RX Audite SDR Switch manual
This controller was designed for antenna sharing to the TRX and CW/RTTY/FT8 skimmer. You can use it also for pan adapter, web SDR etc. There are protections and RF limiters at both RX outputs. RX antenna (INBAND) could be used while TRX is transmitting.
This manual page is for two versions of the rx audite switch. In this useful device you can find lots of powerful parts.
ONE black box with these incredible parts:
- TRX/RX switch controlled by PTT signal
- PTT splitter (IN/OUT) in sniffer mode (IN directly to OUT) or output PTT FET switch
- 2-way rx splitter with low loss
- 2x RF limiter rx protections which is the best on the market :)
- RX switch for INBAND RX antenna only for SDR output
- Both antennas with HPF > 100 kHz
- RX preamplifier (high IP3, 18 dB gain) with variable ATT - version with optional preamp module
- RX lines with High Voltage protections > 60 V AC
- RX lines with SuperFuse current protections > 100 mA
- Very high isolation TX to SDR, between RX ports, INBAND RX and TX/RX ANT port
Front panel description
There are three switches with LED indication and red PTT LED
1. Power ON/OFF switch
- Even the Power Switch is OFF, you are able to switch ON the internal Preamp (Controller must be powered by the DC voltage)
- Signal from the main TX/RX ANT goes to the SDR RX output port. There are protections and RF limiter
2. PTT LED indication
- PTT indication
3. RX preamp module (option)
- PREAMP ON/OFF
- Switch for internal Preamplifier (optional or model with preamp)
4. Second RX ANT switch - SDR RX to
- INB RX ANT: SDR OUT is connected to INB ANT input all the time (TRX RX of TX)
- TX = INB RX ANT: SDR OUT is connected to INB ANT input or dummy load while TRX is transmitting
Rear panel description
There are RF connectors: SO-239 and SMA, DC jack and RCA PTT IN and OUT
1. Protected second RX output
- RX output for second RX, SDR, skimmer etc.
- including protections and limiter
2. Optional RX ANT (INBAND) input
- Input for RX antenna for SDR output
- Could be used while TRX is transmitting or all the time
3. Main TX/RX ANT
- Main TX and RX antenna
- TX for TRX
- Shared for TRX and SDR output
- When the controller is OFF - this antenna is connected to SDR out
- TRX port
- RX protections included
5. PTT RCA - IN and OUT
- PTT IN from TRX (station controller)
- IMPORTANT for the right function
- PTT out for PA or another device
- NO delay between PTT IN and OUT
6. Power supply input DC
- DC input
- DC 13.8 V recommended
7. GND screw
- connection for common ground in hamshack
⚠ PLEASE, do not forget to connect PTT from your TRX. This controller does not have V0X, you have to connect TX information from your TRX. PTT OUT has got no delay. There is internal PTT splitter and you can connect another device there (PA).
There are two versions, the first is without internal RX preamplifier and second one with it. This preamplifier could be added later too. This is wide band high IP3 preamplifier module. This RX preamplifier could help with insertion loss (protections, splitter etc.). You can set gain as you need. It is preset to 10 dB, what is IL +6 dB of the additional gain.
RX Audite with the internal preamplifier board and variable gain eliminates insertion loss of the internal RX splitter and also allows you to connect external splitter for two or three RX at the RX (SDR) output port.
Optional preamp module
Internal preamp could be used to eliminate controller insertion loss. Thanks to variable ATT you can comfortable gain value as you need. This optional preamp module could be installed also later as an option.
1. Current check point
- disconnect jumper JP1
- connect mA meter there (200 mA scale is fine)
- connect supply voltage to the controller (13.8V)
- switch preamp ON by front panel switch
2. Bias Current set
- turn the resistor trimmer BIAS and set bias current - it should be around 40 mA
- then connect jumper JP1 back
3. Variable ATT
- with the resistor trimmer ATT you can set amplifier gain as you need from 0 to about 18 dB
- turn the ATT (R_ATT1 201) - multi turn trimmer
Examples of the block diagrams for all functions
There is simply blog diagram of the controller. RX lines have got high voltage and current protection, High Pass Filter (100 kHz), 2-way RX splitter and optional RX preamplifier. You can see functions at the pictures below.
Controller is switched OFF
Even the Power Switch is OFF, you are able to switch ON the internal Preamp - controller must be powered by the DC voltage
Signal from the main TX/RX ANT goes to the SDR RX output port. There are protection and RF limiter
Controller is switched ON
Signal from the main TX/RX ANT goes to the TRX and SDR RX output port via the 2-way splitter
There are protections and RF limiters for both outputs
You can use Preamplifier if it is built inside - if you have not the version with preamplifier, you can order the optional preamp module.
Controller is switched ON: TRX is transmitting
TRX is transmitting to the main TX/RX ANT and SDR RX output port is connected to the internal dummy load or to the INBAND RX ANT port
There are protections and RF limiter
Controller is switched ON: SDR RX out switched to INBAND RX ANT by the front panel switch
In this case main TX/RX ANT goes to the TRX port via the protections and limiter and you can use also preamplifier
SDR RX output port is connected to INBAND RX ANT input
There are protections and RF limiter
1. INBAND or DUMMY LOAD
SDR output could be connected to Inband RX antenna or internal 50 Ohm dummy load. When you do not use Inband RX antenna, please set this jumper to internal dummy load or connect external small dummy load to Inband SMA connector.
2. OPTIONAL PREAMP
- Remove this jumper when the optional preamp is installed
- Must be shorted while there is no preamp module
3. PTT OUT
- Selecting between sniffer mode and PTT FET
- Please, see next picture with an explanation
4. PREAM ON/OFF
This jumper allows you to switch preamp only while the controller box is ON (main power switch is ON) or you can switch preamp independently on main power ON switch and use preamp also while the controller is OFF (this is in case you want to have preamp for SDR all time ON).
- Size of the box is 155x50x130 mm including RF connectors.
- Weight of the package is 0.63 kg (version without internal preamplifier) or 0.65 kg (version including internal preamplifier).
- Use DC power supply, well filtered and stabilized. Recommended is 13.8 V, current is less than 0.7 A.
- There are protections and RF limiter in the way.
- When the optional preamplifier is built in, you can use it for RX (SDR) output. Controller must have +13.8 V connected.
- You CANNOT TRANSMIT while controller is switched OFF. TRX will show high SWR - protection disconnect it. RX (SDR) output is protected.
- There are more protections at all RX path. One of them is resettable SuperFuse which breaks circuit when the current is over 100 mA (< 1W RF). Another protection in line is RF limiter. This circuit does soft-clipping with low IMD.
- Maximal output power is 13 dBm (20mW). Also, internal 2-way RX splitter works as protection. Own isolation between ports (more than 30 dB) helps in the total protection.
- This box is tested with 100 W TRX at TRX port and also at main TX/RX antenna port. Maximal RF peak signal at SDR RX output port is 4 dBm (<3 mW).
- When you forget to connect PTT, your TRX will break SuperFuse and SWR goes higher. SuperFuse will restart again when transmitting ends.
- Controller is designed to route the RF signal from main TX/RX antenna port via the protections and RF limiter to the RX (SDR) output SMA port.
- There is small insertion loss due to all protections.
- When you switch the controller OFF by the front panel switch and left DC input voltage running, you are able to switch preamplifier ON by the front panel switch.
- Then the RF signal goes from main TX/RX ANT port via protections and RF limiter to the preamplifier and to RX (SDR) output SMA port.
- Front panel switch "SDR RX to" is in position "TX = INB RX ANT" - signal from main TX/RX ANT port goes via protection, preamplifier (if ON) to 2-way splitter. Continues via RF limiter to RX (SDR) and TRX outputs.
- Front panel switch "SDR RX to" is in position "INB RX ANT" - RX (SDR) port is connected to RX ANT (INBAND) and TRX (RX) is connected to main TX/RX ANT. Both with protections and RF limiters. TRX can use preamplifier.
- No, this input works only with RX (SDR) output.
- This depends on from panel switch "SDR RX to". When:
- is in position "TX = INB RX ANT" - RX (SDR) port is connected to internal dummy load or to RX ANT (INBAND) port. Please see jumper settings too.
- is in position "INB RX ANT" - RX (SDR) is connected to dummy load or RX ANT (INBAND) port all time.
- There are more protections in the order:
- high voltage protection based at low voltage Neon lamp (65V AC) and higher power GDT (Gas Discharge Tube) - eliminating electrostatic voltage accumulation
- current protections by resettable SuperFuse. Breaks circuit while current is over 100 mA (about 1W RF). Reseted when the current ends.
- RF limiter circuit - soft clipping diode limiter. Reduces output power to max 13 dBm (20 mW).
- RF limiters cut RF single to max 13 dBm (20 mW). Measured peak RF signal was lower than 10 dBm (10 mW).
- insertion loss for TX way is very low. Less than 0.1 dB at 10m (less than 2W).
- it is important to have PTT IN connected for right controller work.
- If you need more PTT from one TRX, it is recommended to use our 4-way PTT splitter.
- There are two PTT OUT possibilities:
- Default is PTT OUT FET. PTT OUT works only when the controller is powered ON. Output FET is able to switch any hardware with current lower than 0.5 A DC and open voltage 35 V DC.
- You can switch internal jumper to sniffing mode - there PTT IN is directly connected to PTT OUT and controller only sniff PTT status. This could not be compatible with some devices.
- in sniff mode PTT OUT works also while the controller is powered OFF.
- All depends on the energy from lightning and also ground connection.
- The GDT protections is able to discharge higher level of energy.
- RF limiters protect outputs
- It is highly recommended to connect controller to the common ground.
- Controller and DC plug cable.
- Internal relays could handle high power but it is recommended to use controller with maximal 250 W.
- This filter works as a DC decoupling and also as AC noise filter.
- yes, preamplifier could be retrofitted also by you - customer. See manual page for more information.
- This is optional RX ANT input for RX (SDR) output. You can connect any RX antenna there and use it while TRX is transmitting or all time - depends on front panel switch position.
- If you do not use this antenna port, please set internal jumper to the internal dummy load - see jumper setting.
- INBAND antenna must have some parameters to make the sense.
- There must be reasonable isolation from TX antenna. You can do it thanks distance and also polarisation.
- Different polarisation from TX antenna and distance allow you to listen while you transmitting.
- RX parameters are also key thing (my RedPitaya 14 bit is able to work with +10 dBm (10 mW) at the input).