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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

Tech Night – EME II: Station Construction and Operation

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EME II - Station Construction and Operation

EME II Tech Night – Station Construction and Operation

We recently did a second Tech Night Program on EME as part of the Nashua Area Radio Society’s Tech Night program. I wanted to share the presentation and video from this Tech Night so that our readers might learn a little more about how to build and operate an EME station for the 2m band.

January 2021 Tech Night – EME II: Station Construction and Operation

You can view the Tech Night presentation by clicking on the video above. Here’s a link to the presentation that goes with the video. You can learn more about the Nashua Area Radio Society’s Tech Night program here. There is a demonstration of an actual live EME contact on the 2m band at 57:57 in the video.

The first Tech Night in the EME Series was about Getting Started in EME Communications. You can view that Tech Night here.

We are in the process of upgrading our EME station to include adaptive polarity. you can read more about that project here.

A key part of optimizing our EME Station was to reduce RFI from the network in our home. You can read about the installation of Fiber Optic Networking to reduce RFI and improve our EME station’s performance here.

Fred, AB1OC

EME Station 2.0 Part 11 – Station Hardware In Shack

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EME Station Hardware Components

EME and Satellite Ground Station Hardware Components

Now that our 2m EME Antenna Array is fully installed, we have turned our attention to the setup of the equipment in our Shack. We plan to mix JT65 Digital and CW operation with our 2m EME Station.

The image above shows our station’s equipment dedicated to EME and Satellite operations. We built some shelves to make room for all of the equipment and create space to move our Satellite Ground Station 4.0 to this same area. The components in our 2m EME station include (left to right):

We’ll explain each of these components and the supporting shack infrastructure we are using for EME below.

Phase 1 EME Station Architecture

EME Station Block Diagram - Phase 1

EME Station Block Diagram – Phase 1 (Manual Rx Polarity Selection)

Unfortunately, the LinkRF Receiver and Sound Card to enable a full MAP65 Adaptive Polarity installation are not currently available. As a result, we’ve created a Phase I Architecture that uses an SDR Dongle and manual selection of Receive Polarity via a switch. We also added a receive splitter and a Transmit/Receive relay in front of an Icom IC-9700 Transceiver, which is dedicated to our EME setup to enable both the MAP65 and one of either the WSJT10 or WSJT-X Software Decoders to operate simultaneously.

This approach has some significant advantages when conditions are poor, as one of either MAP65 or WSJT10/WSJT-X will often decode a marginal signal when the other will not. More on this in the next article in this series which will explain the software we are using more.

Transceiver, SDR Receiver, and Sequencing

IC-9700 Transceiver and Sequencer

IC-9700 Transceiver and Sequencer

A combination of an Icom IC-9700 Transceiver and M2 Antennas S2 Sequencer handle the Transmit side of our EME Station, including the associated sequencing of the preamplifiers and Transmit/Receive Switching, which is part of our Antenna System. The IC-9700’s receiver is also used with the WSJT10 Decoder in our setup.

IC-9700 Frequency Drift and Stability

Controlling IC-9700 frequency drift - GDSO Injection Board Installed in IC-9700

Controlling IC-9700 Frequency Drift – Reference Injection Board Installed in IC-9700 (Leo Bodnar Website)

To ensure good frequency stability and limit IC-9700 frequency drift in our setup, we installed a Reference Injection Board from Leo Bodnar in our IC-9700.  The Reference Injection Board uses Leo Bodnar’s Mini Precision GPS Reference Clock (the small device on top of our IC-9700 in the photo above) to lock the IC-9700 to a highly accurate GPS-sourced clock. The installation and configuration of the Reference Injection Board in our IC-9700 were simple, and Leo Bodnar’s website covers the installation and setup procedure for these components. FUNcube Dongle Pro+

FUNcube Dongle Pro+

In our setup, we used a FUNcube Dongle Pro+ as a second Software Defined Radio (SDR) Receiver and as an I/Q source to drive the MAP65 Software. Information on configuring the MAP65 software to work with this dongle can be found here.

EME Station RF Paths and Sequencing

EME Station RF Paths and Sequencing

The diagram above shows the RF Paths and associated sequencing in our Version 1 EME Station. A Manual Antenna Switch is used to select either Horizontal or Vertical polarity when in receive mode. The S2 Sequencer handles polarity selection during transmission. A splitter divides the Rx signal between the FUNcube Pro+ Dongle for MAP65 and a Transmit/Receive Switching Circuit in front of our IC-9700 Transceiver. The relay enables the IC-9700 to provide Transmit signals for the MAP65 and WSJT10/WSJT-X Software applications. The IC-9700 drives a 1.2 Kw Amplifier during Transmit, and the final Tx output is metered using a WaveNode WN-2 Wattmeter.

Completed T/R Relay Assembly

Completed T/R Relay Assembly

To enable both the receivers in our IC-9700 and the FUNcube Dongle to function simultaneously, we built a circuit using a CX800N DPDT RF Relay and a Mini-Circuits 2-Way RF Splitter. We also built a simple driver circuit for the relay using a Darlington Power Transistor and some protection diodes. The circuit enabled our S2 Sequencer to control the relay along with the rest of the sequencing required when changing our EME Station from Receive to Transmit and back.

Finally, we configured a 30mS transmit delay in our IC-9700 to ensure that the S2 Sequencer had some time to do its job as the station changed from Receive to Transmit. This delay and the Transmit delays built into the MAP65 and WSJT10 software ensure we will not hot-switch the MAP65 Preamp System on our tower. One must be very careful to ensure that RF power is not applied before the sequencer can transition to the Transmit state or damage to the Preamplifiers and/or relays at the tower will occur.

Amplifier and Rotator Controls

EME Station Hardware Components

EME and Satellite Ground Station Hardware Components

The Elevation Rotator from our Antenna System was added to the Green Heron RT-21 Az/El Rotator Controller previously installed in our shack, and both the Azimuth and Elevation Rotators were roughly calibrated. Our EME station requires quite a few USB connections to our Windows 10 Computer, so we added a powered USB hub to our setup. Chokes were added to the USB cables which run to our IC-9700 Transceiver and our FUNcube Dongle to minimize digital noise from getting into our receivers.

Our 2M-1K2 Amplifier can produce about 1KW of power on 2m when operating in JT65 mode, and this should be enough power for our planned EME wor. Our S2 Sequencer also controls the keying of our Amplifier as part of the T/R changeover sequence in our EME station.

WaveNode WN-2 Wattmeter

WaveNode WN-2 Wattmeter

We added a 2m high power sensor to the output of our Amplifier and connected it to a free port on one of the WaveNode WN-2 Wattmeters in our station to provide output and SWR monitoring of the Transmit output of our EME station.

Supporting EME Station Infrastructure

VHF+ Antenna Switching Console

VHF+ Antenna Switching Console

We had some work to do to configure our station’s antenna, grounding, and DC power infrastructure. We redid the manual switching in our VHF/UHF Antenna Switching consoles to accommodate our new EME Antenna System and prepare for our Satellite Station to be moved into our shack soon. The console on the right provides the Grounding of the Transmit and Receive sides of our EME Antenna System as well as the selection of the Antenna’s Horizontal or Vertical polarity for decoding.

We also expanded our station grounding system to provide a ground point directly behind our EME equipment. Our DC power system was also expanded to accommodate our EME equipment.

GPS NTP Server

GPS NTP Server

Our station already has a GPS Controlled NTP Time Server installed, and we’ll use it to ensure that the clock on the PC, which will run the MAP65 and WSJT10 software, will have very accurate clocks for JT65 decoding.

EME Tower CAM

EME Tower CAM

We already have cameras that cover our Main and Satellite Towers. We’ve added a third camera to allow us to view our EME Tower’s operation from our shack. This ensures that we can visually confirm the operation of our antennas and detect any problems should they occur.

Next Steps

All of the new EME equipment has to be integrated and tested with the software components which provide digital operation, tracking of the moon, logging, and other functions in our station. The software setup, as well as our initial experience with operating our new EME station, will be covered in the next article in this series.

You can read more about our EME station project via the links that follow:

If you’d like to learn more about How To Get Started in EME, check out the Nashua Area Radio Society Tech Night on this topic. You can find the EME Tech Night here.

A key part of optimizing our EME Station was to reduce RFI from the network in our home. You can read about the installation of Fiber Optic Networking to reduce RFI and improve our EME station’s performance here.

Fred, AB1OC

EME Station 2.0 Part 5 – Control Cables and Rotator Controller

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Control Cable Junction Box on EME Tower

Control Cable Junction Box on EME Tower

Snow is coming to New England this weekend so we wanted to get the control cables run to our new EME Tower before the ground is covered with snow. The project involved installing a Utility Enclosure on our tower and running three control cables to our shack for the following devices:

Az-El Rotor and Preamp Switching Control Connections

Az-El Rotator and Preamp Switching Control Connections

We began by install some barrier strips and a copper ground strap in the Utility Enclosure. The copper strap provides a good ground connection to the tower and associated grounding system. The enclosure is clamped to the tower using two stainless steel clamps.

We ran three new control cables through the conduits that we installed between the tower and our shack and terminated them in the utility enclosure. We only needed 6 leads for control of the planned MAP65 Switching and Preamp System which will go on our tower later so we doubled up some of the higher current connections using two wires in the 8-conductor cable.

Green Heron RT-21 Az-El Rotator Controller

Green Heron RT-21 Az-El Rotator Controller

The final step was to hook up our rotator cables to a Green Heron RT-21 Az/El Rotator Controller in our shack.  We do not yet have our elevation rotator so we tested the M2 Orion 2800 Azimuth Rotator that is installed in our tower. The azimuth rotator is configured so that the rotator’s dead spot faces north. This is a good configuration of our planned EME operation.

With all of our control cabling in place, we are ready to begin preparing our Antennas, Elevation Rotator, H-Frame, and MAP65 components to go on our EME Tower. We’re hoping that the weather will cooperate and enable us to get these steps completed during this winter.

Here are some links to other articles in our series about our EME Station 2.0 project:

If you’d like to learn more about How To Get Started in EME, check out the Nashua Area Radio Society Teach Night on this topic. You can find the EME Tech Night here.

Fred, AB1OC

GPS Time Server

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GPS NTP

GPS Controlled Time Server

There are many reasons to have an accurate time source in your station. Getting the best performance from WSJT-X modes like FT8 requires your computer clock to be synchronized within a second for example. You can set your clocks accurately using NTP servers on the Internet. This is the most common way that most stations set their clocks.

What if you are portable and don’t have Internet access or what do you do if your Internet connection goes down? One way to solve these problems is to use a GPS-controlled NTP time server in your station. We recently installed one from Leo Bodnar in our station.

GPS NTP

GPS Antenna

This device is simple to install. It just requires an Ethernet connection to your network and a GPS antenna. The antenna is included with the unit. The antenna will need to be outdoors with a reasonably clear view of the sky.

GPS NTP

GPS Satellite Lock Screen

After a minute or so after it is installed and powered up, the unit will synchronize to the visible GPS satellites in your location and report its coordinates. This indicates that you have a good GPS system lock and that the clock in the unit is accurate to within a microsecond.

GPS NTP

NTP Summary Screen

The unit gets its IP either from DHCP or via a fixed IP address that you can program. Once the unit is set, you use its IP address as the NTP server in your software to set your clocks. You would set your NTP server in a program like Dimension 4 to accurately set your computer’s clock for example. You will want to disable your computer’s normal Internet clock setting function to avoid conflicts with Dimension 4. Once this is set up, your computer clock will be synchronized to the GPS system and will be very accurate and you will get the best performance from WSJT-X.

Fred, AB1OC

Satellite Station 4.0 Part 7 – Flex SDR Satellite Transceiver

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Flex-6700 SmartSDR in Satellite Mode

A major part of our plans for Satellite Station 4.0 includes the ability to operate our home satellite station remotely over the Internet. We’ve been using our Flex-6700 Software Defined Radio (SDR) as a Remote Operating Gateway (GW) on the HF Bands and 6m for some time now. Our latest project is to upgrade our Remote Operating GW to support satellite operations on the 2m, 70cm, and 23cm bands.

Remote Gateway Rack with Satellite Additions

Adding the additional bands for satellite operations involves adding a 2m Amplifier, a 70cm Transverter, and a 23cm Upconverter to our SDR-based Remote GW. We decided to repackage our Remote GW set up in a rack mount cabinet on casters. This allows all of the required gear to be placed under the desk in our station in a way that is neat and reliable.

We also added an Ethernet Switch, a pair of USB hubs, and upgraded power and remote controls to improve our ability to manage our station remotely and to simplify the interconnections between our Remote GW and the rest of our station. The final assembly mounts all of the components in the rack on 5 levels as follows:

The purpose of these components is explained in more detail below.

All of these devices are powered from 13.8 Vdc station power to avoid the potential for noise from wall wart transformers inside the rack. Also, attention was paid to the isolation of the digital and RF components on separate levels to minimize the chance that noise from digital signals would leak into the RF chains.

Satellite SDR

Remote Satellite SDR System Design

The diagram above shows how the added components for the satellite bands interconnect with the Flex-6700. The new components include:

The Flex-6700 can generate and receive signals on the 2m band but it does this at IF power levels. The 2m LPDA brings the IF power level up to a maximum of 75 watts. The DIPs device enables the Flex-6700 to operate in U/v, V/u, and L/v modes.

The 28 MHz splitter allows a total of 4 transverters/upconverters to be connected to the radio. This will enable us to add 5 GHz and 10 GHz bands to our satellite station in the future.

Our Flex-6700 includes a GPS Disciplined Oscillator (GPSDO) which provides an accurate and stable 10 MHz reference output to lock the 70cm and 23cm transverter frequencies. The 10 MHz Reference Distribution Amplifier expands the single 10 MHz on the Flex-6700 to drive up to 4 transverters or upconverters.

The two USB cables allow the Flex-6700 and SmartSDR to control the LPDA and PTT for the 70cm and 23 cm bands.

2m/70cm Shelf

The rackmount arrangement uses shelves which provide ventilation for the components and enable us to use zip ties to tie down all of the components. The photo above shows the layout of the shelf which contains the 2m LPDA, the 70cm Transverter and many of the RF interconnections. Velcro tape is used to secure the smaller components to the shelf.

2m/70cm Shelf RF Interconnection Details

The photo above shows the RF interconnections. The 70cm Transverter is on the upper left and the 2m LPDA is on the upper right. The rectangular boxes coming from these devices are the sensors for the WaveNode WN-2 Power and SWR Meter that we are using. They are terminated in 50-ohm dummy loads for initial testing. The DIPS device is center bottom and the 4-port device above it is the 28 MHz splitter. All of the interconnections are handled using 50-ohm BNC cables and the unused ports on the 28 MHz splitter are terminated with 50-ohm BNC terminators.

Rear View of Remote Gateway Rack

The photo above shows the rear of the unit. The 10 MHz Reference Distribution Amplifier (bottom center) and the two Industrial 12V powered USB hubs are visible at the bottom of the unit. The DC power distribution components are at the upper left and a set of Internet-controlled relays are at the upper right.

USB Connections via Hubs

One of the USB hubs fans out a single USB connection from the host PC to the USB controlled devices in the Remote GW rack. The other USB hub expands the USB outputs of the Flex-6700 to accommodate the control cables for the devices in the rack and the CAT cable which provides frequency data to the microHam SMD Antenna Controller.

Power Control and Distribution Design

Remote control and distribution of DC power to all of the devices in our Remote GW is an important design consideration. In addition to proper fusing, one must be able to remotely turn devices on and off remotely. The diagram above shows the power distribution and control architecture that we are using.

13.8 Vdc Power Distribution

RigRunner power distribution blocks are used to fuse and distribute power to all of the accessory devices in the rack.

Remote Gateway Power Controls

The RigRunner 4005i provides remote power control via the Internet for all of the major units and accessories in the rack. In addition to controlling power on/off states and providing electronic fusing, the RigRunner 4005i monitors voltage and current to the equipment in the Remote GW. These controls are accessed via a web browser and a network connection. Login/password security is also provided.

Remote Control Relay Unit

A microBit Webswitch device provides Internet controlled relays to manage various station functions including:

After some configuration of the Transverters and PTT controls in SmartSDR, the satellite portion of our Remote GW is up and running. There is quite a bit of software installation and configuration left to do and we’ll cover that in a future post.

You can find other articles about our Satellite Station 4.0 project here:

Can learn more about the SDR-based Remote Operating Gateway at our station here.

Fred, AB1OC

Satellite Station 4.0 Part 6 – Tower Finishing Touches

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New Shack Entry and Ground Block

We recently completed the finishing touches on our new VHF/Satellite Tower. The first step was to install a second set of entry conduits into our shack and a new ground block for our satellite antennas. This involved installing 4″ PVC conduits into our shack. The new entries are very close to the base of our tower and this will allow us to keep our feedlines as short as possible.

Hardline Coax Cables Up The Tower

We also replaced the section of our feedlines which run down the tower with 7/8″ hardline coax. We installed a total of four runs for 6m, 2m, 70cm, and 23cm. The use of hardline coax will help reduce our feedline losses – especially on 70cm and 23cm.

Hardlines at Base of Tower

The new hardlines are connected one of the two entries into our shack. The 6m hardline enters on the side closes to our antenna switching matrix and the 2m, 70cm, and 23 cm hardlines will enter the shack via the newly created entry which will be close to our satellite transceiver.

The next step in our project will be to upgrade our Flex-6700 SDR based Remote Gateway for operation on the satellite bands. You can find other articles about our Satellite Station 4.0 project here:

Fred, AB1OC

Upgrading our 2.0 Satellite Station for ARISS Contacts

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We have been working with Hudson Memorial School near Nashua, NH, to prepare for a possible ISS crew contact. The ARISS folks work with schools and their Ham Radio helpers to prepare for these contacts. ARISS provides recommendations for ground station equipment to help ensure a good experience for the students. The ground station recommendations provide solid specifications to support communications with the ISS on the 2m band. The recommendations include things such as:

  • A requirement to build both a primary and a backup ground station
  • Radio and power specifications (a 200W amp is recommended)
  • Antenna specifications, including recommendations to provide for switchable LHCP and RHCP
  • Computer-controlled azimuth/elevation positioning of antennas to track the ISS
  • Use of a receive preamplifier at the antenna
Portable Satellite Station 3.0 Antenna System

Portable Satellite Station 3.0 Antenna System

We have recently completed the construction and testing of our Portable Satellite Station 3.0, built specifically to meet the primary station requirements for our ISS contact.

Our plan is to add some upgrades to our Portable Satellite Station 2.0 to create a Portable 2.1 Station that meets the backup station requirements. These upgrades will include:

All equipment needed to upgrade our 2.0 Portable Station to 2.1 is here or will arrive shortly. Here’s some more information on the planned equipment.

Icom IC-910H Transceiver

Icom IC-910H Transceiver

The Icom IC-910H was Icom’s flagship Transceiver for Satellite work before the IC-9100 was released. It’s a very nice satellite radio! Dave, K1DLM, graciously lent us his IC-910H for use in our backup station.

Green Heron RT-21 AZ/EL Rotator Controller

Green Heron RT-21 AZ/EL Rotator Controller

We already have a Green Heron Az/El Rotator controller setup for the Yaesu Rotator system on the 2.0 Antenna Tower, and we will be reusing it for the 2.1 station.

GHTracker Running On A Raspberry Pi 3

GHTracker Running On A Raspberry Pi 3

We are also planning to build a second Raspberry Pi Rotator Interface for it.

M2 Antenna Systems PS2MCP8A Polarity Switch

M2 Antenna Systems PS-2MCP8A Polarity Switch

M2 Antenna Systems recently added a new 2M polarity switch, the PS-2MCP8A, designed for use with the 2M antenna in their LEO Pack, which we use in our 2.0 Antenna System. We will install this relay and a PS-70CM polarity switch relay for the LEO pack’s 70cm antenna as part of the 2.1 Antena System upgrade.

DXEngineering EC-4 Control Box

DXEngineering EC-4 Control Box

We will add another DXEngineering EC-4 BCD Control Console to control the polarity switching relays on the upgraded antennas.

m RM ITALY LA-250V Amplifier

RM ITALY LA-250V Amplifier

The final new component in our 2.0 to 2.1 upgrade is the addition of a 200W RM ITALY LA 250 power amplifier. We have opted for the version of this amplifier with the cooling fans. The unit is very well made, and we are anxious to see how it performs on the air.

Some of our readers might be wondering what we are planning to do with all of the Portable Satellite Ground Station equipment in the long run? We plan on keeping the 1.0 Portable Station for grid square activations and demonstrations. Its simple, battery-powered approach and small antenna make it ideal for this work.

The upgraded 2.0 Portable Station with enhanced polarity switching will become our transportable station for License Class and Field Day use. It will be converted at the end of 2018 to use our Icom IC-9100 Transceiver, which is currently part of the 3.0 station.

We plan to use the Portable 3.0 Station throughout the year (2018) to support the planned ARISS contact, Field Day, and some demonstrations at local Ham Fests and schools. Once these are complete, we plan to permanently install it here at our QTH, and it will become our main satellite ground station at our home QTH.

You can view all the articles about our Portable Satellite Stations via the links below.

We will begin construction of the 2.1 upgraded station once a few remaining components arrive here. We plan to share more about the construction and initial testing of our 2.1 Portable Station here.

Fred, AB1OC

PTT Router for Satellite Station 3.0

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ARR Satellite Preamp

Advanced Receiver Research Remote Preamp

Our Satellite Station 2.0 antenna system uses a pair of Advanced Receiver Research Remote preamplifiers at the antennas to boost weak signals. These preamps have RF sensing and switching to protect them during transit. While this system works well; we are always concerned about the impact of the RF power affecting the long-term reliability of these devices and the associated radio equipment.

M2 Antenna Systems S3 Sequencers

M2 Antenna Systems S3 Sequencers

Our Satellite Station 2.0 uses a pair of M2 Antenna Systems S3 Sequencers to control the preamps remotely. For U/V and V/U mode satellites, it’s simple to turn off the uplink band preamp to protect it against RF during transmission. The problem with this approach comes when working satellites and the International Space Station in simplex (single band) modes. In these situations, we need a solution that keys the sequencers externally so that the sequencers can properly control the changeover of the preamps from receive to transmit mode before keying our radio (an Icom IC-9100). We also wanted a solution that could also allow the radio to initiate the keying of the sequencers for CW break-in keying and digital modes.

PTT Router

PTT Router

Our solution was to design and build a simple Push-To-Talk (PTT) router. This device allows an external source, such as a footswitch or a trigger switch, to initiate the keying. The design also includes indicators that confirm that the keying sequence has been completed.

PTT Router Schematic Diagram

PTT Router Schematic Diagram

Our first step was to create a simple design that allowed an external switch or the radio to initiate keying. The PTT source switch (S1) selects the keying source and uses the Hsend  (2m key) and Vsend (70cm/1.2 GH key) lines on the Icom IC-9100 accessory jack as either the means to key the radio or the means to detect that the radio has initiated a transmit keying sequence. A second switch (S2) selects which VFO is keyed when the keying source switch (S1) is in External mode. Finally,  indicators for power and keying complete were added.

Rear Panel Connectors

Rear Panel Connectors

A small enclosure was used to house the switches, indicators, and connections to the rest of our Satellite Station. The image above shows the rear-panel connections to external PTT sources, the S3 Sequencers, the IC-9100 Radio, and a 12 Vdc station power source.

PTT Router Internal View

PTT Router Internal View

A pair of terminal strips were mounted inside the enclosure to make connecting all components easier. The wiring around the front and rear panels is pretty dense, so connections were insulated with heat shrink tubing. A small PCB could easily be created to make replicating the prototype easier should we build more copies of the design.

Satellite Station 3.0 Controls

Satellite Station 3.0 Controls

Our new PTT router was easy to integrate into our Satellite Station 3.0 setup. Integration required custom cables to connect our PTT router to the sequencers and the accessory jack of the radio. With the integration completed, we are now able to properly sequence the control of the preamps and the radio in all modes of operation. Here are some more articles which include more about our portable satellite stations –

Fred, AB1OC

An 80m Broadband Matching System

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Our Tower with 75m Loop

Our Tower with 75m Loop

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

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

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

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

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.

Layout of Components in Enclosure

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

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

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

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

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

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

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

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

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.

Fred, AB1OC