F.A.Q. is self-explanatory, we collected frequently asked questions and presented answers to them. In time F.A.Q. will grow bigger.

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1. Make sure you've installed the ExpertSDR2 version for your device. Each device has a special version of the ExpertSDR2, other versions of ExpertSDR2 won't work with your device and may ruin it.

2. Add ExpertSDR2 to the Windows Firewall exceptions list for both Private and Public networks, or just disable Firewall and your antivirus software.

3. Check that AnyDesk doesn't block the ports which are used by the ExpertSDR2/3 – 50001 and 50002. The procedure is explained in the next segment. ExpertSDR2/3 always uses two ports for each radio; one is indicated in the Options-> Device menu-> Expert tab and +1 e.g.: 50001 (indicated) and 50002.

4. Make sure your PC/notebook has a fixed IP address with subnet 16 e.g.: Your PC/notebook should always be in the same subnet with the radio, otherwise you won’t be able to use it.

5. For the first run, you need to connect the radio directly to your PC with Ethernet cable. When you make sure that PC and radio are in the same subnet you can connect your radio to the router.

6. Run ExpertSDR2, open Options-> Device menu-> press the Discover button.

7. In the new SDR radio window, press USE in front of your radio.

8. Start the radio by clicking the red Start button in the ExpertSDR2 window.

Most likely AnyDesk software already uses the port 50001. In this case, just either completely AnyDesk or delete AnyDesk then change the port in the ExpertSDR2 to unused port (50003 for example) in the Options-> Device-> Expert tab then install AnyDesk again.
To check what ports are used in the system you can use the TCPView application. Select UDP v4 and sort all ports by Local Port as on the screenshot.

As an alternative you can determine what application uses a certain UDP-port using the terminal. To determine PID of the application open the terminal (press Windows+R, in the appeared window, write cmd, and press enter). In the appeared terminal enter the following command:
netstat -aon | findstr 0.0:PORT_NUM
example: netstat -aon | findstr 0.0:50001
result: UDP *:* 2740
If there is no application that uses this port, then the terminal won't give you any result.

To determine application name by PID write the following command in the terminal:
tasklist /svc /FI "PID eq PID_NUM"
where PID_NUM is PID of the application, which is given by the previous command
example: tasklist /svc /FI "PID eq 2740"
If there is another application that uses the same UDP-port as SunSDR2 DX/PRO/QRP/MB1 just change the port to the available one.
Probably your Firewall or other antivirus software blocks data exchange between PC and the radio. Short data exchanges do pass through, like SDR info, but large pieces of data are considered a threat. Add ExpertSDR2/3 software to the exceptions list of your Windows Firewall and antivirus software.
series01 1
Warning! The below guide will require following incredible effort from its follower:
1. Ability to read and understand line by line (not jumping down up, missing the paragraphs, as usual)
2. Follow the instruction step by step (that is hard, we know, but essential)

Absolute Prerequisites:
1. You already have tried everything.
2. You are confident to be "stuck".
3. You have SunSDR2 / SunSDR2 PRO / SunSDR2 DX model (not applicable to MB1)
4. You have Windows or Mac compatible version.

Step-by-step instruction:
  • 1. Read this guide line by line, before even touching anything.
  • 2. Read this guide again. Line by line. Now with attention.
  • 3. Set proper IP address
    3.1. Using ExpertSDR2, set the transceiver IP to default: (instruction how to do that is in User Manual).
    3.2. Completely close ExpertSDR2.
    3.3. Power off and power back on the transceiver.
  • 4. Make sure you connect transceiver to PC with direct RJ45 LAN cable. (Interim steps: Are you sure it is a working cable? if "yes" - go to step 5. If "no" - get yourself a working cable).
  • 5. Change IP address of your PC to with mask (no Default Gateway needed, no DNS needed). If your PC has multiple network connections (i.e. dual LAN, WiFi, etc) - make sure you disconnect them all, leaving for a moment only PC-transceiver network connected.


  • 6. Make sure, that when PC and tranceiver are powered up, the transceiver power LED is solid green. If it is not (flashing or whatever but solid green -> then your network connection is faulty -> troubleshoot (see User Manual how)).
  • 7. For advanced dummies only: make sure your PC network adapter set to Auto Negotiation.
  • 8. Make sure you understand the difference between terms "Device Manager" and "Firmware Manager". Because those two are related, but different things. You have to use both in this procedure.

device manager

firmware manager

9. Double check that transceiver is powered up, LED is solid green and transceiver is connected to PC via RJ45 cable. Open terminal window and type 'ping'. Correct result you should get:

right ping


Wrong result -> Troubleshoot (see User Manual how).

wrong ping

  • 10. Launch ESDR3 (Prerequisites: make sure you have read "How to setup the transceiver" and there is nothing on your PC blocking UDP port 50001) -> you should see the "Device Manager" window.
  • 11. Locate "Firmware Manager" button.
  • 12. Press "Firmware Manager" button - this will open "Firmware Manager Window". You should see connected device S/N, IP address and port plus UPGRADE button on right side (not shown on this screenshot because this device is already upgraded). Press "Upgrade" button - the progress bar will appear with the word "Preparing".

firmware manager1

    • 13a. SunSDR2 DX users ONLY: you should see progress bar moving and FW upgrading, finished in less than 10 sec. After finished - power off / power on transceiver. Now it is ready, you can start main application.
    • 13b. SunSDR2 / SunSDR2 PRO users ONLY: if the progress bar with the word "Preparing" sits there for 30+ seconds:
      13b.1 Close "Firmware Manager Window". Do NOT close any other window, do NOT disconnect anything.
      13b.2 Power off transceiver by power button, wait 10 sec, power transceiver back on.
      13b.3 From the "Device Manager" window, press "Firmware Manager" button: there are two potential scenarios from here:
      - it is either start upgrading automatically or
      - (if it did not start in 5 sec) you should press "Upgrade" button once -> the upgrade will be finished in less than 10 sec.
      After it's finished - power off / power on transceiver. Now it is ready, you can start main application.

What to do if you still in "I am Stuck!" mode?

Real examples, which have been observed through the several months:

Issue: Transceiver's power LED is not becoming solid green.
Option: Did you already tried RESET and DEEP RESET procedures? No? Then it is just a time.

Issue: Did RESET and DEEP RESET, but still not solid green.
Option: Try to activate "the bootloader mode" while using ESDR2:
1. Switch off the transceiver with the PWR button;
2. Press and hold the BT button on the rear panel of the transceiver (you will hear a light click);
3. Switch on the transceiver with the PWR button. The LED will blink with a single green light;
4. Release the BT button;
5. Launch ExpertSDR2 software and open Options-> Device menu-> Expert tab and press Firmware update;
6. After the firmware update is finished, the LED will turn to constant green light;
7. Go to section 1 of Step-by-step instruction.

Issue: Cannot ping transceiver
Option: Verify IP settings on PC and transceiver

Issue: Can ping transceiver, but cannot connect to it
Option1: Return PC network adapter to Auto Negotiation mode
Option2: Kill any application (Anydesk, IC9700, etc) which is blocking UDP port 50001 on your PC
Option3: Double check firewall settings
Option4: Reinstall OS


Still in "I am Stuck!" mode?
1. Stop harrassing your PC and transceiver for a while. Go to feed you dog, wife or garden. Wait 1-2 days for the brain cells to cool down (use cold drinks or conditioner if needed).
2. Open this manual and start over

And still in "I am Stuck!" mode after all above done?
Congradulations, your won a nomination of Super Dummie! Contact EE technical support.
Note: The above guide is non-official and applicable to ExpertSDR3 aplha/beta versions.

Here is the short "as is" movie of Downgrading from ESDR3 to ESDR2 and Upgrading back from ESDR2 to ESDR3 in one move (download recommended). Fair warning - you still have to go through the step-by-step procedure, as described above.

series01 2

For this demostration I am using macbook, however, it is absolutely the same step-by-step in Windows and Linux.

As per "I am Stuck"©™ Series tradition" - fair warning, before we start.
Warning! The below guide will require incredible effort from its follower:
1. Ability to read and understand line by line (not jumping down up, missing the paragrahps, as usual)
2. Follow the instruction step by step (that is hard, we know, but essential)

1. You have (accidentaly, of course) installed ESDR3 alpha/beta
2. You are desperate to divert back to ESDR2
3. You have tried everything
4. You are confident to be "Stuck"
5. You have SunSDR2 / SunSDR2 PRO / SunSDR2 DX hardware version (not applicable to MB1)
6. You have compatible Win / Mac / Linux OS

Step-by-step instruction:

1. Read this guide line by line, before even touching anything.

2. Read this guide again. Line by line. Now with attention, yes?

3. Set proper IP address
3.1. Using ExpertSDR3, set the transceiver IP to default:

1 IPadd

When you click "Set New Address" button, the ExpertSDR3 will pop up, asking if you really want this - click "Yes". The next two windows will pop up - one is confirming that new IP address is set and next one, just a second after, saying "Failed to read device calibrations!":

2 calib

Do NOT panic. Do not PANIC as well. The message "Failed to read device calibrations!" is (completely, purely, absolutely) normal. That is how it ment to be. Just press OK and go to next step.

3.2. Completely close ExpertSDR3.

3.3. Power off and power back on the transceiver.

4. Make sure you connect transceiver to PC with direct RJ45 LAN cable. Remember? You have got the working cable somewhere before, when you bravely decided to upgrade, hah? Go get it, you will need it now.

5. Change IP address of your PC to with mask (no default gateway and no DNS required)
Somehow I am sure 95% of readers are still on WiFi, when come to this step ... Hence, here is the hard part - it is time to get direct cable between PC and transceiver.

See? I have only PC-transceiver network active. Shutdown all other networks (WiFi, dual LAN, whatever you may have on your PC) for a moment untill successful downgrade:

3 setIP

6. Make sure, that when PC and transceiver are powered up, the transceiver power LED is solid green. If it is not (flashing or whatever but solid green -> then your network connection is faulty -> troubleshoot and get it working, before you go to next step).

7. Make sure your PC network adapter set to Auto Negotiation.
(When you did the upgrade, you may ask yourself, "why?" Well, if you really think you need that extra knowledge, just read here. And the reason Step 7 is here - just because, by our experience, there are smart users who are already have messed up with Auto Negotiation, resulted in failing upgrade-downgrade Firmware.)

8. Remind yourself the difference between "Device Manager" and "Firmware Manager". If you have Dory-fish-like memory, just see Step 8 in previous issue of our very successful "I am Stuck"©™ Series.

9. Double check that transceiver is powered, LED is solid green and transceiver is connected to PC via RJ45 cable. Open terminal window and type 'ping'.
The correct result you should get:

4 ping1

The incorrect result is below, if you get it - troubleshoot:

5 ping2

9.1. Launch ESDR3 and double check if it is seeing the transceiver with correct IP address and port:

6 esdr3

9.2. Completely close ExpertSDR3 and double check if there is any of its process (or part of it) still running in background.

10. Launch ExpertSDR2 (you can use any version of 1.3.1, I am using 'update 8').

11. Press On/Off button on ExpertSDR2 - it will pop up, saying you need to update Firmware. Click Yes.
I know that some of you will try to do that different (their own) way. And will get stuck. Well... that is why we have this very successful "I am Stuck"©™ Series, savvy? Just do it as it said: Press On/Off button on ExpertSDR2:

8 esdr2

11.1. For SunSDR2 DX users only: The Firmware update (pop-up) process will go through Step 1, then reset and complete in a total of few seconds.
Now you're all set and can start using ExpertSDR2.

11.2. For SunSDR2 / SunSDR2 PRO users only: if the Firmware update (pop-up) process is sitting with no move for more than 30 sec, then:
11.2.1. Do Not close any software window, leave Firmware update (pop-up) untouched.
11.2.2. Power off transceiver by power button, wait 10 sec, power transceiver back on.
11.2.3. When transceiver is back on - watch the Firmware update (pop-up) will go throug step 1, then reset and complete in a total few seconds..
Now you all set and can start using ExpertSDR2.

Here is the short "as is" movie of Downgrading from ESDR3 to ESDR2 and Upgrading back from ESDR2 to ESDR3 in one move (download recommended). Fair warning - you still have to go through the step-by-step procedure, as described above.

Answer (author Pavel VK6NX, original text):

With migration from ESDR2 (based on Qt5 framework) to ESDR3 (based on Qt6 framework) it is important for ESDR3 user to understand the fundamentals of default audio drivers and codecs within various OS, alongside with existing cross-dependencies.

This understanding might be able to help the user to set the correct expectations and select the proper (both) ESDR version and computer platform/OS for his needs in HAM radio.

In general, the topic about "audio" should be split in two major parts:
OS (Linux/OS X/Win) audio, and
Qt versions (Qt5 and Qt6) differences in delivering audio within ESDR2 and ESDR3

OS ( Linux | OS X | Win ) audio


Windows, certainly, the popular one OS in ESDR/SunSDR world. Also, historically ESDR was started as Windows-only, then became cross-platform in latest versions of ESDR2 and full cross-platform in ESDR3.

Through the years of ESDR2-3 development, Windows users also have been moving between OS versions. Older Windows versions were "known" for much higher audio latency, compared to Linux and macOS. To improve the audio experience, the proprietary Audio Stream Input/Output (ASIO) sound card driver protocol was often in use in prior Win10/11 (including earlier versions of Win10).

Clearing misunderstanding and misinterpretation of ASIO in correlation with ESDR2/3.
There are some important things about ASIO, which ESDR user needs to understand.

First and foremost: ASIO is a 3rd party (Steinberg) protocol, which is, actually, never was officially supported by Windows. It, actually, works the opposite way: 3rd party ASIO developers are supporting Windows OSes, introducing both: software protocol (which can bypass OS-defined audio path and connect the ASIO-based application directly to the installed audio hardware) and ASIO-capable hardware (sound-cards).

Second: MS, from their side, (and in earlier versions of the OS) was allowing this protocol to bypass in-build audio path. However, with initially introduced (in later versions of Win10, and moved into Win11) new Windows Audio Architecture, MS practically removed from their OS the way of ASIO to work. From the other side, the newest Windows Audio Session API (WASAPI) enables practically the same functionality, which was available earlier only in ASIO: client applications to manage the flow of audio data between the application and an audio endpoint device. Practically, it means that in latest Win10 and all versions of Win11, use of WASAPI (Win default) demonstrates same or better results in terms of low latency audio than use of ASIO.

Summary for Windows:
ASIO is a valid way to obtain low latency audio, when ESDR2 and earlier versions of Windows OS (including Win10 prior 20H2) are in use. Still, you can easily use MS in-build audio. The way how you are setting up your Windows is really dependent from your HAM tasks.

With ESDR3 and latest Win10/Win11 the WASAPI is the preferred audio option.

Links to expand your knowledge and understanding of Windows Audio in Win10/11:
Windows Audio Architecture
Audio Devices Design Guide
Low Latency Audio
Some discussions on MS forums in regard to ASIO (also feel free to use search on MS forums)

OS X (Mac)

In a nutshell - Mac devices are low latency by nature. (The payback for such comfort - is the device's price. And much less 3rd party available software, in comparison to Win, however this is changing over last years).

Apple is using native Core Audio set of frameworks. The frameworks are integrating application audio with the OS itself and the platform Hardware Abstraction Layer (HAL). In-build Mac devices audio hardware addresses the HAL before hitting the OS, providing "true on playback".

The above described architecture has an advantage of using Core Audio device's ability to address multiple applications simultaneously.

There are practically nothing need to be adjusted in latest OS X versions - 9,10 (ESDR2) and 11,12,13(ESDR2/3) - to make them work with ESDR2/3, it is pretty much plug-and-play functionality out of the box with majority of microphones, headphones, etc.

Links to expand your knowledge and understanding of OS X audio:
Core Audio Overview
Core Audio Essentials
Core Audio in iOS and OS X


With ESDR2 (latest versions) and ESDR3 currently supported by Ubuntu only, we are focusing on this OS only.

And, usually, Linux active users of ESDR2/3 are already across audio details and setup nuances - this is pretty much led by Linux OS nature.

Linux is kind of "in between" Win and Mac in terms of audio low latency: it is certainly capable to provide with perfect audio results much cheaper (in device cost) that same on Mac; however it requires really deep knowledge and understanding - of the OS kernel, various audio libraries and HW compatibility - from its user.

Linux is predominantly found in use within developers; this is, certainly, true about EE development team and wide range of 3rd party developers.

If you are new to Linux and still evaluating whether you wish to start using Ubuntu, you may like the idea to kind of "test" your level of knowledge by reading the following official blog. The expected outcome - if you have no problem in understanding blog's provided information/terminology/etc., then you're pretty much "ready to go":

Low latency Linux for industrial embedded systems – Part I
Low latency Linux for industrial embedded systems – Part II
Low latency Linux for industrial embedded systems – Part III

Qt5 and Qt6 frameworks: "how it works" with OS's audio

The key points to understand are around those two below:
  • 1. ESDR2 is build with Qt5. ESDR3 is build with Qt6.
  • 2. There is massive difference between Qt5 and Qt6 in terms of how each framework version works with different OSes audio. Hence, there is massive difference how ESDR2 works with OS audio in comparison with ESDR3.
The key output from two key points above: when running ESDR2 and ESDR3 on the same hardware PC and same OS, you may get very different results in terms of low latency audio. The difference is much bigger under Windows, less in Ubuntu and practically nil in Mac.

There are heaps of information about the difference between Qt5 and Qt6 in "Qt Multimedia" (the part of Qt framework, responsible for audio interaction between application and OS). In a nutshell - and directly related to ESDR2/3 topic:
- Qt5 is using complex plugin and OS dependent infrastructure for audio backend and practically non-consistent frontend API; and those issues led to inconsistent cross-platform support.
- Qt6 is using an architecture of "no plugin" and "one backend for all multimedia" (including audio), providing unified cross-platform support within single code.

To simplify the understanding of the Qt5 vs Qt6 difference in Multimedia, it is, pretty much:

"have driver for each and every OS separately build into application code" (Qt5 way)
"pass the audio stream from application directly to OS API" (Qt6 way).

(Perhaps now, it is more clear why someone may struggle with re-using ASIO with ESDR3 and Win11, when it still perfectly works with ESDR2 and Win7 - it is because there is no API for ASIO in Win11. Another "knowledge" from above - when something is not working in the OS audio, it is not, per se, ESDR3 - it is OS.)

Further knowledge expansion: 30-min video
With the release of ExpertSDR3, we've made a lot of changes to the TCI protocol.
ExpertSDR3 1.0.4 Beta uses TCI 1.9.
ExpertSDR2 1.3.1 still uses TCI 1.4.
Most third-party software developers try to keep up with the latest TCI, that's why latest versions of JTDX, for example, are better suited to work with ESDR3. It's not the case with SDC, the latest official version with TCI support (15.24) was released in March 2022, thus it works OK only with ESDR2.
In ESDR2 the default TCI port is 40001.
In ESDR3 the default TCI port is 50001.



Nominal (PEP) HF output power of the MB1 and SunSDR2 DX is 100W and for SunSDR2 PRO it's 20W. For 100W in SSB mode it might differ from 30 W up to 80 W. The reason for that is peak-factor, it equals 3 for voice signals. TONE signals have constant output power 100 W. Voice signals with peak power of 100 W have real power approximately 3 times lower. To increase the real power of voice signals use the compressor and other features in the TX processing module.
Currently, all our devices have one ADC, thus you can use only one antenna input at the same time for RX mode.
ExpertSDR2/3 supports two independent software receivers, which can use different antenna inputs, but cannot receive at the same time. Each receiver (RX) has its own separate panorama, set of settings, and can use different modes. In case a certain third-party software does not support TCI, each RX has its own independent CAT and VAC interfaces. The second RX can be viewed in a separate window on the second monitor. Each RX has two SubRXs.
Each of SubRXs has independent volume and balance controls, any of them may be selected for transmission. You may use up to four "slices" simultaneously.
No, each transceier has two software receivers, but one ADC, you can use both receivers to work either in hte first 0...80 MHz or the second 80...160 MHz Nyquist zone of the ADC.
You can transmit on the 4M band via low power output (DAC OUT), max 10mW. To get more power you can use an external power amplifier. To RX on this band use direct input/output of high-speed ADC/DAC. In case of MB1, for comfortable RX operation connect a narrow pass filter between the RX IN and RX OUT. Also, it may be required to use an external LNA.
To TX on the LW band you'll have to make some tweaks in ExpertSDR2.
Via low power output (DAC OUT) you can transmit on: 0.1kHz - 150MHz with maximum power of 10mW.
- Harmonics may appear while transmitting out of amateur bands.
- I have to mention that, we can not guarantee the proper functioning of our devices with changed parameters and we are not responsible for the customers transmitting on the frequencies out of HAM range, this could be done only with the proper license.

To RX on these frequencies, we'll recommend to us the ADC IN because standard antenna inputs will have low sensitivity.
Maximum allowed signal level on the ADC IN connector is 0.3V of the active voltage (RMS). Do not exceed it, it may result in the transceivers overload and ADC fatal damage.

ADC cannot receive DC, receiving available from 9 kHz and higher, never tested below 9 kHz.
RX below 100 kHz will have low sensitivity, we've never tested our devices on these frequencies.

High-speed ADC in the TRX simultaneously receives several Nyquist zones, 0-80 MHz, and 80-160 MHz. Signals from different Nyquist zones overlay each other as image channels. For example, 15 MHz on HF is reflected on 145 MHz. For ADC to avoid HF stations when operating on VHF, we installed SAW filter with pass frequencies 144-148 MHz. Also, there is another VHF wideRX bandpass filter: 95-155 MHz (Butterworth - 5 Order) for the whole 2nd Nyquist zone.
VHF SAW filters final attenuation for HF frequencies is around -60-70 dB. For example, there is an S-9 station on the 20M band, you'll see it on VHF as an S-1 station or lower. If you want to completely attenuate HF stations, you can install the additional HPF we manufacture for the MB1, with 100 MHz cut frequency. From our experience, HF stations can be received on VHF 6-15 dB above the noise floor, depending on the VHF antenna quality. Good VHF antenna is an additional band filter. If you'll receive VHF stations on an unmatched HF antenna (as an experiment), you'll see that AFC of the internal filter will be corrupted and attenuation of HF stations worsened.
Max signal level on the receiver's input is (enabled АТТ -20dB) ~S9+100dB on the S-meter scale, which is approximately 4.5V of HF voltage peak-to-peak. A 1000W station may be in 10-20 meters from you and receiver will still function properly.

The S-Meter shows the signal level in the RX filter bandwidth.

When no antenna is connected, the S-Meter shows the level of the radio's internal noises.

The readings depend on the filter bandwidth, if you set SSB mode with 3 kHz bandwidth, the readings will be at the higher level, if you set CW with 100 Hz bandwidth, the S-Meter readings will be lower.

The radio's internal noises also depend on the Preamp level (sensitivity). If you set -20 dB ATT, the sensitivity will be at its worst and S-Meter readings higher, if you set Preamp +10 dB, the sensitivity will be higher and radio's own noises will be at their lowest.

S-Meter in the ExpertSDR2 has two different calibrations for HF (0-30 MHz) and VHF (30-300 MHz).

HF and VHF signals with the same dBm level have different S-scale values.

You can find calibrations tables for HF (Table 3) and VHF (table 4) at the following link http://hamwaves.com/decibel/en/

For example:

29 MHz -127 dBm ~ S0.5 (preamp on)

52 MHz -127 dBm ~ S3.5 (preamp on)

To verify you may connect a signal generator to an antenna port and compare the generator signal with the S-Meter readings for all S-levels, compare to tables from the link above.

Also, you can see the IARU recommendations for HF and VHF S-Meter calibration at the following link https://en.wikipedia.org/wiki/S_meter
For HF S9 = -73 dBm = 50 uV (50 Ohm), for VHF S9 = -93 dBm = 5 uV (50 Ohm).

S-Meter in the ExpertSDR2 corresponds to the IARU recommendations, each device is calibrated at the factory during manufacturing.

SunSDR2 Q9
1. Noise level on the spectrum scope depends on its resolution. Divide panorama sample rate (in Hz) by the FFT size (in the Spectrum settings) you'll get the minimum FFT bin band - let's call it "single-unit filter". The whole panorama consists of such single-unit filters. Each such filter displays resulted power in its own band and this power is displayed as a point on the panorama. A spectrum line is drawn based on these points. If there is a strong useful signal, with a high signal-to-noise ratio, inside the single-unit filter, then panorama and S-meter readings will be the same. As a rule, it applies to monochrome and/or narrowband signals like CW or PSK, e.g. someone's tone signal. If there are no useful signals, then will be displayed the noise power in the filter bandwidth.
2. S-meter displays summed signal power in the filter bandwidth. i.e. a sum of useful signal and noises in the bandwidth.
Let's look at the noise receiving:
Sample rate 156250 Hz. FFT size 16384 (max). SSB filter bandwidth 2.9 kHz, noise level on panorama -118 dBm. A receiver receives air noise.
Note: Approximate readings from the screenshot - RX mode.
Task: calculate S-meter readings.
Note: Let's agree that these readings are unknown to us.
Step 1. Let's calculate the FFT bin band (single-unit filter). 156250/16384 = 9,53 Hz. This is the bandwidth of a single-unit filter.
Step 2. Let's calculate the difference between RX filter bandwidth and single-unit filter. 2900 Hz / 9,53 Hz = 304 (times). Filer bandwidth is approximately 304 times wider than a single-unit filter.
Step 3. Let's calculate the difference in dB between summed noise power in single-unit filter bandwidth and summed noise power in RX filter bandwidth. 10*log(304) = 24.8 dB. i.e. noise power in 2.9 kHz bandwidth will be higher than in single-unit filter on 24.8 dB.
Step 4. Let's calculate S-meter readings. -118 dBm + 24,8 dB = -93,2 dBm.
Approximate S-meter readings will be -93.2 dBm.
Conclusion: as you see, the calculated value of the S-meter readings is equal to real readings on the screenshot. The difference is 1 dB, it could be explained by the fact that the noise level slightly differs from -118 dBm, we assumed from the screenshot.
If there is a useful signal in the RX filter bandwidth, e.g. SSB signal, S-meter will also display the summed power of all voice components in the filter bandwidth. On panorama, each separate voice component will be displayed lower than overall S-meter readings. This statement is also valid for TX mode.
Note: If you are in CW, with filter bandwidth 20 Hz, sample rate 312 kHz, and FFT size 16384, S-meter readings and panorama noise level will be approximately equal.

S-meter values and audio level have program compensation when you use the attenuator because the signal level on the antenna input is always the same and doesn't depend on the attenuator level. With this solution, a user doesn't need to calculate real values on his own, every time when the -20-dB attenuator is used. Also, he doesn't need to adjust AF or RF level every time when the -20-dB attenuator is used, like in most classic transceivers.
Attenuator influences only receiving dynamic range, S-meter and audio level stay the same. If you disconnect the antenna, you can see how the receiver’s noises are changing when you switch the ATT. The receiver's noise level is lower when you select ATT 0 dB, which means that RX sensitivity is higher. When you select ATT -20 dB, it means that the RX noise level is higher, but RX sensitivity is worse. It is done in the hardware.

MB1/SunSDR2 DX/SunSDR2 PRO and ExpertSDR3 have two independent software RXs, which can be used by one or two operators. So yes, the 1st operator can receive and the 2nd operator can transmit, but to do that we should implement the Duplex mode on the firmware level.
The current hardware of our transceivers supports Duplex mode. When you transmit with one antenna connector (A2 or A3) the other one can be used for RX mode, either on one band or on different bands.
At this point, the Duplex is not implemented, while you transmit on the 2nd RX, receiving on the 1st RX will be blocked.
Do the following steps:
1. Perform a Reset procedure.
Each transceiver requires very similar actions to do that, just check the user manual for your radio.
2. Open ExpertSDR2-> Settings-> Expert tab-> press Read then Write button.
3. That's it, everything should be back to normal.
No, there is a hardware limitation, these transceivers have two software receivers, but one ADC and for Diversity Reception you need to have at least two ADCs, thus two hardware receivers. This way each ADC can work with a separate antenna which allows to phase and eliminate an unwanted interference.



The following information is presented for those who are curious about how to use the XVTR feature implemented in ExpertSDR3. First of all you should know that in XVTR mode you can use all antenna ports and ADC IN (for RX mode) and DAC OUT (for TX mode) connectors.
For example, If operating frequencies of your XVTR are 430...431 MHz, enter them in Begin freq and End freq fields. Frequency of internal XVTR LO is 402 MHz, enter it in RX LO freq and TX LO freq fields.
Now deduct XVTR LO frequency from XVTR operating frequency to get IF of your transceiver (real frequency which your transceiver will transmit on).
Example: 430 - 402 = 28 and 431 - 402 = 29.
You can see receiver IF (RX IF), transmitter IF (TX IF) and correct settings indicator. If IF correlates with one of the ham bands and XVTR bandwidth is within a ham band limit, you’ll see a green marker, it means that your settings are correct, and you can work on the air.
XVTR settings
Also, we've added control of the antenna switch for XVTR bands, now you can select required antenna input/output depending on the IF.
XVTR settings



The maximum panoramic resolution requires a lot of CPU resources. Not all PCs are able to process all data, so this leads to sound issues.
We recommend lowering panorama resolution if at higher sample rates your PC has sound issues.
DIGL/DIGU modes are identical to LSB/USB, the only difference is that tuning frequency is shifted by the offset value relative to 0 Hz by LF. User can manually set this value in Options-> Device-> TX-> DIGL/DIGU-> offset.
It was done for comfortable tuning on digital stations by the mouse click on the ExpertSDR2 panorama.
The ExpertSDR2 software separates the radio signal of the DRM station, then passes it to the third-party software (Dream DRM, WIN DRM, etc.) for decoding via VAC (Virtual Audio Cable).
Bandscope has its own DDC software receiver in the radio's hardware, it works in parallel with the main receiver.
1) For simultaneous operation of 2 transceivers/receivers on the same PC, you need to make sure these radios have different IP addresses and ports. To do that, you need to connect one of the radios to a PC and adjust its Static IP and Port, so it differs by at least 2 from the default value.
2) Create two ExpertSDR2 versions, to do this: create two different ExpertSDR2.exe shortcuts on the Desktop and make canges to the "Object" line e.g. "options_any_text.ini". So you'll have:
1st Shortcut: "C:\Program Files\ExpertElectronics LLC\ExpertSDR2 SunSDR2\ExpertSDR2.exe" options1.ini
2nd Shortcut: "C:\Program Files\ExpertElectronics LLC\ExpertSDR2 SunSDR2\ExpertSDR2.exe" options2.ini
In this case software will save 2 different Options files.



ALC is not supported in the ExpertSDR2, we plan to implement it in the ExpertSDR3.
In the meantime, we recommend you to set max output power per band in the power correction menu: Options-> Device-> Expert tab-> power correction. It allows you to send a corrected power level to the PA without overloading the PA itself. ALC system has a small delay, and it's a cause of the short overload. ALC is worse than a fixed (set up) power correction per band.

To use the transceiver with the external PA, you need to adjust the max TX output power per band: When you use the Tune button in ExpertSDR2/3, with the Tune slider at 100%, TRX sends a carrier signal on the air with maximum output power. This carrier has a stable amplitude, and you'll be able to set the max output power of the transceiver for each band. Then you can set the Drive slider to maximum and TRX will send the same output power as in Tune mode.

Note: The Tune slider is a special control of the output power for the carrier signal in tuning mode. For all other modes, for normal operations, you should use the Drive slider. Power correction coefficients are adjustable numbers, they are not equal to real output power e.g., coefficient 50% on 20M does not equal 50W, it can be 60W (in case od MB1 or SunSDR2 DX). Coefficients are not the same for every band, so please be careful and start from lower values. That's how we suggest adjusting output power per band.

Transceivers are supposed to operate with loads around 50 Ohm impedance. This is one of the main requirements.
From our experience, antenna SWR may rise up to 4...5 for RX mode without a significant drop in receive quality. For TX we do not recommend going above SWR 1.7...2.
For the X8 switch to work properly, enable the РА button in the ExpertSDR2 software.
You hear HF crosstalks of the transceiver on the PHONES jack and crosstalks detected on nonlinearity of the schematic. Try to use ferrite beads with transparency 1000-4000 on the coax cable of the antenna and Mic cable. Make 5-10 winds of cable around the bead.
As a rule, this effect happens because of the HF current on the cable surface (instead of inwards). These crosstalks also may cause feeding of an external PA, so they should be eliminated.
If your transceiver is connected to the router directly then you can find it in the router's ARP list. Find the transceiver's IP address in the list, there will be the MAC address.
Yes, you can use a straight key, to do that, you should disable the Break-In in the ExpertSDR2 and use one of the contacts of the KEY jack. See user manual for your exact transceiver.
Yes, you can. Ext CTRL switches are open collectors and can give you either open line or shorted to ground lines.
If you want to get TTL level 0V or +5V (+12V), you should tie serial resistors 1-10 kOhm.
When the switch is on - it gives logical "0", when off - logical "1". You can adjust the Ext CTRL table for the required band combination.
If you need 5 V TTL levels, you can use 5V zener diode from each line to GND and put resistors with diodes into Ext CTRL connection box.


Select ADC IN in the ExpertSDR2, in this case the signal goes:
A1 ANT-> BPF-> RX OUT-> there you put your external BPF/ATT/PREAMP-> RX IN
There are two ways to connect an external speaker to the MB1:
1) Connect a multimedia speaker via adapter jack 3.5-6.3 to the PHONES jack on the front panel.
2) Connect a multimedia speaker to the headphone jack 3.5 on the rear panel, then open: Options-> Sound card-> Output list (first in the list). Set the Enable check box, now you can listen to the sound from a multimedia speaker.
Note: If you don't need the internal load speaker, you can disable it in the audio menu, see manual.
If you use PC's sound card via rear connector it can produce some latency. Minimal latency can be reached only via the front panel PHONES jack and internal loudspeaker.
Being the software defined radio, there is no provision for hardware generated FSK in the MB1, but from our users' experience, AFSK is better in so many ways including decoding ability, seeing bad activity and so on. When you use DIGI software in the MB1 and make a virtual audio connection, the quality of TX signal the same as in FSK.
We would recommend simplifying data operation by using the MB1's own computer for hosting the RTTY software. Also, you may run the RTTY software on the external PC and use a mic (input) and a line (output) on the rear panel to get the AFSK audio into the MB1.
Yes, the MB1 has internal protection, output power is automatically decreased if SWR exceeds the manually set in the ExpertSDR2 value 2-5.
Yes, phones and the Mic jacks can be configured for operation in DIGI modes or for voice operations if you use voice macroses from the Log. MB1 uses 2 channels for one receiver, but if you use 2 different receivers (RX1, RX2), you can adjust balance for each receiver, e.g. RX1 for the left channel, RX2 for the right channel. Yes, they are independent of the MIC GAIN and AF OUT knobs, because these inputs/outputs are used in VAC menu and have their own RX and TX gain settings, which can be adjusted by the user.
The Windows gain settings also can be used for gain adjustments, but we recommend to use only ExpertSDR2 gain settings.
*Yes, they are independent of the MIC GAIN and AF OUT knobs because these inputs/outputs are used in VAC menu and have their own RX and TX gain settings, which can be adjusted by the user.

The Windows gain settings also can be used for gain adjustments, but we recommend to use only ExpertSDR2 gain settings.

If used VAC menu, TX monitoring doesn't work.
The ExpertSDR2 software has an additional line output menu, where you can select the audio output device e.g. speaker on the front panel. It contains RX/TX signals, normally this menu is used for recording QSOs in contests, but if you need you can use it for other operations.
The rear Mic input is mono, but it is split into two channels.
*Yes, it can. When the PTT signal goes from the PTT footswitch, TX button on the front panel, TX button in the software window - will be used an audio signal from the Mic input (front panel inputs).
To set up independent audio output from the front and rear panels of the MB1 you should:
- Open Realtek HD Audio Manager (in Windows system tray) or open Control Panel\Hardware and Sound\Realtek HD Audio Manager
- Press Device advanced settings
- In Playback Device set Make front and rear output…
- Press OK
Realtek HD Audio Manager
For more comfortable use:
- Open Control Panel\Hardware and Sound\Sound
- To rename your connections, press Properties of each connection and rename it to Rear Panel and Front Panel
- This way, with selected MME driver, ExpertSDR2 will detect audio outputs as Rear Panel and Front Panel.
Control Panel Hardware and Sound Sound
Shut down the MB1, unplug, wait 2 minutes, reconnect. Double check antenna selection and settings.
MB1 internal video card Intel® HD Graphics 530 (3,4,5 batches) supports the simultaneous operation of two displays, either two external or one external and the internal. So you can connect 2 external monitors, one via DPORT and the other via HDMI, but your internal display will be blank.
To fix that, you should use the internal video card for the built-in display and one external monitor (HDMI or DPORT). The second external monitor should be connected via USB-to-HDMI or USB-to-DVI adapter.
You should remember that:

1. SDR uses UDP ports and TCI uses TCP ports.

2. MB1 SDR IP address is, but MB1 PC should be in a different subnet, something like

3. In your logger (McLoggerDX for example) you should indicate local address or 50001 (default TCI server port depending on the ExpertSDR version).



The top operating temperature is 75 Celsius. When the transceiver will reach this temperature, the special protection will trigger and shut down the transceiver.
If the temperature is below 75 Celsius, it may be considered as normal.
Yes, it has an automatic protection of the internal PA. In parallel to each antenna connector there is a 2W 1kOhm resistor, to remove slowly accumulating static discharges in the receiver, and also to provide an SWR=20 in case of antenna disconnect.
HF/VHF output stages can operate with high mismatches, up to SWR=20, but at the same time, they get warmer. Output stages can easily endure short mismatches.
SWR-based protection is not implemented in SunSDR2 PRO, yet it's not afraid of high-SWR since the max output power is 20W max. Nevertheless, we do not recommend to work with SWR higher than 2. Among our TRXs we've implemented SWR-based protection in SunSDR2 DX and MB1.
Press the L/W button once again and wait until the LED turns green.
We can recommend a power supply with +15V DC voltage and 5A current. A power supply can be either transformer or impulse.
If you prefer impulse power supply, you need to pay attention to filtering of the output voltage and presence of the filtering paths on the 220V line. It's common when distortions are created via 220V line. A power supply creates distortion and wiring act as an antenna. Filtering paths are mandatory, also we recommend to install ferrite beads on both ends of the power supply cable.
Note: Max power output is guaranteed only with 15 V power supply voltage.
You can use any PA which requires input power below 20W.
SunSDR2 PRO supports max output power correction for operation with external PAs.
It means that you can set max output power in SunSDR2 PRO, e.g. 8W and can adjust the Drive level from 0 to 100%, output power will be adjusted from 0 to 8W (not to 20W). This way you cannot damage your PA by overload on the PA input.
We can recommend HLA-150 Plus or 300 Plus.
In Tone mode, with 2% on Tone slider:
On HF (14MHz) min output power ~ 4.4 mW.
On VHF (145.5 MHz) min output power ~ 0.5 mW.
Note: These values may slightly differ in different transceivers.
Internal WLAN access point (standard 802.11 n) allows you to setup wireless connection between your transceiver and PC. For example, your transceiver set up at your workstation and switch to WLAN mode. Using a notebook with a built-in WLAN you can work on the air being in another room, or basically anywhere where you can reach this WLAN.
The only thing you need for internal WLAN to work is to connect a miniature antenna supplied with the module to the transceiver, that is the main difference between the internal WLAN module and an external. An external access point is a separate device with power supply and requires a cable connection to the transceiver. From the operational standpoint, both solutions are the same.
You can revert any changes done to the internal access point or transceivers IP address, by pressing the RST (reset) button on the rear panel of the transceiver. Press the RST button, then while holding it on switch on the transceiver, release the RST button. At this moment LED on the front panel of the transceiver will start blinking. You need to wait until LED will stop blinking and turns to constant green. Your transceiver is ready to work.
Note: the RST micro-button is very sensitive and may fail if you press it too hard. Be careful!



LED blinks - it means the transceiver is initializing and not ready for operation. If it constantly blinks, it means there is no network connection.

LED is stable (NOT blinking) - transceiver is ready for operation and can be connected to the ExpertSDR2.

In the SunSDR2 QRP we used an advanced stack of a local network, so you have 4 options for local operation:

1. DHCP Auto mode is set by default. It works this way: in the beginning, transceiver works in DHCP Client mode and tries to get the IP-address automatically from an external server, if it gets the IP address, LED will stop blinking, becoming stable green color. If transceiver can't get the IP address within ~20 seconds, it will automatically turn to DHCP Server mode and provide IP address, in this mode LED will become stable orange.

2. DHCP Server mode is for direct connection of the transceiver and a PC. In this case, the transceiver will provide a PC with the correct IP address, so you don't have to adjust network card settings. In this mode, LED will become stable orange. in this mode, the transceiver will also have a static IP address

3. DHCP Client is for connection of the transceiver to the home local network, where you have a DHCP-server, which automatically provides IP addresses, for example, router or ADSL-modem. In this mode, LED will become stable green.

4. Static IP, in this mode transceiver, has a static IP address, works the same as in SunSDR2PRO - in this mode LED will become stable orange. By default, IP address is This mode requires to set up PCs network card according to the same instruction as for SunSDR2PRO. We do not recommend to use this mode without special need.

Note: if you have a direct connection, after initialization process you may change a network mode to DHCP Server, this will save you about 20 seconds after switching on.



The normal operating temperature is +45...+55 C because the ADC chip is using the casing as a heat sink.
ColibriNANO connected to RPI3 (with our image) via USB connector, RPI3 connected to a router via LAN.
RPi3 will automatically get the IP address from a router. You'll need to set up port forwarding (5050 by default for the ExpertRS and 80 if you want to remotely control the receiver via WEB-client) from a router into RPI3 IP address, you can find the example in Paragraph#3 in the User Manual for the ExpertRemote system. Now you can use remote control.
Note: ColibriNANO is not a network device, as other our devices.



1) Connect the ColibriDDC to your PC with Ethernet cable.
2) Connect the ColibriDDC to your transceiver via CAT-system in the ExpertSDR2, using the OmniRig (Options-> CAT-> Interface-> OmniRig).
You should have installed OmniRig SW on your PC.

3) In the OmniRig settings (in the ESDR2) set the Enable checkbox.

4) Press the Configure button to open the OmniRig SW settings window.

5) All further information you can find in the User Manual-> CAT Menu.
Then you set up the OmniRig to operate with a certain transceiver via a certain COM-port.

High-speed ADC in the ColibriDDC can receive signals in 0-800 MHz range, but this range is divided into special Nyquist zones. The Nyquist zone bandwidth is 62.5 MHz. ColibriDDC can receive only in one Nyquist zone at the same time e.g. 0-62.5 MHz, 62.5-125 MHz, 125-187.5 MHz etc.
For each zone, you should use BPF, for the 1st Nyquist zone ColibriDDC has its own Low Pass Filter 0-60 MHz (Chebyshev I - 7 Order).