QRO.cz RX Audite SDR Antenna Switch Controllers

QRO.cz RX Audite SDR Antenna Switch 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 (RBN). The RX-Audite features frequency coverage of 100kHz–60 MHz including 160 through 6 meters with a maximum transmit power handling of 200W.

The RX-Audite is the brainchild of Jan Sustr, OK2ZAW, who created it to solve the problem of being able to monitor the Amateur Radio bands with an SDR while simultaneously operating on one or more of those bands. The RX-Audite 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. While transmitting, the RX-Audite bypasses the RX SDR port with 100dB isolation, allowing the transceiver to operate normally. Functionally, when the controller is OFF, the main TX/RX antenna goes to the SDR RX output and includes 10mW RF limiter protection. When the controller is ON, the Main TX/RX antenna is shared between TRX and SDR outputs. A front panel switch allows selection for the SDR RX output to be the Main TX/RX antenna or the INBAND RX ANT input port. During transmissions, the SDR RX output can be set to connect to either the INBAND RX ANT input or an internal dummy load (jumper set).

The RX-Audite includes protective circuitry to ensure that neither the transceiver nor a connected SDR is damaged by coexisting with a transmit antenna. When the PTT is asserted by the transceiver, the RX-Audite and the SDR connected to it are isolated from the transmitted RF path. Whether you select the transmit antenna (TX = INB RX ANT) or the in-band receiving antenna (INB RX ANT) on the front panel of the RX-Audite, there are extensive provisions made to protect your SDR from damage, either from your own transmitter or from other nearby transmitters (in the case of a multi-op station). Neon tubes, gas discharge tubes and resettable positive temperature coefficient (PTC) fuses protect attached receivers and the internal preamplifier (included in the QRO-RX-AUDITEPRE) from damage. When transmitting, with PTT asserted, the transmitted signal is isolated from the SDR, as is with any separate receiving antenna that is in use. Hedging against a possible operator error or equipment failure, if the PTT circuit to the unit is not activated, a resettable fuse protects the RX-Audite from damage and it reverts to presenting an open circuit to the transceiver, causing its SWR protection to cut power to a minimum, even as the built-in protection shields the SDR.

The QRO-RX-AUDITE does not include an internal preamplifier.

The QRO-RX-AUDITEPRE model features a HIGH IP3 internal preamplifier that can be used for insertion loss compensation, with variable gain up to 14dB. For RX SDR output, the preamplifier can be switched ON, even when the controller is in the OFF state.

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Included in the Package:

RX-Audite Switch – Assembled and Tested

DC Cable – DC barrel connector to stripped and tinned wires

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Additional Features and Specifications:

• Frequency Range: 0.1-60 MHz

• Impedance: 50 Ohm

• Front End Protection: Input and Output

• Main TX/RX ANT Splitter to Two RX

• RX RF Limiter protections for both RX outputs

• HPF (> 100 kHz), high voltage and current protection at both RX outputs

• RX ANT (INBAND) input - works only for SDR output

• TX-RX switch controlled by the PTT

• Designed for 2nd RX, WEB-SDR, SKIMMER or Panadapter

• Controller OFF = TX/RX ANT port to SDR RX out via RF limiter protections - Skimmer/web-SDR

• Controller ON = TX/RX ANT port split to TRX and SDR RX out via RF limiter protections

• TRX TX to main TX/RX ANT = SDR RX out to dummy load or INBAND RX ANT input via RF limiter protections

• Front panel Switch - SDR RX output to RX ANT (INBAND) during transmit or all time

• Very high isolation when TRX transmitting and SDR goes to RX ANT (INBAND) 100 dB @ 14 MHz and 80 dB @ 50 MHz

• Preamplifier – Installed in the QRO-RX-AUDITEPRE Model: insertion loss compensation, up to 14 dB of additional gain

• Preamplifier Can be turned ON for SDR even if the controller is OFF

• Supply Voltage: 12-14 VDC (13.8 VDC recommended)

• Supply Current: DC Max. 0.7A with Preamp

• Maximal TX Power: 250W, 200W Recommended

• High Isolation when TRX Transmitting and SDR Goes To RX ANT (INBAND): 100 dB @ 14 MHz and 80 dB @ 50 MHz

• PTT IN open PTT = RX, GND = Transmitting

• PTT OUT Sniffer (IN = OUT) or Output FET (max. 35 VDC and 0.5A)

• PTT is not designed for QSK: You can use switch right PTT lead/tail/TX delay time: min. 20/20 ms

• Default configuration: SDR to the internal dummy load (older 2211xx to RX ANT (INBAND) input) while TRX transmitting

• Low insertion loss

• TX insertion loss: less than 1 W from 100 W @ 28 MHz

• RF limiters

• Limiter for RF Signal: o + 13 dBm = 20 mW (could be + 17 dBm) @ 50 Ohm

• Current SuperFuse - Able to survive high input power (current) for long time. The soft clipping reduces the IMD products of a classic hard diode clip limiter

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QRO-RX-AUDITEPRE PREAMP Model

• High IP3 Preamplifier Module with 18 dB Gain

• 2SC5551 Transistor

• Real OIP3: +34 dBm

• Preset to 40 mA @ 13.8 VDC

• Low Noise Figure (NF): < 2 dB (60 mA 50 MHz)

• Variable Gain: By Output ATT

• Preset to 10 dB for TX/RX ANT to both RX outputs = insertion loss + approximately 6 dB (1S) of gain

• Bypass Relays