A Portable Satellite Station Part 3 – 2.0 Station Radio and Supporting Equipment

Satellite Station Transceiver and Related Equipment

Satellite Station Transceiver and Related Equipment

With the Antenna System for our 2.0 Portable Satellite Station complete, we turned our attention to assembling the Transceiver and supporting equipment. The equipment used for this part of the project includes:

The Icom IC-9100 provides 100W on 2M and 75W on 70 cm which is more than enough power for our application. It also has some nice satellite features such as support for synchronized VFO tracking between the 2M and 70 cm VFOs in the radio. This radio also uses a single USB connection to allow computer control of the radio and creation of a sound card interface on the host computer. A Heil Pro 7 Headset will be used for operator audio to avoid feedback due to our audio coming back from the satellite. The Icom SP-23 speaker is included to allow observers to hear satellite contacts while they are in progress.

Radio Management via MacDoppler

Radio Management via MacDoppler

The MacDoppler software provides automated control of the IC-9100 including mode selection and automatic correction of both VFOs for doppler shift. These features greatly simplify the operation of the radio, especially when satellites with SSB/CW transponders are used.

The video above shows MacDoppler’s management of the IC-9100 Transceiver during a pass of AO-73. The constant adjustments of the VFOs takes care of doppler shift correction and ensure that our signal stays at a fixed position in the transponder passband of linear transponder satellites.

Preamp Sequencers and Output Monitoring

Preamp Sequencers and Output Monitoring

M2 Antenna Systems S3 Sequencers are used to provide control of the Advanced Receiver Research low-noise preamps on our portable tower. One of the nice features of the Icom IC-9100 is that it can be configured to provide separate keying lines for the 2M and 70cm VFOs. This allows a preamp to remain enabled on the receive VFO while the other VFO is in transmit mode with its preamp shutdown by the sequencer. This arrangement is very useful during tuning when one needs to hear your own signal coming back from a satellite. A custom-made cable assembly was made to interconnect the S3 Sequencers with the ACC socket on the IC-9100, the Weatherpack connector on the tower preamp control cable, and DC power.

We used the excellent WaveNode WN-2 Wattmeter again in our portable satellite setup. This is a modular output monitoring system which has sensor for VHF/UHF use as well as voltage, signal quality and other monitoring functions.

DC power for the setup is provided via a Powerwerx SS-30DV Power Supply and a RigRunner 40007U distribution unit. We use this power supply in all of our portable setups. It is light weight, provides plenty of power for a 100W station and accessories, and is quiet from an RF perspective.

Equipment Packing and Protection

Equipment Packing and Protection

With the transceiver test of the station complete, we turned our attention to transporting the setup. Proper protection of the equipment during transport was provided via a large case from Pelican. We combined this with a roller bag and an inexpensive storage bin for documentation and accessories which are not very fragile. We also included our RigExpert antenna analyzer in the setup to make testing of the station during setup in a portable environment easier.

Station Packed and Ready for Transport

Station Packed and Ready for Transport

With all of the assembly and testing of the components of our 2.0 Portable Satellite Station complete, we packed up all the components. We used an inexpensive furniture dolly to allow us to roll the tower around to load and unload it.

We are ready to test our new station in a portable application. More on that in the final article in this series. Other articles in the series include:

You may also be interested in the satellite station at our home QTH. You can read more about that here.

Fred, AB1OC

A Portable Satellite Station Part 2 – 2.0 Station Goals and Antenna System

M2 Antenna Systems LEO Pack On Display at Dayton 2016

M2 Antenna Systems LEO Pack on Display at Dayton 2016

We came upon the M2 Antenna Systems booth while walking around the exhibit halls at Dayton last year. M2 had one of their LEO Pack satellite antenna systems on display there. This got us thinking about building a new, more capable version of our portable satellite station. The LEO Pack is a relatively lightweight circularly polarized antenna system for working satellites using the 2 m and 70 cm bands. It turns out that AMSAT members can purchase the LEO Pack at a discount. Starting with the LEO Pack in mind, I began to lay out some goals for a new, 2.0 Portable Satellite Station:

  • Be capable of working all active Amateur LEO Satellites including those using linear transponders and digital modes
  • Be portable and manageable enough to be setup in an hour or less
  • Be simple enough to operate so that HAMs who are new to satellites can make all types of satellite contacts with a relatively short learning curve
  • Be manageable to transport and store
  • Utilize computer controlled antenna tracking to aim the antennas
  • Utilize computer control to manage radio VFOs to compensate for doppler shift
  • Be easy to transport and store
Computer Controlled Satellite Station Via MacDoppler

Computer Controlled Satellite Station via MacDoppler Software

We decided to take a computer controlled approach for both antenna aiming and Transceiver VFO management to meet our goal of making the station simple to operate for new satellite operators. After some research on the available options, we choose MacDoppler from Dog Park Software Ltd. for this purpose. MacDoppler runs under Mac OS/X and works well on our MacBook Air laptop computer which is very portable. This program also has broad support for many different rotator and transceiver platforms and is very easy to understand and use. Finally, the program features high quality graphics which should make the station more interesting to folks with limited or no experience operating through Amateur Satellites.

With the satellite tracking software chosen, we made selections for the other major components in the 2.0 Portable Satellite Station as follows:

I will explain these choices in more detail as our article series proceeds.

Glen Martin Roof Tower

Glen Martin 4.5′ Roof Tower

Our solution to making the antenna system portable is built around a Glen Martin 4.5′ Roof Tower. This short tower is a high-quality piece made of extruded aluminum parts. The tower is very sturdy when assembled and is light in weight. We added a pair of extended “feet” to the tower which are fabricated from 36″ x 2″ x 1 /4″ strap steel. This gives the tower a firm base to sit on and allows us to use sandbags to weight it down (more on this later).

Our chosen Yaesu G-500 AZ/EL Rotator is a relatively inexpensive Azimuth/Elevation rotator which is suitable for light-weight satellite antennas such as those in the LEO Pack. This rotator can be installed as a single unit on the top of a tower or separated using a mast. We choose the latter approach as it is mechanically more robust and helps to keep the center of gravity for our portable antenna system low for improved stability.

Yaesu G-5500 Elevation Rotator

Yaesu G-5500 Elevation Rotator

Separating the Yaesu AZ/EL rotator requires as short mast and a thrust bearing to be used. The mast was made from an 1-3/4″ O.D. piece of EMT tubing from our local hardware store. The thrust bearing is a Yaesu GS-065 unit. Both of these pieces fit nicely in the Glen Martin Tower. The thrust bearing provides support for the LEO Pack and G-500 elevation rotator and greatly reduces stress on the azimuth rotator. We also added a Yaesu GA-300 Shock Absorber Mount to the azimuth rotator. This part provides shock isolation for and reduces strain on the azimuth rotator during the frequent starts and stops which occur during satellite tracking.

LMR-400 Feed-lines And Antenna Connection Jumpers

LMR-400UF Feed-lines and Antenna Connection Jumpers

We decided to use LMR-400 UltraFlex coax throughout our antenna system. LMR-400UF coax provides a good balance between size, flexibility and loss for our application. To keep feed-line losses reasonable, we choose to limit the total length of the coax from the transceiver output to the antenna feed point to 50′. This results in a loss of about 1.3 dB on the 70 cm band. The result is that our planned IC-9100 Transceiver which has a maximum output of 75W on 70 cm will deliver a little more than 50W maximum at the feed point of the 70 cm yagi. This should be more that enough power to meet our station goals. Allowing a total of 15′ for antenna rotator loops and transceiver connections, we settled upon 35′ for the length of our coax feed-lines between the tower and the station control point.

Portable Tower Cable Connections and Base Straps

Portable Tower Cable Connections and Base Straps

We added some custom fabricated plates to the tower to act as a bulkhead for feed line and control cable connections and to mount our low-noise preamplifiers. The control connections for the rotators and preamps were made using 6-pin Weatherpack connectors and rotator control cable from DXEngineering. The control cables are also 35′ long to match the length of our coax feed lines. This length should allow the tower and the control point to be separated by a reasonable distance in portable setups.

Low-Noise Preamplifiers From Advanced Receiver Research

Low-Noise Preamplifiers from Advanced Receiver Research

We added tower-mounted Low-Noise Preamplifiers from Advanced Receiver Research to improve the receive sensitivity and noise figure for our satellite antenna system. Two preamps are used – one each for the 2 m and one for 70 cm antennas. While these units can be RF switched, we decided to include the preamp control lead in our control cable to allow for control of the preamp switching via sequencers. This was done to provide an extra measure of protection for the preamps.

Levels And Compass For Tower Setup

Levels and Compass for Tower Setup

We added a compass and pair of bubble levels to the tower assembly to make it easier to orient and level it during setup. This picture above also shows the Yaesu shock absorbing mount for the azimuth rotator.

Weight Bags To Anchor Portable Tower

Weight Bags to Anchor Portable Tower

Finally, we added a set of weight bags to securely anchor the tower when it is set up in a portable environment. These bags are filled with crushed stone and fasten to the legs of the Glen Martin tower with velcro straps.

LEO Pack Antenna Parts

LEO Pack Antenna Parts

With the tower and rotator elements complete, we turned our attention to the assembly of the M2 LEO Pack. The LEO pack consists of two circularly polarized yagis for the 2m and 70 cm bands. The 2m Yagi is an M2 Systems 2MCP8A which has 8 elements (4 horizontal and 4 vertical) and provides 9.2 dBic of forward gain. The 70 cm Yagi is an M2 Systems 436CP16 with 16 elements (8 horizontal and 8 vertical) and provides 13.3 dBic of forward gain. Both Yagi’s are meant to be rear mounted on an 8.5′ aluminum cross boom which is included in the LEO Pack. The picture above shows all of the parts for the two antennas before assembly. It took us about a 1/2 day to assemble and test the antennas and both produced the specified SWR performance when assembled and test in clear surroundings.

Assembled LEO Pack On Portable Tower

Assembled LEO Pack on Portable Tower

The picture above shows the assembled LEO pack on the portable tower. We attached a short 28″ piece of mast material to the cross boom as a counterweight to provide better overall balance and to minimize strain on the elevation rotator. The antennas and the two outer sections of the mast can be easily removed to transport the antenna system.

2m Circularly Polarized Yagi Feed Point

2m Circularly Polarized Yagi Feed Point

The LEO Pack yagis achieve circular polarization via a matching network which drives the vertical and horizontal sections of the antennas with a 90 degree phase shift. The phase shift (and a final 50 ohm match) is achieved using 1/4 wave delay lines made of coax cables. We configured our antennas for right-hand circular polarization. The choice between right and left hand circular polarization is not a critical one in our LEO satellite application as most LEO satellites are not circularly polarized. The advantage of circular polarization in our application is the minimization of spin fading effects.

Green Heron RT-21 Az/El Rotator Controller

Green Heron RT-21 AZ/EL Rotator Controller

The final step in the construction of our antenna system was to add the rotator controller and test the computer aiming system. We have had very good results using Green Heron Engineering rotator controllers in our home station so we selected their RT-21 AZ/EL rotator controller for this application. The RT-21 AZ/EL rotator controller is really two rotator controllers in a single box. The rotator control parameters such as minimum and maximum rotator speed, ramp, offset, over travel and others can be independently set for each rotator.

Rotator Test Using MacDoppler

Rotator Test Using MacDoppler

The RT-21 AZ/EL Rotator Controller connects to our computer via a pair of USB cables. We run Green Heron’s GH Tracker software on our MacBook Air laptop to manage the computer side of the rotator controller and to provide a UDP protocol interface to the MacDoppler tracking software. The picture above shows the test setup used to verify the computer controlled antenna pointing system.

Mixed OS/X and Windows Software Environment

Mixed OS/X and Windows Software Environment

One challenge associated with selecting a Mac OS/X platform for computer control is what to do about the inevitable need to run Windows software as part of the system. In addition to the GH Tracker software, the WaveNode WN-2 Wattmeter and digital modem software for satellite/ISS APRS and other applications require a Windows run-time environment. To solve this problem, we use a virtual machine environment implemented using VMware Fusion and Windows 10 64-bit on our MacBook Air Laptop along with Mac OS/X. Using the Unity feature of VMware Fusion allows us to run windows apps such as GH Tracker as if they were native Mac OS/X apps. The picture above shows an example of this.

Rotator Controller and Software Configuration

Rotator Controller and Software Configuration

With the antennas removed from the cross boom, we tested the operation of the computer controlled tracking system. The Yaesu G-5500 AZ/EL Rotator have some limits as to its pointing accuracy and backlash performance.  Experimentation with the combination of  the RT-21 AZ/EL rotator controller, GH Tracker and MacDoppler setups was required to achieve smooth overall operation. We finally settled on a strategy of “lead the duck” tracking. The idea here is to set up the rotators so that they over-travel by a degree or so when the computer adjusts them and couple this with a relatively wide 2-3 degree tracking resolution. This maximizes the overall accuracy of the pointing system and minimizes the tendency towards constant start-stop operation of the rotators during satellite tracking. Our current configuration for all of the elements involved in the tracking system is shown above.

With the antenna system complete and tested, we can move onto the next step in our project – the construction of a computer controlled transceiver system. We will cover this element in the next part  in this series. Other articles in the series include:

You may also be interested in the satellite station at our home QTH. You can read more about that here.

Fred, AB1OC

Why Ham Radio?

Scorpion SA-680 Screwdriver Antenna

Fred’s Truck with Antenna

Every so often, I drive Fred’s truck into work and people ask me what that big antenna on the back of the truck is for. I explain to them that it is for Ham Radio.  But the reply is usually, why ham radio – isn’t that outdated technology?  We have cell phones and IM, etc…what do we need Ham Radio for?  So I thought I would put down my thoughts as a relatively new Ham about why I enjoy spending so much of my time with Ham Radio.


Amateur Radio for Public Service

Public Service

The number one reason we still need Ham Radio along with all the other technology we now have is for public service.  When there is a disaster and cell phones, television, etc are all not working, Ham Radio operators provide the critical communication.

Ham Radio operators help locally to keep hospitals and first responders in contact with each other to help those affected by the disaster.

Hams also use our ability to communicate around the world on HF bands to help family members around the world to get in touch with loved ones affected by a disaster.

Ham Radio operators have been on the scene helping in every disaster from the earthquakes in Nepal to the recent flooding in California.


Amateur Radio Cube Satellites

Technology and the Maker Movement

I only became a Ham 5 years ago but many of my fellow Ham Radio operators got their license when they were in their early teens and used what they learned to launch their careers. Many have had very successful careers in STEM fields, all launched by their interest in Ham Radio at a young age.  As technology advances, so does the technology used in our hobby.   We even have a nobel laureate, Joe Taylor K1JT who is a ham. Joe has developed weak signal digital communication modes that let us communicate by bouncing signals off the moon!

As technology has advanced, so has the use of it in Ham Radio.   Most Ham Radio operators have one or more computers in their shack.  Many also have a software designed radio (SDR), where much of the radio functionality is implemented using Software, we use sound cards to run digital modes, which are a lot like texting over the radio, and we use the internet extensively as part of operating.  We can also make contacts through satellites orbiting the earth and even the International Space Station.

Most hams love do-it-yourself technical projects, including building a station, home brewing an antenna, building a radio or other station component.  In my day job, I am a program manager for software development projects, but its been a while since I have built anything. As a Ham I taught myself how to code in Python and about the Raspberry Pi and I built the DX Alarm Clock.


QSL Card from VK6LC in Western Australia

International Camaraderie

One of the coolest things about being an amateur radio operator is that you can communicate with other hams all over the world. Ham Radio is an international community where we all have something in common to talk about – our stations and why we enjoy ham radio.    The QSL card above is from a memorable QSO with Mal, VK6LC, from Western Australia, who was the last contact that I needed for a Worked All Zones award.  I must have talked to him for 1/2 hour about his town in Australia and his pet kangaroos!


Amateur Radio Map of the World

Geography Lesson

I have learned much about geography from being on the air and trying to contact as many countries as I can.  There are 339 DX Entities, which are countries or other geographical entities and I have learned where each one is in order to understand where propagation will allow me make a contact.  I have learned a great deal about world geography. Through exchanging QSL cards often get to see photos from so many areas of the world.


DXCC Challenge Award Plaque

Achievement – DXing and Contesting

DXing and Contesting provide a sense of achievement and exciting opportunity for competition. Many Hams work toward operating awards. You can get an operating award for contacting all 50 states, contacting 100 or more countries, contacting Islands, cities in Japan, countries in Asia, or anything else you can imagine.  Each of these operating awards provides a sense of accomplishment and helps to build skills.  Contesting builds skills through competition among Hams to see who can make the most contacts with the most places in 24 or 48 hours. Contesting also improves our operating skills and teaches us to copy callsigns and additional data accurately.


Teaching a License Class

Teaching Licensing Classes – Passing it On

Recently I have joined a team of club members who teach license classes to others who want to get licensed or upgrade their existing Amateur Radio licenses.  Teaching provides a way to improve my presentation skills and also helps me to really understand the material that we teach about Amateur Radio.  It is always a thrill at the end of the class to see so many people earn their licenses or upgrades.

There are so many interesting aspects of Ham Radio which is what makes is such a great hobby.  Getting your license can open up a world of possibilities.  Upgrading to a new license class provides more opportunities to communicate over longer distances.  Ham Radio clubs, including our local club, the Nashua Area Radio Club,  provide many resources to help you get your first licenseupgrade to a new license class, and learn about the many aspects of our hobby.

A STEM Learning Project for Young People

High Altitude Balloon At The Edge Of Space

High Altitude Balloon At The Edge Of Space

As some of you may already know, Anita and I have been working with our local Radio Club on a project to promote STEM learning and interest in Amateur Radio among young people in our area. The idea is to work with kids grades 7-12 to plan, build, launch and recover a High-Altitude Balloon carrying Amateur Radio. Our balloon should be able to reach an altitude of about 100,000 ft before it bursts and the payload returns to earth via a parachute system. The payload will include a computer, GPS and a 2 meter APRS transmitter to record the balloon’s flight track, atmospheric data and altitude throughout the flight. The balloon will also carry a video camera and will capture a video record of the entire flight. You can learn more about our project here.

Project Team Members Will Analyze and Report On Scientific Data

Project Team Members Will Analyze and Report On Scientific Data

We are working with local schools to put together a team of young people to plan and execute our project. This will include designing the on-board science experiments, analyzing the data collected and providing a presentation about what was learned to fellow students and others who are interested.

You can learn more about our project and view a video that shows what our balloon flight will be like on our Club website. This project is part of our Club’s on-going program to promote interest in Amateur Radio among young people. The folks at HAMNation recently featured a video which included some information about our club’s activities for young people as well.

We are working to raise the necessary funds to enable the project to be completed during the current school year. We have setup a GoFundMe page to facilitate the fund raising aspect of our project. We know that we have many readers around the world who follow our blog and it would be wonderful if some of our readers could help us by contributing to funding our project.

Anita and I will continue to post information about our project here.

Best and 73,

Fred (AB1OC)