Amatuer Radio Video How-To – Putting Up A Tower

July 2019 Tech Night – Putting Up A Tower

We recently did a how-to presentation on Putting Up A Tower at a Nashua Area Radio Society Tech Night. The video from this presentation can be viewed above.

Putting Up A Tower Video – Topics Covered

We covered a variety of information related to planning, building and integrating Guyed and House-Bracketed towers. You can view the accompanying presentation materials here.

The Nashua Area Radio Society produces similar how-to training materials on almost a monthly basis and we make these materials available to our Members an Internet Subscribers (folks that live too far from our location to be regular members) for a small cost which supports our new Ham development programs and covers the production and storage costs associated with the video material. Here’s a list of the training topics that we’ve produced to date:

2019 Tech Nights

  • Fox Hunting: Radio Direction Finding for Beginners including a Tape Measure Yagi Build by Jamey Finchum, AC1DC
  • Surface Mount Technology by Hamilton Stewart, K1HMS
  • RF Design with Smith Charts, Building a First HF Station, and Begining with CW – Hamilton Stewart, K1HMS; Anthony Rizzolo, KC1DXL; and Jerry Doty, K1OKD
  • All About Field Day 2019 by our Field Day Planning Team
  • Putting up a Tower by Fred Kemmerer, AB1OC

2018 Tech Nights

  • Operating Your Station Remotely by Fred Kemmerer, AB1OC
  • Transceiver Frequency Measurement and Calibration by George Allison, K1IG.
  • DMR Radios and Programming by Bill Barber, NE1B
  • WSJT-X: FT8, WSPR, MSK144 and More by Fred Kemmerer, AB1OC
  • Getting Started with Raspberry Pi Computers by Anita Kemmerer, AB1QB, Jamey Finchum, AC1DC,  Brian McCaffrey, W1BP, Fred Kemmerer, AB1OC, and Craig Bailey, N1SFT
  • All About Field Day 2018 by our Field Day Planning Team
  • Portable Operating Gear – demonstrations by Nashua Area Radio Society Members
  • K1EL Kits by Steve Elliott, K1EL
  • Antenna Modeling I by Scott Andersen, NE1RD.
  • Building and Operating a Mobile HF Station by Fred Kemmerer, AB1OC

2017 Tech Nights

  • High-Altitude Balloons: Amateur Radio at the Edge of Space and was presented by our HAB Team.
  • Getting On The Air 2.0 by Fred Kemmerer, AB1OC, and B. Scott Andersen, NE1RD
  • All About n1fd.org – Getting the most from our Website by Fred Kemmerer, AB1OC.
  • Digital Modes: RTTY, PSK, and WSJT-X by Mike Struzik AB1YKAnita Kemmerer AB1QB, and Fred Kemmerer, AB1OC
  • Bonding and Grounding by Jeff Millar, WA1HCO and Fred Kemmerer, AB1OC.
  • All About Field Day 2017  by Dave Merchant, K1DLM, and our Field Day Planning Team.
  • Building and Operating a Satellite Ground Station by Burns Fisher, W2BFJ and Fred Kemmerer, AB1OC.
  • DXing and QSLing by Anita Kemmerer, AB1QB; Bill Barber, NE1B; Fred Kemmerer, AB1OC; and Dick Powell, WK1J.
  • Weak Signal VHF and UHF Stations by Jeff Millar, WA1HCO and Bill Barber, NE1B.
  • Getting the Most from your HF Transceiver and More by Fred Kemmerer, AB1OC and Dave Michaels, N1RF.

2016 Tech Nights

  • Popular Loggers – Ham Radio Deluxe and DXLab Suite by Dave Merchant, K1DLM and Fred Kemmerer, AB1OC.
  • Low-Band Antennas by Dennis Marandos, K1LGQ; Hamilton Stewart, K1HMS; Brian McCaffrey, W1BP; and Fred Kemmerer, AB1OC.
  • RF Simulation and Matching by Jeff Millar, WA1HCO
  • Directional Antennas by Fred Kemmerer, AB1OC; Dave Michaels, N1RF; Brian Smigielski, AB1ZO; and Greg Fuller, W1TEN
  • All About Field Day 2016  by our Field Day Planning Team.
  • Surface Mount Soldering and Desoldering, a Hands-On Presentation by Jeff Millar, WA1HCO
  • Building Your First Station and Getting On The Air by Fred Kemmerer, AB1OC, and Dave Michaels N1RF
  • Software Defined Radios by Fred Kemmerer, AB1OC and Skip Youngberg, K1NKR
  • Advanced Repeaters (DMR, EchoLink, DMR, and D-STAR) by Anita Kemmerer; AB1QB, Fred Kemmerer, AB1OC; and Bill Barber, NE1B
  • Antenna Modeling with EZNEC by Fred Kemmerer, AB1OC

You can gain on-going access to the full library of Amateur Radio Training and How-To materials by supporting our work to bring new people and young people into the Amateur Radio Service as a Nashua Area Radio Society Internet Subscriber. You can learn more about how to become an Internet Subscriber here.

Fred, AB1OC

Field Day Satellites, VHF+ and Fox Hunting

We will have lots of great activities for folks who are interested in operating on the VHF and above bands at Field Day 2019. Here are some of the activities that we’ll be doing:

  • Satellites Contacts using a Portable Computer Controlled Satellite Stations
  • Weak Signal SSB, CW, and FT8 Contacts on 6m, 2m, and 70cm
  • Fox Hunting using Radio Direction Finding (RDF) to find hidden 2m Radio Transmitters
  • Satellite Station, VHF+ Station, and Fox Hunting Training

Source: Field Day Satellites, VHF, and Fox Hunting – Field Day 2019

The Nashua Area Radio Society always brings something new to each Field Day that we do. In addition to our Computer Controlled Satellite Station, we will be adding a state of the art Weak Signal Antenna System and Station to our Field Day 2019 lineup. Our VHF Station will use a dedicated 40 ft Tower with Tower Mounted Preamps and low-loss feedlines. You can see what is going on at Field Day 2019 on 6m and above via the preceding link.

Fred, AB1OC

Final Field Day Station Test

What goes into an 11A Field Day? Well, for starters, 13 stations! We got together at AB1OC/AB1QB’s QTH a couple of weekends ago to set up ALL of our Field Day stations at once and test them together. Here’s a rundown of our final Field Day Station Test…

Source: Final Field Day Station Test – Nashua Area Radio Society

The Nashua Area Radio Society does a pretty big Field Day Operation each year. We will be 11A for Field Day 2019 with 4 towers up. Did you ever wonder what goes into pulling off a Field Day this large? Well, it’s all about planning and preparation. Take a look at the article above to see some of the preparation that we are doing for Field Day 2019.

Fred, AB1OC

Satellite Station 4.0 Part 8 – GPSDO Frequency Locking

Remote Gateway Rack with Satellite Additions

Frequency accuracy and stability become more challenging for transceivers that operate at 400 Mhz and above. Our 4.0 Satellite Stations operate at frequencies approaching 1.3 GHz and we want to be sure that their operating frequencies are accurate and stable. Our Flex-6700 SDR includes a GPS Disciplined Oscillator (GPSDO) so the radio and all of the transverters associated with the radio use the radio’s GPS disciplined 10 MHz output for frequency synchronization.

Portable Satellite Station 4.1

We wanted to add GPSDO frequency control to the Icom IC-9700 Transceiver in our Portable Satellite Station 4.1 station. Icom just released a version 1.11 firmware update for the IC-9700 which makes this possible.

Leo Bodnar GPSDO Kit

We choose a GPSDO from Leo Bodnar. The unit is compact, USB powered, and comes in a nice case which includes a GPS antenna and a USB cable. The unit has two GPS disciplined frequency outputs which can be configured for a wide range of frequencies and levels via a Windows application.

GPSDO Connected to an IC-9700

The GPSDO is connected to the 10 MHz reference input on the back of the IC-9700 with a BNC to SMA cable and the GPSDO is powered via a USB connection to our iMac. We configured the GPSDO output frequency to 10 Mhz and for an output level of +7.7dBm (drive setting 8mA). We also added a 20 dB pad in line with the GPSDO output to better match the drive level requirements of the IC-9700’s 10 MHz input.

Locked GPSDO

The GPSDO will lock in a very short period of time (less than 1 minute) once GPS antenna and power connections are made the unite t. The unit has a red LED on each of its outputs and the unit is GPS locked when the LEDs are on and not flashing.

Configured and 10 MHz Input Locked IC-9700

The last step in the setup process is to configure the IC-9700 to sync its reference frequency to the 10 MHz input. This is easily done in the IC-9700’s Set/Function Menu.

It was pretty easy to add GPSDO locking to the IC-9700 and the arrangement described here works well. While this upgrade is not essential for satellite operation, it’s nice to know that our satellite transceiver frequencies are accurate and stable.

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

Fred, AB1OC

 

HAB-4 to Launch on Sunday from Hollis-Brookline High School

Students and Teacher Ready To Launch Their High-Altitude Balloon

Students and Teacher Ready To Launch Their High-Altitude Balloon

We are planning the fourth launch of our High-Altitude Balloon (HAB-4) this Sunday, June 9th between 10:30 am and 11:30 am ET. We will be launching locally from the Hollis-Brookline HS here in Hollis, NH. Read on to learn more about our HAB projects and how to track our HAB while it is in flight.

Source: HAB-4 to Launch on Sunday from Hollis-Brookline High School

HAB-4 Flight Path Prediction

HAB-4 Flight Path Prediction

It’s to easy to track our HAB! All you need is a web browser and Internet access follow our HAB to the edge of space and back. Check out the article (link above) for more information about our HAB and how to track it.

Fred, AB1OC

Satellite Station 4.0 Part 7 – Flex SDR Satellite Transceiver

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:

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

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

Remote Satellite SDR System Design

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

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

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

Our Flex-6700 includes a GPS Disciplined Oscillator (GPSDO) which provides an accurate and stable 10 MHz reference output to lock the 70cm and 23cm units 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 individual and groups of 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:

Fred, AB1OC

Satellite Station 4.0 Part 6 – Tower Finishing Touches

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

Satellite Station 4.0 Part 5 – New IC-9700 Transceiver

Portable Satellite Station 4.0

Portable Satellite Station 4.0

The new Icom IC-9700 transceiver has begun shipping and we’ve recently added one to our Portable Station. The addition of the IC-9700 completes a key part of our Satellite Station 4.0 upgrade plans.

New IC-9700 In Satellite Mode

New IC-9700 In Satellite Mode

The IC-9700 is based upon Icom’s direct sampling SDR platform. It supports all modes of operation on the 2m, 70cm, and 23 cm bands. The radio also supports satellite modes and D-STAR.

MacDoppler Controlling the IC-9700

MacDoppler Controlling the IC-9700

The new IC-9700 replaced the IC-9100 in our Portable Satellite Station. An updated version of MacDoppler is available which supports the IC-9700 and we tested MacDoppler using both the USB and CI-V interfaces. In both cases, MacDoppler handled the new radio including band and mode selection, doppler correction, and access tone setting properly. Our setup uses an iMac running MacDoppler and MacLoggerDX for radio control, antenna control, and logging and a windows laptop running UISS and MMSSTV for APRS and SSTV. Our setup was easily accomplished by connecting the IC-9700’s CI-V interface to the iMac and the USB interface (for audio and PTT) to our windows laptop.

IC-9700 Display and Waterfall - Working FO-29

IC-9700 Display and Waterfall – Working FO-29

We’ve made about 50 contacts with the IC-9700 so far. The radio is a pleasure to use. The touch screen layout and functions are very similar to the IC-7300 and one does not need to spend much time with the manual to become comfortable using the radio. The Spectrum Scope and associated waterfall are really nice for operating with linear transponder satellites. The screenshot above shows the IC-9700 display while working contacts using FO-29. As you can see, it is very easy to see where stations are operating in the passband of a linear transponder. The Spectrum Scope also makes it very easy to locate your signal in the satellite’s downlink and then adjust the uplink/downlink offset for proper tone.

We’ve also done a bit of APRS operation through the ISS using the IC-9700 and the UISS software. The direct USB interface was used to a windows laptop for APRS. Setting up PTT and the proper audio levels were straightforward and the combination of MacDoppler controlling the VFO in the radio and the PC doing the APRS packet processing worked well.

The IC-9700 can power and sequence our external ARR preamplifiers and we plan to use this capability to eliminate the outboard sequencers that we are currently using with our preamps. We’ll need to climb our tower to change the preamps over to be powered through the coax before we can complete the preamp control changeover.

All in all, we are very happy with the new IC-9700 for Satellite operations. We’ve also noticed that quite a few satellite operators also have the new IC-9700 on the air.

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

Fred, AB1OC

Satellite Station 4.0 Part 4 – Tower Camera and J Mode Desensitization Filter

IP Camera View of New Tower

IP Camera View of New Tower

It is winter here in New England and it is not the best time of year to work outdoors. I have been able to complete a few finishing touches on our new Satellite and 6m Tower.

Installed IP Camera

Installed IP Camera

The first enhancement is the addition of an SV3C IP Camera. The camera allows us to see what is going on with our antennas. The camera has IR illumination so we can see our antennas when operating at night as well. The camera will also be useful for demonstrations when we operate our satellite station remotely in the future. This camera can use Power Over Ethernet (PoE) for power and is compatible with most popular security and webcasting software.

The video above is from our IP Camera while our antennas are tracking AO-7 during a high-elevation pass.

The second enhancement relates to VU Mode (or J Mode) satellites such as SO-50 and FO-29 which use a 2 m uplink and a 70 cm downlink. Satellite ground stations are prone to problems with 70cm downlink receiver desensitization when transmitting on a 2m uplink. The symptom of this problem is difficulty in hearing your own transmissions in your downlink receiver while being able to here other operators in the downlink just fine. Our antennas are separated enough here that we have only minor problems with J Mode desensitization at our station. Fortunately, this is not a difficult problem to take care of.

Comet CF-4160N Duplexer

Comet CF-4160N Duplexer

Installation of a good quality duplexer in the 70 cm path between the antenna and electronics such as our 70 cm preamp provides about 60 dB of additional isolation when operating in J Mode. The Comet CF-4160 Duplexer is a good choice for this application.

J Mode FIlter Installed In Preamp Box

Duplexer J Mode FIlter Installed In Preamp Box

We added one to the preamp box on our tower to create a J Mode desensitization filter. The duplexer is mounted on the left side of the 70 cm preamplifier which is on the right side in the image above. The 70 cm output of the duplexer connects to the feedline from our 70 cm antenna and the common output goes to the input of our 70 cm preamp. We also added a connector cap to the unused 2 m port on the duplexer to protect it from moisture. You can read more about this approach to J Mode desensitization filtering here.

The next stage of our project will be to add hardlines to our new tower and install a second entry to our shack near our new tower to bring our feedlines and control cables permanently into our shack. These projects will have to wait until spring. For now, we are enjoying operating our new antennas from a temporary station set up in our house. We also have a new IC-9700 Transceiver on the way and we should have it installed sometime during the next couple of months.

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

Fred, AB1OC

Raspberry Pi Satellite Tracker Interface How To

GHTracker Running On A Raspberry Pi 3

Sat Tracker – GH Tracker Running On A Raspberry Pi 3 B+

I have received several requests to share the image and construction details for the Raspberry Pi Satellite Tracker Interface that we use with MacDoppler as part of the Satellite Stations here. You can read more about the motivation for this project and its initial design and testing here.

This article explains how to put a Sat Tracker together.

The information and software described here are provided on an “as is” basis without support, warranty, or any assumption of liability related to assembly or use. You may use information and software image here only at your own risk and doing so releases the author and Green Heron Engineering from any liability for damages either direct or indirect which might occur in connection with using this material. No warranty or liability either explicit or implicit is provided by either AB1OC or Green Heron Engineering.

Now that we have that out-of-the-way, here are the components that you need to build your own Sat Tracker:

The Sat Tracker image includes a display driver for the specific touch display listed above and will most likely NOT WORK with any other touch display. You will also need a Green Heron RT-21 Az/El or a pair of Green Heron RT-21 single rotator controllers from Green Heron Engineering that are properly configured for your rotators.

If you have not worked with the Raspberry Pi before, it’s a good idea to begin by installing NOOBS on your SD card and getting your Raspberry Pi to boot with a USB Keyboard, USB Mouse, and an HDMI display attached. This will give you a chance to get familiar with formatting and loading your SD card with the Raspbian build of the Debian OS for the Raspberry Pi. I’d encourage you to boot up the OS and play with it some to get familiar with the OS environment before building your Sat Tracker.

Etcher Writing Raspberry Pi SD Card Image

Etcher Writing Raspberry Pi SD Card Image

The first step in building your Sat Tracker is to put together the hardware and write the image to your SD Card. Use the enclosed instructions or search the web to find information on how to do each of these steps:

  1. Install the Heat Sinks on the Raspberry Pi 3 B+ Motherboard. Make sure your chipset heat sink will clear the back of the case. If it won’t, it’s fine to just install the CPU Heatsink.
  2. Assemble your case to the point where it is built up to support the touch display
  3. Carefully install your touch display on the Raspberry Pi Motherboard
  4. Install the remaining pieces of your case including the nylon screws and nuts which hold the case parts together
  5. Download the SD Card image from the link below, unzip it, and load the image onto your SD card using Etcher
  6. Install your SD card in the slot on your Raspberry Pi Motherboard
  7. Connect your Raspberry Pi to the outside world as follows:
    • Connect Two USB cables – one end to the Elevation and Azimuth ports on your Green Heron Engineering RT-21 Controller(s) and the other ends to two of the USB connections on the Raspberry Pi
    • Connect a wired Ethernet Cable to your Raspberry Pi via a common Ethernet Hub or Switch with a PC or Mac that has VNC Viewer Installed. You will need a DHCP server running on the same network to supply your Raspberry Pi with an IP address when it boots. Your router most likely provides a DHCP function.
    • Connect your USB power supply to the Raspberry Pi Motherboard and power it up

Your Sat Tracker should boot up to the desktop with GH Tracker V1.24 running. The touch display works fine for using GH Tracker but its a bit small for configuring things. To make the configuration steps easier, the image comes up running VNC Server. I like to use VNC Viewer on my PC to connect to the Sat Tracker using VNC to perform the steps that follow. Note that both the Raspberry Pi and your PC must be on the same sub-network for the VNC connection to work. I’ve also included the following commands in the Sat Tracker image which can be run from the Raspberry Pi terminal window to make the configuration process easier:

$ setdisp hdmi # Disables the TFT display & uses the HDMI interface
$ setdisp tft  # Disables the HDMI interface & uses the TFT display
$ reboot       # Reboots the Raspberry Pi causing
               # the latest display command to take effect

If you select the HDMI interface, you will find that VNC Viewer produces a larger window enabling you to perform the following configuration steps:

  1. First, you need to determine the IP address of your Sat Tracker. This can be done via your DHCP server or by touching the network icon (up and down arrows) at the top of the display on the Sat Tracker.
  2. Use VNC Viewer on your PC or Mac to connect to the IP address of your Raspberry Pi. The default password is “raspberry“.
  3. Once you are connected, open a terminal dialog on the Sat Tracker, set your display to hdmi mode via the command shown above, and reboot your Sat Tracker.
  4. Reconnect VNC Viewer to your Sat Tracker and click on the Raspberry button (Start Menu Button) at the top left of the screen, select Preferences, and run Raspberry Pi Configuration. Select Expand Filesystem from the System Tab. This will expand the filesystem to use all of the available space on your SD Card. You can also change the system name of your Sat Tracker and your login password if you wish. When you are done making these changes, reboot your Sat Tracker.
  5. Reconnect to your Sat Tracker via VNC Viewer and select Setup -> Rotator Configuration from the menu in the GH Tracker App. Select the TTY devices (i.e. COM Ports) associated with the Azimuth and Elevation connections to your RT-21 Controller(s) via the two dropdown boxes. You can also configure the operational parameters for GH Tracker at this time. The ones that I use with our Alfa-Spid Az/El Rotators are shown below.

    GH Tracker Rotator Configuration

    GH Tracker Rotator Configuration

  6. Configure your Green Heron Engineering RT-21 Controllers to work with your rotator(s). The settings below are the ones that we use with the RT-21 Az/El controller and Alfa-Spid Az/El Rotators that we have here.

    GHE RT-21 Az/El Controller Settings for Alfa-Spid Rotator

    SettingAzimuthElevationNotes
    Park Heading0 degrees90 degreesSet via MacDoppler. Minimize wind loading and coupling to antennas below. Also enables water drainage from cross-boom tubes.
    Offset180 degrees0 degreesAzimuth dead spot is South. Elevation headings are from 0 to 180 degrees.
    Delays6 sec6 secMinimize relay operation during computer tracking
    Min Speed23Creates smooth start and stop for large array
    Max Speed1010Makes large movements relatively quick
    CCW Limit180 degrees355 degreesCCW and CW limits ensures predictable Azimuth heading for range around 180 degrees. Elevation limits permit 0 to 180 degree operation. Elevation limits shown can only be set via GHE configuration app.
    CW Limit179 degrees180 degrees
    OptionSPIDSPIDAlfa-Spid Az/El Rotator
    Divide Hi360360Rotator has 1 degree pointing accuracy
    Divide Lo360360
    Knob Time4040Default setting
    ModeNORMALNORMALDefault setting
    Ramp66Creates smooth start and stop for large array
    Bright22Easy to read in shack
  7. Configure the source of tracking data to be MacDoppler (UDP) from the GH Tracker Source Menu. We use UDP Broadcasts with MacDoppler running on the same Mac with VNC Viewer to run our rotator. Finally, press the Press to start tracking button on GH Tracker and run MacDoppler with UDP Broadcast on and Rotators Enabled to start tracking.

    MacDoppler Tracking AO-91

    MacDoppler Tracking AO-91

  8. Once you are satisfied with the operation of your Sat Tracker, use VNC Viewer to access the terminal window on your Sat Tracker one last time, set your display to TFT, and reboot.

The most common problems that you’ll run into are communications between your Sat Tracker and your Green Heron Engineering RT-21 Controller(s). If the Azimuth and Elevation numbers are reversed in GH Tracker, simply switch the TTY devices via the Setup Menu in GH Tracker. Also, note that it’s important to have your RT-21 Controller(s) on and full initialized BEFORE booting up your Sat Tracker.

Most communications problems can be resolved by initializing your tracking system via the following steps in order:

  1. Start with your RT-21 Controller(s) and you Sat Tracker powered down. Also, shutdown MacDoppler on your Mac.
  2. Power up your RT-21 Controller(s) and let the initializations fully complete.
  3. Power up your Sat Tracker and let it fully come up before enabling tracking in GH Tracker.
  4. Finally, startup MacDoppler, make sure it is configured to use UDP Broadcasts for Rotator Control and make sure that Rotators Enabled is checked.

The VNC Server on the Sat Tracker will sometimes fail to initialize on boot. If this happens, just reboot your Sat Tracker and the VNC Server should initialize and enable VNC access.

I hope you have fun building and using your own Sat Tracker.

Fred, AB1OC