Tag Archives: Portable SDRs

The new Malahit-DSP: A portable all-in-one wideband SDR receiver

Many thanks to SWLing Post contributor, H. Garcia (PU3HAG), who writes:

Hey Thomas,

Some very exciting news on the topic of portable all-band receivers comes from Russia! A group of engineers have just released for ordering the new Malahit-dsp. And it’s truly impressive! Picture an Icom IC-R8600 with the size of a Sony 7600G!

It seems it all started in June this year. Back then, RX9CIM George posted a note in QRZ.com forum about a new project he had been working of a standalone, SDR-based, all-band, all-mode receiver called Malahit-dsp.

Fast forward to November and it seems the project is finally complete as new posts started to bubble up in Youtube and in Russian forums. George is now taking orders of the Malahit DSP.

I can’t read Russian, but with the help of Google Translator, we can find some interesting details:

The project authors are RX9CIM George, R6DAN Vladimir and R6DCY Vadim. It seems their goal was to design a low-cost portable SDR radio, using only easily obtainable components and to become the natural successor of the popular Degen and Tecsun radios.

Technical Specifications

  • 1 MHz to 1000 MHz.
  • Bandwidth 160 kHz.
  • Modulation types AM, WFM, NFM, LSB, USB.
  • Powered by one Li-ion cell.
  • Consumption up to 300 mA
  • Main chip ARM STM32H743VIT6 MCU High-performance and DSP with DP-FPU, ARM Cortex-M7 MCU with 2MBytes Flash, 1MB RAM, 400 MHz CPU
  • Printed circuit board is used four-layer, factory-made; for purchase, refer to RX9CIM. malahit_sdr@rambler.ru

PCB only: ~ USD 17.22
Finished receiver delivered inside Russia: USD 195.65

From the forum, there is also this important note: “Attention! Fraud/Scammers detected! You can purchase components or finished devices from George only ”

It seems the project is open source, the schematic, PCB and software are available to download.

I really hope this receivers becomes popular and available world wide. I also hope this new project “shakes” a bit the industry of shortwave receivers. Since the Degen 1102/03, Tecsun 450/600, Tecsun PL310/880, we have been seeing only iterations of the same designs.

Pages

Group dedicated to Malahitdsp
https://vk.com/malahitdsp

Recent discussion on Malahit, annoucement of ordering is now available, pictures and videos
http://hamforum.ru/viewtopic.php?t=193

Videos

Video 1: Shows the soldering of large components (encoders, speaker, SMA jack) on the radio board and installing it into the metal enclosure. Next a demo of receiver working. Prepared by Sergeyenkov Alexander:

Video 2: It shows a bit of the manufacturing process and demonstrates how one can build the receiver at home using kit pre-made board and components acquired in AliExpress. Also includes a test of the receiver barebones. Prepared by R2AJI Vladimir on his YT channel “HAM Radio Channel”

Wow!  Thank you so much for sharing this!  The Malahit-DSP looks like a fantastic little receiver–I especially love the fact that it has a backlit color touch screen with both a responsive spectrum and waterfall display. It also looks and sounds like the built-in speaker is of decent quality and the audio amplification is more than adequate.

I’ll see if I can get one to evaluate. Thanks again for the tip!

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Mike’s overview and review of the $40 Soft66RTL3 SDR by Kazunori Miura (JA7TDO)

RTL3

Many thanks to SWLing Post contributor, Mike Ladd, for the following guest post and overview of setting up and using the Soft66RTL3 SDR:


Soft66RTL3 SDR: A low cost…Good performer direct from Japan

by Mike Ladd

Much has changed in the last 8 years in the world of SDR radios. Fast forward to 2016 and just about everyone in the hobby has heard the buzz word “SDR radio”. When SDRs first came out to the market they were all aimed at HF listening and you had two types to pick from. The first being soundcard based and the second being direct sampling. The price gap between the two were several hundred dollars. The more expensive being direct sampling. As the hobby progressed, so did the technology and the prices started to shift dramatically.

You can now purchase a TV dongle for $10.00 and turn it into a SDR. The Soft66RTL3 is basically a TV dongle but with a lot more features.

The Soft66RTL3 comes from an engineer who is no stranger to the world of SDRS. Kazunori Miura (JA7TDO) has been designing and selling many models of SDRS over the internet and shipping them direct from Japan for about 7 years. The Soft66RTL3 is his latest of model hot off his bench. This SDR is a dual input RTL-SDR with a built in 50 MHz upconverter along with 4 user selectable band pass filters that greatly increase your signal to noise ratio in the HF bands.

Soft66RTL3-board-001 Soft66RTL3-Board 2 Soft66RTL3-board

The frequency range of the RTL3 is from DC to Daylight (0.4 kHz to 1.7 GHz). Miura also addressed a heat issue with the previous version (RTL2) by adding a thermal pad and heatsink. RTL dongles are notoriously unstable due to overheating. In theory, the thermal pad should add frequency stability and keep drift to a minimal.

RTL3-TrimmerPot

The last feature of the RTL3 is the input gain trimmer pot (see image above). The trimmer pot is for the HF side of the SDR and is already set before it’s shipped from Japan. If you would like to reduce or increase it the trimmer pot is easily accessible. I would suggest leaving it as is.

The RTL3 is broken down into two sections: the HF input side and the VHF/UHF input side.

Soft66RTL3-encoder

The HF side of the SDR (above) has a red rotary encoder and trimmer pot port. The VHF/UHF side (below) has the USB Mini-B connection.

Soft66RTL3-back

Both sides of the RTL3 terminate to a SMA-Male connection and Power comes from a single USB Mini-B cable.

Soft66RTL3-BandPassFilter

Band pass filter selection

If you look at the rotary encoder (red cap cover) you will see a small notch window. The 12 o’clock position is #5 on the encoder dial. One click clockwise will take you to switch position #6 and one click counterclockwise will take you to #4. You should pull the red cap cover off to have a look and get your bearings.

The band pass filter selection is as follows:

  • #4 enables BPF 0.4 to 1.2MHz
  • #5 enables BPF 1.2MHz to 5MHz
  • #6 enables BPF 5MHz to 15MHz
  • #7 enables BPF 15MHz to 30MHz
  • #8 or #9 enables the VHF UHF side of the SDR

All other positions will bypass the filtering section on the HF side of the SDR.

Installation

If you already have a RTL-SDR on your system then all you need to do is swap it out with the RTL3 and change the offset of -50,000,000 in HDSDR or SDR# to listen to the HF side of the RTL3–but if this is your first SDR we will need to install 2 items: the front end app and the driver.

I will assume your system is Win-7 or better and we will be using SDR# as our program of choice to drive the RTL3. The RTL3 runs just fine in HDSDR and SDR-Console, but by choosing SDR# it will reduce our setup time considerably.

ScreenShot-SDR

  1. Plug in the RTL3
  2. Make a folder on your desktop and name it SDR#
  3. Download the latest version SDR# from www.airspy.com and copy the contents of the zip file to your newly created SDR# folder
  4. Inside of your SDR# folder, double click on install-rtlsdr
  5. After the batch completes, double click on the “zadig.exe” inside your SDR# folder

screengrab

When you run the “zadig.exe” make sure you select “list all devices” as shown above.

ScreenGrab-Window

The next 3 steps are:

  1. Select “Bulk-In Interface” (Interface 0)
  2. Make sure the proper USB device is selected (2838)
  3. Click “install driver”

The RTL3 is now ready to be used and no further setup is required.

For a more detailed installation I would visit RTL-SDR.COM for a complete setup instructions: http://www.rtl-sdr.com/rtl-sdr-quick-start-guide

I will assume you did not have any issues setting up the ZADIG driver and now move on to using the RTL3 inside of SDR#. I will show you real world conditions that are not from any scientific standpoint.

Antenna wise, for the HF side I will be using a G5RV mini and for the VHF/UHF side I will be using a Scanntenna ST-2.

You can now launch SDR# and check the following settings (see image below).

SDRSharp-Settings

For the VHF/UHF side of the RTL3 you will want the rotary encoder on position #9. You want the cutout in the encoder cap showing the 5 o’clock position.

Summary

I have been using this SDR for a little over 3 months. Out of all the low cost SDR’S on the market, this one gives you the most bang-for-your-buck and it is a great entry level SDR with some “Pro” features.

Pros:

  • Low Price
  • HF VHF/UHF in one package
  • Works with any app that supports the RTL-SDR front end
  • 4 user selectable band pass filters for HF
  • Highly sensitive user controlled input RF amp
  • Small & very compact metal case
  • Dual input SMA jacks
  • ESD protection diode

Cons

  • Some intermod in the 460-470 MHz range
  • Inputs are on opposite sides of the SDR body

The Soft66RTL3 price is $40.00 US shipped–click here to order.


Mike, thank you so much for this excellent overview of the Soft66RTL3!  I’m especially appreciative of the time you’ve taken to explain the installation process–for many, this is one of the more difficult RTL-SDR learning curves.

I’m very tempted to check this out for myself–I love the fact that this little SDR has bandpass filters.

Post Readers: I suspect Mike will monitor the comments in this post, so feel free to ask questions. Make sure to check out Mike’s website, where you’ll find more articles about software defined radios.

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PortableSDR: The Holy Grail of portable SDR transceivers?

PortableSDRMany thanks to my buddy, Bennett Kobb (AK4AV), who shares information about the PortableSDR, one of five finalists in The Hackaday Prize.

PortableSDR creator, Michael R Colton, describes his project on Hackaday:

“The PSDR is a completely stand-alone (no computer needed), compact, Portable Software Defined Transceiver (hence the name, sorta). Originally designed for backpacking use by Ham Radio operators. It includes complete coverage up to about 30Mhz (plus 144Mhz), it has a 168Mhz ARM processor, color display, and an innovative interface.

Vector Network Analysis (which includes antenna analysis) and GPS functions are included.

The entire design is Open Source. The electronics are designed and laid out to be easy to understand and tinker with. In addition to source code, schematics, board layout and parts lists, articles and videos describing the theory of the design are being created.”

He includes this video of his working prototype:

I will certainly follow this project with interest. I love the fact that PortableSDR has such a small form factor, yet still manages to include room for a battery, display and CW paddles.

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