Tag Archives: Portable Station

Portable Satellite Station Design and Operation

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Building and Operating a Portable Satellite Station Presentation

Portable Satellite Station Design and Operation Presentation

Anita and I attended the New England Regional Hamvention this past weekend. We gave a presentation on Portable Satellite Station Design & Operation there. You can view a copy of our presentation here.

Satellite Station Portable - Radio and Supporting Equipment

Portable Satellite Station 2.0 at a Recent License Training Class

The Videos from our presentation are below –



We did two additional talks about the Nashua Area Radio Club’s activities, including one on our High-Altitude Balloon Project. You can view those presentations here.

Also, we are planning to have our 2.0 Portable Satellite Station setup at the Nashua Area Radio Club’s upcoming Technician License Class on Sept. 30 – Oct. 1. If you are in the area and would like to see the station in operation, please contact us at activities@n1fd.org to arrange for a visit. You can do that here if you’d like to register for one of our license classes.

Fred, AB1OC

Portable 6m Station for SOTA and Contesting

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Fred, AB1OC and Curtis, N1CMD Operating

Fred, AB1OC and Curtis, N1CMD Operating

I got really excited when Jamey, KC1ENX set our Club’s first Summits On The Air (SOTA)/Parks On The Air (POTA) activation for the same day as the June VHF Contest! Jamey chose Pack Monadnock in Miller State Park here in New Hampshire as the site for our activation. With Jamey’s help, we prepared a portable 6m station for the activation.

Solar Panels

Solar Panels

The idea was to use an IC-7300 to create a 100W station and a Solar/Battery combination to power the setup. Solar/Battery made us “legal” as a SOTA activation. We combined two 90W solar panels, which I had with an MPPT solar charging system and two LiPo batteries, to create the power system for the activation.

6M Antenna Going Up

6M Antenna Going Up

The antenna system was built around an M2 Antenna Systems 6M3 Yagi and an 18 ft. push-up mast from Max-gain systems.

Portable 6M Antenna

Portable 6M Antenna

All this gear was carried to the site and set up in about an hour. A 25 ft. section of LMR-400UF coax completed the station. The mast was guyed with rings, allowing us to turn the mast/antenna combination to point the Yagi in any direction.

Anita, AB1QB and Curtis, N1CMD Operating in the June VHF Contest

Anita, AB1QB and Curtis, N1CMD Operating in the June VHF Contest

Between the SOTA/POTA activation and the June VHF contest, we made over 130 contacts on 6m. We did not have any real Es openings, so most of our contacts were regional. The elevation provided on Pack Monadnock made us quite loud for the stations that could hear us. Several of our club members got on 6M and joined the fun. We did have a brief Es opening and managed to work a station in Alabama and one in Florida.

Mike, AB1YK Portable 6M

Mike, AB1YK Portable 6M

Mike, AB1YK has a much more portable 6m setup and uses lower power to have some fun on 6M.

Al, KC1FOZ and Tom, KC1GGP Operating Portable

Al, KC1FOZ and Tom, KC1GGP Operating Portable

Al, KC1FOZ, and Tom, KC1GGP, put together a nice station and operated it using battery power. Several other club members came out with portable stations as well.

Our first SOTA/POTA activation was a lot of fun, and Anita and I are looking forward to the next one!

Fred, AB1OC

LEO Satellite Contacts via Easy Sat and Linear Transponder Satellites

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Satellite Antenna Details

LEO Satellite Station 2.0 Antennas

We recently did a Tech Night at our club on Building and Operating an LEO Satellite Ground Station. As part of my portion of our Tech Night presentation, I recorded several LEO satellite contacts. I made videos showing the operation of the computer controlling our Satellite Station 2.0 during these contacts. These videos give an idea of what it’s like to operate through LEO satellites.

The video above records several contacts through SO-50 – an FM “Easy Sat.”

In the next video, several contacts were made through FO-29, a linear transponder satellite.

The distortion you hear in my voice results from my voice coming back delayed through the satellites.

We will have our Satellite Station 2.0 setup at Field Day this year. If you are local to Nashua, NH, you are welcome to visit us during Field Day and see our Satellite Station in operation.

You can read more about the station used to make these contacts here on our Blog.

Fred, AB1OC

GoKit for Field Day and EMCOMM

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Completed VHF/UHF GoKit for EMCOMM and Field Day

Completed VHF/UHF GoKit for Field Day and EMCOMM

We’ve been thinking about building a portable GoKit for VHF/UHF EMCOMM and Field Day Applications for a while now. The following is a list of our requirements for a GoKit –

  • 2m and 70cm operation with FM simplex and repeaters
  • APRS capability and tactical display for portable coordination
  • Digital messaging capability
  • Weather band monitoring capability
  • AC Power with flexible battery backup options

A plan to build our GoKit came together during our Dayton Hamvention trip this year, and we used it during Field Day.

Kenwood TM-D710GA At Dayton

Kenwood TM-D710GA At Dayton

The heart of any GoKit is the Transceiver. We’ve been using Kenwood equipment for our APRS iGate for some time now, and we have had good results with it. Kenwood’s latest 50W transceiver with APRS is the TM-D710GA. This unit provides full support for APRS tactical applications and now includes a built-in GPS receiver making it ideal for our GoKit application.

GoKit AvMap GeoSat 6 APRS Tactical Display at Field Day

AvMap GeoSat 6 APRS Tactical Display

We have been using the Kenwood TM-D710 and an AvMap GeoSat APRS display in our APRS iGate setup, and the combination works very well. The AvMap display lets one see the location of portable and mobile APRS stations on a map display. This arrangement is perfect for coordinating activities in an EMCOMM situation. The AvMap GeoSat 6 APRS display is no longer in production, but I was able to locate a nearly new unit on eBay.

3 - iPortable Enclosure

We had a chance to look at the iPortable enclosure at Dayton and decided that their Pro 2 4U deep unit would be a good choice for our GoKit application. The iPortable enclosures are based on a portable rack mount case and include a DC power system, speaker and headphone hookups, a light, and provisions for a cooling fan.

Radio Shelf

Radio Shelf

With all the components in hand, we began the construction of our GoKit. Reliability is important in any portable system like this, so we put some time into securely mounting all the equipment and neatly arranging the cabling. First came the shelf containing the Kenwood transceiver and a SignaLink USB sound card. A combination of drilling the shelf to secure gear with large cable ties and #8 stainless hardware was used here.

Coax Connector Cables

Coax Connector Cables

Our iPortable case was equipped with SO-239 and N-connectors on the front panel to allow antennas and feed lines that use either connector type. To make the changeover between the connector types easy, we installed separate PL-259 jumper cables for each connector. One simply connects the appropriate jumper to the radio.

Display and Power Shelf

Display and Power Shelf

The power and AvMap display shelves were next. The AvMap display mount was dissembled and modified to accept a custom mounting bracket.

PWRgate Battery Interface and Charger

PWRgate Battery Interface and Charger

The iPortable enclosure was drilled to mount a West Mountain Radio PWRgate to handle backup battery charging and management. The PWRgate supports instantaneous switching between an AC power supply and a backup battery and can accommodate various battery types and sizes.

Backup Battery

Backup Battery

The PWRgate was configured to properly charge our 18AH AGM backup battery. Note using a fuse in series with the battery for safety reasons. We used a Powerwerx SPS-30DM adjustable power supply set to 14.5Vdc to operate our GoKit and to provide proper charging voltage for our AGM battery.

Diamond X-30 EMCOMM and Field Day GoKit Antenna and Mast

Diamond X-30 Antenna and Mast for Field Day and EMCOMM

The last piece of the setup was the antenna. We wanted something that was portable, easy to set up for Field Day, and would provide good performance. We choose a Diamond X-30A 2m/70cm ground plane antenna and mounted it on a 12′ fiberglass push-up mast. The feed line is made from 25′ of LMR-400UF coax. Several bungee cords are used to attach the mast to a fence post or other vertical structure.

10 - GoKit In Use at Field Day and EMCOMM

The picture above shows the completed GoKit in operation. We typically set one side of the Kenwood TM-D710GA as an APRS transceiver and Digipeater and the other to operate on a local repeater or simplex FM. The SignaLink sound card is used with a laptop computer running Fldigi and NBEMS for messaging applications. The iPortable case has a 13.8V lighter socket which connects to a power brick to power our laptop PC.

GoKit Packaged for Transport to Field Day or EMCOMM

GoKit Packaged for Transport

The GoKit is quite portable when closed. All of the equipment and cable connections are enclosed and protected by the case’s removable end caps. We’ve tested our GoKit during our club’s weekly repeater net, and it worked great. The first real use of our new GoKit will be at Field Day this year. It will be located in our public information tent and will be used as a “talk-in” system.

Fred, AB1OC

Nashua Area Radio Society’s 2017 Field Day Station Test

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ARRL Field Day is the Nashua Area Radio Society’s largest and most popular annual activity. You can see more about our recent Field Day activities on our Field Day page and our Blog. We recently got together for a Field Day Station Test.

Dave Merchant K1DLM, our Field Day chairman, is bringing 21st-century radio and computer technology to our Field Day setup this year. There are several aspects to this new component of our Field Day plans, including –

  • Two Flex-6700 Software Define Radios running over a network  for our new Digital and enhanced GOTA Stations
  • An on-site WiFi Network to enable using the N1MM+ Logger in network mode for sharing log information, station activity, real-time scores, and messages
  • A central Score Board and Field Day Information Computer in our public information tent
2017 Field Day Site - Upper Field Layout

2017 Field Day Site – Upper Field Layout

We will again be holding our 2017 Field Day operation at the Hollis-Brookline High School in Hollis, NH. We plan to use the upper baseball field area as our main operating location. We have decided to add a third tower this year and locate it on a soccer practice field several hundred feet from our main operating area. Our antennas and equipment will lie within the required 1000′ circle, but the third tower would situate those operating at that location away from the rest of our group. Dave’s solution to this problem was to set up a network and operate two Software Defined Radios (SDRs) at the lower site remotely from our location on the upper field.

Dave has enlisted Piece Fortin, K1FOP, as our IT Chairman for Field Day this year. Pierce has been instrumental, along with Dave, in the planning and testing of this new technology. Pierce and Dave have a great deal of networking, IT experience, and knowledge, and we could not have put together what is described here without them.

Dave K1DLM, Piece, Hamilton K1HMS, Mike Ryan K1WVO, Anita AB1QB, and I have gotten together multiple times to set up and test this new technology. I wanted to share more about the equipment and the associated testing (staged in the kitchen at our QTH – thank you, Anita!).

We began the testing process by setting up our 20m CW station.

20m CW Station Test

20m CW Station Test

This station uses an Elecraft K3S Transceiver, a K1EL WinKeyer, and the N1MM+ Logger on a Windows 10 Laptop PC. We used this station to get our basic N1MM+ setup, including our Field Day CW keying macros working.

40m SSB Station Test

40m SSB Station Test

Next came our 40m SSB station. This setup uses an Icom IC-7300 Transceiver, allowing us to set up and test N1MM+ on the fly audio macro recording and playback. All three SSB stations will have on-the-fly recording and playback capability, allowing each SSB operator to record and use a custom set of audio macros.

Digital Station Test

Digital Station Test

Next came our Digital Station. This station uses one of the two remote Flex-6700 SDRs.

Remote Flex-6700 SDRs and Antenna Switch

Remote Flex-6700 SDRs and Antenna Switch

Dave, K1DLM put together a really nice package for the two Flex-6700 SDRs and associated equipment, which will be located on the lower field. He used a rack system to mount the two SDRs, power supplies, a three-band Tri-plexor, a set of bandpass filters for 80m, 40m, 20m, 15m, and 10m, and a 403A 8×2 networked antenna switch. This setup allows either of the two SDRs to share the tri-band yagi or the 40m and 80m Inverted-V antennas on the tower on the lower field and operate on any of the 5 available HF bands. Antenna and filter switching automatically track the frequencies of the two SDRs making the setup simple.

Digital Station Second Display - SmartSDR & More N1MM+

Digital Station Second Display – SmartSDR and N1MM+

The Digital Station’s remote SDR will be operated using a SmartSDR client running on the Digital Station laptop PC. This station will have a second monitor to better accommodate all of the windows associated with it.

Digital Station Main Display - N1MM+

Digital Station Main Display – N1MM+

The main display associated with the Digital Station will run decoders for all PSK and RTTY modes. The ability to decode multiple PSK signals simultaneously and multiple RTTY decodes are available. The Digital station also acts as the N1MM+ master station in our Field Day setup for all other stations that use N1MM+.

Satellite Station Test

Satellite Station Test

Our Satellite Station 2.0 was also added to the test setup. It uses a MacBook Air laptop running MacDoppler to control the antenna rotators and the Icom IC-9100 Transceiver, part of our Satellite Station. A Windows 10 Surface Pro computer, which runs N1MM+ and provides logging and other network functionality for our Satellite Station, is included.

GOTA Station Test

GOTA Station Test

We also tested our GOTA station, which uses the second Flex-6700 SDR and a FlexRadio Maestro to provide a more conventional “buttons and knobs” interface for our GOTA operators. This station will also have a laptop PC running N1MM+ for logging.

Scoreboard Computer

Scoreboard Computer

We also built and tested a Scoreboard PC. This computer will be in the Public Information tent at Field Day and connected to a large display. It will show our real-time score, QSOs being logged as they are made, and other useful information about our Field Day operations. This computer will also continuously play videos from our Video Collection and provide access to IP video cameras monitoring the tower and equipment on the lower field.

Pierce, K1FOP and Hamilton, K1HMS Testing CW Stations

Pierce, K1FOP and Hamilton, K1HMS Testing CW Stations

Our networked N1MM+ testbed contained at least one station of each type (CW, SSB, Digital, Satellite, and GOTA) that will be part of our Field Day setup this year. The Station Masters for the additional CW and SSB stations came by to test their setups using the test bed.

Field Day Networking System

Field Day Networking System

The networking system Dave and Pierce built is central to all the technology described here. All of the gear is mounted in a single rack which will be located on the upper field during Field Day. The setup includes a Firewall/DHCP server, a commercial-grade outdoor WiFi access point, a 4G LTE modem for Internet access, an Ethernet Switch, and a UPS power supply.

MoCA Data Link Cable

MoCA Data Link Cable

The upper and lower fields at our Field Day site are separated by several hundred feet. A thick line of trees between the two locations raised concerns about connecting the upper and lower sites using WiFi. Pierce came up with a great solution to this problem – we will be using MoCA Data Modems and RG6 Quad Shield 75 ohm Coax Cable to provide a 10 Mbps data link between the two sites. We tested the MoCA link using a much longer coax cable run than we needed at Field Day and confirmed the full 10 Mbps throughput.

N1MM+ Talk Window

N1MM+ Talk Window

Our networked N1MM+ setup will allow any station in our setup to send messages to everyone who is operating at Field Day. We can use this capability for important communications like “Lunch is ready!” or “I need help from Pierce (our IT chairman) on the 40m SSB station,” or “The 6m band is wide open!”.

Our GOTA and Digital stations will be together in the same tent and will provide our Field Day 2017 visitors to see and use 21st-century Amateur Radio technology to make contacts. We are expecting young people who participated in our High-Altitude Balloon project and from other local schools where we have done Amateur Radio activities to attend. In addition to being a learning opportunity for all of us in the Nashua Area Radio Society, we hope that the state-of-the-art technology that we are using will generate interest among our visitors. If you are local to the Nashua, NH, USA area, come pay us a visit during 2017 Field Day. We’d enjoy providing you and your family a tour and a chance to Get On The Air. Hope to see you at Field Day!

Fred, AB1OC

A Portable Satellite Station Part 4 – 2.0 Station First Contacts!

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Station Packed and Ready for Transport

Station Packed and Ready for Transport

With our new 2.0 Satellite station built, tested, and packed; we were ready to try it in a portable environment. Fortunately, the Nashua Area Radio Club had a Technician License class coming up and we thought that the new station test would be a great way for our students to learn about Amateur Radio Satellites.

Satellite Status from AMSAT Website

Satellite Status from AMSAT Website

Final preparations included checking the operational status of potential satellites on the AMSAT website. The page shown above is like a spotting cluster for LEO Satellites – it shows satellite activity reported by HAM satellite operators. Using this information, we configured MacDoppler to track the active satellites.

Satellite Pass Predictions

Satellite Pass Predictions

Next, we used MacDoppler to generate pass predictions for the weekend of our Technical Class. We assembled this data for all of the potential satellites and color-coded the available passes to identify those which had the best chance of producing contacts.

With this done, we loaded our portable tower, antennas, and all of the rest of the gear into our pickup truck and transported it to the class site.

Sateliite Antennas Setup Portable

Satellite Antennas Setup Portable

The first step at the class site was to unload all of our gear and move the portable tower to a suitable location. We used a compass to orient the tower to true north and leveled it. We used the weight bags that we made up to anchor the tower securely and then installed the antennas, rotator loops, and control cables. The antenna system worked out very well in the portable environment and was easy to set up.

Satellite Antenna Details

Satellite Antenna Details

Here’s a closer look at the LMR-400 UF coax cables which connect the antennas to the rest of the system. The loops just behind the antennas are necessary to keep the coax from affecting the pattern of the antennas. The coax cables shown were made long enough to allow the antennas to be rotated through their full travel in the azimuth and elevation directions without binding.

Satellite Station Portable - Radio and Supporting Equipment

Satellite Station Portable – Radio and Supporting Equipment

The final step in the portable setup was to put the IC-9100 Transceiver and Supporting Equipment together in the building and check everything out. We heard an ON4 station through FO-29 near the end of a low-angle pass as soon as we got everything hooked up and working. A very good sign!

We took some time to fine-tune the calibration of our rotators and to check the operation of the computer controls – everything checked out fine. The video above shows MacDoppler controlling the Azimuth/Elevation rotator and the IC-9100 Transceiver during the testing.

First Contact using New 2.0 Station (AO-85)

First Contact using New 2.0 Station (via AO-85)

With all the setup done, it was time to try to make our first contact. Fortunately, we did not have long to wait. We caught a medium-angle pass of AO-85, a U/V Mode FM Easy Sat. With MacDoppler setup and tacking, we immediately heard contacts being made through AO-85. I gave a whistle and adjusted my uplink VFO until I heard my signal coming back through AO-85. I gave a quick CQ call and immediately got a response from Jonathan, NS4L in Virginia, USA! It took a few seconds to exchange call signs and grid squares, and our first contract with our new station was in the log.

Explaining Satellite System to License Class

Explaining Satellite System to License Class

Our Technician License Class students were very interested in the station. We spent some time explaining the setup and demonstrating how it worked. We made more contacts between our class sessions using AO-85 and FO-29 (a V/U Mode Linear Transponder Satellite). Our most interesting contact was with Burt, FG8OJ, in Guadeloupe through FO-29. Working DX using the new station the first time we used it was great.

We learned several things during our first use of the new station. First, while the 35 ft. maximum separation allowed between the antenna system and the rest of the station is adequate in many applications, the antenna system’s close proximity to the building we were in blocked passes to the west of us with this separation. We have subsequently made up an additional set of feed lines using a pair of 100 ft. long 7/8″ hardline coax cables to allow for a greater separation in portable deployments such as this one.

We were glad we had the Heil Pro 7 Headset with us, and we used it for most of our contacts. The separate speaker allowed our students to hear the contacts well, and the boom microphone on the Pro 7 Headset eliminated feedback due to our voice coming back through the satellites. We improvised a mono-to-stereo converter cable to connect the Heil Pro 7 Headset to one of the two speaker outputs on the IC-9100 Transceiver. This allowed the radio to drive the separate speaker and the headphones at the same time.

We were glad to have the low-noise preamps available. These were especially useful during low-angle satellite passes, and our sequencing setup worked well.

All in all, the first test of our new 2.0 Portable Satellite station was a success. Our license classes students enjoyed learning about Amateur Satellites and had fun, along with us making contacts through a few of them. Our next goal will be to get packet modes and APRS working with our setup. We plan to do another article in this series when this part of our project is completed. Other articles in this series include:

We plan to add larger antennas and switchable polarity to our portable satellite station soon. This will enable us to make contacts using Satellites and the ISS in more difficult conditions.

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 3 – 2.0 Station Radio and Supporting Equipment

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Satellite Station Transceiver and Related Equipment

Portable 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 radio’s 2M and 70 cm VFOs. This radio also uses a single USB connection to allow computer control of the radio and the 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 the 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 take 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 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 modular output monitoring system has sensors 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 lightweight, 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 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 our 2.0 Portable Satellite Station components 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

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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 set up in an hour or less
  • Be simple enough to operate so that HAMs who are new to satellites can make all types of satellite contacts with a relatively short learning curve
  • Be manageable to transport and store
  • Utilize computer-controlled antenna tracking to aim the antennas
  • Utilize computer control to manage radio VFOs to compensate for Doppler shift
  • Be easy to transport and store
Computer Controlled Satellite Station Via MacDoppler

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 easy to understand and use. Finally, the program features high-quality graphics, making 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 is fabricated from 36″ x 2″ x 1 /4″ strap steel. This gives the tower a firm base and allows us to use sandbags to weigh it down (more on this later).

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

Yaesu G-5500 Elevation Rotator

Yaesu G-5500 Elevation Rotator

Separating the Yaesu AZ/EL rotator requires a short mast and a thrust bearing. The mast was made from a 1-3/4″ O.D. piece of EMT tubing from our local hardware store. The thrust bearing is a Yaesu GS-065 unit. Both of these pieces fit nicely in the Glen Martin Tower. The thrust bearing provides support for the LEO Pack and G-500 elevation rotator and greatly reduces stress on the azimuth rotator. We also added a Yaesu GA-3000 Shock Absorber Mount to the azimuth rotator. This part provides shock isolation for and reduces strain on the azimuth rotator during the frequent starts and stops which occur during satellite tracking.

LMR-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 limit the coax’s total length 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. Our planned IC-9100 Transceiver, which has a maximum output of 75W on 70 cm, will deliver a little more than 50W maximum at the feed point of the 70 cm yagi. This should be more than enough power to meet our station goals. Allowing a total of 15′ for antenna rotator loops and transceiver connections, we settled upon 35′ for the length of our coax feed lines between the tower and the station control point.

Portable Tower Cable Connections and Base Straps

Portable Tower Cable Connections and Base Straps

We added custom fabricated plates to the tower to act as a bulkhead for the 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 our satellite antenna system’s receive sensitivity and noise figure. Two preamps are used – one for the 2 m and one for the 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 a pair of bubble levels to the tower assembly to make it easier to orient and level it during setup. The picture above also shows the Yaesu shock-absorbing mount for the azimuth rotator.

Weight Bags To Anchor Portable Tower

Weight Bags to Anchor Portable Tower

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

LEO Pack Antenna Parts

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. The Yagi’s are meant to be rear-mounted on an 8.5′ aluminum cross boom included in the LEO Pack. The picture above shows the parts for the two antennas before assembly. It took us about a 1/2 day to assemble and test the antennas, and both produced the specified SWR performance when assembled and tested in clear surroundings.

Assembled LEO Pack On Portable Tower

Assembled LEO Pack on Portable Tower

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

2m Circularly Polarized Yagi Feed Point

2m Circularly Polarized Yagi Feed Point

The LEO Pack yagis achieve circular polarization via a matching network that drives the vertical and horizontal sections of the antennas with a 90-degree phase shift. The phase shift (and a final 50-ohm match) is achieved using 1/4 wave delay lines made of coax cables. We configured our antennas for right-hand circular polarization. The choice between right and left-hand circular polarization is not critical 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 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 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. The Unity feature of VMware Fusion allows us to run Windows apps such as GH Tracker as 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 has some limits as to its pointing accuracy and backlash performance.  Experimentation with the combination of the RT-21 AZ/EL rotator controller, GH Tracker, and MacDoppler setups was required to achieve smooth overall operation. We finally settled on a strategy of “lead the duck” tracking. The idea here is to set up the rotators so that they over-travel by a degree or so when the computer adjusts them and couple this with a relatively wide 2-3 degree tracking resolution. This maximizes the overall accuracy of the pointing system and minimizes the tendency towards the constant start-stop operation of the rotators during satellite tracking. Our current configuration for all elements involved in the tracking system is shown above.

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

You may also be interested in the current satellite ground station at our home QTH. You can read more about that here. Our first permanent satellite station at our home QTH used Eggbeater antennas. You can read more about that system here.

Fred, AB1OC

A Portable Satellite Station Part 1 – A Simple Station for AO-85

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Portable Satellite Station Contact

Portable Satellite Station Contact

Our club, the Nashua Area Radio Club, has quite a few members who are interested in space communications. We built a simple portable satellite station last year for our 2016 Field Day operation to learn about satellite communications and create something new for folks to work with during 2016 Field Day.

Simple Portable Satellite Station

Simple Portable Satellite Station

Our 1.0 Portable Satellite Station was a relatively simple setup built around an HT, an Elk 2m/70cm satellite antenna, and some gear to improve the receive performance and transmit power output of the HT. All of the gear was mounted on a board to make it easy to transport and it is powered by a LIPO rechargeable battery. The gear in our 1.0 station is made up of the following:

Improved Satellite Antenna Mount

Improved Satellite Antenna Support

Our first contacts with our 1.0 station were made using the Elk Antenna hand-held. Later, we created a “plumber’s special” setup with a camera tripod to make pointing the antenna easier. Note the angle meter from a local hardware store which measures the elevation angle of the antenna.

AO-85 (Fox-1A) U/V Mode FM Cube Sat

AO-85 (Fox-1A) U/V Mode FM Cube Satellite

This setup worked great for making FM contacts through AO-85 (Fox-1A), a  U/V mode FM EasySat. We used the 1.0 station on multiple occasions including Field Day 2016 and several of our club members used it to make their first satellite contacts. The Full-Duplex HT allowed us to hear our own signal coming back from the satellite which was an important tool to help with aiming the antenna properly. The ELK Dual-Band antenna is also a good choice because it uses a single feed point and a single polarization for both the 2m and 70cm bands.

1.0 Station Team Operating Approach

1.0 Station Team Operating Approach

We used the team operating approach outlined above. This worked especially well for new folks who had not made a satellite contact before as it enabled each of the three team members involved in making the contact to focus on a specific part of the contact. We used orange plastic tent stakes to make AOS, Time of Closest Approach, and EOS to mark headings for each satellite pass. Small flashlights used at the stakes made them glow for night-time passes.

We certainly had a lot of fun with our 1.0 Satellite Station and I expect that we’ll continue to use it. As we gained a little experience with AO-85, we decided that we wanted to build a more capable Portable Satellite Station that we could use to operate with linear transponder satellites and which included a tracking system and better antennas. I know from experience with our home satellite station that DX contacts are possible using higher altitude linear transponder satellites like FO-29.

We would also like to be able to use APRS and other digital modes through satellites as well as receive SSTV pictures from space.

These goals have become the basis for building our Portable Satellite Station 2.0. More on the new station in Part 2 of 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.

73,

Fred, AB1OC

2016 ARRL Field Day!

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2016 Field Day Site Layout

2016 Field Day Site Layout

I had the privilege of acting as the Field Day Incident Commander for the Nashua Area Radio Club this year. Field Day is the most important operating event for the Nashua Area Radio Club each year. We operated under our club callsign, N1FD and we were 7A here in New Hampshire, USA. We included some new antennas including a Three Element 40m V-Beam, a Satellite Station, and a 70cm Digital ATV Station in our operation this year. You can see some of the details which went into the planning of our 2016 Operation on our Club’s Tech Night Page.

The video above shows highlights from our 2016 Operation. As you can see, we had a lot of fun this year. Our club has 120+ members and we had a large turnout for Field Day. You can see more about our 2016 Field Day operation on our Field Day Page including photos, a score summary, and a recap presentation shared at a recent club meeting. I hope that you enjoy sharing our memories.

73,

– Fred, AB1OC