Most multi-antenna HF stations reach the same point eventually: you have more antennas than you have coax sockets on the back of the radio, and changing between them means either a manual cable swap or a dedicated antenna switch. A good antenna switch is one of those accessories that sounds straightforward until you start looking into what separates a basic unit from a well-engineered one — power handling, grounding of unused ports, control cable requirements, and whether the switching can be integrated into your logging or SDR software.
ML&S now stocks the full range from SO9I, a specialist manufacturer whose entire product line is built around antenna switching. The range covers seven products across three tiers: simple remote switches controlled by a desktop unit, a weatherproofed outdoor version for mast-mounted use, a dual-radio 6x2 switch, and the fully networked HamCore series with browser-based control and automatic band switching.
The Standard 6x1 Switch (SO9I-AS-6X1)
The foundation of the SO9I range. The Standard 6x1 Switch connects up to six antennas to a single transceiver, with selection handled by the separately purchased 6x1 Controller. The design deliberately keeps complexity out of the switch unit itself: there are no full control electronics at the antenna end, only relays and LEDs. This makes the unit more robust, simpler to install, and easier to understand if anything needs attention later.
Each antenna port has its own LED to show which antenna is currently selected, useful when the switch is positioned somewhere visible such as at the base of a mast or in an outbuilding. Unused antenna ports are automatically grounded when not in use, which helps bleed off static charge and adds a layer of protection to your station. Control runs over standard twisted pair cable, so no specialised cabling is required between the switch and the controller.
Build quality is solid throughout: black powder-coated housing, UHF connectors, a reinforced copper layer on the PCB, and a power handling rating of 4kW, covering any realistic amateur radio operating scenario.
The Outdoor 6x1 Switch (SO9I-EAS-6X1)
Mechanically the same switch as the Standard 6x1, but built for permanent external installation. The Outdoor 6x1 is designed to sit at the mast or tower, exposed to UK weather, without the switch housing acting as a point of failure. If your antenna installation means the switch needs to live outdoors rather than in a dry enclosure, this is the appropriate model to choose. It pairs with the same 6x1 Controller as the Standard version.
The 6x2 Switch (SO9I-AS-6X2)
For stations running two transceivers or two operators, the 6x2 Switch extends the concept to two simultaneous radio connections. Up to six antennas can be shared between two transceivers, with the 6x2 Controller managing which radio has access to which antenna. This is particularly relevant for contest stations running SO2R setups, or for club and group shacks where two operating positions share a common antenna farm. Like the 6x1 models, unused ports are automatically grounded and power handling is rated to 4kW.
The Controllers
Both the Standard and Outdoor 6x1 switches, and the 6x2 switch, require a dedicated controller for operation. These are compact desktop units with a selector knob and confirmation LED, connecting to the switch over standard twisted pair cable.
SO9I Controller 6x1 (SO9I-CTL-6X1)
Desktop controller for the Standard and Outdoor 6x1 switches. Selector knob, confirmation LED, and twisted pair connection to the switch unit. Required for operation of any SO9I 6x1 switch.
View at ML&SSO9I Controller 6x2 (SO9I-CTL-6X2)
Desktop controller for the 6x2 switch, managing antenna selection across two radio connections. Required for operation of the SO9I 6x2 switch.
View at ML&SThe HamCore Series: Networked Antenna Switching
The HamCore switches represent a significant step up from the controller-based models. Rather than a separate desktop controller connected by twisted pair cable, the HamCore has its control system built in and connects to your shack network via Ethernet, Wi-Fi or its own access point. Once connected, it is controlled from any web browser on any device, with no dedicated application to install.
That is convenient in itself, but the more interesting capability is automatic antenna selection. Each of the six antenna ports can be named and assigned to one or more amateur radio bands. When you change operating frequency on a compatible transceiver, the HamCore reads that information and automatically switches to the correct antenna for that band, without any manual intervention. For operators who regularly move between bands during a session or a contest, this removes a source of errors and distraction.
Software Integration
The HamCore integrates with three commonly used platforms:
- FlexRadio via network connection, including PTT sensing
- N1MM+ logging software
- DXLog contest logging software
Integration with these platforms allows the HamCore to receive operating frequency data and act on it automatically. For FlexRadio users, the PTT signal can also be delivered over the network connection, which means no additional cabling is required for hot-switch protection.
TX and RX Antenna Configuration
The HamCore supports separate transmit and receive antenna assignments. Operators who use a dedicated receive antenna, such as a Beverage or a small loop, can configure the HamCore to switch the receive path independently of the transmit path. When the PTT is keyed, the system switches automatically to the assigned transmit antenna; when receive resumes, it returns to the configured receive antenna.
Hot-Switch Protection
All HamCore models include protection against hot switching, preventing the antenna relay from changing position while RF is being transmitted. The PTT signal can be received wirelessly from a FlexRadio system over the network, or via an RCA input from any other transceiver. This safeguard is important for protecting the relay contacts and any connected equipment from RF switching transients.
Network Connection Options
| Mode | How it connects | Best suited for |
|---|---|---|
| Ethernet | LAN cable to router or switch | Fixed stations where stable wired connection is available |
| Wi-Fi | Connects to existing home or shack network | Stations where running a cable is impractical |
| Access Point | Creates its own Wi-Fi network | Remote sites or locations where no existing network is available |
HamCore 6x1 (SO9I-HCS-6X1)
The single-radio networked switch, covering up to six antennas from one transceiver. All the features described above, browser-based control, automatic band switching, separate TX/RX configuration and hot-switch protection, in a single unit with no separate controller required. Currently available to pre-order at ML&S.
HamCore 6x2 (SO9I-HCS-6X2)
The dual-radio networked switch, extending the same HamCore feature set to two simultaneous transceiver connections. Six antennas shared between two radios, with full network control, automatic antenna selection for both radios, and independent TX/RX configuration on each port. The natural choice for SO2R contest stations or two-position club shacks that want full automation rather than manual switching.
The Full Range at a Glance
| Product | SKU | Type | Radios | Antennas | Control |
|---|---|---|---|---|---|
| Standard 6x1 Switch | SO9I-AS-6X1 | Remote switch | 1 | Up to 6 | 6x1 Controller (separate) |
| Outdoor 6x1 Switch | SO9I-EAS-6X1 | Outdoor remote switch | 1 | Up to 6 | 6x1 Controller (separate) |
| 6x2 Switch | SO9I-AS-6X2 | Dual-radio remote switch | 2 | Up to 6 | 6x2 Controller (separate) |
| Controller 6x1 | SO9I-CTL-6X1 | Desktop controller | For Standard and Outdoor 6x1 switches | ||
| Controller 6x2 | SO9I-CTL-6X2 | Desktop controller | For 6x2 switch | ||
| HamCore 6x1 | SO9I-HCS-6X1 | Networked switch | 1 | Up to 6 | Browser, Ethernet / Wi-Fi / AP |
| HamCore 6x2 | SO9I-HCS-6X2 | Networked dual-radio switch | 2 | Up to 6 | Browser, Ethernet / Wi-Fi / AP |
Which SO9I Switch Is Right for Your Station?
For a straightforward single-transceiver setup where you simply want to switch between antennas without physically swapping coax, the Standard 6x1 paired with the Controller 6x1 is the cleanest solution. If the switch needs to live outdoors at the mast rather than in a dry location, choose the Outdoor 6x1 instead. Both deliver the same switching performance with the same 4kW rating and automatic port grounding.
If you run two radios or two operating positions sharing an antenna farm, the 6x2 with the Controller 6x2 handles that without compromise.
If you want automatic antenna selection when you change bands, integration with FlexRadio, N1MM+ or DXLog, browser-based control from any device, and the ability to manage separate transmit and receive antennas without any additional cabling back to the shack, the HamCore 6x1 or HamCore 6x2 is the appropriate choice. The HamCore models cost more but deliver a level of station automation that a controller-based system simply cannot match.
View SO9I at ML&S
Disclaimer: This post is based on SO9I's published product information, current at the time of writing. The HamCore 6x1 is currently listed as a pre-order item. Specifications, availability and pricing are subject to change. Please check the individual product pages at ML&S for current stock status before ordering.
