The AO-27 FM satellite is back on the air! AO-27 is an FM V/U Mode satellite that was launched back in 1993. The satellite’s Amateur Radio payload became inoperative about 7 years ago due to an internal communications failure. Thanks to some great work by Micheal, N3UC who was one of AO-27’s original designers, the satellite is back on the air on a limited-time basis (4 minutes, twice per orbit over the mid-latitudes).
I was able to make my first contact through AO-27 this morning. The contact was with AI9IN in Indiana, USA. I’m looking forward to making more contacts using this satellite in the near future. Here are the current frequencies for the uplink and downlink (no PL tone is required):
Uplink – 145.850 MHz FM
Downlink – 436.7975 MHz FM
It’s great to have yet another FM satellite that we can all use. I hope that other satellite operators will give AO-27 a try.
We get quite a few requests from folks to explain how to get started with Amateur Radio Satellites. Requests for information on how to build a computer-controlled ground station for Linear Satellites are also pretty common. I recently got such a request from our CWA class so I decided to put together a session on this topic.
We covered a number of topics and demonstrations during the session including:
How to put together a simple station and work FM EasySats with HTs and a handheld antenna
A recorded demonstration of some contacts using FM EasySats
How-to build a computer-controlled station and work Linear Transponder Satellites
Fixed and Portable Satellite Station Antenna options
A recorded demonstration of some contacts using Linear Satellites
We’ve recently received our L24TX Transmit Converter from Down East Microwave. The unit is compact, simple, and produces up to 25W output in the satellite section of the 23 cm band (1260 MHz – 1270 MHz, actually 24 cm). The L24TX is a transmit-only device that is intended to enable L-band uplinks for Satellite use. This article is about our most recent project which involved integrating the L24TX into our Flex SDR Satellite System.
24 cm Tx Converter Rear Panel
Connecting the unit is straightforward. The unit requires an IF input, a 10 MHz reference oscillator, DC power, and a transmit keyline. The later two inputs are provided via a 7-pin connector and a DEM supplied cable. We ordered our unit with the following configuration options:
IF 28 Mhz = 1260 MHz output
Max IF Drive Level – +10 dBm
Fan and Case configured for mounting in the shack
Fortunately, our feedlines for the 23/24 cm band are hardline-based and relatively short. The unit is also available in a configuration that would enable it to be remotely mounted in an enclosure on a tower.
24 cm Tx Converter Installation in our Remote Gateway SDR Rack
The unit fits nicely into our Remote Gateway SDR Rack. The L24TX does not include a power output display so we used a 23/24 cm sensor and our WaveNode WN-2 Wattmeter to monitor output power from the unit. The unit does have leads that output a voltage that is proportional to output power. This could be used to build a power output bar display or meter. the front panel indicates display a power-on indication, lock to the 10 MHz clock input, and Tx when the unit is transmitting.
Overall Satellite SDR System Design
Integration into our Satellite SDR System was straightforward. Our system already included splitters for the 10 MHz GPSDO and the 28 MHz Transverter outputs from our Flex 6700 SDR. I had hoped to use one of the leads from the SmartSDR BITS cable we are using to key our 70 cm Transverter but the BITS cable did not have an adequate drive level to key the L24TX.
Remote SDR Gateway Tx Band Settings
Fortunately, the Flex 6700 has configurable TX1-TX3 outputs for keying devices like Transverters. The use of the TX2 output to key the L24TX was easily configured in the SmartSDR’s TX Band Settings.
23 cm Tx Converter Setup in SmartSDR
It is necessary to configure SmartSDR for the L24TX. The required settings are in the XVTR options tab. In addition to configuring the mapping between the Flex 6700’s XVTR IF frequency and the unit’s output Frequency, one needs to set the IF drive levels. We used the default drive level of 6.0 dBm and adjusted the IF Gain Control on the L24TX until the full output of 25W was reached while transmitting a tone. The correct adjustment is apparent when further gain increases do not provide a proportional increase in output power. The proper setting of the RF drive and gain will keep the L24TX’s output in its linear range of operation.
SDR Satellite System Remote Power Control via a RigRunner 4005i
The RigRunner is remotely accessible over the Internet and our network via a password-protected web interface. This enables us to easily power down or power cycle individual components in the Satellite SDR System remotely.
MacDoppler Tracking AO-91
With all of the hardware installation and calibration steps complete, we are turning our attention to the software side of the setup. We will be using MacDoppler for satellite tracking and VFO control of our Satellite SDR System. This creates a need to connect the MacDoppler program which runs on a Mac to SmartSDR and the Flex 6700 which is a Windows-based system. Fortunately, MacDoppler provides a UDP broadcast mode that transmits az/el antenna position information as well as data to control radio VFOs to adjust for Doppler shift.
FlexBridge Software Beta
We are working on a custom windows application called FlexBridge to enable MacDoppler to run our Flex SDR-based Satellite System. FlexBridge runs on a Windows PC. It receives and parses the UDP broadcast messages from MacDoppler and uses the FlexLib API to properly configure and control the Flex SDR’s VFOs.
SmartSDR Operating With AO-92 in L-V Mode
At present, FlexBridge can configure and control SmartSDR (or a Maestro Client) that is operating our SDR Satellite System. The screenshot above shows the MacDoppler, FlexBridge, SmartSDR combination operating with AO-92 in L/V mode. This software is still an in-progress development and we plan to add the ability for FlexBridge to connect to the radio via SmartLink as well as support for the Green Heron RT-21 Az/El Rotator Controller that we are using. We’ll be sharing more about FlexBridge here as the software development progresses.
The next step in our Satellite Station 4.0 Remote Gateway project will be to move our satellite antenna controls and feedlines into the shack and begin testing the complete setup using local control. Once this step is complete, we’ll focus on the final steps to enable remote operation of our satellite station via the Internet.
Here are links to some additional posts about our Satellite Station 4.0 Projects:
We continued to test our Portable Satellite Station 4.0 as part of AMSAT’s 50th Anniversary Celebration WAS Activations. You can read about the activations and our station’s performance via the link above. Overall, we were pleased with how the portable setup performed. The weakest link was the downlink performance of our antenna system. We are working on some ideas to improve this element of our setup – more to come on this project…
It seems that Hams struggle a bit to get their HTs programmed with the right set of repeaters and other memory settings. The Nashua Area Radio Society will be offering a custom HT Programming Clinicat HamXposition @ Boxboro 2019 to help hams get their HT’s programmed…
I’d like to invite our readers who are planning to attend the Northeastern HamXposition 2019 @ Boxboro on September 7th and 8th to bring their HT. We will be providing an HT Programming Clinic at the show and we’d be happy to create a custom program for your HT and location. Our custom programs can also include FM Satellites, Foxes, and more!
Portable Satellite and Grid Square Activation Station
We were up on Mt. Washington here in New Hampshire this past weekend and we decided to use the SOTA activation as a test for our updated Portable Satellite Station 4.0. It turned out that the station was also a great SOTA and Grid Square Activation station for terrestrial contacts.
A Solar-Battery Power system capable of operating the station continuously for a full day
A laptop computer for Satellite Tracking and Doppler correction
Portable Antenna System
Elk Antenna on Tripod
We decided to keep our antenna system simple and quick to deploy. We choose a portable 2m/70cm antenna from Elk and mounted it on a camera tripod. A carpenter’s slope gauge is used as an elevation indicator and our iPhone serves as a compass to point the antenna in the azimuth direction. A weighted bag, Bungie cord, and a tent stake anchor the tripod in the windy conditions on the mountain. A 15 ft length of LMR-240uF coax with N-connectors makes the connection between the antenna and the rest of the station.
Station Transceiver and Supporting Gear
Portable Station Transceiver and Preamps
We decided to mount the station Transceiver and supporting gear on a piece of plywood to make it easy to transport and setup. The components from lower-right moving counter-clockwise include:
The preamps are powered and sequenced by the IC-910H through its coax outputs. The 70cm side of the second diplexer is used as a filter to prevent transmissions on 2m uplinks from de-sensitizing 70cm downlink signals.
Portable Station Electronics
The use of the mounting board for all of the components allows the station to deployed quickly and helps to ensure reliable operation.
We used a MacBook Air Laptop running MacDoppler to control the transceiver’s VFOs (via a USB CI-V cable). MacDoppler also provided azimuth and elevation data used to point the antenna during satellite passes.
Portable Solar-Battery Power System
Powering a 100w radio in a way that allows continuous use for a day can be a challenge. It’s important to do this in a way that does not generate noise so we do not disturb others trying to enjoy the outdoors. We met all of these needs using a combination of solar power and batteries.
Portable Solar Power
The primary source of power comes from a pair of 90w foldable solar panels from PowerFilm. The panels are wired in series and connected to an MPPT Charger which charges a pair of batteries. This approach allows the system to provide usable power when it is cloudy and the voltage output of the solar panels drops.
We use a pair of A123 10 Ah LiPo battery packs to supply high-current capacity when transmitting. The solar-battery combination is capable of maintaining full battery voltage while supporting the continuous operation of our station for a full day.
The MacBook Air Laptop batteries are adequate to operate the station during the available satellite passes. We have a 12V DC to 120 VAC inverter which can power the computer from our solar battery setup if needed.
View from Mt. Washington Summit
Our portable station did very well during its initial test! I had to move the antennas and operate the station by myself on this activation which limited my ability to make a large number of contacts during the limited number of satellite passes that were available. Still, I was able to make 6 solid contacts through AO-91 and AO-85 while on Mt. Washington. I did not have a suitable linear satellite pass to make contacts but I was able to hear the EO-88 beacon with no problems and confirm that the doppler correction system was working well.
The station also put in a great performance visa-vie 2m terrestrial contacts. We made a total of 70 contacts using 2m FM and USB! We received many good signal reports with our longest contacts being some 275 mi from our location. We also worked stations on four other SOTAs this way.
Learnings and Next Steps
Our station exceeded my expectations during our initial test on Mt. Washington – especially in terms of the number of Terrestial Contacts that I was able to make with it. I did notice that the transmit side of the system was quite a bit stronger than the receive side. This is an indication that a better antenna would help.
We changed the antenna polarization to vertical for 2m FM contacts and to horizontal for 2m USB contacts. This helped the receive side performance quite a bit.
I found that a headset was essential for satellite and terrestrial weak-signal operation in USB mode. I was able to use the hand microphone and the radio’s speaker for most of the 2m FM contacts that I made. This gave interested onlookers a chance to experience Amateur Radio.
Satellite operation would have been much easier and more productive with a helper to handle pointing the antenna while we operated. This improvement will need to be coupled with a headset/speaker combination that allows the person that is pointing the antenna to hear the quality of the downlink while moving the antenna and finding the best polarization.
I am looking forward to doing some grid-square activations using our upgraded portable station. It was a pleasant surprise to find as much interest in Terrestial contacts on the 2m band as we did. The Nashua Area Radio Society does several SOTA activations each year and I am looking forward to using that station for these as well.
Here are links to some additional posts about our Satellite Station 4.0 Projects:
We have created a program that we call Ham Bootcamp. Bootcamp to helps recently licensed and upgraded hams to get on the air. We are making this program available to up to 100 HamXpostion attendees on a first-come-first-served basis.
Our Bootcamp program will run from 9 am to noon on Saturday, September 7th in the Federal Room. Bootcamp will feature tracks for both Technician and General class license holders. It is also a great place for folks who are not yet licensed to learn more about Amateur Radio and how to get on the air.
Our Bootcamp program will include:
How to make a contact and join a repeater net
Putting together an HF station
Radio, antenna, and feed line choices
Getting started with FT8 and digital modes
Exchanging QSL cards
Learning Morse code
Tips on upgrading
Introduction to ham radio kit building
Handheld radio programming tutorials
Ham Bootcamp is free. Participants will receive discount certificates for a kit build at the show and for purchase of Ham Radio Gear from Ham Radio Outlet.
I wanted to share our plans for several hands-on activities at HamXposition @ Boxboro in September. We hope that Ham Bootcamp will be of particular interest to folks getting into Amateur Radio. You can learn more about Ham Bootcamp and all of our planned activities via the link above. We hope to see some of our readers at HamXpostion next month!
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
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.
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.
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.
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: