Honza OK2ZAW brings a new product to hamparts.shop: a small 6+1 antenna switch for receiving antennas. This anténny prepínač bol špeciálne vyvinutý na priame pripojenie k SDR prijímaču WEB-888, pričom umožňuje jednoduché prepínanie medzi šiestimi anténami directly from the SDR web interface. Of course, the switch can also be used with other IP relé alebo mechanickým rotačným prepínačom, čím sa zvyšuje jeho flexibilita v rôznych prevádzkových scenároch.
In the article you will read
Why does the switch have 7 inputs when we are talking about 6 antennas?
The switch has 7 antenna inputs, labeled 0 to 6. Six of them (1–6) are remote controlled, while port 0 is always active when none of the controlled options are selected. This means that even when the switch is turned off or there is a power failure, port 0 remains active. In practice, this can serve as a basic RX port or as a backup output antenna.
-
Ports 1 and 2 can be configured as open, connected to ground, or terminated with a dummy load.
-
The other ports (3–6) are automatically grounded when not active.
Advanced SDR receiver protection
Each antenna port is equipped with multi-level protection, which significantly increases the security of the connected receiver:
-
A gas discharge tube (GDT) with a threshold voltage of 75 V protects against overvoltage caused by atmospheric discharges or ESD.
-
SuperFuse – a current limiter that also functions as a circuit breaker. It is resettable, so it does not need to be changed after a surge.
-
RF limiter – key protection of the SDR receiver. Thanks to the transformer design and output signal power limitation, it can reduce the level to a typical 10 dBm (10 mW). Even with a transmit power of 100 W on the ANT port, the output to the receiver will not exceed a safe level.
However, these protections only work effectively if the grounding screw ("GROUND ME") is thoroughly connected to a quality grounding point.
Control of additional devices – SSR relay outputs
The switch contains 4 SSR relays (solid-state relays) that can be used to power preamplifiers or active antennas. The relays are automatically activated when ports 1, 2, 3 and 4 (or 0) are selected. These contacts can switch voltages up to 0.4 A AC or DC.
Example of use: If you have a Preamplifier connected to port 1, selecting this port will also turn on a relay that can power the preamplifier from an external source. Turning off the port will interrupt the power supply.
Technical parameters
| Parameters | Value |
|---|---|
| Antenna inputs | 7 (ports 0 - 6) |
| Frequency range | DC to 60 MHz |
| Input impedance | 50 or 75 Ohms |
| Insulation | > 80 dB at 30 MHz |
| Insertion loss | < 1.4 dB at 30 MHz |
| GDT protection | 75 V |
| RF limiter | typ. 10–12 dBm |
| Ports 1 and 2 | open / grounded / dummy load |
| Other ports | grounded if not active |
| Supply voltage | 5V DC |
| Typical current consumption | 60 mA |
| Control voltage | 3 to 5 V (max. 5.5 V) |
| Surge protection | on control wires |
| SSR contacts | ports 1, 2, 3 and 4 (or 0) |
| Switched current through SSR | max. 0.4 A AC/DC |
| RF connectors | SMA female |
| Dimensions | 125 × 77 × 27 mm (without DIN rail mount) |
| Delivery version | Assembled and tested version |
Summary of features
-
✅ 6 remote controlled + 1 default port
-
✅ High isolation between ports
-
✅ Integrated surge protection (GDT, SuperFuse, RF limiter)
-
✅ Control for external preamplifiers via SSR
-
✅ Fully compatible with SDR WEB-888
-
✅ Protection of sensitive SDR inputs even with strong signals
-
✅ Suitable for RX applications in bands up to 60 MHz
If you are looking for a reliable, safe and compact antenna switch for an SDR receiver like the WEB-888, the OK2ZAW product is an excellent choice, whether for an experimenter or a demanding amateur radio operator. Thanks to its emphasis on protection and easy operation, it is one of the most practical solutions in its class.
Source: