Field Day 2019.
Frequency accuracy and stability become more challenging for transceivers that operate at 400 Mhz and above. Our 4.0 Satellite Stations operate at frequencies approaching 1.3 GHz and we want to be sure that their operating frequencies are accurate and stable. Our Flex-6700 SDR includes a GPS Disciplined Oscillator (GPSDO) so the radio and all of the transverters associated with the radio use the radio’s GPS disciplined 10 MHz output for frequency synchronization.
We choose a GPSDO from Leo Bodnar. The unit is compact, USB powered, and comes in a nice case which includes a GPS antenna and a USB cable. The unit has two GPS disciplined frequency outputs which can be configured for a wide range of frequencies and levels via a Windows application.
GPSDO Connected to an IC-9700
The GPSDO is connected to the 10 MHz reference input on the back of the IC-9700 with a BNC to SMA cable and the GPSDO is powered via a USB connection to our iMac. We configured the GPSDO output frequency to 10 Mhz and for an output level of +7.7dBm (drive setting 8mA). We also added a 20 dB pad in line with the GPSDO output to better match the drive level requirements of the IC-9700’s 10 MHz input.
The GPSDO will lock in a very short period of time (less than 1 minute) once GPS antenna and power connections are made the unite t. The unit has a red LED on each of its outputs and the unit is GPS locked when the LEDs are on and not flashing.
Configured and 10 MHz Input Locked IC-9700
The last step in the setup process is to configure the IC-9700 to sync its reference frequency to the 10 MHz input. This is easily done in the IC-9700’s Set/Function Menu.
It was pretty easy to add GPSDO locking to the IC-9700 and the arrangement described here works well. While this upgrade is not essential for satellite operation, it’s nice to know that our satellite transceiver frequencies are accurate and stable.
You can find other articles about our Satellite Station 4.0 project here:
Adding the additional bands for satellite operations involves adding a 2m Amplifier, a 70cm Transverter, and a 23cm Upconverter to our SDR-based Remote GW. We decided to repackage our Remote GW set up in a rack mount cabinet on casters. This allows all of the required gear to be placed under the desk in our station in a way that is neat and reliable.
We also added an Ethernet Switch, a pair of USB hubs, and upgraded power and remote controls to improve our ability to manage our station remotely and to simplify the interconnections between our Remote GW and the rest of our station. The final assembly mounts all of the components in the rack on 5 levels as follows:
The purpose of these components is explained in more detail below.
All of these devices are powered from 13.8 Vdc station power to avoid the potential for noise from wall wart transformers inside the rack. Also, attention was paid to the isolation of the digital and RF components on separate levels to minimize the chance that noise from digital signals would leak into the RF chains.
Remote Satellite SDR System Design
The diagram above shows how the added components for the satellite bands interconnect with the Flex-6700. The new components include:
The Flex-6700 can generate and receive signals on the 2m band but it does this at IF power levels. The 2m LPDA brings the IF power level up to a maximum of 75 watts. The DIPs device enables the Flex-6700 to operate in U/v, V/u, and L/v modes.
The 28 MHz splitter allows a total of 4 transverters/upconverters to be connected to the radio. This will enable us to add 5 GHz and 10 GHz bands to our satellite station in the future.
Our Flex-6700 includes a GPS Disciplined Oscillator (GPSDO) which provides an accurate and stable 10 MHz reference output to lock the 70cm and 23cm transverter frequencies. The 10 MHz Reference Distribution Amplifier expands the single 10 MHz on the Flex-6700 to drive up to 4 transverters or upconverters.
The two USB cables allow the Flex-6700 and SmartSDR to control the LPDA and PTT for the 70cm and 23 cm bands.
The rackmount arrangement uses shelves which provide ventilation for the components and enable us to use zip ties to tie down all of the components. The photo above shows the layout of the shelf which contains the 2m LPDA, the 70cm Transverter and many of the RF interconnections. Velcro tape is used to secure the smaller components to the shelf.
2m/70cm Shelf RF Interconnection Details
The photo above shows the RF interconnections. The 70cm Transverter is on the upper left and the 2m LPDA is on the upper right. The rectangular boxes coming from these devices are the sensors for the WaveNode WN-2 Power and SWR Meter that we are using. They are terminated in 50-ohm dummy loads for initial testing. The DIPS device is center bottom and the 4-port device above it is the 28 MHz splitter. All of the interconnections are handled using 50-ohm BNC cables and the unused ports on the 28 MHz splitter are terminated with 50-ohm BNC terminators.
Rear View of Remote Gateway Rack
The photo above shows the rear of the unit. The 10 MHz Reference Distribution Amplifier (bottom center) and the two Industrial 12V powered USB hubs are visible at the bottom of the unit. The DC power distribution components are at the upper left and a set of Internet-controlled relays are at the upper right.
USB Connections via Hubs
One of the USB hubs fans out a single USB connection from the host PC to the USB controlled devices in the Remote GW rack. The other USB hub expands the USB outputs of the Flex-6700 to accommodate the control cables for the devices in the rack and the CAT cable which provides frequency data to the microHam SMD Antenna Controller.
Power Control and Distribution Design
Remote control and distribution of DC power to all of the devices in our Remote GW is an important design consideration. In addition to proper fusing, one must be able to remotely turn devices on and off remotely. The diagram above shows the power distribution and control architecture that we are using.
13.8 Vdc Power Distribution
RigRunner power distribution blocks are used to fuse and distribute power to all of the accessory devices in the rack.
Remote Gateway Power Controls
The RigRunner 4005i provides remote power control via the Internet for all of the major units and accessories in the rack. In addition to controlling power on/off states and providing electronic fusing, the RigRunner 4005i monitors voltage and current to the equipment in the Remote GW. These controls are accessed via a web browser and a network connection. Login/password security is also provided.
Remote Control Relay Unit
A microBit Webswitch device provides Internet controlled relays to manage various station functions including:
After some configuration of the Transverters and PTT controls in SmartSDR, the satellite portion of our Remote GW is up and running. There is quite a bit of software installation and configuration left to do and we’ll cover that in a future post.
You can find other articles about our Satellite Station 4.0 project here: