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RX Audite SDR Switch manual

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

4. TRX

- 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 VOX, 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).

Comparison

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

Installation

- disconnect the device from cables and power
- open the device - remove the top cover
- remove the two screws in the place of installation of the preamp module
- screw two spacer bolts (sleeves) instead of these screws
- tighten slightly
- remove the jumper marked OPT PRE used (point 2 at this manual)
- insert the preamplifier module into the pin header
- check the insertion of all ten pins
- screw in the two screws for fixing the module
- connect the power supply and turn on the preamplifier switch on the front panel
- check if the yellow LED on the module is lit
- connect all cables and test the gain
- if you need, it is possible to increase or reduce the gain (Variable ATT at this manual, image)
- install the top cover and the assembly is complete

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.

Block diagram

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

Jumper settings

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).

FAQ

Size and weight

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).

Power Supply

Use DC power supply, well filtered and stabilized. Recommended is 13.8 V, current is less than 0.7 A.

When the controller is switched OFF

When the controller is switched OFF, main TX/RX antenna is connected to RX (SDR) output.

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.

What happens when PTT IN failure?

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.

What is the RX signal way when the controller is switched OFF?

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.

Can I use preamplifier for RX (SDR) output when the controller is switched OFF?

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.

What is the RX signal way when the controller is switched ON

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.

Can I use RX INBAND antenna also for TRX?

No, this input works only with RX (SDR) output.

When transmitting

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.

How the protections work?

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).

What is maximal signal after protection?

RF limiters cut RF single to max 13 dBm (20 mW). Measured peak RF signal was lower than 10 dBm (10 mW).

What is insertion loss for TX way?

insertion loss for TX way is very low. Less than 0.1 dB at 10m (less than 2W).

PTT IN

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.

PTT OUT

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.

Do the protections also act as protection if lightning strikes nearby to protect the devices?

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.

Is a plug-in power supply unit or a connection cable included?

1m long DC plug cable is included. Marked wire is positive voltage.

What is included in the package?

Controller and DC plug cable.

What is maximal TX power?

Internal relays could handle high power but it is recommended to use controller with maximal 250 W.

What is function of the HPF > 100 kHz?

This filter works as a DC decoupling and also as AC noise filter.

Could be the preamplifier retrofitted?

yes, preamplifier could be retrofitted also by you - customer. See manual page for more information.

What is RX ANT (INBAND)?

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).

Product details

Included in package

Audite switch assembled and tested
Optional preamp module assembled and tested (preamp version)
DC plug - image

Weight brutto (kg)	0.62 to 0.67 kg

Manufacturer:

Ing. Jan Šustr
ID 05476356, VAT CZ8407024780
Palachova 1777/7, 591 01 Žďár nad Sázavou, Czech republic, Europe

General instructions:

Please also read general instructions before handling the product.

European Union Declaration of Conformity

Manufacturer Ing. Jan Šustr (QRO.cz):

ID 05476356, VAT CZ8407024780
Palachova 1777/7, 591 01 Žďár nad Sázavou, Czech republic, Europe

declares that the assembled product:

RX AUDITE SDR SWITCH

is compatible with the relevant Union harmonisation legislation directives:
EMC Directive 2014/30/EU
ČSN EN 61000-6-3 ed. 2
ČSN EN 61000-6-1 ed. 2 (333432)

On behalf of Ing. Jan Šustr (QRO.cz)
Ing. Jan Šustr, CEO
1st January 2023

Recommended!

I purchased an RX Audite to use with an ANAN SDR that has dual independent receive channels. I had previously attempted to use two other SDR T/R switches from much better known manufacturers. All I can say is that the RX Audite is far superior in concept, design, and manufacture. In particular it is the first switch of this type I have tried that has sufficient transmit isolation that it is transparent in operation, you can switch it on and then it just works perfectly. Five stars recommended!

- Tony -

I'm very happy user!

i'm a very happy user of your SDR Splitter and can't say enough how I'm happy with it; It's saved countless QSO on 6m when my FT2000 alone is unable to decode anything. I'm used to have 2 different instances of JTDX, one running with my old FT2000 and the other one using a Colibri-NANO SDR. Of course while using the same antenna, so this is where the SDR Splitter is really wonderful. The Preamp is working like a charm, I thought I would never use it, in the end, it's always On. Brillant and reliable product, using it for more than 8 months now. Would recommend to anyone

- Cédric, F5UKW -

Love this little thing!

Hi Jan, first of all, my RX-Audite worked perfect during the last contest feeding my RSP1A SDR with CW-Skimmer. No overload, perfect switching. Love this little thing :-)

- Mike, DF3VM -

Space technology compared to others!

I bought the preamp version. It works wonderful. I am electronic engineer, I work at Hellenic Civil Aviation, at Santorini airport, and when I examined how you had constructed the item I was impressed. Space technology compared to others. RX AUDITE was my oneway to my shack.

- Nikolaos, SV8DJW -

NICE EQUIPMENT!

We used RX Audite throughout CQWW CW and it worked wonderfully. Congratulations! Nice equipment! We use a single SDR RSP1A + CW Skimmer Server + Aggregator. Despite the SDR only working on 3 bands at the same time and the old notebook we didn't notice a loss of performance and the information arrived in great quantity/quality. We had a quality leap in the multiplier hunt. Now let's calmly study what we will do to improve what we already have based on what was observed during the contest.

- Julio, PP2BT -