We installed a 75m loop for SSB operation on our tower when we built it. The loop is full size and is diamond shaped so that our lower SteppIR DB36 yagi can rotate inside of it. The loop is fed at the bottom corner about 20 ft up from the ground. It works great for SSB operation on 75m, but we have often wished we could use it across the entire 80m Band. This goal led to a project to create a matching system for the antenna. The idea was to use a set of loading coils in series at the feed point to create a good match in all segments of the 80m band.
EZ-NEC Model for 75m Loop
The first step in designing our 80m matching system was to build a model of our current loop using EZ-NEC. The model was then used to determine the correct values of a set of series loading inductors to match different segments of the 80m band.
Matching System Design Analysis
We also considered how likely different segments of the 80m band were to be used by profiling historical spotting data from DXSummit. All of this analysis led to the creation of a final design which is captured in the spreadsheet shown above. The final design requires our current 75m loop to be shortened to work well at the very top of the 80m Band.
Modeled Loading Coil Inductance Values
A set of 5 different inductor pairs can be used in series with the loop’s feed point to create a good match across the 80m band. The modeled values for the series-matching inductors are shown above.
Matching System Modeled SWR
Our microHAM control system can easily implement the switching of the various inductance values based on the frequency that a radio using the antenna is tuned to. The resulting modeled SWR for the final 80m loop and match combination is shown above. The design should achieve an SWR < 1.5:1 across the entire 80m Band except for the very top, where the SWR remains < 2:1. Also, the design optimizes the system’s SWR in the important CW DX, SSB DX, and Digital windows on the 80m band.
The layout of Components in Enclosure
With the design completed, we chose an enclosure and all components. Here are the details of what we used:
The first step in the construction was to lay out all of the components in the enclosure. Attention was paid to keeping the two series inductors at right angles to avoid coupling and to keep RF connections as short as possible. The relays were arranged to keep the leads connecting to the coils of roughly equal length. Finally, the control circuitry was kept as far removed from the RF leads as possible.
Enclosure Mounting Ears and Clamps
The matching system attaches to a tower leg via saddle clamps. We fabricated a set of mounting ears and spacer blocks to position the enclosure far enough away from the tower so that the antenna connections do not interact with the tower.
80m Matching System Construction
A summary of the completed matching system construction is shown above. The design uses a set of four double-pole double-throw relays to switch in different coil taps, which selects the loading inductance provided by the matching system.
We did a set of calculations and found that our relays would be subjected to a worst-case peak-peak voltage of about 2.1 KVp-p at the coil tap points.
The relays are arranged such that two sets of contacts have to be traversed to select any given coil tap. The relays we are using have a third pole which we are not using. We disassembled each relay and removed the internal contact wiring for the center pole, which improves both the coil-to-contact voltage rating and the isolation values of the relays.
These steps combine to improve the voltage rating of the system. This is an important design element given that the match will operate at legal limit power.
Completed RF Deck
The completed RF deck and control circuitry is shown above. The enclosure we chose came with a removable plastic plate that made mounting and wiring all of the components simple.
Loading Coil Mounting and Taps
The loading inductors are mounted using nylon hardware with the ends connected to the two antenna terminals on the sides of the enclosure. The coils use movable tap clips to allow us to fine-tune the match once the system is installed with the antenna on our tower. The initial clip locations are set to create the inductance values modeled during the design phase.
Relay Control Circuit Connections
The relay control leads use twisted pair wiring to minimize RF pickup. The control leads are routed away from the RF connections to minimize potential RF coupling.
Relay Control Circuit Details
The control circuits for each relay use a combination of a Diode, a Varistor (MOV), and a filter capacitor in parallel to avoid relay coil switching interference and to suppress control line noise.
1.5 to 1 Matching Balun
The matching system is designed to operate at 75 ohms which is close to the resonant impedance of our 75m loop. The current antenna uses a 1.5:1 Balun to match the loop to our 50-ohm coax feedline. We disassembled an identical matching balun (actually a 75-ohm balun plus a 1.5:1 unun) and used it without its enclosure to create a final 50-ohm match.
MicroHAM Setup to Control 80m Matching System
The final step in constructing our matching system was to program our microHAM antenna switching system to properly configure the relays in our matching system. This was quite simple to do using microHAM’s frequency-dependent antenna control capabilities. The microHAM system automatically operates the appropriate relays to create the best possible match as the radio which is using the matching system is tuned across the 80m band.
Unfortunately, we are in the middle of winter here in New England, so I will have to wait for warmer weather to install our new matching system on the tower and make the final adjustments. I am planning another article here when the final integration steps are done to cover the performance of the completed project.
We have been quite impressed with the performance of our Icom IC-7300’s radio receiver. As a result, we have decided to upgrade the second radio in Anita’s operating position to an Icom IC-7610. We expect the IC-7610’s receiver performance to be as good as or better than the IC-7300.
Icom IC-7610 External Display
The Icom IC-7610 also provides a very nice external display capability, allowing us to take the best advantage of the radio’s pan adapter. We believe that the IC-7610 will integrate easily into our microHAM system. It should be a “drop-in” replacement for our current IC-7600. We hope to see the IC-7610 shipping before the end of this year.
Elecraft KPA1500 Legal Limit Solid State Amplifier
Our microHAM Station Automation System can accommodate shared amplifiers. We will utilize this capability when integrating the Elecraft KPA1500 into our station. The shared amplifier setup will also allow us to eliminate one of our bandpass filters. The KPA1500 amplifier integrates autotuner and wattmeter functions into the amplifier and provides a direct Ethernet interface for remote control and management. These enhancements should eliminate the need for several of the remote control server software applications that we are currently running on a PC in our shack. Also, we can manage all of these functions from a single client application on a remote client PC. These simplifications will make our remote operating gateway setup more reliable and easier to use.
FlexRadio Maestro Control Console
We plan to share more on these projects in future posts here on our Blog. The FlexRadio Maestro and all the other components we need for Remote Operating Gateway enhancements have arrived. We will complete this part of our project in the very near future and post more here.
Also, the local control interface to the new Elecraft KPA1500 amplifier appears nearly identical to that used by our current Elecraft KPA500 Amplifier. This means that we can begin our shared amplifier upgrades using the KPA500. We do not have a firm date for the IC-7610 to ship and that portion of our upgrade plans is likely to be our last step in the project.
Special thanks to Dave, K1DLM, who has helped us with ideas for several aspects of this project.
Be portable and manageable enough to be set up in an hour or less
Be simple enough to operate so that HAMs who are new to satellites can make all types of satellite contacts with a relatively short learning curve
Be manageable to transport and store
Utilize computer-controlled antenna tracking to aim the antennas
Utilize computer control to manage radio VFOs to compensate for doppler shift
Be easy to transport and store
Computer Controlled Satellite Station via MacDoppler Software
We decided to take a computer-controlled approach for both antenna aiming and Transceiver VFO management to meet our goal of making the station simple to operate for new satellite operators. After some research on the available options, we choose MacDoppler from Dog Park Software Ltd. for this purpose. MacDoppler runs under Mac OS/X and works well on our MacBook Air laptop computer which is very portable. This program also has broad support for many different rotator and transceiver platforms and is very easy to understand and use. Finally, the program features high-quality graphics which should make the station more interesting to folks with limited or no experience operating through Amateur Satellites.
With the satellite tracking software chosen, we made selections for the other major components in the 2.0 Portable Satellite Station as follows:
I will explain these choices in more detail as our article series proceeds.
Glen Martin 4.5′ Roof Tower
Our solution to making the antenna system portable is built around a Glen Martin 4.5′ Roof Tower. This short tower is a high-quality piece made of extruded aluminum parts. The tower is very sturdy when assembled and is light in weight. We added a pair of extended “feet” to the tower which is fabricated from 36″ x 2″ x 1 /4″ strap steel. This gives the tower a firm base to sit on and allows us to use sandbags to weigh it down (more on this later).
Our chosen Yaesu G-500 AZ/EL Rotator is a relatively inexpensive Azimuth/Elevation rotator which is suitable for lightweight satellite antennas such as those in the LEO Pack. This rotator can be installed as a single unit on the top of a tower or separated using a mast. We choose the latter approach as it is mechanically more robust and helps to keep the center of gravity for our portable antenna system low for improved stability.
Yaesu G-5500 Elevation Rotator
Separating the Yaesu AZ/EL rotator requires a short mast and a thrust bearing to be used. The mast was made from a 1-3/4″ O.D. piece of EMT tubing from our local hardware store. The thrust bearing is a Yaesu GS-065 unit. Both of these pieces fit nicely in the Glen Martin Tower. The thrust bearing provides support for the LEO Pack and G-500 elevation rotator and greatly reduces stress on the azimuth rotator. We also added a Yaesu GA-3000 Shock Absorber Mount to the azimuth rotator. This part provides shock isolation for and reduces strain on the azimuth rotator during the frequent starts and stops which occur during satellite tracking.
LMR-400UF Feed-lines and Antenna Connection Jumpers
We decided to use LMR-400 UltraFlex coax throughout our antenna system. LMR-400UF coax provides a good balance between size, flexibility, and loss for our application. To keep feed-line losses reasonable, we choose to limit the total length of the coax from the transceiver output to the antenna feed point to 50′. This results in a loss of about 1.3 dB on the 70 cm band. The result is that our planned IC-9100 Transceiver which has a maximum output of 75W on 70 cm will deliver a little more than 50W maximum at the feed point of the 70 cm yagi. This should be more than enough power to meet our station goals. Allowing a total of 15′ for antenna rotator loops and transceiver connections, we settled upon 35′ for the length of our coax feed-lines between the tower and the station control point.
Portable Tower Cable Connections and Base Straps
We added some custom fabricated plates to the tower to act as a bulkhead for feed line and control cable connections and to mount our low-noise preamplifiers. The control connections for the rotators and preamps were made using 6-pin Weatherpack connectors and rotator control cable from DXEngineering. The control cables are also 35′ long to match the length of our coax feed lines. This length should allow the tower and the control point to be separated by a reasonable distance in portable setups.
Low-Noise Preamplifiers from Advanced Receiver Research
We added tower-mounted Low-Noise Preamplifiers from Advanced Receiver Research to improve the receive sensitivity and noise figure for our satellite antenna system. Two preamps are used – one each for the 2 m and one for 70 cm antennas. While these units can be RF-switched, we decided to include the preamp control lead in our control cable to allow for control of the preamp switching via sequencers. This was done to provide an extra measure of protection for the preamps.
Levels and Compass for Tower Setup
We added a compass and a pair of bubble levels to the tower assembly to make it easier to orient and level it during setup. The picture above also shows the Yaesu shock-absorbing mount for the azimuth rotator.
Weight Bags to Anchor Portable Tower
Finally, we added a set of weight bags to securely anchor the tower when it is set up in a portable environment. These bags are filled with crushed stone and fastened to the legs of the Glen Martin tower with velcro straps.
LEO Pack Antenna Parts
With the tower and rotator elements complete, we turned our attention to the assembly of the M2 LEO Pack. The LEO pack consists of two circularly polarized yagis for the 2m and 70 cm bands. The 2m Yagi is an M2 Systems 2MCP8A which has 8 elements (4 horizontal and 4 vertical) and provides 9.2 dBic of forward gain. The 70 cm Yagi is an M2 Systems 436CP16 with 16 elements (8 horizontal and 8 vertical) and provides 13.3 dBic of forward gain. Both Yagi’s are meant to be rear-mounted on an 8.5′ aluminum cross boom which is included in the LEO Pack. The picture above shows all of the parts for the two antennas before assembly. It took us about a 1/2 day to assemble and test the antennas and both produced the specified SWR performance when assembled and tested in clear surroundings.
Assembled LEO Pack on Portable Tower
The picture above shows the assembled LEO pack on the portable tower. We attached a short 28″ piece of mast material to the cross boom as a counterweight to provide better overall balance and minimize strain on the elevation rotator. The antennas and the two outer sections of the mast can be easily removed to transport the antenna system.
2m Circularly Polarized Yagi Feed Point
The LEO Pack yagis achieve circular polarization via a matching network that drives the vertical and horizontal sections of the antennas with a 90-degree phase shift. The phase shift (and a final 50-ohm match) is achieved using 1/4 wave delay lines made of coax cables. We configured our antennas for right-hand circular polarization. The choice between right and left-hand circular polarization is not a critical one in our LEO satellite application as most LEO satellites are not circularly polarized. The advantage of circular polarization in our application is the minimization of spin-fading effects.
Green Heron RT-21 AZ/EL Rotator Controller
The final step in the construction of our antenna system was to add the rotator controller and test the computer aiming system. We have had very good results using Green Heron Engineering rotator controllers in our home station so we selected their RT-21 AZ/EL rotator controller for this application. The RT-21 AZ/EL rotator controller is really two rotator controllers in a single box. The rotator control parameters such as minimum and maximum rotator speed, ramp, offset, over travel, and others can be independently set for each rotator.
Rotator Test Using MacDoppler
The RT-21 AZ/EL Rotator Controller connects to our computer via a pair of USB cables. We run Green Heron’s GH Tracker software on our MacBook Air laptop to manage the computer side of the rotator controller and to provide a UDP protocol interface to the MacDoppler tracking software. The picture above shows the test setup used to verify the computer-controlled antenna pointing system.
Mixed OS/X and Windows Software Environment
One challenge associated with selecting a Mac OS/X platform for computer control is what to do about the inevitable need to run Windows software as part of the system. In addition to the GH Tracker software, the WaveNode WN-2 Wattmeter and digital modem software for satellite/ISS APRS and other applications require a Windows run-time environment. To solve this problem, we use a virtual machine environment implemented using VMware Fusion and Windows 10 64-bit on our MacBook Air Laptop along with Mac OS/X. Using the Unity feature of VMware Fusion allows us to run windows apps such as GH Tracker as if they were native Mac OS/X apps. The picture above shows an example of this.
Rotator Controller and Software Configuration
With the antennas removed from the cross boom, we tested the operation of the computer-controlled tracking system. The Yaesu G-5500 AZ/EL Rotator has some limits as to its pointing accuracy and backlash performance. Experimentation with the combination of the RT-21 AZ/EL rotator controller, GH Tracker, and MacDoppler setups was required to achieve smooth overall operation. We finally settled on a strategy of “lead the duck” tracking. The idea here is to set up the rotators so that they over-travel by a degree or so when the computer adjusts them and couple this with a relatively wide 2-3 degree tracking resolution. This maximizes the overall accuracy of the pointing system and minimizes the tendency towards the constant start-stop operation of the rotators during satellite tracking. Our current configuration for all of the elements involved in the tracking system is shown above.
With the antenna system complete and tested, we can move on to the next step in our project – the construction of a computer-controlled transceiver system. We will cover this element in the next part in this series. Other articles in the series include:
NCC-1 Receive Antenna System Control Unit and Filters
Anita and I like to take advantage of the mild fall weather to do antenna projects at our QTH. We have completed two such projects this fall – the installation of a Two-Element Phased Receive System and a rebuild of the control cable interconnect system at the base of our tower.
The NCC-1 System can be used to peak or null a specific incoming signal. It can also be applied to a noise source to null it out. The direction that it peaks or nulls in is determined by changing the phase relationship between the two Active Antenna Elements via the NCC-1 Controller.
NCC-1 Filter Installation
The first step in the project was to open the NCC-1 Control Unit to install a set of 80m and 160m bandpass filter boards. These filters prevent strong out-of-band signals (such as local AM radio stations) from overloading the NCC-1. The internal switches were also set to configure the NCC-1 to provide power from an external source to the receive antenna elements through the connecting coax cables.
Installed Active Receive Antenna Element
The next step in the project was to select a suitable location for installing the Receive Antenna Elements. We choose a spot on a ridge that allowed the two Antenna Elements to be separated by 135 ft (for operation on 160m/80m) and which provided a favorable orientation toward both Europe and Japan. The antenna elements use active circuitry to provide uniform phase performance between each element’s 8 1/2-foot whip antenna and the rest of the system. The antenna elements should be separated by a 1/2 wavelength or more on the lowest band of operation from any towers or transmit antennas to enable the best possible noise rejection performance.
Received Antenna Element Closeup
The two Antenna Elements were assembled and installed on 5 ft rods which were driven into the ground. To ensure a good ground for the elements and to improve their sensitivity, we opted to install 4 radials on each antenna (the black wires coming from the bottom of the unit in the picture above). The Antenna Elements are powered through 75-ohm flooded coax cables which connect them to the NCC-1 Control Unit in our shack. The coax cable connections in our setup are quite long – the longer coax of the pair being approximately 500 ft. The use of flooded coax cable allows the cables to be run underground or buried. Should the outer jacket become nicked, the flooding glue inside the cable will seal the damage and keep water out of the cable.
Receive RF Choke
It is also important to isolate the connecting coax cables from picking up strong signals from nearby AM Radio stations, etc. To help with this, we installed Receive RF Chokes in each of the two coax cables which connect the Antenna Elements to the NCC-1. These chokes need to be installed on ground rods near the Antenna Elements for the best performance.
Underground Cable Conduit In Our Yard
We ran the coax cables underground inside cable conduits for a good portion of the run between the antenna elements and our shack. The conduits were installed in our yard when we built our tower a few years back so getting the coax cables to our shack was relatively easy.
Receive Antenna Coax Ground System
The last step in the outdoor part of this project was to install a pair of 75-ohm coax surge protectors near the entry to our shack. An additional ground rod was driven for this purpose and was bonded to the rest of our station’s ground system. We routed both of the 75-ohm coax cables from the two Antenna Elements through surge protectors and into our shack. Alpha-Delta makes the copper ground rod bracket shown in the picture for mounting the surge protectors on the ground rod.
Antenna Equipment Shelf In Our Shack (The NCC-1 Control Unit Is At The Bottom)
The installation work in our shack began with the construction of a larger shelf to hold all of our antenna control equipment and to make space for the NCC-1. The two incoming coax cables from the Antenna Elements were connected to the NCC-1.
microHAM Station Master Deluxe Antenna Controller
Antenna switching and control in our station is handled by a microHAM System. Each radio has a dedicated microHAM Station Master Deluxe Antenna Controller which can be used to select separate transmit and receive antenna for the associated radio. The microHAM system allows our new Receive Antenna System to be shared between the 5 radios in our station.
The Antenna Elements must be protected from overload and damage from strong nearly RF fields from our transmit antennas. In a single radio station, this can be handled via a simple sequencer unit associated with one’s radio. In a multi-op station such as ours, it is possible for a different radio than the one which is using the Receive Antenna System to be transmitting on a band that would damage the Receive Antenna System. To solve this problem, we built a multi-radio sequencer using one of the microHAM control boxes in our station. The 062 Relay Unit shown above has one relay associated with each of the five radios in our station. The power to the Receive Antenna System is routed through all 5 of these relays. When any radio transmits on a band that could damage the Antenna Elements, the associated relay is automatically opened 25 mS before the radio is allowed to key up which ensures that the system’s Antenna Elements are safely powered down and grounded.
Updated microHam Antenna System Diagram
With all of the coax and control connections complete, I was able to update the microHam system design information for our station and add the new receive antenna system to our setup. You can find more about the programming of our microHam system here.
So how well does the system work? To test it, we adjusted the NCC-1 to peak and then null a weak CW signal on 80m. This is done by first adjusting the Balance and Attenuator controls on the NCC-1 so that the incoming signal is heard at the same level by both Antenna Elements. Next, the B Phase switch is set to Rev to cause the system to operate in a signal-nulling configuration, and the Phase control is adjusted to maximize the nulling effect on the target signal. One can go back and forth a few times between the Balance and Phase controls to get the best possible null. Finally, the incoming signal is peaked by setting the B Phase switch to Norm.
Peaked And Null’ed CW Signal
The picture above shows the display of the target CW signal on the radio using the NCC-1 Antenna System. If you look closely at the lower display in the figure (nulled signal) you can still see the faint CW trace on the pan adapter. The difference between the peak and the null is about 3 S-units or 18 dB.
NCC-1 Used For Noise Cancellation
The NCC-1 can also be used to reduce (null out) background noise. The picture above shows the result of doing this for an incoming SSB signal on 75m. The system display at the top shows an S5 SSB signal in the presence of S4 – S5 noise (the lower display in the picture). Note how clean the noise floor for the received SSB signal becomes when the unit is set to null the noise source which comes from a different direction than the received SSB signal.
We are very pleased with the performance of our new Receive Antenna System. It should make a great tool for DX’ing on the low bands. It is a good complement to our 8-circle steerable receive system which we use for contesting on 160m and 80m.
Tower Control Cable Interconnects (Bottom Two Gray Boxes)
Our other antenna project was a maintenance one. We have quite a number of control leads going to our tower. When we built our station, we placed surge protectors at the base of our tower and routed all of our control leads through exposed connections on these units. Over time, we found that surge protection was not necessary and we also became concerned about the effects that sunlight and weather were having on the exposed connections. To clean all of this up, we installed two DXEngineering Interconnect Enclosures on our tower and moved all the control cable connections inside them.
Inside View Of Interconnect Enclosures
We began with a pair of enclosures from DXEngineering and we mounted screw terminal barrier strips on the aluminum mounting plates in each enclosure. The aluminum plates are grounded via copper strap material to our tower.
Closer Look At One Of The Interconnect Enclosures
The picture above shows one of the interconnection boxes. This one is used to connect our two SteppIR DB36 Yagi Antennas and some of the supporting equipment. The barrier strips form a convenient set of test points for troubleshooting any problems with our equipment on the tower. There are almost 100 control leads passing through the two enclosures and this arrangement keeps everything organized and protected from the weather.
With all of our antenna projects complete, we are looking forward to a fun winter of contesting and low-band DX’ing.
In the previous articles in this series, we explained how we integrated a FlexRadio-6700 Software Defined Radio (SDR) into our station and how we used it as a platform to build the Remote Operating Gateway for our station. The project has turned out to be somewhat involved so we will be providing a series of articles to explain what we did:
With all of the hardware and software installed and the integration steps complete, we will show some examples of using our remote operating setup on the air in this article. The first set of operating examples was made using the Remote Operating Client PC in our Home Office. This system is shown in the picture above.
Working The VK9WA DXpedition – Left Monitor
We were able to make several contacts with the VK9WA DXpedition to Willis Island using our remote operating setup. The picture above provides a closer look at how we set up our Remote Client PC to work VK9WA (you can click on the pictures here to see a larger view). We just completed a CW contact with the VK9WA DXpedition on 40m and you can see that we have the QSO logged in DXLab’s DXKeeper. We used CW Skimmer to help determine where the operator was listening (more on this in a bit). We also used our Elecraft KPA500 Amplifier to make it a little easier to break through the pileup.
VK9WA DXpedition 30m Pileup Viewed From CW Skimmer
The video above shows the VK9WA DXpedition operating split in CW mode on the 30m band. Note how CW Skimmer allows us to see exactly where the operator is listening (the VK9WA operator’s signal is the green bar at the bottom and the stations being worked can be seen sending a “599” near the top). You can see many of the folks trying to work the VK9WA DXpedition move near the last station that is worked in the pileup video.
VK9WA DXpedition 30m Pileup Viewed From SmartSDR
The next video shows the VK9WA pileup in the SmartSDR application which controls the radio. This video provides a closer look at how SmartSDR is set up for split operation. Can you find the station that the VK9WA operator worked? It is not quite in Slice Receiver B’s passband.
Laptop Remote Operating Client
We also configured our Laptop PC to be a Remote Operating Client for our station. Our Bose SoundLink Bluetooth Headset is used as both a wireless microphone and headphones with this system. Our Laptop Client PC can be used from any location on our property via the WiFi Wireless extension of our Home Network.
Window Arrangement For remote Operating From Laptop
Since our Laptop PC has limited screen space, we created a configuration of overlapping windows to provide access to SmartSDR, key elements of the DXLab Suite, and the applications which control/monitor our KPA500 Amplifier and Antennas. Each window is arranged so that a portion of it is always visible so that we can click on any required window to bring it forward when we need to use it.
Operating From Our Remote Laptop Client – A 20m SSB QSO
The video above shows a QSO that we made with AD0PY, David, and his friend Daniel in Missouri, USA. We used the FlexRadio-6700 SDR/SmartSDR combination in VOX mode to make transmit keying simpler. At the beginning of the QSO, we turned our antennas to point to AD0PY. Also, note the operation of the KPA500 Amplifier when we transmit in the video. The QSO is logged in DXLab’s DXKeeper at the end of the contact in the usual way. It’s fun to make casual contacts this way!
As you can see from this post, there is very little difference when we operate our station remotely or from our shack. This was an important goal that shaped the design of our Remote Operating Gateway and Client PC setup. Future posts will provide some details on how we set up the CW Skimmer and Digital Mode (RTTY, PSK, and JT65/JT9) software to work on our Remote PC Clients.
Flex-6700 Software Defined Radio And Remote Operating Gateway
We’ve been planning to add a remote operating capability to our station for some time now. We also did some previous work with a FlexRadio Software Defined Radio (SDR) in our station, and we felt that an SDR would be a good platform to build a remote operating project around. We decided to combine our remote operating goals with a next-generation SDR upgrade (a FlexRadio-6700) for our station. This project has turned out to be somewhat involved, so we will be providing a series of articles to explain what we did:
Part 1 – System Design and Hardware Installation (this post)
We will tackle our goals of building a Remote Operating Gateway (GW) in two stages. Stage 1 will focus on operating our station from other rooms in our house (our Home Offices are prime locations for this). Stage 2 will involve operating our station “On The Go” from anywhere in the world that has sufficient Internet Access is available. We also want to enable full control of our station when operating remotely, including:
The first step in this project was to develop a system design (pictured above). We opted for an architecture that uses the Flex SDR as a third radio in Anita’s Operating Position. Her position is now an SO2R setup with a Yaesu FTdx5000 as the primary radio and a choice of either an Icom IC-7600 or the Flex-6700 SDR as the second active radio.
The additional microHAM SMD allows the Flex-6700 SDR to access and control our entire antenna system and associated rotators.
Our setup also includes a K1EL WinKeyer to enable computer-controlled CW keying of the Flex-6700 SDR. This device is relatively inexpensive in kit form and was fun to put together. We have a Bencher Iambic Paddle connected to the WinKeyer for in-shack CW operation.
SDR microHAM Integration
The diagram above shows the details of the device interconnections which make up the SDR Radio System. The microHAM SMD Antenna Controller requires a serial CAT interface to its host Flex-6700 SDR to determine what band and frequency the SDR is on. The Flex-6700 SDR does not provide such an interface directly, but it does create CAT control virtual ports on a host Personal Computer (PC).
DDUtil Setup – SDR Virtual CAT Access
DDUtil Setup – Bridging Physical Serial Port To SMD
To solve this problem, we used an application called DDUtil to bridge the derived CAT port associated with the SDR to a physical serial port on the PC. The PC’s physical port is then connected to the microHAM SMD associated with the Flex-6700 SDR. The pictures above show how DDUtil is set up to do this.
Station COM Port Configuration
The microHAM gear, WinKeyer, Rotators, Radio CAT Interfaces, Amplifier/Auto Tuner Interfaces, etc., all use serial or COM ports on a host PC for control. It’s also true that many loggers have trouble accessing serial ports above COM16. This requires a carefully developed COM port allocation plan for a complex station like ours. The figure above shows this part of our design.
The Flex-6700 SDR Hardware is controlled and operated via FlexRadio’s SmartSDR Application over a network. We have 1 Gbps wired and an 802.11 b/g/n Wireless Ethernet systems in our home and the SmartSDR/Flex-6700 SDR combination works well over either network. The software-based approach used with most SDR allows new features to be added to the radio via software upgrades.
SmartSDR Setup – Tx Keying And Interlock
It is very important to prevent the Flex-6700 SDR and the associated Amplifier from keying up when the antennas in our station are being switched or are being tuned. The screenshot above shows the configuration of SmartSDR to enable the keying and interlock interfaces between the Flex-6700 SDR and its associated microHAM Station Master Deluxe Antenna Controller to implement these functions. This setup enables the Tx Keying and Tx Inhibit interfaces between the Flex-6700 SDR and the microHAM Station Master Deluxe to work properly to key all of the equipment in the setup (SDR, Amplifier, active Rx antennas, etc.) and to lock out keying when antennas are being switched or when one of our SteppIR antennas are tuning.
Amateur Radio Highlights – our 2014 Readers Around The World
It is again time for our annual 2014 Year Amateur Radio highlights post. First, I’d like to thank our readers for their continued interest in our Blog. Our blog was viewed about 100,00 times in 2014 from 165 countries worldwide. You, our readers, have made 2014 our busiest year yet, and this provides Anita (AB1QB) and me with great encouragement to continue to provide content for our readers.
2014 was a very busy year in Amateur Radio for us. Our activities included a continued focus on station building, contesting, WRTC 2014, special events, providing presentations to help others in the hobby learn about new things, attending several HAM Events, progress on operating awards, and most importantly – time spent on the air operating.
microHAM Station Master Deluxe Antenna Controller
This year, we upgraded our fixed station to include a microHAM Station Automation system. This major project added some nice SO2R capabilities to our Multi-one station and automated the sharing of our antennas between our two SO2R operating positions. More of this project can be found here:
Eggbeater LEO Satellite Antennas And Preamps Systems On Tower
We also added LEO Satellite capabilities to our station with the addition of some new antennas and electronics on our tower. This allowed us to make our first contacts through LEO birds with linear transponders. Our articles on this project include:
Our final major station-building project was constructing a state-of-the-art mobile HF station in our Ford F-150 pickup truck. We did this project in phases, starting with a simple setup using a 100W radio and HAM Stick antennas through the installation of a Screwdriver Antenna System for the 160m – 10m HF bands and concluding with the installation of an amplifier to enable high-power mobile HF operation. You can view the articles on this project here:
Anita (AB1QB) and I continued to be active in several contests this year. We both continued to develop our skills as contesters and our scores and place in the rankings reflected this. You can read more about our contesting activities and what we learned in the following articles:
We prioritize devoting a significant amount of our Amateur Radio time to helping others in the hobby learn new things. In addition to writing this Blog, Anita and I try to create and deliver several presentations each year on a variety of topics of interest to the Amateur Radio Community. This year’s presentation included an update of our presentation on Amateur Radio Station Design and Construction and an Introductory Presentation on the DXLab Software Suite. We are always interested in working with Amateur Radio Clubs to deliver the presentation in person, where practical, or over the web.
Anita (AB1QB) and I with Bob Heil (K9EID)
We had the fortune to meet some of the legends in Amateur Radio this past year. Anita and I had the opportunity to get meet Bob Heil, K9EID and to appear on his Ham Nation podcast. Bob is an amazing gentlemen and we feel truly fortunate to have the opportunity to get to know him. We also had the opportunity to meet Fred Lloyd, AA7BQ, the President and Founder of QRZ.com. Fred visited our station and did an article about our station on QRZ.com. Anita and I both learned a great deal about HAM Radio and how it came to be what it is today as a result of the time these fine folks spent with us.
Joe Taylor’s WSJT Presentation At the ARRL Centennial Convention
Amateur Radio Conventions and HAM Fests were a major part of our Amateur Radio fun again this year. We were fortunate to attend and speak at the ARRL Centennial Convention in Hartford, CT USA this year – truly a once in a lifetime Amateur Radio experience. We also attended the Dayton Hamvention in 2014 where we had a chance to see all of the latest and greatest in Amateur Radio Equipment.
Our 2014 QSOs By Callsign
We were quite active on the air making almost 26,000 contacts between the two of us. As you can see from the graphic above, about 45% of our contacts were as part of Special Event Operations. We also made a little over 500 contacts from our mobile station, working over 100 DXCC entities in 2014 from the mobile.
We mostly operated in the SSB phone mode in 2014. Anita and I both continue to work on our CW skills, and we managed a little over 800 QSOs using CW in 2014. Anita was very active in the RTTY mode as part of her RTTY contesting efforts.
13 Colonies K2K New Hampshire QSL!
All of this operating resulted in quite a bit of QSL activity. We sent a total of almost 4,200 QSL cards in 2014!
We again made a video showing all of our contacts around the world in 2014. As you can see from the video, we were fortunate to work quite a bit of DX in 2014.
Anita and I had a lot of fun with Amateur Radio in 2014. We look forward to another great year of HAM Radio fun in 2015. We hope to share some of what we learn and our experiences with our readers here on our Blog.
I recently had the opportunity to do a presentation introducing the DXLab Software Suite for several local radio clubs. The idea was to provide a fairly comprehensive introduction to DXLab and to show how it can be used to make Amateur Radio operations, QSL’ing, and Award Management easier and more enjoyable. There are several good DXLab introductory presentations and web pages on the internet, so we decided to do ours with some “live” demos of DXLab in use within our station.
Why Computer Logging And DXLab?
Not all hams have converted to computer-based operation and logging, so we began by covering the motivation for and some of the advantages of Computer-based operation and logging.
DXLab Suite Components Overview
The next part of the presentation provided an overview of each of the components of the DXLab Suite and some of the basics of how they work together. This was covered via a set of “live” demonstrations using our station. You can view these demonstrations as videos via the following links:
The next part of the presentation covered some common DXLab “use cases” that one would likely encounter when making contacts, QSL’ing, and managing progress toward operating awards.
Casual Contacts With DXLab
The first demonstration showed the use of DXLab to make casual or “rag chew” contacts. The emphasis here is on using the Suite to automate station configuration and logging tasks and to provide information to enhance the quality of your contacts. This demonstration covers the basics of how the components of the DXLab Suite work together to help you make and log a contact. You can view a video of this demo via the following link:
The next demonstration showed the use of DXLab to find and work DX contacts. This demonstration uses more components of the DXLab Suite, including the spotting cluster and propagation prediction features. You can view a video of this demo via the following link:
The next demo shows how to use DXLab to QSL and confirm contacts. The demo covers QSL’ing via the Logbook of the World (LoTW) and the eQSL online QSL services, the generation of paper QSLs, and the assistance that DXLab provides to determine QSL route information. You can view a video of this demo via the following link:
The presentation includes links to useful tools and information to help you get the most from the DXLab suite. Dropbox is a useful file-sharing tool that can help you keep your logs and DXLab configurations in sync across multiple computers. This allows you to use DXLab to access your current logs or to operate your station from different computers.
I hope this overview of the DXLab suite will encourage our readers to try it. Anita (AB1QB) and I have successfully used the DXLab suite with our station for several years now. It does a great job automating many aspects of our Amateur Radio operations, QSL’ing, and award management. It easily handles the complexities of our multi-operator station, and it also handles logging and QSL’ing for multiple call signs that Anita and I operate under. We also use DXLab for our portable, Field Day, and mobile operations, and it handles all of these scenarios very well.
DXLab was created, enhanced, and maintained by David Bernstein, AA6YQ. He makes this excellent software suite available as freeware for the benefit of the Amateur Radio community. The DXLab suite is available for download here. Here, you can download a copy of our DXLab presentation (without the videos). The DXLab Yahoo! Group provides a good place to seek support and answers to questions about DXLab. I hope that our readers will give the DXLab suite a closer look. For those who already use DXLab, we hope you pick will up some new ideas from how Anita and I use the suite as part of your Amateur Radio operations.
We plan to talk about how our station is performing against our original design goals and we’ll have some updated video too!
For those who are attending the ARRL Centennial Convention in Hartford Connecticut, I hope you stop by and say hello to Anita and me. We’re anxious to meet as many of our readers as we can at the event. For those who cannot make the trip, we will be taking lots of pictures and we plan to post a summary of what we saw here after the event.
Anita’s second radio is an Icom IC-7600 and it’s integration into the system went very smoothly. We also integrated the control of our Power Amplifiers (a combination of Icom PW-1s and an Elecraft KPA500) into the microHAM system. As you can see from the diagram above, the amplifiers are dedicated to specific radios and can be controlled directly by each radio’s Station Master Deluxe (SMD). We used microHAM supplied amplifier control cables for the PW-1s and I built a custom control cable for the Elecraft KPA500 (this was not difficult – both microHAM and Elecraft provide good documentation for the interfaces involved).
With the cabling done, I next configured the SMDs to correctly set the control leads to switch the Amplifier and Bandpass filter bands based on the Transmit (Tx) frequency of the associated transceiver. The picture above shows the configuration for the bandpass filters. The configuration for the amplifiers is similar.
Control Box Configuration
The next step in the process was to add some additional microHAM Control Boxes to the uLink bus and configure their addresses. The picture above shows the control interfaces in our system including the four SMDs. The addressing convention that we use in our station has 40-series control boxes which control our 4×10 antenna switching matrix, 50-series control boxes which control our Tx antennas and 60-series control boxes which control our Receive (Rx) antennas and associated equipment. The picture above also illustrates some of the Units that we’ve defined on our Control Boxes to create interfaces to amplifiers, filters, antenna switching and other controls.
Palstar Dummy Load
The first step in the cut over of our antennas was to connect the antennas and devices which did not require complex control. This included our OCF Dipole and our Palstar High-Power Dummy Load. As each antenna was connected, the associated path was configured in the system and tested to ensure that everything worked as expected.
Dummy Load Modification
I made a simple modification to the Dummy Load to allow its lamp to be switched on when one of the radios in the shack selects it. This involved adding a couple of binding posts to the device and running the lamp bulb circuit though the binding posts. The posts are connected to a RELAY6 control box and the microHAM system is configured to close the associated relay whenever a radio selects the Dummy Load. This makes it easy to see that the Dummy Load is selected and extends the life of the bulb.
Transmit Antenna Controls
The next step in the cut over process was to move all of our transmit antennas and rotators to the system one at a time and test them. This required the construction and testing of some RS-232 serial cables to connect our three SteppIR Antennas and our Green Heron RT-21D Rotator Controllers to their associated DATA Control Boxes (top row in the picture above).
SteppIR DB36 Control
The picture above shows the configuration for one of our SteppIR Antennas – The Upper DB36 Yagi. This particular configuration step involved assigning the antenna to a DATA Control Box as well as telling the system the type of control protocol to use to control the antenna. The microHAM system “knows” about a wide array of serial and other controllable devices and implements the necessary protocols.
Receive Array Control And Sequencer
The integration of our 8-Circle Low-Band Receive Array involved some special steps at both the Hardware and Configuration levels. The connections on the RELAY10 control box shown above are used to “steer” the Rx array and to enable or disable the associated shared Low-Noise pre-Amplifiers (LNAs). To protect this antenna from damage from nearby transmit antennas, power to the array must be removed a few milliseconds before transmit begins. This is normally done by a sequencer in a single radio station. Our station can have up to four different radios transmitting on any one of several different antennas on the low bands. To solve this problem, I used a RELAY6 control box to create a multi-radio sequencer. Each antenna that can transmit on the 160m – 60m bands has one of the relays on the RELAY6 shown above associated with it.
80m Delta Loop Sequencer
These relays are controlled via an optional SEQ control unit that is configured for each of associated antennas. All of these relays are wired in series with the power lead for the 8-Circle Receive Array. Whenever any radio transmits on any band from 160m – 60m on one of the low-band Tx antennas, the associated relay is first opened (with appropriate delay) before Tx is enabled. This approach implements a multi-radio low-band sequencer across the four radios in our station. The control logic also powers down the array when it is not in use by any radio.
Virtual Rotator For 8-Circle Receive Array
The other “special” step involved in the integration of our 8-Circle Receive Array was the implementation of a “virtual rotator” for it. This involves creating a table in the system configuration which maps all possible headings to one of the eight available direction settings for this antenna. Once this is configured, the antenna behaves as if it had a conventional rotator associated with it. When its selected, loggers like the DXLab Suite and N1MM can automatically steer the antenna to the best possible direction selection to work a given station. The front panel rotator controls on the SMDs can also be used to turn the antenna just as if it had a “real” rotator.
Available Antenna Paths
With all of the antennas and other RF devices properly configured and interconnected in the configuration, the microHAM router software generates a list of available antennas paths as shown above. The software automatically determines the path and associated control resource needed to connect a given antenna to a given radio. Note that some of our antennas have multiple paths by which they can be reached. The software detects this and allows the alternative paths to be selected or, if configured as is the case with our 8-Circle Receive Array, be used by multiple radios at the same time. This table represents all of the antenna selections that are possible in our system.
Antenna Selection Configuration
The final step in the configuration process is to determine which antennas may be used by which radios on a each of the available bands. The microHAM router software initially populates this table with all of the possible choices based upon the “available antennas”. I edited the automatically generated configuration to remove a few choices which were not needed and to reorder the lists for each band so that the displays on the SMD would be the most logical for us to use. With these steps done, our configuration was complete.
Yagi Stack Control
The system is quite easy to use and provides easy to read and useful displays. The picture above shows the selection of our Stack of two SteppIR DB36 yagis on one of radios. That radio (an Icom IC-7800) is currently on the 20m band tuned to 14.267 MHz for both transmit and receive. The two white squares show that both yagis are currently included in the stack. Options exist to use either antenna independently and to use them either in or out of phase in the stack. Both SteppIR DB36 antennas are pointed to 45 degrees (we can turn them independently) as can be determined from the numbers next to the white blocks and the direction of the arrow next to them. The row of buttons numbers 1 – 7 show the available antenna selections for this radio on the 20m band.
80m Split Tx/Rx Antenna Selection
The picture above shows the SMD display for the same radio when tuned to 3.658 MHz on the 80m band. Note that the available antenna selections have changed to those available in our station for the 80m band. In this example, I am using different antennas for Tx (our 80m Delta Loop) and Rx (our 8-Circle Receive Array). The virtual rotator for the 8-Circle array is active and you can see that this antenna is pointed toward 245 degrees (the virtual rotator input was actually 255 degrees and the SMD picked the closed direction selection on the Rx antenna). Our 80m Delta Loop is vertically polarized and omnidirectional which is indicated by the symbol next to it on the display.
Station Master Deluxe Keypad
In addition to the buttons and rotary controller on each of our SMDs, antennas can also be selected and steered via a keypad that is associated with each SMD. The keypads enable many functions including direct entry of rotator headings, antenna selection and setup for split Tx/Rx antenna operation.
MK2R+ Virtual COM Port Configuration
The microHAM platform (MK2R+ and SMDs) create an interface to all of our logging and control software on our PCs via a series of Virtual COM Ports. The ports for radio CAT interfaces, PTT and FSK (RTTY) keying, and control of the CW and Voice Keyers in the MK2R+ are created by the microHAM Router as shown above. Each of the two radios at a given operating position have a unique set of ports for CAT and keying.
Station Master Deluxe Virtual COM Ports
In addition, the SMD associated with each radio creates addition virtual COM ports to allow software programs to control the rotator associated with the currently selected antenna(s) on that SMD. The control also includes any “virtual rotators” associated with antenna(s) that may be selected on a given SMD.
DXLab Radio Control
We use both the DXLab Suite and the N1MM Logger at our station and both work well with the microHAM system. Shown above is DXLab including its Commander component (lower-right) which provides the radio interface to the suite. If you look closely, you can see the Commander radio buttons which select either of the two radios at this position. DXLab (and N1MM) know the microHAM control protocol and will automatically switch the associated MK2R+ to use the appropriate radio. This includes setting which radio is active to Tx as well as what audio is heard in the headphones/speakers and what audio goes to the sound card for the associated MK2R+ and its radios. The appropriate routing of the shared microphone and CW paddles is also automatically configured.
DXLab and HRD Rotator Control
The picture above shows our rotator control software. We are using two programs here. In the upper left is DXLab’s DXView program which will steer our antennas in the direction associated with the callsign which is currently entered into the logger. The other rotator controller is HRD Rotator (lower right) which displays a map of the world and a path. We can click on any location on HRD’s Rotator’s map and the software will turn the currently selected antennas in that direction. The use of independent rotator control programs is made possible by the microHAM Router which implements two separate Virtual COM Ports for the rotator(s) associated with each SMD’s selected antenna(s) for its associated radio.
As you can probably tell from the articles in this series, the microHAM system is very powerful and can handle most any station’s setup including those which are much more complicated than ours. While the construction and configuration work described here may seem a little complex, it’s really not that difficult if you create a good plan for your system at the outset (see the first post in this series). The documentation for the microHAM system is very good and Jozef (OM7ZZ) and Joe (W4TV) at microHAM were very good about answering my questions and steering me in the right direction as I built and configured my system. There is also a good Yahoo! group for the microHAM system. You may want to look at the other articles in this series for more information as well:
We are considering the addition of legal limit solid state amplifiers and high-power bandpass filters to our station and these will be integrated into the microHAM system when installed. I am also experimenting with the addition of a software defined radio to the setup. I plan to provide additional articles here as those projects proceed.