Category Archives: Antennas and Feedlines

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Greencube (IO-117) – A Portable Station for Activating Grid Squares

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Portable Station for Greencube

Portable Station for Greencube

We’ve been having a lot of fun with the Greencube (IO-117) satellite, so I decided to put together a portable ground station for activating grid squares. I wanted a station that –

  • Has adequate antenna gain and power for reliable Greencube operation
  • Uses solar-battery power so that it is quiet when operating in public places
  • Uses computer management for Doppler correction
  • Can provide accurate grid locator information via  a GPS receiver
  • Is easy to set up in the field in less than 30 minutes

Station Components

We already have a solar-battery power system that we build for portable operation with a 100w transceiver as well as an IC-9700 transceiver that we use as part of our transportable satellite ground station. We also have Windows and Mac laptop computers that we can use as part of our Greencube (IO-117) portable ground station. With these components in mind, here are the hardware components that we are using as part of our Greencube portable station –

We are using the following software for our portable Greencube (IO-117) ground station:

Portable Station in Pelican Case

Portable Station in Pelican Case

We also purchased a case (Pelican Air 1555) to package the transceiver and accessories.

Antenna System

M2 Antenna Systems 440-11X Antenna

M2 Antenna Systems 440-11X Antenna

We choose the M2 Antenna Systems  440-11X Antenna for our portable ground station. This antenna has more than adequate gain for use with Greencube, and its lightweight rear-mounted design makes it ideal for use with our heavy-duty video camera tripod.

Portable Antenna System

Portable Antenna System

The antenna is attached to the tripod using a Camera Tripod Ball Mount, a Handlebar Ball Mount Clamp, and a Double Socket Ball Arm. The Handlebar Clamp grips that antenna’s rear extension and allows the antenna to be easily rotated to align its polarity with Greencube’s antenna during a pass. A short section of water pipe with a cap, hook, and a 1,000-gram weight provides a counterweight to balance the antenna on the tripod.

Portable Antenna System Details

Portable Antenna System Details

A Magnetic Digital Angle Guage is used to adjust the elevation angle of the antenna.

A coax-powered LNA from Advanced Receiver Research (an available alternative is the SSB Electronic SP 70 preamp) is attached to one of the legs of the tripod and is connected to the antenna with a short LMR-240uF coax cable. a 20′ length of LMR-400uF coax connects the antenna system to the transceiver. N-connectors are used throughout the feedline system.

Radio, Computers, and Software

IC-9700 Transciver and Computers

IC-9700 Transceiver and Computers

Our setup uses an Icom IC-9700 transceiver and two computers. The IC-9700 transceiver is connected to the Windows computer via the radio’s USB port and to the MacBook Air via a CI-V cable.

The Windows computer runs the following software programs to provide the client terminal, modem, and logging functions required to operate with Greencube –

The configuration of these programs is covered in more detail here.

GPS Dongle NMEATime Software

NMEATime Software used with GPS Dongle

The Windows laptop also runs the NMEATime application and uses a USB GPS Dongle to accurately determine the grid locator where we are operating from. The grid locator from NMEATime is used to configure MacDoppler to ensure accurate tracking information for aiming our antenna.

MacDoppler Tracking Greencube and Controlling the M2 LEO Pack

MacDoppler Tracking Greencube and Controlling the Uplink/Downlink Frequencies

The MacBook Air laptop runs MacDoopler. MacDoppler is connected to the IC-9700 transceiver via a CI-V cable and controls the IC-9700’s uplink and downlink frequencies to provide Doppler correction. MacDoppler is also used to determine the azimuth and elevation of Greencube to enable manual pointing of our antenna.

Power System

Solar-Battery Power System

Solar-Battery Power System

Powering a 100-watt transceiver in a portable application during extended operating sessions can present a challenge. I also wanted a setup that was quiet as we often operate portable in public locations. For these reasons, I decided to put together a solar-battery setup that consists of the following components:

90W Foldable Solar Panels

90W Foldable Solar Panels

The solar panels are wired in series and provide about 34 Vdc in bright sunlight.

MPPT Charge Controller, NLiPo Batteries, and Power Distribution

MPPT Charge Controller, LiPo Batteries, and Power Distribution

The MPPT Charge Controller automatically determines the best balance between cell voltage and current to provide maximum power transfer to charge the batteries. The batteries provide the extra power capacity needed when transmitting. The resulting power setup can sustain the full power operation of our portable station, even on cloud days.

The laptops run on their internal batteries and are changed via automotive lighter socket power adapters between operating sessions.

Operating Using Greencube

Portable Telemetry from Greencube

Portable Telemetry from Greencube

My initial tests of the portable station were done using the station to receive Telemetry from Greencube. This allowed me to learn to steer the antenna and adjust it for the best polarity during passes. The station had no trouble hearing and decoding Greencube’s telemetry transmission from horizon to horizon.

Compass App on iPhone

Compass App on iPhone

It was relatively easy to point the antenna based on the azimuth and elevation information from MacDoppler. I used a compass app on my iPhone to set the antenna’s azimuth heading and the Digital Angle Guage to set the antenna’s elevation. Pointing the antenna to within +/- 10 degrees of accuracy was adequate for reliable operation with Greencube.

I turned the speaker volume on the radio high enough so I could hear Greencube’s signal while adjusting the antenna polarity. Finding the polarity that caused Greencube’s signal to be weakest and then rotating the antenna 90 degrees from this point worked well.

Portable QSOs with EA8ARI via Greencube

Portable QSOs with EA8ARI via Greencube

I was able to make 15-20 contacts on each Greencube pass with our portable ground station. The RSSI graph in the Greencube terminal is a good indicator to determine when to adjust the antenna’s heading and polarity to track Greencube during a pass. It’s best to have a helper with one person making contacts and the other adjusting the antenna, but it’s possible for a single operator to do both jobs and still make many contacts during a pass.

More Fun With Greencube

I am quite pleased with the performance of our new portable ground station for Greencube (IO-117). Anita and I are planning a portable grid square activation trip for later in the fall to make use of the station.

This article is the fifth in a series that we are working on. You view the other articles via the links below. This is a work in progress, and we’ll be creating additional Greencube-related posts in the near future:

You can also read more about our Satellite Ground stations here.

Fred, AB1OC

Greencube (IO-117) – M2 Antenna Systems LEO Pack – Will It Work?

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LEO Pack Transportable Satellite Antenna System

LEO Pack Transportable Satellite Antenna System

Quite a few folks have the M2 Antenna System LEO pack antenna. I wanted to see how this antenna system would perform with Greencube (IO-117). Our LEO Pack is set up on a Glen Martin roof tower that we’ve modified to create a transportable ground station. Here are some of the specs for the setup we’ve tested:

The specifications for the 70cm antenna are as follows:

  • Frequency Range: 432 To 438 MHz
  • Gain: 13.3 dBic
  • Front to back: 15 dB Typical
  • Beamwidth: 42° Circular

The published gain number for this antenna meets the requirements for operation with Greencube, so we set up our transportable station in our backyard and proceeded to do some testing.

Transportable Ground Station

LEO Pack Transportable Ground Station Radio and Computers

Transportable Ground Station Radio and Computers

The ground station setup includes an IC-9700 Transceiver, a Green Heron RT-21 AZ/EL Rotator Controller, and two computers.

MacDoppler Tracking Greencube and Controlling the M2 LEO Pack

MacDoppler Tracking Greencube and Controlling the M2 LEO Pack

The Mac laptop runs MacDoppler, which handles steering the antennas and Doppler correction, and the Windows laptop runs the modem and client software to access Greencube’s Digipeater.

The antennas are located about 100 ft from the rest of the ground station and are connected using LMR-600uF coax cable. This results in about 40 watts of power being delivered to the feedpoint of the 70 cm antenna.

Testing The LEO Pack With Greencube’s Digipeater

Greencube (IO-117) QSOs with the LEO Pack Antenna System

Greencube (IO-117) QSOs with the LEO Pack Antenna System

I am happy to report that the LEO Pack 70cm antenna enabled us to make quite a few contacts using the Greencube Digipeater. The setup required the remote preamp to be on and the use of the polarity switching controls to optimize losses due to mismatched polarity, which occurred frequently during Greencube passes. The LEO Pack antenna/preamp combination provided consistent decodes of Greencube’s packets. The challenge was getting our packets to be Digipeated by Greencube. On some passes, this worked very well. During other passes, we were only able to get reliable Digipeats during the approaching portion of a pass at elevations above 25 degrees.

Optimizing Our Station

MacDoppler Optimized Frequency Settings for Greencube

MacDoppler Optimized Frequency Settings for Greencube

I spent a lot of time determining the best uplink frequency to use with Greencube’s Digipeater. The settings above are what I finally settled on for uplink and downlink frequencies.

Optimized Soundmodem Settings

Optimized Soundmodem Settings for Greencube (IO-117)

I also spent some time experimenting with the Soundmodem settings. The lengthened Tx lead-in and tail settings above helped Greencube decode our signals more reliably.

These adjustments also improved the Digipeating performance of the larger antennas used in our main ground station, so they are not specific to the LEO Pack.

Conclusions About The LEO Pack and Greencube

I probably made about 50 contacts using Greencube and our LEO Pack antennas. If you already have a ground station built around the LEO Pack Antenna System, I would encourage you to add a preamplifier if you don’t already have one and try Greencube.

If you are building a fixed ground station for use with Greencube, it might be better to step up to a larger antenna such as the M2 Antenna Systems 436CP30.

I have also found that antennas with circular polarity are not necessarily the best for Greencube. This is likely due to a combination of the lengthened path through the ionosphere due to Greencube’s altitude, resulting in stronger polarity rotational effects and mismatches with the circularly polarized antennas we are using. I am anxious to do some more testing with the non-circularly polarized yagi that we are using with our portable station to see if I can confirm this.

More Fun With Greencube

This article is the fourth in a series that we are working on. You view the other articles via the links below. This is a work in progress, and we’ll be creating additional Greencube-related posts in the near future:

You can also read more about our Satellite Ground stations here.

Fred, AB1OC

6m Antenna Upgrade Part 5 – Antenna Installation and Station Integration

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6m Antennas on our Main Tower

The final stage of our 6m Antenna Project was completed earlier this week. I began by gathering all of the hardware and components for the installation and staged them near our tower.

Project Components Ready for Installation

The installation of our new 6m antennas was a big project, and I was fortunate to have Matt Strelow, KC1XX, and Andrew Toth of XX Tower here to do the installation. We had many things go well during this project, and some good luck on a few items where we needed it.

Rearranging Antennas for the 7-Element LFA

The first step in the installation was to rearrange the antennas on the mast on our main tower. We moved our existing 2m yagi up to make space for the new 7-Element LFA yagi and installed it on our mast. We pulled the new LFA yagi about 30 ft above the ground on a tram line to check the SWR and adjusted the driven element before installing it on the mast.

New 7-Element LFA Yagi on Tower

New 7-Element LFA Yagi on the Tower

The first bit of luck was that we had enough rotator loop slack for our existing 2m yagi to move it up our mast about 4 ft without making a new feedline.

Removing 6m Elements from SteppIR’s

6m SteppIR Element Removal

SteppIR 6m Passove Element Removal

Our SteppIR yagis had 6m passive elements installed, and my modeling indicated that these elements would upset the pattern and performance of the new 6m yagis we are installing. Matt and Andrew came to the rescue on this one – they used an aluminum ladder rigged, as shown above, to remove the passive elements from both SteppIR yagis without taking them down. Note to our readers – do not try this a home!

Building the 6m Stacks

6m West Stack and 7 Element LFA

The next step in the project was to install the eleven 3-element LFA yagis that make up our new 6m stacks. This took some time as we had to work out and adjust mounting heights and the separation between the antennas in the stacks to avoid interference with guy cables, wire antennas, and other components on the tower. Andrew and Matt worked from the top of the tower to avoid climbing around the antennas after they were installed. At the end of the first day, we had the West-facing 3-stack installed on the tower.

All Eleven 6m Antenna Stack Installed

All Eleven 6m Antenna Stack Installed

The photo above shows the additional stacks facing Europe (on the left) and the south (on the right). With all the antennas installed, we were ready for the Power Dividers, feedlines, and electronics.

Feedlines, Electronics, and Switching

Hardline and Control Conduits

We used 1 5/8″ hardline coax for the main feedline from our shack to the 6m switching and electronics on our tower. I had previously installed conduits running from our tower to the shack, and we were able to get the new 1 5/8″ down the 100 ft conduit from our tower to the shack. The new hardline was added to the conduit (front left), which already had two 7/8″ hardlines in it. This part of the installation went smoothly, which was our next bit of good luck.

Hardline Connector Installation

Next, Matt installed N connectors on the new hardline. The photo above shows the hardline prep for the connector installation.

N Connector on the Main Feedline to Shack

N Connector on the Main Hardline to Shack

The photo above shows the completed connector installation.

Power Divider Installed on Tower

Power Divider Installed on Tower

The next step was to install the Power Dividers near the middle of each stack and hook up the phasing lines from the antennas. The photo above shows how the Power Dividers are mounted. We also ran 7/8″ hardline coax cables from the 7-element LFA yagi and from the Power Divider for the West stack on the top half of our tower down to the location where the Preamplifier Housing and Remote Antenna Switch is installed.

6m Preamp Housing and Antenna Switch Main Tower

The final step of the installation was to install the Preamplifier Housing and Remote Antenna Switch near the center of the bottom two stacks and hook all of the components up via LMR-400 coax jumpers.

Control Cable Interconnects on the Tower

Our tower has junction boxes installed at the base for interconnecting the many control cables for our antennas and electronics. It was a simple step to hook up the new Preamp Housing and Remote Antenna Switch to get everything working with our microHam control system. These junction points make it easy to rearrange and test our equipment on the towers when needed.

Updates on our VHF Tower

6m Preamp System on our VHF+ Tower

6m Preamp System on our VHF+ Tower

I built a second Preamp Housing for use with the existing 7-element 6m yagi on our VHF and Satellite Tower, and we installed that unit as well.

Control Cable Interconnect on our VHF+ Tower

Control Cable Interconnect on our VHF+ Tower

The junction box on this tower made the final hookup of the second Preamp Housing a snap.

Final Integration

We adjusted the length of the jumpers between the Power Dividers and the Remote Antenna Switch to optimize the SWRs of the stacks and tested all of the electronics on both towers via our microHam system. The stacks and the new 7-element LFA have SWRs at 1.3:1 or lower in the weak signal section of the 6m Band.

With everything connected and checked out, it was finally time to see what our new 6m Antenna System could do!

Initial Contacts

The Taurids Meteor Shower is active right now, so I’ve been making many Meteor Scatter contacts using our new antennas. The PSKreporter snapshot shows where I was heard this morning using MSK144 mode and the West antenna stack.

PSKreporter – 6m Meteor Scatter Reports

The background noise levels on the new antennas are between 3 dB and 9 dB, better than my previous 6m antennas were. This makes working weaker stations much easier to do.

We have not had much Es propagation since we finished the project earlier this week. I did catch a marginal Es opening yesterday and made an FT8 contact with CE8EIO in Chile. This contact is about 29,350 km from our QTH here in New England. It is the longest 6m contact I have ever made with South America.

PSK Reporter - CE8EIO Contact

PSKreporter – CE8EIO Contact in Chile

As you can see from the PSKreporter data, I was heard very well at CE8EIO. This is very encouraging. I have been making FT8 contacts with the midwest and the southeast United States using the new antennas as well. Given the very limited Es propagation at this time, I would say that the new antennas are a significant improvement.

More About our Project

Here are some links to other articles in our series about our 6m Antenna Upgrade Project:

We have completed all the steps in our 6m Antenna Upgrade Project. I look forward to the Winter Es period to see how well everything will perform. I plan to post more information about the performance of our new antennas once we have some better Es openings.

Fred, AB1OC

6m Antenna Upgrade Part 4 – Building Antennas and Prep for Installation

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First 3 Element LFA Antenna on the Tower

First 3 Element LFA Antenna on the Tower

Our new Loop Fed Array (LFA) antennas, phasing lines, and power dividers have arrived from InnoVAntennas. Our plan for this phase of our project includes the following steps:

  • Build mounts for the stack Power Dividers
  • Design and a mounting and truss system for the 3 Element LFA yagis in our stacks
  • Build the first 3-element LFA yagis, test mount it on our Tower, and adjust the SWR
  • Build the additional ten 3-element LFA yagis
  • Build the 7-element LFA and adjust its SWR

Power Dividers

We are using Power Dividers from InnoVAntennas to construct our three new fixed stacks.

4-Port Power Divider for 50 MHz

4-Port Power Divider for 50 MHz

These units are very well made and perform well, but they did not come with a system to mount them on our tower. I decided to fabricate mounting clamps to attach the Power Dividers to the legs of our tower.

Custom Power Divider Mounting Clamp

Custom Power Divider Mounting Clamp

The clamps are made using stainless steel U-clamps and 1″ square aluminum tubing.

Power Divider Mount Test

Power Divider Mount Test

The mounts worked out quite well, allowing easy access to the connectors on the Power Dividers for attaching coax cables. I made up three sets of clamps to mount the power dividers in our stacks.

3-Element LFA Mounting System

The 3-Element LFA antennas that we are using are a custom variation of InnoVAntennas 3-element LFA design. The antennas are designed to be rear-mounted to a pair of legs on a rotating tower. We are using the antennas on a fixed tower, and we want to be able to adjust the direction they point in. To accomplish this, I decided to fabricate an adjustable system suggested by Matt Strewlow, KC1XX, using a 1/4″ threaded stainless steel rod.

3 Element LFA Mounting System Mock Up

3 Element LFA Mounting System Mock Up

I began by assembling the boom and clamps for one of the 3-element LFA antennas and attaching it to our tower. This allowed me to fabricate and test an adjustable rear clamp to orient the antennas. The clamps and hardware are made from aluminum and stainless steel. The components came from DX Engineering and our local hardware store.

Adjustable LFA Antenna Mounting System

Adjustable LFA Antenna Mounting System

The final step in this part of the project was to install a small eye bolt near the front of the booms and create a simple clamp to attach a boom truss (dacron) rope and a turnbuckle to support the front of the antennas.

Boom Truss Attachment Clamp

Boom Truss Attachment Clamp

Once everything fit and worked properly, I made up 11 sets of mounting hardware to support all of our 3-element LFA yagis.

3-Element LFA Assembly and Test

The next step was to assemble the first 3-Element LFA yagi. These antennas are well-made and go together easily. I assembled the boom, mounting attachments, and the center of the elements in my shop and then moved the antenna outdoors to complete the assembly and final adjustments.

3 Element LFA Assembly

3 Element LFA Assembly

I attached and sealed the phasing lines to the driven elements and checked the SWR with the antenna pointing skyward. Next, I adjusted the length of the driven element loop ends to get each antenna’s SWR where I wanted it.

First 3 Element LFA Antenna on the Tower

First 3 Element LFA Antenna on the Tower

I mounted the first antenna on the tower to confirm that my mounting system worked as planned and to check the SWR adjustment with the antenna at its installed height above ground.

First 3 Element LFA Antenna - Installed SWR

First 3 Element LFA Antenna – Installed SWR

As you can see from the analyzer image above, the antenna tuned up very well.

6m Antenna Farm

The only real problem I encountered was finding enough space to store all 11 antennas after they were assembled and tested. As you can see from the photo above, we had quite an “antenna farm” in our backyard during this part of our project.

7-Element LFA Assembly and Test

The final part of this phase of the project was to assemble the new 7-element LFA yagi. This antenna uses a curved reflector to further improve its pattern and lower its noise temperature.

7 Element LFA - Boom and Element Centers

7 Element LFA – Boom and Element Centers

I had just enough room in our workshop to assemble the antenna’s boom, mast clamp, truss components, and element centers.

7 Element LFA - Final Assembly

7 Element LFA – Final Assembly

I moved the antenna outdoors, where we had more room to complete the final assembly, and attached the feedline. I adjusted the SWR of the antenna with the front elevated skyward. Final SWR and driven element adjustments were made with the antenna suspended about 30 ft above the ground on a tram line.

Next Steps

The final step in our preparations was to run control cables from our shack to the junction box on our towers to enable our microHam system to control the remote Preamp Housing and Antenna Switch.

The next step in our project will be to install everything on our towers and integrate all the antennas and components into our station.

We’ll continue to post more articles in this series as our project proceeds. Here are some links to other articles in our series about our 6m Antenna Upgrade Project:

With all of our preparations complete, we are ready to install our new antennas on our tower.

Fred, AB1OC

6m Antenna Upgrade Part 3 – microHam Antenna Control System

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6m Antennas choices on the Station Master Deluxe

6m Antenna choices on the Station Master Deluxe

The next step in our project is to configure our microHam station management system to support the new antennas and other components in our 6m antenna project. Each radio in our station (we have five that are 6m capable) has a microHam Station Master Deluxe antenna controller that is used to select and control all of our antennas. These units use the band selection and frequency data from their associated Transceivers to present a set of antenna choices and associated rotator, LNA, amplifier, and other controls to the user.

We are adding the following components to our 6m antenna farm that will need to be controlled by our microHam system:

Any of these antennas and their associated Preamp Housings can be used by any of the six Transceivers in our station. There are also two Elecraft KPA-1500 1500w amplifiers (one is shared) that operate on 6m and can be used by three of the five Transceivers in our setup. In this article, I will cover the configuration of our microHam system to support all of the new elements.

Remote Antenna Switching

microHam TEN SWITCH

microHam TEN SWITCH

I choose a microHam TEN SWITCH to handle switching between the new 7-Element LFA and the 6m Antenna Stacks that we will be installing. This switch is can be mounted outdoors on our tower and has good SWR, power handling, and loss performance at 50 MHz. I also chose the option to have N-connectors installed on our TEN SWITCH.

Control Interface Installation

microHam Control Boxes - Relay 10 (Remote Ant. Switch) & Relay 6 (Preamp Housings)

microHam Control Boxes – Relay 10 (Ant. Switch) & Relay 6 (Preamp Housings)

The first step in this part of our project was to install two new microHam Control Boxes to control the new remote antenna switch and the two 6m Preamp Housings. These control boxes are connected to a control bus which allows the Station Master Deluxe antenna controllers associated with our transceivers to control all of our equipment and antennas. The microHam TEN SWITCH that we are using requires ten 12 Vdc control lines to select one of its ten antenna inputs. Each of the two 6m Preamp Housings requires a combination of two 28 Vdc control lines to manage its relays and a 13.8 Vdc line to power its LNA. The microHam Relay 10 Control Box is a good choice for controlling the antenna switch, and a single microHam Relay 6 Control Box can be configured to control the two Preamp Housings. I installed the two new control boxes and a DIN Rail Terminal Block for ground fan out on an existing section of DIN rail in our shack. Finally, I extended the microHam control bus to the new units and connected the control boxes to the 13.8 Vdc and 28 Vdc power systems in our shack, and set the addresses of the two new control boxes.

Relay 10 (Ant. Switch) and Relay 6 (Preamp Housing) Control Box Configuration

Relay 10 (Ant. Switch) and Relay 6 (Preamp Housing) Control Box Configuration

Next, we updated the firmware in the new Control Boxes. We configured their relays into groups for interfacing to the remote microHam TEN SWITCH and the components in the 6m Preamp Housings.

New Antenna and Remote Switch Configuration

microHam Ten Switch on Tower

microHam Ten Switch on Tower

The next step was to define “RF Boxes” in the microHam program for the 7-Element LFA, three fixed-direction 3-Element LFA Antenna Stacks, and the two 6m Preamp Housings that we are going to be installing on our towers.

With this done, we created an additional RF box for the microHam TEN SWITCH that will be located on our main tower. The image above shows how the switch is configured in the microHAM system. We also needed to associate the Relay 10 control box with the switch to enable the microHam system to control it.

6m Preamp Housing Configuration

6m Shared Preamp Housing.jpg

6m Shared Preamp Housing.jpg

The next step was to configure our 6m Preamp Housings. The image above shows the configuration of the shared housing installed on our main tower behind the microHAM TEN SWITCH.

Antenna Switching Matrix

Station Antenna Switching Matrix

The shared Preamp housing will be connected to one of the inputs on our antenna switching matrix shown above.

This arrangement allows us to use the 6m LNA in the housing with any of the 3-Element LFA antenna stacks or the 7-Element LFA antenna we are installing on this tower. One of the features of the microHam system is that it can understand and correctly sequence shared devices like LNAs, amplifiers, and other active RF components.

LNA Controls

Preamp Housing LNA Control

Preamp Housing LNA Control

The image above shows the configuration for the LNA control button that will appear on our SMDs. The configuration above creates a button and display to turn the LNA on or off when an associated button on one SMDs is pressed. This control will appear on the SMDs for any radio using one of the associated 6m antennas.

LNA and PTT Sequencing

Preamp Housing Sequencer

Preamp Housing Sequencer

We also need to configure a sequencing element for each of our 6m Preamp Housings. This ensures that the Push To Talk (PTT) lines and transceiver inhibit lines are properly sequenced for the transceivers, amplifiers, and relays in the Preamp Housing that is part of a path to a selected antenna. The microHam system automatically applies the appropriate timing and sequencing rules to all of the RF elements in the path based on the sequencer settings shown above. Configuring the sequencer also involved associating the appropriate relay control units on the newly installed Relay 6 Control Box with the elements in the sequencer timing diagram above. One item to note here is the 20 – 30 ms tail on the sequencing of the Preamp Housing relays when going from Transmit to Receive. This is done to allow extra time for any stored RF energy in the feedlines during high-power Tx to dissipate before bringing the LNA back into the feedline system.

We also added our second 6m Preamp Housing to the RF path for our existing 7-Element M2 Antenna on our VHF Tower and configured it similarly.

Virtual Rotator for Fixed Antenna Stacks

6m Antenna Stacks - microHam Virtual Rotator

6m Antenna Stacks – microHam Virtual Rotator

The microHam system has a Virtual Rotator feature which is a great way to control selecting between fixed stacks of antennas of the type we are installing. The image above shows the Virtual Rotator we configured for our 3-Element LFA stacks. The Virtual Rotator becomes an additional antenna choice that accepts a direction in the same way that a conventional rotator does. The microHam system figures out which of the available stacks would best match any heading selected and automatically switches the antenna path to the stack that best matches the chosen heading. This capability will be a great tool in VHF contests when we are working multiplier grids on 6m.

microHam Control App - 7-Element LFA, shared LNA, and Rotator Controls

microHam Control App – 7-Element LFA, shared LNA, and Rotator Controls

Final Testing

With all the configuration work done, I downloaded the final microHam program to all of our Control Boxes and SMDs and did some more testing. I connected one of our 6m Preamp Housings to the newly installed Relay 6 Control Box and tested the operation with our Transceivers. Everything worked as expected.

I also used the microHam Control App (shown above) to test the various combinations of 6m antenna selections and configured options. The image above shows the selection of the new 7-Element LFA we are adding. Note the availability of controls for the LNA in the shared Preamp Housing and the controls for pointing the antenna via the associated rotator.

Virtual Rotator for 6m Stacks

Virtual Rotator for 6m Stacks

The image above shows the selections and controls for the 6m Antenna Stacks. The Virtual Rotator choice (STK-VR) is selected in this example. Each SMD has a control knob that can be turned to any heading. When the heading for the STK-VR antenna choice is changed, the system automatically chooses the stack that most closely matches the chosen direction. Choices are also available to choose any of the three stacks directly (ex. EU-STK for the LFA stack facing Europe).

microHam Control App - 6m Split Tx and Rx Antennas

microHam Control App – 6m Split Tx and Rx Antennas

Another nice feature of the microHam system is its ability to use different antennas for Transmit and Receive. The example above shows a setup that uses two different antennas for Tx and Tx.

As you can probably tell, the microHam Station Master Deluxe (SMD) system provides many features for controlling complex antenna arrangements and shared equipment. You can learn more about the microHam SMD system and what it can do here. You can learn more about the programming and operation of the SMD components via the SMD manual.

Next Steps

We’ll continue to post more articles in this series as our project proceeds. Here are some links to other articles in our series about our 6m Antenna Upgrade Project:

Our new LFA antennas and supporting equipment have arrived. The next step in our project will be assembling them and creating an adjustable mounting system for the 3-Element LFA antennas in our stacks.

Fred, AB1OC

6m Antenna Upgrade Part 2 – High-Power Preamp System

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6m High-Power Preamp Housing

6m High-Power Preamp System Housing

The next step in our 6m Antenna upgrade project is to build two high-power preamp housings using high-performance, Low-Noise Amplifiers (LNAs). I plan to use one of the housings with

our existing 7-element Yagi on our house-bracketed tower and the other housing as a shared preamp system for the new 3-element stacks and the new 7-element Yagi on our 100 ft tower. The housings handle legal limit power (1500w) in all modes, including digital modes.

Preamp System Design

6m Preamp System Design

6m Preamp System Design

The diagram above shows the design of the 6m preamp systems we are building. The main RF path is switched via a pair of high-power vacuum relays. The low-noise LNA we choose includes an RF bypass feature so that the un-amplified receive path can be maintained when the LNA is turned off. I added a relay to the system to provide additional isolation and protection for the LNA when the system is in Tx mode. The protection relay also provides terminations for the LNA when the system is in Tx mode. This provides an extra degree of protection and ensures that the LNA is operational and stable as soon as the system switches to Rx mode. I have added a 1N4007 1000V diode across each relay coil to avoid voltage spikes on the control lines when the relays are de-energized.

System Components

6m Preamp Housing Component Details

6m Preamp Housing Component Details

All of the components in the preamp system are mounted in a 12″ x 10″ x 5″ NEMA housing from Cooper B-line (PN 12105-12CHC). I purchased two of these from a local electrical supply store. In addition to the relays and LNA, I used the following components to complete the 6m Preamp Housings:

Sections of 1/4″ aluminum bar stock are bolted to the mounting tabs on the enclosure to provide a means to anchor the enclosure to our towers via Saddle Clamps. Female N connector bulkheads provide the RF connections to the antenna and Amplifier/Feedline sides of the preamp system. The relays and LNA are mounted to the plate that came with the enclosure. A piece of aluminum bar stock material and some aluminum tubing were used to make a stand-off mount for a screw connector terminal block for the control connections to the preamp system.

Main Feedline Path

M2 HPR-1 High Power Coaxial Relay

M2 Antenna Systems HPR-1 High Power Coaxial Relay

I choose the HPR-1 Vacumn relays from M2 Antenna Systems to implement the main Tx/Rx path in the preamp system. These relays handle the power levels required and provide an extra degree of protection should an accidental hot-switch event occur. They provide 32 dB of isolation at 50 MHz which is not quite enough to fully protect the LNA at legal limit power. These relays are 24 Vdc powered and are switched together.

LNA and Protection Relay

6m Antenna Project

Advanced Receiver Research RF Switched LNA

I choose a GaAsFET LNA from Advanced Receiver Research (PN SP50VDG) for the preamp system. This LNA provides 24 dB of gain, has a low noise factor of 0.55 dB, and has a relatively high dynamic range and immunity to overload. The LNA is 12 Vdc powered. I choose at RF switched version of this LNA as it includes an RF relay that bypasses the LNA circuitry when the unit is powered off. This will allow me to turn off the LNA remotely and use my antennas without the additional amplification provided by the LNA. This also allows SWR measurements to be made through the preamp system without having to force the preamp system into Tx mode.

M2 HPR-1 High Power Coaxial Relay

M2 HPR-1 High Power Coaxial Relay

I added a DPDT relay from Tohtsu (PN CX-800N) to provide additional isolation to protect the LNA during Tx. This relay provides an additional 50 dB of isolation and is 24 Vdc powered. The protection relay is used to switch a combination of a short circuit (on the LNA input) and a 50-ohm termination (on the LNA output) during Tx. The combination of the relays provides over 80 dB of isolation during Tx. The isolation relay, the terminations, and the high overload capability of the LNA should ensure safe and trouble-free operation at legal limit power.

Power, Control, and Sequencing

microHAM Control Boxes And Hub

microHAM Control Boxes

I will use our microHam system to provide the switching and sequencing capabilities required to operate the preamp housings. The microHam system enables devices like LNAs to be placed in feedline paths where they can be shared among multiple antennas, amplifiers, and transceivers. The microHam system includes shared control boxes (ex. Relay 6 shown above) that provide relays that we will use to control the LNA powering and relays in our preamp housing. I will share more on this part of the project in the following article in this series. Our station includes bulk DC power supplies that provide 28 Vdc and 13.8 Vdc power to drive the relays and power the LNA in the preamp housings.

Next Steps

We’ll continue to post more articles in this series as our project proceeds. Here are some links to other articles in our series about our 6m Antenna Upgrade Project:

The next step in this project will be to configure our microHam system to support the Preamp Housings and the remote antenna switching elements that are part of our project.

Fred, AB1OC

6m Antenna Upgrade Part 1 – Plans for Antenna Enhancements

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6m LFA Yagi for Field Day and Mountain Topping

6m LFA Yagi for Field Day and Mountain Topping

I’ve been very active on 6m over the past several years. I am closing in on DXCC and Worked All States on the magic band. I operate on 6m daily during Es season. We are also very active in VHF contesting on the 6m band and have worked just under 700 grids on 6m.  This post is about our plans to develop an enhanced 6m antenna system for contesting and DX’ing.

6m LFA Antenna for Field Day

6m LFA Portable Antenna System

We developed an updated 6m antenna system for Field Day and portable use a few years back. The portable setup is based upon a 3-element Loop Fed Array (LFA) antenna from InnoVAntennas. I was impressed with the improvement in the ability to hear weak stations above the noise floor compared to our previous 3-element conventional yagi antenna. Subsequent conversations with Joel Harrison, W5ZN suggested that fixed direction stacks of 3-element antennas would make a very good setup for 6m contesting and grid chasing. This led to our plans for some significant 6m antenna upgrades at our station.

6m Antenna Plans

Our planned 6m antenna upgrade consists of the following elements:

All of these antennas will use 7/8″ hardline coax cables for the main segments of their feedline system.

6m Antenna Project

Advanced Receiver Research RF Switched LNA

I am in the process of building two high-power capable LNA systems for our 6m antennas. These systems will be based upon low noise factor (0.55 dB) GaAsFET RF switched preamps from Advanced Receiver Research. These LNAs should improve the overall noise-factor performance of the 6m receivers in our station by a noticeable amount. We choose the RF switched version of these preamps so that we could disable the preamps and maintain a direct receive path through the LNAs to our antennas. This is desirable for SWR testing and for situations where very strong signals may cause overloading. It also ensures that we can continue to use our antenna should we experience an LNA failure.

I plan to use the shared LNA sequencing capability of our microHam system to control the two LNA systems. All of the antennas for this project will come from InnoVAntennas. The 3-element LFA antennas will be custom-made for fixed direction rear mounting on our tower.

Why LFA Antennas?

The use of a loop-driven element has several advantages, which include:

  • Better suppression of side lobes in the antenna pattern, which results in an antenna that hears better (lower noise temperature)
  • The potential for an efficient direct feed design that does not require driven element matching
  • Wider useful bandwidth
InnoVAntennas 7 Element WOS LFA

InnoVAntennas 7 Element WOS LFA

The 7-element LFA Yagi that I chose takes this one step further by employing a bent reflector to further improve the ability to suppress side and rear lobes in the antenna’s pattern and further improve the antenna’s noise temperature.

6m Antenna Stack Designs

I performed several High-Frequency Terrain Analysis (HFTA) runs to determine the heights and directions for our 4-Stack Antenna Arrays.

6m Antenna Project

4-Stack Facing the EU – Gain vs. Arrival Angles

The example above shows the projected performance of the 4-stack facing Europe. The 3-element LFA Yagi that we are using has a 3 dB azimuthal beamwidth of about 60 degrees. This gives each stack an effect range of azimuth angles approximately the same as the 3 dB beamwidth. The headings that I choose for the stacks are as follows:

  • Europe facing 4-stack – 50 degrees
  • Central/South America and the Caribbean facing 4-stack – 180 degrees
  • The United States facing 3-stack – 260 degrees

I looked at both a 3-Yagi and a 4-Yagi configuration for the U.S.-facing stack on the top half of our tower. It turned out that the 3 Yagi design did a better overall job of covering the range of arrival angles that we can expect. This situation is due to the high elevation of the stack above ground and the wide range of potential arrival angles encountered when working stations across the U.S.

The combination of the new and existing 7-element 6m rotatable Yagis that I am planning or already have installed should cover the remaining directions nicely.

6m Antenna Project

Gain vs. Arrival Angles Towards Oceania – 7-Element Yagi and 3-Stack

The HFTA analysis illustrates the performance of the combination of the west-facing 3-stack and the new 7-element LFA Yagi towards Oceania (ex., Australia and New Zealand). The minimum gain achieved by switching between these two antenna systems is never less than 10 dBi. This part of the analysis also suggests good performance towards Hawaii.

6m Antenna Project

7-Element LFA Yagi Gain vs. Arrival Angles for Japan and Asia

Finally, I looked at the projected performance of the 7-element LFA Yagi towards Japan and Asia. The height above ground for this antenna results in good performance at low arrival angles and a good bit of gain variation across arrival angles. The low noise performance of this antenna, combined with our planned use of high-performance LNAs in the receive path, should provide some opportunities to work stations in Japan and Asia.

I also built a combined EZNEC model to look at possible interactions between these and other antennas on our tower. This analysis indicated that we should be fine if we remove the 6m passives from our SteppIR DB36 antennas. The combination of the stacks and the new 7-element LFA Yagi we are planning will replace the 6m capabilities that our SteppIR antennas have been providing.

Next Steps

The antennas will arrive in the next few weeks, and work is underway to build the high-power LFA housings. I will be posting additional articles about this project as we go. Here are some links to other articles about our 6m Antenna Upgrade Project:

Fred, AB1OC

Plans for Field Day 2021 – Nashua Area Radio Society

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We are holding an in-person Field Day operation at Keyes Memorial Park in Milford, NH. Here’s some more on our plans for Field Day 2021. We’d like to invite you to join us…

Source: Plans for Field Day 2021 – Nashua Area Radio Society

I’d like to invite our friends here on our Blog to visit us during Field Day on Saturday, June 26th, and Sunday, June 27th. We will be at Keyes Memorial Park in Milford, NH.

Testing Our Field Day Satellite Station

Testing Our Field Day Satellite Station

We will have a Tower up with a Triband Yagi and we’ll have our computer-controlled portable satellite station at Field Day.

6m LFA Antenna for Field Day

6m LFA Antenna for Field Day

We’ll also have a new LFA Yagi for the 6m Band. We will be a 4A station with a total of 5 Transmitters on the air. Our stations will be equipped for SSB Phone, CW, and FT8/FT4 Digital modes.

We’ll also be doing training sessions on Satellite Operations, FT8 Digital on 6m, and Fox Hunting at 12:30 pm on Saturday, June 26th. If you have an HT, bring it and you can use it to hunt our foxes. We’ll also have HTs available for folks to use for Fox Hunting.

You can read more about what we are planning and find directions to get to our Field Day site here. I hope that we’ll see some of our followers at Field Day!

Fred, AB1OC

Field Day Satellite Station for 2021 – Setup and Test in Hollis

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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…

Source: Field Day Satellite Station for 2021 – Setup and Test in Hollis

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.

The setup uses an M2 Antenna Systems LEO Pack Antenna System on a Glen Martin Aluminum Tower that is set up to be portable. Feedlines use 100 ft lengths for LMR-400uF and LMR-600uF coax cable for the 2m and 70cm bands. The rotator is an Alfa-SPID Az/El unit. The antenna system also uses coax-powered preamplifiers from Advanced Receiver Research. The station uses an IC-9700 Transceiver, a Green Heron RT-21 Az/El Rotator Controller, and a MacBook Air Laptop running MacDoppler and MacLogger DX.

This setup is an updated version of the portable satellite station that we built for an ISS Crew Contact that a local school did with us some time ago.

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!

Fred, AB1OC

6m LFA Yagi for Field Day and Mountain Topping

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6m LFA Yagi for Field Day and Mountain Topping

6m LFA Yagi for Field Day and Mountain Topping

Our 6m Field Day station will be a portable setup and features a new antenna – a 3-Element Loop Fed Array (LFA) Yagi from InnoVAntennas…

Source: 6m Field Day Station – Nashua Area Radio Society

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.

Fred, AB1OC