Our Satellite Station 2.0 antenna system uses a pair of Advanced Receiver Research Remote preamplifiers at the antennas to boost weak signals. These preamps have RF sensing and switching to protect them during transit. While this system works well; we are always concerned about the impact of the RF power affecting the long-term reliability of these devices and the associated radio equipment.
Our Satellite Station 2.0 uses a pair of M2 Antenna Systems S3 Sequencers to control the preamps remotely. For U/V and V/U mode satellites, it’s simple to turn off the uplink band preamp to protect it against RF during transmission. The problem with this approach comes when working satellites and the International Space Station in simplex (single band) modes. In these situations, we need a solution that keys the sequencers externally so that the sequencers can properly control the changeover of the preamps from receive to transmit mode before keying our radio (an Icom IC-9100). We also wanted a solution that could also allow the radio to initiate the keying of the sequencers for CW break-in keying and digital modes.
Our solution was to design and build a simple Push-To-Talk (PTT) router. This device allows an external source, such as a footswitch or a trigger switch, to initiate the keying. The design also includes indicators that confirm that the keying sequence has been completed.
Our first step was to create a simple design that allowed an external switch or the radio to initiate keying. The PTT source switch (S1) selects the keying source and uses the Hsend (2m key) and Vsend (70cm/1.2 GH key) lines on the Icom IC-9100 accessory jack as either the means to key the radio or the means to detect that the radio has initiated a transmit keying sequence. A second switch (S2) selects which VFO is keyed when the keying source switch (S1) is in External mode. Finally, indicators for power and keying complete were added.
A small enclosure was used to house the switches, indicators, and connections to the rest of our Satellite Station. The image above shows the rear-panel connections to external PTT sources, the S3 Sequencers, the IC-9100 Radio, and a 12 Vdc station power source.
A pair of terminal strips were mounted inside the enclosure to make connecting all components easier. The wiring around the front and rear panels is pretty dense, so connections were insulated with heat shrink tubing. A small PCB could easily be created to make replicating the prototype easier should we build more copies of the design.
Our new PTT router was easy to integrate into our Satellite Station 3.0 setup. Integration required custom cables to connect our PTT router to the sequencers and the accessory jack of the radio. With the integration completed, we are now able to properly sequence the control of the preamps and the radio in all modes of operation. Here are some more articles which include more about our portable satellite stations –
- A Portable Satellite Station Part 1 – A Simple Station for AO-85
- A Portable Satellite Station Part 2 – 2.0 Station Goals and Antenna System
- A Portable Satellite Station Part 3 – Station Radio and Supporting Equipment
- A Portable Satellite Station Part 4 – 2.0 Station First Contacts!
- A Portable Satellite Station Part 5 – Plans for Our 3.0 Station
- A Portable Satellite Station Part 6 – 3.0 Station Initial Contacts
- Plans for Upgrading Our 2.0 Station for ARISS Contacts
- Raspberry Pi Satellite Rotator Interface