We continued our project to add LEO Satellite capability to our station this past weekend (you can read about the design of our LEO Satellite System here). With 370′ of 7/8″ Hardline Coax (LDF5-50A) ordered and with Matt Strelow, KC1XX of XXTowers scheduled to help with the antenna installation on the tower later this week, the only prep work left was to assemble our M2 Eggbeater Antenna System and preamps and test the setup. The first rule of tower work is to assemble and test as much on the ground as possible. To this end, we decided to mock-up the entire antenna system a few feet up from the base of our tower. The first step in the process was to assemble the M2 Eggbeater Antenna System. This step was not difficult.
We next assembled a Rohn sidearm mount and attached it to our tower about 5 feet from the ground. We then mounted the antennas and cross boom on the sidearm mount and did some SWR sweeps on just the antennas with a RigExpert Antenna Analyzer to ensure that the they were performing to specifications. Both antennas checked out just fine. They both had SWR readings of 1.2 or less across a very wide bandwidth.
The final step in the pre-assembly process was to mount the preamp system that we had assembled previously to the tower. We also built all of the coax cables needed to connect the system from the planned 7/8″ Hardline Coax Feedlines (LDF5-50A) through the preamps and to the antennas. We used LMR-400UF Coax for these jumpers along with crimp-on N-connectors (we crimp and solder the pins on these connectors to the inner conductor of the coax to improve reliability). We installed heat shrimp tubing to seal the connectors in the crimp ferrule area and then covered all of the exposed connectors with electrical tape and CoaxWrap sealing tape. We also installed a 200′ length of DX Engineering Heavy Duty Control Cable (DXE-CW8-HD) to the preamp system. With these steps done, we again verified that the SWR performance of both antennas checked out within specifications.
I plan to pre-install a run of control cable from the control line surge protectors at the base of our tower to the shack and hook the control cable up to our M2 Antenna Systems S3 Sequencers sometime later this week. With these steps done, we will be ready to put our LEO Satellite System on our tower and perform the final integration and testing steps with the rest of our station.
Other articles in the series include:
- LEO Satellite System Part 1 – System Design and Electronics
- LEO Satellite System Part 3 – Final Installation and First Contacts
You might also be interested in the series on our Portable Satellite Station. You can read about that here.
– Fred (AB1OC)