RTL-SDR Blog V.3. Dongles User Guide

RTL-SDR Blog V3 Counterfeit Warning!

If you have purchased a counterfeit RTL-SDR Blog V3 device the features described in this guide may not work correctly, if at all. If you were tricked into thinking it was an original RTL-SDR Blog V3, please lodge a dispute with the marketplace platform purchased from. 

Please purchase either directly from our store, or using the links on the store to official marketplace listings or resellers.

Version 3 of our customized RTL-SDR dongles brought out some new interesting features. In this guide we explain how to use those feature. If you are interested, we also have the V3 feature datasheet available here.

We reccomend using our RTL-SDR Blog driver fork here https://github.com/rtlsdrblog/rtl-sdr-blog. Note that SDR# already installs this driver by default when you run install-rtlsdr.bat as described in the quickstart guide.

Feature 1: Direct Sampling HF Mode

This feature allows you to listen to HF signals between about 500 kHz to 28.8 MHz.

To use direct sampling mode:

  1. If you are using our RTL-SDR Blog driver fork, there is nothing to do. Just tune down below 28.8 MHz, and direct sampling will automatically be activated.

For other drivers:

  1. Connect an appropriate HF antenna to the SMA antenna port (this is the same port where you connect your VHF/UHF antenna). 
  2. In SDR# select the Q-branch in the configure menu (the cog icon next to the play button). (If it is greyed out make sure you stop the SDR first, by clicking the stop button in SDR#)
  3. Press Play and tune to 500 kHz - 28.8 MHz.


VHF antennas like small discones or short whip antennas will probably not pick up HF signals very well, if at all. If you have one of our dipole antennas, try connecting a long 5 meter or longer wire to the element connected to the coax center wire. To check which element is connected to the center coax you can open the lid on the black dipole base. Ideally you should use a 9:1 unun with the long wire antenna for optimal reception. Even more ideally you'd use an antenna tuner, though this is expensive.

We can also highly recommend the use of low cost active magnetic loop antennas like the MLA30+.

MW Attenuation Curve Note: In newer RTL-SDR Blog V3 batches the attenuation curve for direct sampling has been tweaked in order to provide greater attenuation in the MW band (below 2 MHz). The reason for this is that many users experience severe overload from strong broadcast AM stations which can cause problems with reception above 2 MHz.

The result is that reception of the MW broadcast AM band will be poorer, but reception above 2 MHz could be improved in many cases where overload was present before. However, reception on the MW bands with an appropriate HF antenna even with the attenuation is not usually a problem due to their extreme high power and local location.

HDSDR/GQRX and Other Software

Other software like HDSDR and GQRX can also support direct sampling. It may entail setting a device string, and for the Q-branch, the value should be 2 (or sometimes 3). In GQRX the device string would be "rtl=0,direct_samp=2" (without the quotes). In some installs that use different drivers it may be "rtl=0,direct_samp=3" instead. Make sure that there is no space after the comma. SDR-Touch on Android has a direct sampling option available in its settings page.

To go back to listening to frequencies above 28.8 MHz remember to change the sampling mode back to "Quadrature Sampling".

Note that this feature makes use of direct sampling and so aliasing will occur. The RTL-SDR ADC samples at 28.8 MHz, thus you may see mirrors of strong signals from 0 - 14.4 MHz while tuning to 14.4 - 28.8 MHz and the other way around as well. To remove these images you need to use a low pass filter for 0 - 14.4 MHz, and a high pass filter for 14.4 - 28.8 MHz, or simply filter your band of interest. (Note that that 28.8 MHz is downsampled on chip resulting in the 3.2 MHz bandwidth)

Modified rtl_tcp for direct sampling

The standard Osmocom version of rtl_tcp only allows for direct sampling on the I-branch, which is useless as we need direct sampling on the Q-branch. Please see our RTL-SDR-Blog Drivers for a version that includes a -D direct sampling flag. The Releases page has a Windows release.

Forcing Direct Sampling To be Always ON

This feature is now disabled and superseded by the feature that automatically activates direct sampling mode when the frequency is set below 28.8 MHz.

Feature 2: Software Selectable Bias Tee

V.1. and V.2. of our dongles included a bias tee which could manually be enabled by opening the case and soldering two pads on the PCB together. V.3. introduces a 4.5V bias tee that can be toggled entirely in software. The bias tee can continuously pull up to 180 mA of current.

WARNING: Before using the bias tee please ensure that you understand that you should not use this option when the dongle is connected directly to a DC short circuited antenna unless you are using an LNA. Although the bias tee circuit is dual protected against accidental shorts with a thermal self-resetting fuse and overcurrent protection on the LDO, short circuiting the bias tee for an extended period of time (days) could damage the LDO or fuse permanently. Only use it while connected to an actual powered device, like an LNA, active antenna or the SpyVerter.

To make things clearer: DC Short Antenna -> LNA -> Coax -> V3(bias tee on) is absolutely fine. What's not good and makes no sense anyway is DC Short Antenna -> Coax -> V3(bias tee on). DC Short Antenna -> Coax -> V3(bias tee off) is fine.

Note that the legacy DVB-T TV drivers will activate the bias tee by default. On Linux ensure that you have properly blacklisted the DVB-T drivers. More info on how to blacklist on the Linux section on the quickstart guide.

Optional Video: Bias tee tutorial by SignalsEverywhere available here.

To enable the bias tee in Windows:

  1. Download and extract all the files in this zip file to a folder on your PC. It contains two batch files that can be run.
  2. Make sure all SDR software like SDR#/HDSDR/SDR-Console etc is fully closed.
  3. Run the biastee_on.bat file to turn the bias tee on. It will run and open a CMD prompt that will briefly say "Found Rafael Micro R820T Tuner". The CMD prompt will close soon after upon success.
  4. The bias tee is now on. To turn it off repeat steps 2 & 3, but instead run the biastee_off.bat batch file. Alternatively, simply disconnect and then reconnect the SDR to turn the bias tee off.

If you have multiple dongles connected you'll need to edit the batch file to specify what dongle's bias tee you want to activate. Open the bat file with any text editor, like Notepad, and add the dongle selector "-d" flag. For example to activate the bias tee on the dongle that was plugged in second you'd need to change it to "rtl_biast -b 1 -d 1".

If you get a Smart Screen message, click on More Info, and then on Run Anyway. Also note that some versions of Windows may fail to run batch files due to misconfiguration or aggressive antivirus software. If you cannot fix these problems with Windows or your antivirus, run the command manually on the CMD line.

To run it manually on the CMD line first browse to the directory where the bias tee software is stored using "cd" (e.g. cd C:\SDR\bias_tee_folder), and then run:

  1. ON: rtl_biast -b 1
  2. OFF: rtl_biast -b 0
  3. If needed select a particular RTL-SDR device with the -d flag.

To enable the bias tee in Linux:

In Linux or MacOS download the source from git, compile it the same way you do the regular RTL-SDR drivers, and then run ./rtl_biast -b 1 to turn the bias tee on and ./rtl_biast -b 0 to turn the bias tee off. The procedure is:

git clone https://github.com/rtlsdrblog/rtl-sdr-blog
cd rtl-sdr-blog
mkdir build
cd build
cd src
./rtl_biast -b 1

If you want to be able to run the bias tee program from anywhere on the command line you can also run "sudo make install".

If you have trouble running the bias tee check with a multimeter if there is 4.5V at the SMA port. Also check that your powered device is actually capable of receiving power. Remember that not all LNA's can accept bias tee power. We recommend Adam 9A4QV's LNA4ALL, as you can order this from his store with the bias tee power option enabled. If you need further help please contact us at [email protected].

Enabling the Bias Tee in PiAware

Please see this link for instructions, or see below to see how to force the bias tee to be always on.

Forcing the Bias Tee to be Always On

If you are using our RTL-SDR-Blog driver branch you can force the bias tee to be always on by setting a flag in the EEPROM. The rtl_eeprom command is "rtl_eeprom -b 1". Run the opposite command "rtl_eeprom -b 0" to disable the forced bias tee.

Feature 3: Selectable Clock & Expansion Headers

This is for advanced users who need to daisy chain clocks together for coherent experiments, or need to access other ports. You can either bridge the clock selector the directly with a solder bridge, or solder on a 1.27mm 2x2 header pin jumper.

To add a jumper to the CLK selector header.

  1. Carefully remove the 0 Ohm resistor.
  2. Very carefully solder a 1.27mm 2x2 header onto the clock selector pads.
  3. You can now select your clock input.

How to connect the CLK jumpers:


 The first position allows you to output the dongles clock to the CLK pads. The second position allows you to input an external clock.


An example of CLK daisy chaining is shown below. One dongles TCXO is connected to two other dongles who have disconnected clocks.


Feature 4: Additional GPIO Ports

Please see the guide written by Rodrigo Freire here.

LF/MF Improvement / Bias Tee Disable Mod:

If you want to improve the performance at LF/MF (below 500 kHz) and do not require the bias tee, then you can remove the bias tee inductor at L13. Of course remember that if you are interested in VLF/LF, it might be a better idea to use an upconverter like the SpyVerter, which can be powered by the bias tee on the dongle.

Notes to be aware of:

I opened my RTL-SDR V3 dongle and found that the thermal pad has a small air gap between it and the enclosure, is this normal?

This is normal. The purpose of the thermal pad is to fix L-band VCO lock problem that are related to PCB heat build up. The RTL-SDR V3 only requires very minor heat sinking to overcome this issue, and a small air gap does not reduce the thermal transfer enough to cause issues. In fact the V3 PCB has already been redesigned to dissipate heat better, so the thermal pad is not strictly required, except in very warm climates.

My RTL-SDR V3 is getting hot.

Please remember that these units do get hot to the touch especially when used in warm climates. This is not an issue and is normal. The temperature will normally be about 20 - 25C above ambient. We have improved the thermal bonding and heat transfer between the chips and the metal case. This results in making the metal case hotter, but it keeps the chips much cooler, resulting in better performance. To lengthen the life of the dongle we recommend keeping the unit away from direct hot sunlight.

Current Known Issues:

We're constantly trying to improve our units and we always make note of what issues exist and how to fix them.

2019 Onwards:

No known issues.

2019 and earlier units (no longer shipping):

Note that the following problem has been fixed in newer batches with a new design.

0.2 - 0.3% of units may have a faulty RTL2832U chip. This is characterized by higher than normal USB currents (normal is 0.28A - 0.3A), and often random disconnections from the USB as well as increased heat. The same problem affects all brands of RTL-SDR.

2018/8 Batch (no longer shipping):

A small number of these units (~approx 300 units) had faulty bias tee LDO chips which caused the bias tee to be permanently on. The cause was bad silicon in the LDO chip. These units run normally in all other ways, except that the bias tee cannot be turned off. They can continue to be used normally, without the bias tee. The thermal fuse will protect against short circuits.

If you have one of these, feel free to contact us at [email protected] for a replacement, or if the bias tee is not important to you and you can solder, removing the L13 inductor will fully disable the bias tee.  

Known V3 Batch 1 Issues (limited quantity batch, no longer shipping):

  1. Increased sideband noise on very strong narrowband signals. This should not be a significant problem as it only affects very strong signals. The hardware fix is to add about 100-220uF of capacitance on the 3.3V power line. Batch 2 will reduce this noise.
  2. The bias tee when turned on adds a large spur in direct sampling HF mode. This may be problematic only if you intend to use a bias tee powered HF LNA in direct sampling mode. This can be fixed by adding about 2.2uF of capacitance to the output of the LDO, before the inductor. Batch 2 will fix this.
  3. The bias tee can be damaged by accidentally short circuiting the output for a few seconds while it is on. This damage only occurs on USB3.0 and USB2.0 ports that can provide up to 1A or more or current. Batch 2 will add a resettable fuse to prevent damage.


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I am trying to get a receiver for the 900 Mhz band in order to decode my smart meter consumption data using this project: https://github.com/bemasher/rtlamr Does this module support this frequency? Thanks

Richard Blibit

It most certainly does. I use it for the 900 to 928 ISM band for my Ubiquiti Bridge unit. It is very sensitive in this band. You can’t beat the price, either. And I glad since I am on a tight budget!

charles mitchell

I have been playing with the settings and now can’t receive anything, not even FM radio stations. What are the standard settings to get back where it was at when it came out of the package I have tried everything I know
[email protected]


Hello everyone, when playing SDR # or SDRConsole via TCP with raspberry, the reception of the signal is strong, but the reception of the audio is frequently interrupted which makes it impossible to decode the data sent. The Raspberry is connected via 5GHz WiFi to the router (D-Link DAV 5582) and the PC is connected to the router via wired.
Could it depend on the bandwidth of raspberry’s USB ports? Any suggestions?
thanks in advance

Ben in Seattle

Hey Salvatore, I doubt it’s the bandwidth of the USB ports. You may have to shield the Pi. My Raspberry Pi 3B puts out a lot of RF noise, sometimes even stomping on its own bluetooth signal with its WiFi. Try a test with with the WiFi and Bluetooth turned off and see if that makes a difference. (To shutoff all radio transmissions, you can type ‘sudo rfkill block all’; use ‘unblock’ when you’re done testing).


thanks a lot. I will try it.


Hello everyone, when playing SDR # or SDRConsole via TCP with raspberry, the reception of the signal is strong, but the reception of the audio is frequently interrupted which makes it impossible to decode the data sent. The Raspberry is connected via 5GHz WiFi to the router (D-Link DAV 5582) and the PC is connected to the router via wired.
Could it depend on the bandwidth of USB ports? Any suggestions?
thanks in advance


Hello everyone,
on raspberry when i put this command: rtl_biast -b 1 i found 4.5V after sma connector of RTL dongle, bu twhen i put : rtl_tcp -a 192.168.1.xxx biast is going OFF.
Everyone knows what appened?


Perform a rtl_tcp -h and look for the -T . If your rtl_tcp already has the -T Tbias cmd….You don’t need the rtl_biast anymore..just use rtl_tcp -a xxx.xxx.xxx.xxx -p 1234 -T


Great! it works well! Thank


Received V3 dongle yesterday. Works fine on HF with direct sampling in Qubic sdr and GQRX on OSX.
device string used in Gqrx is rtl=0,direct_samp=3.

I can however not get it to produce any signal on VHF or UHF.
In GQRX I used device strings rtl=0,direct_samp=0 / 1 and 2 (seperately) but no signal not even on FM broadcast. In Qubic I changed the Direct sample mode to off and also there i get no VHF or UHF signals.
It is not an antenna problem since a second dongle (not the V3 but a generic cheap plastic one ) produces fine signals. Also signals when I transmit with my handheld in UHF are not seen. Please help? Is the unit faulty or am I missing something?


Thanks for the reply. But it still is not receiving on vhf/uhf.
I use ‘rtl=0’ string. This works with my other rtl dongle…


It works with 14.400 -28.800 Mhz, i updated the version of sdrsharp and use the RTL-SDR Usb mode. It is OK


I have an V3 Blog fabrication, in Q-Branch, it works fine with a loop antenna from 1 to 14.400 Mhz
I receive australia (14400 km) , south Africa, Japan from Paris in FT8. But from 14.400 to 28.800 Mhz, it receive nothing. It runs on SDRSharp v1443. Is it normal ?


yes. See manual :
Note that this feature makes use of direct sampling and so aliasing will occur. The RTL-SDR samples at 28.8 MHz, thus you may see mirrors of strong signals from 0 – 14.4 MHz while tuning to 14.4 – 28.8 MHz and the other way around as well. To remove these images you need to use a low pass filter for 0 – 14.4 MHz, and a high pass filter for 14.4 – 28.8 MHz, or simply filter your band of interest.


hi to All.
I encountered problems:
txco does not work correctly with upconverter;
txco with Direct sampling is ok, but can not reduce the rtl gain, this generates ghost stations between 3000 to 8000mhz in my websdr. Not good.

Ricardo Fernandes from Brazil


Hi, Having trouble getting RTL-SDR V.3 to show up as a source in AirSpy. Device manager shows USB devices / Bulk-In, Interface (Interface 0), and Human Interface devices / HID Infrared Remote Receiver. They both go away if I remove the RTL-SDR, so I assume that it installed OK. Any help appreciated.

Thomas Simpson

I purchased a V3 dongle via your store and it arrived this week.
1. It works OK on MultiPSK if used via their IQ interface option.
2. It is recognised under SDR-Console but when clicking on Start the program closes down
3. It is not recognised at all under SDR#
4. It appears in Device Manager as RTL2838UHIDR
5. Zadig has been run, and 3 other RTL-SDR devices all work OK on this PC (I have also tried it on a 2nd PC)

Any ideas as to what the problem is (either with the device or me?)


Have you tried USB2.0 port? My dongle (received yesterday) doesn’t work when connected to 3.0.

Thomas Simpson

Yes, and I have tried it on a second PC. Strange thing, it works with both ACARSDeco2 and MultiPSK (when using direct IQ interface) but not with SDR# or SDRConsole. Not to worry, I can use it for ACARS and VDL2 decoding and thats what I bought it for.

Thomas Simpson

Thanks Admin,
I had run the install-rtlsdr.bat file, but in a second copy of SDR#, my mistake and apologise about this, working fine now.


For Auto-Start V3 bias-t at boot

(1) With dump1090-mutability v1.15~dev on Raspbian Jessie or Stretch:

(2) With Flightradar24’s Pi24 image (Raspbian Stretch with integral dump1090-mutability v1.14)


Hello, someone could help me, I have successfully installed the SRDruno program, but when I open the option OPT select imput, RTL2832 does not appear to be able to select it.
Thanks in advance..




Hola, alguien podria ayudarme, he instalado con exito el programa SRDruno, pero cuando abro la opción OPT select imput, no aparece RTL2832 para poder selecionarlo..
Gracias anticipadas..

Jeff Barteltt

I have used the scripts to set up bias t with my V3 dongle. I have loaded the USB drivers etc and the dongle is working under 1090 mutability.

Ok, with the bias t files loaded, 1090 mutability turned off, using rtl_test -t, I get

Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6
[R82XX] PLL not locked!
Sampling at 2048000 S/s.
No E4000 tuner found, aborting.
what I should be. On using ./rtl_biast -b 1, I get 4.5v out of the V3 dongle, yay !!

But as soon as I turn mutability back on, back to error “usb_claim_interface error -6” and ./rtl_biast -b 1, no voltage.

So it works but I need to find the correct scripts, using 1090 mutability, for the two to work together.

Jeff Barteltt

Running dump 1090 is turning bias t off. raspian stretch lite?? and RTL2832U Osmocom drivers

CF Pajak

Same Problem with rtl_power. BaisT runs and I get correct voltage. As soon as I run rtl_power, BaisT stops. Raspbery pi Headless Strech.

Carl Pajak

FIXed: rtl_power -T option passes BaisT without issue. My bad for not reading the help file. was stuck on the GPIO pins discription (with Raspberry Pi). No GPIO usage needed!

Billy Bob MOOD5

FAO Admin.
Great product and excellent value for the money,and they work extremely well.sensitivity is that of my Yaesu HF receiver.compare this to a funcube dongle and i laugh at those who buy them.
A+++++ I like ..thumbs up..
Humour…A television commercial in the 1980s Great Britain..Victor kiam said i liked this product so much i bought the company.


could someone please tell me the value of inductor L10 (that’s the first inductor on the input lowpass filter of HF amplifier, right from D12 ESD diode, 0603 part). Damaged it by being clumsy with tweezer. I could only count 26turn under microscope, not brave enought to guess the value.. Since it’s part of the HF low pass filter, I’d like to replace it with the exact value as original.
Thank you,

Daniel W

While the sampling frequency of the RTL-SDR sets the upper frequency bound for the direct sampling HF mode, mostly out of beginners curiosity, what sets its lower frequency bound to 500KHz? Is it a hard limit, or more a ballpark figure based on what kind of antenna a typical RTL-SDR might use? I see some other modded RTL-SDR specify a range down to 100KHz. Do all of those feature upconverters, or, if not, what makes them able to reach that low?


Wondering why I can receive HF transmissions on the VHF band when using Direct Sampling Q-branch? If I tune to, for example, 14500 kHz, I can receive this station also on 43300 kHz. Why is that?


Will a female to male usb 2.0 cable work on the rtl-sdr 3.0?

I like to oerate mobile and the dongle has proven vulnerable in that use.

R vd Meer

I have a active usb cable,but it gives a lot of noise on reception,so i dont use it anymore.
Mine solution is a 5 meter usb cable to the attic,there its connected to a usb hub on wich i have multiple rtlsdr sticks.


Does anyone know how much current the bias-t can handle? I want to play with some old C-Band LNAs. I can hardly wait for my V3 to arrive. Thanks.

Beer It

Did you check the datasheet ?


“The V3 makes use of a low noise LDO and one of the GPIO pins on the RTL2832U to provide a 4.5V bias tee that can be activatedin software. The bias tee can pull about 100 mA continuously so is suitable for the majority of 3-5V powered LNAs that are popular with RTL-SDR devices. The bias tee is protected against accidental short circuits at the LDO level, and with a thermal auto-resetting PTC fuse. See ‘Activating the Bias Tee’ for more nformationon software for activating the bias tee.”


you’re probably all over this, but but i thought i’d throw this out there for general public; be aware of what you have; old c band LNAs are just that, and good for 4ghz. c band lnb’s often have a LO at 5150mhz, which means the modulation is inverted since the lo is higher than the downlink. no biggie for some modulation types but deadly for others. also be advised that the old old DRO LNBs are drifty as hell. the thinking was that since carriers at the time often took a whole transponder, you’d achieve lock even if you’re a few megs off. Power for most of these are 12-24v, 300ma.


Not only that, but the newer LNBFs use voltage to change polarity (~15v for Vertical and up to 24v for Horizontal.). Some however, use two bands worth of freq’s to provide both polarities at once. Definitely research what you have before playing with it.
Happy happy joy joy.



I’m a blind bcl listener, I plugged the RTLSDR Blog 3 dongle on Adroid with SDR Touch app, because the Windows and Mac programs are not accessible with the screen reader software.
I would like to receive some BCL signal in am, and ham radio in ssb, but unfortunately I do not get any useful signal.
I connect the smartphone to the rtlsdr with an otg cable that powered both devices.
I set preference / direct sampling to the “branch q direct sampling” function useful for short waves,
I use a wire antenna of 10 meters, and with my Sony icf 7600 I received many signals in same frequences.


Giorgio De Nunzio

Hi Sauro, I have just received my dongle an hour ago and performed a rapid test, so mine is not an expert’s reply…
Have you had better results since then?
Have you tried to adjust radiofrequency gain?
Best regards

Paul L Rodenhuis

I have a Uniden Bearcat UBC9000XLT scanner and discone antenna. What will the V3 dongle give me that I don’t have already?


The simoultaneous view of all the signals in the band. You don’t need to scan at the speed of light to catch some signal, you see them all.



Paul Rodenhuis

Hi. I have just ordered a V3 and awaiting its arrival. Some questions if I may:
1. I have a Vista PC (old, I know) with Vista and Ubuntu 16.xx. Is one better/quicker than the other? Is Windows easier to setup and get going than Linux? I also have this 8.1 laptop, an XP netbook and several Android tablets.
Apart from the laptop, are the others useful?
2. Is SDR# the best s/w to install?

Eric Faden

So if I have a LNA4ALL with the bias-t mod done, can I safely place it on the RTL SDR before enabling the Bias-T? I am trying to figure out the correct order to safely do this? I don’t want to burn anything up, but I thought I wasn’t supposed to place a bias-t enabled device on the RTLSDR before bias-t was enabled, and not to enable it without a bias-t enabled device… but this seems like a catch-22 since it is software enabled.


How do I know what batch my rtl-sdr dongle is from?


It will be silver and have a v2 stamped in the corner


Strike that… V3


I’m having an issue with the bias-t stopping when i run gr-iridium or multimon-ng in ubuntu 16.04. When i use any other program (gqrx + decoders for example), the bias-t stays active. Thought it might be a blacklist issue, so i have done that. Any ideas please?


Just tried to turn BiasT on, BUT ” ‘rtl_biast’ is not recognizedas an internal or external command, operable program or batch file.”
Downloaded the ZIP file, running on Windows 10 Pro. Using a RTL_SDR v3.


Seeking recommendations for an F-Connector Splitter with one port DC Power Pass through.

Running 2x RTL-SDR dongles with an LNA near antenna. Seeking to have one dongle BIAS-T power the LNA.
Splitter must be F-Connector. Any recommendations?

Jim Williams

I am new to SDR. I just purchased one of your rtl-sdr blog v3 dongles from Amazon and am trying to use it in direct sampling mode. I am using Gqrx on an iMac running macOS 10.12.5 Sierra. In normal mode, your dongle shows up as Realtek RTL2838UHDIR SN:00000001 and it receives FM broadcast signals just fine. To switch to direct sampling, I change the device string to “rtl=0,direct_samp=2” (without quotes) per the instructions above. I also set the input rate to 2048000 consistent with your instructions for SDR#. I then tune to a very strong local AM broadcast station and hit start. I get nothing at all on either display. When I go back to check I/O devices, the device has switched to “Other.” Can you tell me where I have gone wrong? (Congratulations on America’s Cup!)

Jim Williams

1.010 mHz (WINS in NYC).

Hopefully this will get a screenshot to you.

/Users/jim/Desktop/Screen Shot 2017-07-07 at 2.51.53 PM.png



I am using a Mac here running OS X 10.11.6 (El Capitan) so not quite the same as you. However, I found that I had to update my GQRX with the latest version. I used MacPorts, which also updates the RTL-SDR driver. When I did that, the direct sampling option worked fine. (Beforehand, it gave me nothing at all, similar to you.)

If you are not using MacPorts, you should give it a try. After installing it (see the web page for instructions), the command would be

sudo port install gqrx

and then you would run GQRX from the command line as:


Perhaps this will help.


Thanks very much for your help!


Hello! I accidentally gave a food of the active antenna on sdr entrance (12v). Sdr works in VHF When I pereklyuat VHF of strengthening is not present and nothing is heard. I ask to prompt what detail most likely is subject to replacement. Thanks. I ask to specify the name.


Yes, I accidentally applied 12 volts to the antenna input. I listened at this time to a frequency of 3600 MHz. (In the settings was Q-branch). I checked BAV99, it works. The capacitor is good. I turn on the frequency of 144 MHz, everything works well, I hear signals from the walkie-talkie. When I translate in the settings the direct conversion (Q-branch) and put the frequency of 3600 MHz the scale shows an even level and there are no signals from the antenna. There are no noises. Is there a possible cause in the stabilizer is 4.5 volts. I think I need to replace it (LP2985AIM5-4.5 / NOPB tell me this stabilizer is used in SDR). I measured the voltage at its input, it is


equal to 5 volts. The output should be 4.5 volts. There is no voltage at the output.


Thank you. I understood. So the stabilizer does not turn on when the Q-branch value is set. If the amplifier is damaged, then why do I receive a 144 MHz signal with good gain, the SDR works as expected, without any problems receiving the signal, and when I switch Q-brunch and put 3600, there is no gain. Is it possible in this case? Or at a frequency of 144 MHz, another amplifier is involved?


I checked D12, the diode. It doesn’t pass a signal in one side. Write please brand and model of the D12 diode. And Most likely the amplifier as the signal passes very poorly burned down. It is heard but is very silent on the korotkikhkh waves. The amplifier is precisely used by BGA2867,115?


Spasiboza help. I have delivered to Bga2712. I have successfully earned everything.


wow, just wow… for the price this dongle really does it all! i’m glad i waited until V3, as the ability to get HF, along with VHF in a single small package is just fantastic! i am using gqrx under OS X 10.10.5 and also under GNU/Linux – works very well indeed – kudos!


Hello. I would like to use the dongle in combination with a Transcierer. Is it possible to connect a Tx line at some point on the board of the dongle, so that it is kind of muted during Transmission ! And if it is possible, how could it be done ?


Is it possible to use the V3 dongle in direct sampling mode for HF in combination with the command-line tools rtl_power or rx_power?


Yes it is.. The rx_power utility accepts a -D mode argument which sets direct sampling mode. Values for mode can be set as 0 (disable/default), 1 (I-branch), 2 (Q-branch) and 3 (no-mod). I just used the V3 dongle to log activity on the 40m band with the following command: rx_power -D 2 -f 6.98M:7.21M:200 -i 10 -d driver=rtlsdr -g 50 outfile.csv


I am using a v3 to run ADSB on a RPi3 but unfortunately it doesn’t work with my ADSB program Dump1090 mutability – just causes the error usb_claim_interface error -6 when run 🙁

Is there a way to get biasT set to on when the RPi3 is started and which is compatible with the Dump1090 program OR a way to hardware mod the unit so it is active when switched on?.

Many thanks for your assistance.


Can’t find the RF impedance…do we assume it is 50ohms ?


Hello to all,

I tested my “RTL-SDR.COM V3” key at 1545 MHz (L band), with a patch antenna and a LNA supplied by the key. This key seems to have a very low drift and a small shift of 2 KHz from the nominal frequency, which is a pleasure not to have to consider drift and shift.

I noted that a sampling frequency of 250 KHz introduces an additive noise of about 4 dB compared to a sampling frequency of 1 MHz, So on SDR#…, avoid this 250 KHz sampling frequency (I will switch all modes in Multipsk at a sampling frequency of 1 MHz instead of 250 KHz (except ADSB which needs 2 MHz)).



Is there a way to have the bias-t on in DVB mode in linux? I want to use the dongle as a normal TV dongle, and I have an antenna with a built-in LNA that requires bias-t to work…


Very nice. Didn’t take long at all to set up my V.3 dongle. The only thing that tripped me up is that you have to hit “stop” to change from Quadrature Sampling to Q-Branch and vice versa. Thanks for a great set of instructions.


Hi, still learning all this sdr stuff, can this V-3 dongle still be installed in the dolphin labeled up converter ??? I bought the V-3 as an upgrade to the cheap one that comes with the kit, thank you in advance for any answers…