Cheap spectrum analyzer and signal generator

In search for some cheap and useful RF test hardware, I came by Geekcreit® Spectrum Analyzer USB LTDZ_35-4400M_Spectrum Signal Source with Tracking Source Module RF Frequency Domain Analysis Tool at sale price of aroundy $30/EURO30. It looked to have quite promising specifications:

Attribute: RF frequency domain analysis tool
Interface: usb
Power supply: usb
Standby current: ≤100mA
Sweep current: ≤350mA
Sweep bandwidth: 33mHz—4400mHz
Turn on the tracking source output bandwidth 33mhz—3000mhz
Sweep step: ≥ 33~68.75mHz/125Hz, 68.75~137.5mHz/250Hz, 137.5~275mHz/500Hz, 275~550mHz/1kHz
550~1100mHz/2kHz, 1100~2200mHz/4kHz, 2200~4400mHz/8kHz,
Sweep speed: ≥800 points / sec
Sweep dynamic log ratio: > 50dB
Point frequency or sweep output power: ≈0 dBm
Input detection: ≤10dbm
Background: ≈ -60dBm
Software used on the computer side: NWT4.11.09 version
Computer operating system: winxp, win7, win10
Provide software (English language) and instructions for use.
If you need the with shell version: please buy Product ID: 1494125

Ready for use:

Did not come with case so I needed to build something of my own (there are more expensive versions with case):

Software

The device connects to PC and needs of course software and documentation. The product page gave link to RAR file to download. I downloaded the RAR file mentioned but my 7zip tells that the RAR file is damaged. After some searching it seems that I was not the only one having this problem.  Thus lead me to look for alternative download location, like http://myosuploads3.banggood.com/products/20190421/20190421205201LTDZ35-4400M.rar that did not work better.

Finally I decided to test to update my 7zip to new version (2019-02-21). That helped a to solve the issue.  Not the RAR file opened nicely. I got the document and software files.

2019-08-10-6

Here the winnwt_4_09.exe is the software installation package for Windows computers. It installed nicely to Windows 10 computer.

The CH341ER.EXE are the drivers for the USB to serial converter chip that the card uses. I did not need to install that, because I know my computer already had driver for this quite commonly used USB to serial chip. The device shows as COM port when connected to USB, in my case COM3

There are also two pdf files that have instructions for use (Chinese/English) and circuit diagram of the card.

The software is LinNWT / WinNWT which supports many similar devices. It supports many functions.

The main function is a frequency sweeping using tracking generator. It can be used to measure the frequency response of RF circuits. To use tracking generator, the user needs to press once the button on the board to turn on tracking gnerator before measurements (one press is enough, after turning on it stays on for many measurements.

Here is the control window:

2019-08-10-1

Hare is the measurement results window:

2019-08-10-2

Other functionality is RF signal power measurement:

2019-08-10-3

The tracking generator can also be used as RF signal source:

2019-08-10-4

The software seemed to work OK.

https://www.banggood.com/Geekcreit-Spectrum-Analyzer-USB-LTDZ_35-4400M_Spectrum-Signal-Source-with-Tracking-Source-Module-RF-Frequency-Domain-Analysis-Tool-p-1450129.html?p=27131452996820140438

Alternative software sources

Because I has initially problems in getting the “official” software to work, I did some Google searches for alternative software or alternative download location. I found there some potential alternatives.

Page https://lzhomelab.blogspot.com/2015/02/recently-i-managed-to-buy-collect-and.html?view=magazine says to download the newest version of WinNWT4. The software should have been at http://www.dl4jal.eu/hfm9.htm but trying to download just gave “The requested file does not exist.” Browsing http://www.dl4jal.eu/ did not help. It seems that software could not be found here anymore for some reason.

I also checked https://vma-satellite.blogspot.com/2016/12/vma-simple-spectrum-analyser-new.html. It looked interesting but download link did not work. Also page https://www.eevblog.com/forum/testgear/presenting-my-new-software-for-the-sma-spectrum-analyzer-138mhz-4-4ghz/ suggested “Download it from here http://www.filedropper.com/smasimplespectrumanalyzer-2016-08-30” but that file does not exist.

Page https://www.banggood.com/qa-answer-420788-1.html says try www.giga.co.za/Kit_Drivers/winnwt4_v4_11_09.zip and Before I tested those I got the original package to work.

Alternative software

At page https://www.banggood.in/qa-question-1450129-1.html one user says WINNWT5 appears to work. But sensitivity drops off above 446mhz to 0. That version should be available atwww.giga.co.za/Kit_Drivers/WinNWT5_v5_0_3_1730_setup.zip. I have not tested that.

Finally I found this page http://alloza.eu/david/WordPress3/?page_id=478.Page is in French and software in English. Fortunately Google translate helps to read the page. Here are some selected translations from the page:

SNASharp is a (free) software, written in C # language intended to drive (at first) scalar analyzers compatible with NWT software from DL4JAL: http://www.dl4jal.eu/

The supported protocol is at the level of the one managed by the version 4.11.09 of 29/09/2013 of LinNWT and WinNWT. These versions are not currently released by DL4JAL.

There is no installation to perform, just take the zip archive and unzip it into a directory.

All software writes (calibration files, new scanners supported, preferences …) are performed in subdirectories in the installation directory. Deleting this directory will erase all data.

This software worked well for me in the initial testing.

2019-08-10

Documentation of hardware

In the original software+documentation package two pdf files that have instructions for use (Chinese/English) and circuit diagram of the card. Here is view to circuit diagram:

2019-08-10-7

The web page https://vma-satellite.blogspot.com/2016/12/history-of-sma-simple-spectrum-analyser.html tells some story of the hardware:

The NWT devices where originally developed in Germany by amateur radio addicts. At one point this was featured in the magazine http://www.funkamateur.de. The software (WinNWT and LinNWT) was written DL4JAL for this magazine and is documented on his web-seite: http://www.dl4jal.eu. The initial devices were the FA-NWT, up to the NWT500, NWT7 and HFM9. They can offer a lot of extra functionality, like software controlled attenuator, etc.

The Chinese radio amateur BG7TBL cloned the design and used the ADF4350 chip for an increased frequency range. Other models followed up. They are all compatible with the original design, because they rely on the WinNWT/LinNWT software. Sadly, the Chinese selling the cloned hardware include the WinNWT/LinNWT without any authorisation, causing the author DL4JAL a lot of problems with people asking for help.

The more expensive NWT4000-1/2/3 models are either sold with or without a case. Bear in mind that you definitely need a case! If you don’t have one, don’t just buy the PCB version. It will not be immune to interferences and chances are that you will destroy it sooner or later, by touching some traces with a cable connector.

Page https://vma-satellite.blogspot.com/2016/12/vma-simple-spectrum-analyser-new.html points to manual at http://www.mediafire.com/file/jndwv7kmwzl77y6/VMA+Simple+Spectrum+Analyser+-+2016-12-27.pdf

Article links for more information:

https://vma-satellite.blogspot.com/2016/12/history-of-sma-simple-spectrum-analyser.html

https://lzhomelab.blogspot.com/2015/02/recently-i-managed-to-buy-collect-and.html?view=magazine

https://wiki.hackerspace-bremen.de/geraetschaften/amateurfunk/fa-nwt_plus

http://www.dl4jal.eu/

http://www.dalbert.net/?p=219

https://vma-satellite.blogspot.com/2016/12/vma-simple-spectrum-analyser-new.html

https://vma-satellite.blogspot.com/2016/06/138m-44g-usb-sma-signal-sourcesignal.html

https://vma-satellite.blogspot.com/2016/06/the-travellers-guide-to-spectrum.html

https://vma-satellite.blogspot.com/2016/06/sma-spectrum-analyzer-138mhz-44ghz.html

https://www.eevblog.com/forum/testgear/presenting-my-new-software-for-the-sma-spectrum-analyzer-138mhz-4-4ghz/

50 Comments

  1. Tomi Engdahl says:

    The basic parameters of antenna can be observed by tracking source and radio
    frequency reflection bridge.
    With a tracking source, you can measure the parameters of S12 and S21 of the network, and
    the parameters of the antenna can be measured by a reflection bridge.

    Reply
  2. Vitor Martins Augusto says:

    Hi,

    I am the author of the “VMA Simple Spectrum Analyser” software. You can always download the latest version of my software and manual here: https://vma-satellite.blogspot.com/2016/12/vma-simple-spectrum-analyser-download.html

    Kind regards,
    Vitor

    Reply
  3. Ritu says:

    really so nice information

    Reply
  4. Tomi Engdahl says:

    Is this the same HW with display added?
    [US$145.99 14% OFF]Geekcreit® LTDZ 35M-4400M Handheld Simple Spectrum Analyzer Measurement of Interphone Signal Module Board from Electronics on banggood.com
    https://banggood.app.link/1NzLwrnkE2

    Reply
  5. Mohan20 says:

    this really amazing and so useful

    Reply
  6. Maddy Bris says:

    it is and powerful hardware to work in all requirements parameters.

    Reply
  7. sanjay says:

    Wao! This is really impressive

    Reply
  8. arju says:

    I am so impacted

    Reply
  9. niraj says:

    Interesting. Learned a lot

    Reply
  10. mohit says:

    Very educative!

    Reply
  11. arij says:

    Very Helpful Information

    Reply
  12. CLAUDIO MANOEL DA SILVA says:

    i’m gonna teste your software and return.

    Reply
  13. Karl Kaefer says:

    Hi everybody,
    my LTDZ didn´t work with NWT4000 (all versions), neither with Win10 nor with Ubuntu Linux (com ports were configured ok). I stumbled across the software of Vitor in the internet and that one works fluently after configuring to the LTDZ. So I suppose that a firmware change in the LTDZ, which Vitor reports, is responsible that none ot the different versions of NWT4000 software collaborate with newer versions of the LTDZ, starting with firmware 1.14.
    Good luck and more communications in 2021!

    Reply
  14. Benjamin Salazar R. says:

    Adquiri de Banggood un 35M-4400 Spectrum Analizer, el cual esta dañado. Sucede que el barrido siempre es el mismo, no detecta la antena, ya probe con varias frecuencias y siempre es igual.Soy ingeniero electronico, y mi diagnostico es que esta dañado el mixer que recibe la señal de la antena, Dicho circuito viene con las siglas 810 1920, pero en ningun lado encuentro informacion. En BangGood alcanzo a ver las letras 810 97D4 ó quiza 9704, y con Uds. leo 810 9617, En cualquiera de los casos estoy debidamente equipado para sustituirlo, PERO ¿donde lo puedo conseguir??? Gracias por el soporte que puedadn brindarme.

    Reply
  15. Benjamin Salazar R. says:

    Adquiri de Banggood un 35M-4400 Spectrum Analizer, el cual esta dañado. Sucede que el barrido siempre es el mismo, no detecta la antena, ya probe con varias frecuencias y siempre es igual.Soy ingeniero electronico, y mi diagnostico es que esta dañado el mixer que recibe la señal de la antena, Dicho circuito viene con las siglas 810 1920, pero en ningun lado encuentro informacion. En BangGood alcanzo a ver las letras 810 97D4 ó quiza 9704, y con Uds. leo 810 9617, En cualquiera de los casos estoy debidamente equipado para sustituirlo, PERO ¿donde lo puedo conseguir??? Gracias por el soporte que puedadn brindarme.

    Reply
    • Tomi Engdahl says:

      Google translation:
      “I purchased a 35M-4400 Spectrum Analyzer from Banggood, which is damaged. It happens that the sweep is always the same, it does not detect the antenna, I already tested with various frequencies and it is always the same. I am an electronic engineer, and my diagnosis is that the mixer that receives the signal from the antenna is damaged, This circuit comes with the acronym 810 1920, but nowhere do I find information. In BangGood I can see the letters 810 97D4 or maybe 9704, and with you I read 810 9617, In either case I am properly equipped to replace it, BUT where can I get it ??? Thanks for the support you can give me.”

      For me the board worked well. Try Banggood support to report that you have received damaged device. They should be able to send you a new one or offer refund.
      For some other products (very few) that have been broken I have received a new working device after some time.

      Reply
  16. Tomi Engdahl says:

    As mildly exotic silicon has become cheaper and the ingenuity of hardware hackers has been unleashed upon it, it’s inevitable that some once-unattainably expensive instruments will appear as cheap modules from China. The LTDZ spectrum analyser on the bench today covers 35 MHz to 4.4 GHz, and has a USB interface and tracking source. It has been available from all the usual outlets for a while now either as a bare PCB or in a metal box about the size of a pack of cards….

    https://hackaday.com/2021/03/08/what-can-a-30-usb-spectrum-analyser-do-for-me/

    Reply
  17. suraj kumar says:

    Very Helpful Information

    Reply
  18. PeterC1309 says:

    I’m using my LTDZ with NWT4.11.09, obtained from http://www.giga.co.za/Kit_Drivers/winnwt4_v4_11_09.zip as is mentioned above. A calibration sweep from 10 MHz to 1GHz, with the tracking generator (TG) directly linked to the analyser’s input as instructed, showed that the signal vanishes below “3.5 MHz” and above “445 MHz”, as other users have noted. I was puzzled by this, and indeed all the spectrum plots I was getting, until I tested a narrow notch filter centred on 125 MHz. This revealed that the actual frequency coming out of the TG was **ten times** the value that I had selected in the NWT4 sweep dialog. (I verified this at low frequency on my scope, but it doesn’t go above 40 MHz.) The analyser was therefore working between 35 MHz and 4450 MHz, its correct specified range. So, to obtain valid sweeps with NWT4 I must type in one-tenth of the frequencies I want for the sweep parameters. Strange that nobody else has commented about this! I guess it might be a firmware error? My LTDZ has version 1.19. Or maybe a bug in NWT4. Another important point is that the TG’s output is 200 mV p-p, which is too high and will overdrive the analyser’s input. Therefore an attenuator should always be used, if you want to get valid spectrum measurements. NWT4 has software attenuator settings, but they don’t appear to do anything.

    Reply
  19. PeterC1309 says:

    PS. I forgot to mention that NWT Version 4.09 (more widely available) behaves exactly the same way as Version 4.11.09 does, with my LTDZ spectrum analyser. Both versions also have an option to “multiply frequency by 10″ which doesn’t seem to affect the real TG frequency, but it does change the plot scalings.

    Reply
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