Welcome to our new blog! At SO9I Engineering, we have been providing solutions for years that help radio amateurs build efficient and safe stations. In our first post, we want to introduce a product that serves as the foundation for any advanced SO2R (Single Operator Two Radios) or Multi-Operator setup – our 6×2 antenna switch.
More than just simple switching
Most users view a 6×2 switch as a simple tool to connect two radios to six antennas. While true, the possibilities go much further:
- Band Management: Each of the 6 outputs can be dedicated to a specific band. When combined with triplexers and BPF filters, this allows for simultaneous operation on different bands using a single multiband antenna.
- Cascading: Our switch is designed to allow additional switches to be connected in a chain, enabling the creation of complex and expanded RF signal distribution systems.
Heavy-duty construction for demanding users
We do not compromise on quality. SO9I Engineering switch features:
- Exceptional Thermal Stability: The PCB is designed with a very thick copper layer, which drastically reduces trace heating during high-power operation. This ensures that the switch parameters remain stable even during the most intense contest marathons.
- 4000W Power Rating: We use the highest quality relays, allowing for safe operation with power up to 4 kW across the entire HF spectrum.
- Durability and Aesthetics: The enclosure is powder-coated in black with dedicated, wear-resistant labels, ensuring a professional look and durability for years to come.
80 dB Isolation – Why is it so important?
A key parameter for SO2R and Multi-Op environments is the isolation between radio ports. In our switch, this isolation is at least 80 dB. To understand the scale of this difference, let’s look at the math:
If you are transmitting with 4000W (approximately +66 dBm), an isolation of 80 dB means the signal leaking into the second radio is attenuated to just 0.00004W (40 microwatts), or about -14 dBm.
For comparison, a standard S9 signal is -73 dBm, and the S-meter calibration level for “60 dB over S9” is -13 dBm. This means that thanks to our design, the signal from your transmitter reaches the second receiver at a level that is safe and does not risk damaging sensitive input circuits. As noted by renowned expert VA6AM, isolation at the -80 dB level is the “golden standard” for seamless full-power operation without mutual interference.
Safety and Intuitive Operation
- Mechanical Interlock: Inside the device is a hardware circuit that physically prevents two transmitters from connecting to the same antenna at the same time.
- Clear Signaling: Each antenna port features a bi-color LED – Red indicates the antenna is assigned to Radio 1, and Green to Radio 2.
- Grounding: All unused antenna ports are automatically grounded, which improves port separation and overall station safety.
Control and Automation
The switch is extremely flexible regarding control options. It features two DB9 sockets (one for each input), and is controlled by a +12V DC signal.
We offer a dedicated manual controller with rotary switches that includes an internal Interlock system. It operates on a “First Win” principle – the radio that selects an antenna first locks it out for the second operator. For fans of full automation, our switch is fully compatible with the MOAS II management system as well as third-party solutions like the Station Master DeLuxe by microHAM.
Installation? It’s simple. Thanks to the integrated mounting holes, you can easily mount the switch to a wall or under your desk, saving valuable space in your shack.
Do you have questions about implementing our switches in your station?
Contact us – we are happy to help optimize your antenna system!
