With some help from Matt Strelow, KC1XX of XX Towers, we’ve gotten our LEO Satellite Antennas and Preamp System installed on our tower. We installed the antennas on a sidearm at about 80 ft and installed the preamp system (the upper left gray box) next to the antennas on the tower. The design and construction of our LEO Satellite System was covered in the Part 1 and Part 2 articles here on our blog.
I choose 7/8″ Heliax Hardline Coax (Andrews AVA5-50) for the feedlines between the antennas on the tower and the shack. I choose this type of cable to hold our losses to end-to-end to about 1.0 dB for the 432 MHz side of the system. Our Icom IC-9100 Transceiver which we will use for satellite work provide 75W of output on the 70cm band which results in a maximum of about 45W at the antenna – plenty of output power for LEO satellite uplink work. The end-to-end loss on the 144 MHz side is about 0.6 dB resulting in 85W out maximum from 100W in. The antennas were connected to the preamps and through to the hardline coax cables using short LMR-400UF coax jumpers and crimp-on N-type connectors were used throughout the system. The conduits that are buried under our lawn had plenty of capacity for the two additional hardline cables (the lower pair of large coax cables in the picture above). I also routed the control cables for the preamps through one of our smaller conduits.
The two sides of the LEO Satellite Antenna and Preamp system were terminated on our VHF – UHF switching console in our shack. The console uses Hofi-Technik Rotary UHF Antenna Switches to allow selection of the LEO Satellite Antennas as well as our M2 Antenna Systems 144 MHz and 432 MHz Yagis and a Diamond X-300NA 2m/70cm ground plane vertical which we use for repeater work.
We also terminated the control cable from our Preamp System on Control Line Static Suppressors at the base of our tower.
The Preamp Control Cable was routed to a pair of M2 Antenna Systems S3 Sequencers (top units in the picture above) to enable proper Tx/Rx sequencing to protect the tower mounted Preamps from damage during transmit. These units allow the 144 MHz and 432 MHz Preamps to be turned on/off separately as well as enabling the noise test function on the 144 MHz preamp. With all of the installation work done, I confirmed that the SWR reading on both antennas was in specification at the input to the IC-9100 Transceiver and that the both Preamps work working (via an observed increase in noise level) when they were turned on.
The final step was to install the Nova For Windows program and download the latest Keplerian Elements for the HAM satellites that are currently operational. Nova For Windows allows me to determine when a given satellite is making a pass that covers both my QTH and the area where I want to try to make contacts. The program can also predict future passes which makes planning satellite operating times easier. The picture above shows the footprint of the FO-29 and the ISS during a pass over my location.
On the day and time that I tried to make my first contacts, only satellites with Linear Transponders were making useful passes overhead. I choose to try my first contact through FO-29 (Fuji Oscar 29) which is a V/U Mode (145 MHz uplink/435 MHz downlink) satellite.
With my IC-9100 setup in Satellite/SSB Phone mode to transmit and receive on the proper frequencies and side-bands and with the Tx and Rx sides set to track each other (this is one of the useful satellite Features provided by the IC-9100), I began by locating a clear frequency on FO-29’s transponder and transmitting on the uplink while adjusting my Rx offset until I could hear my own transmissions coming back from the bird. Once I found my receive frequency, I began looking for a station to work. As good luck would have it, I found Pablo, EA1QS in Spain and made my first contact! It took some care to stay on frequency during the brief contact as the doppler shift associated with the path through FO-29 was changing fairly rapidly.
I also made two contacts with W1AW/9, the ARRL Centennial QSO Party Operation in the state of Illinois, USA. I made these two contacts through two different satellites. The first contact was made through VUSat VO-52, a U/V Mode (435 MHz Uplink/145 MHz Downlink) satellite and the second one was made using FO-29 again. I was quite fortunate to make the contact through VO-52 as its batteries failed and the bird went out of service just 12 days after my contact was made.
My early experiences with our new LEO Satellite System have been good. The M2 Antenna Systems Eggbeater Antennas and tower mounted Preamp System work quite well when the Satellites being worked are 30 degrees or more above the horizon. I can use our weak signal 2m and 70cm yagis (top two antennas shown above) and the associated tower mounted Preamp Systems (two grey boxes just below the top of the tower) for Satellite passes that are below 30 degrees. This mode of operation will require computer tracking which I can do via Nova For Windows or the Ham Radio Deluxe Satellite Software both of which I already have. I plan to try this combination in the future and will provide additional setup and operational results for this configuration sometime in the future.
Its been a very busy summer and I have not as much time to operate using LEO Satellites as I would like. With WRTC 2014, the ARRL Centennial Convention over, and the 13 Colonies Special Event and W1AW/1 New Hampshiree portable operations completed, I hope to have more time to devote to Satellite Operation. It’s a lot of fun to make contacts through satellites and this mode of operation will give us the chance to learn some new skills.
Other articles in the series include:
- LEO Satellite System Part 1 – System Design and Electronics
- LEO Satellite System Part 2 – Antenna Assembly and Ground Test
You might also be interested in the series on our Portable Satellite Station. You can read about that here.
– Fred (AB1OC)