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Last year, DX Engineering was pleased to add RX Audite SDR Antenna Switch Controllers from QRO.cz. The 2025 DX Engineering Amateur Radio Products Catalog spotlighted many additional QRO.cz devices now available at its website.
Founded by contester Jan Sustr, OK2ZAW, the small company makes finely engineered equipment, including devices that were employed over many years in the building of the OL7M contest station of the Czech Amateur Radio Club. QRO.cz products are widely used by big gun stations, contesters, DXers, SWLers, satellite operators, and hams like you. Here is a brief rundown of some of the QRO.cz devices you’ll find at DX Engineering.
RX Audite SDR Antenna Switch Controllers
The brainchild of Jan, OK2ZAW, the RX Audite was created to solve the problem of being able to monitor the amateur bands with an SDR while simultaneously operating on one or more of those bands. The unit is installed in the feedline between a transceiver and an amplifier or transmitting antenna and diverts that antenna to the RX (SDR) Output whenever the PTT is not active.
These controllers combine the functionality of a T/R switch, a receive antenna input, and a receive splitter with specialized switching—all with RF limiter protection. The transmit/receive (TX/RX) main antenna can be shared with both outputs, transceiver and receiver (SDR) with RF power limiter protection. These versatile devices are perfect for use with a separate SDR receiver for Spectrum Panadapter, WebSDR, or as a Skimmer Server to contribute spots to the Reverse Beacon Network. The RX Audite features frequency coverage of 100 kHz-60 MHz including 160 through 6 meters with a maximum transmit power handling of 200W.
The QRO-RX-AUDITEPRE model features a HIGH IP3 internal preamplifier (not included with the QRO-RX-AUDITE) that can be used for insertion loss compensation, with variable gain up to 14 dB. For RX SDR output, the preamplifier can be switched ON, even when the controller is in the OFF state.
What Do Hams Say About the RX Audite?
“Build quality and performance are excellent, with low insertion loss. Preamp is adjustable with excellent dummy-proof SDR protection. Easily installed with my FT-710, SDRPlay, RSP1B, and Step Attenuator running SDRConsole. The signals I hear and see now are simply amazing especially from a noisy city apartment. It is on the pricey side with the preamp option but definitely money well spent.”
James, DX Engineering Customer
4-Way Active PTT Splitters
These compact keying relays distribute a single PTT (Push-To-Talk) signal to up to four independent devices. They are typically used between a transceiver amplifier keying output and other accessories without delay or signal degradation. They’re perfect for managing amplifiers, transceivers, or switching systems in complex station setups and are ideal when multiple devices need to be triggered simultaneously from one PTT source.
The PTT Splitters come fully assembled in a durable enclosure. Providing plug-and-play installation, they protect your transceiver’s PTT output from potential damage caused by connected accessories. Each output is optically isolated, safeguarding your transceiver from voltage spikes or grounding issues. Whether you’re integrating power amplifiers, interlock systems, or RX devices, these 4-Way Active PTT splitters ensure safe and reliable operation. They are also available in a PCB-only version (below).
Classic 2-Wire Bi-Directional Beverage Antenna Systems
The single-output model (QRO-BEV21) RX-only system provides efficient direction switching using an internal relay, with control achieved directly over the coaxial cable. When no voltage is present on the coax, the antenna operates in the reverse direction (compared to a single-wire beverage). Applying voltage to the coax switches the antenna to the forward (straight) direction, matching the behavior of a single-wire beverage antenna.
The system comes with assembled and tested bi-directional box and di-directional terminator. Antenna wire and coaxial cable not included.
Key features include:
- Use as a low-band receiving antenna, including LF, MF, and HF SWL frequencies
- Low noise floor and improved directivity for enhanced reception quality
- Can be integrated as part of a phased array system for directional control and gain
- Isolated ground to prevent common-mode noise
- 50-ohm feedline impedance; 600-ohm antenna impedance
- Broadband frequency range of 0.2-30 MHz
- Common-mode coax choke included at output
- Common-mode choke isolation of more than 30 dB
- High-quality connectors and stainless steel hardware
- IP56 weather-resistant enclosures
The dual-output model (QRO-BEV22) is designed for advanced receiving setups, particularly in contesting and multi-radio environments. This system features two SO-239 output connectors, each corresponding to a different direction. Both outputs are active simultaneously, allowing the antenna to receive signals from opposite directions at the same time.
Stack Match High-Power Broadband Antenna Phasing Switch
The Stack Match 1:2 is an easy-to-use device for connecting two antennas together to achieve more gain, a different direction, or a different elevation. The same or different antennas can be used. An external switch (not included) is used to select either antenna 1, antenna 2, or an interconnection of both antennas. Both antennas are connected either via a broadband, internally installed phase shifter system or via a narrowband external bypass line made of coaxial cable (not included).
The interconnection of the two antennas results in different directional effects depending on the phase position (in phase, out of phase), as well as in the elevation. You can use the fast switching in a contest or in a DX pileup to receive a better signal and to fade out QRM. When transmitting, the transmit power can always be switched to both antennas or only to one antenna (e.g., to cover both local and distant areas simultaneously in a contest). This 1.8-30 MHz device is power rated at 3 or 5 kW (100% CW, SSB, and non-contesting RTTY; 75% for CW and SSB in contest mode; 50% for RTTY and FT8 contesting).
Other QRO.cz devices available at DX Engineering:
- Bias Tee Receive Feedline Voltage Injector
- RX Preamp Module Box
- RX Preamp and Bias Tee Module Box Combo
- MK2 Classic 6-to-2 Antenna Switch (below)
- OLI 12 IP-Based Station Controller
- OLI 16 IP-Based Station Controller
- Remotius 64 Advanced IP-Based Station Controller
Stay tuned to OnAllBands for more on QRO.cz products. We’ll be featuring the company’s versatile IP-based station controllers in a future post.
