Spectrum Analyzer

I’ve decided to move Spectrum Analyzer information here to keep it mostly out of the blog posts.  I’ve finally got almost all the parts I need, so I’ll be able to start writing build pages.  I’m excited, are you!? 🙂  Anyway, stay tuned to this place for more information….

I’ve started building and testing boards in earnest, and I’ve started a list of boards that I’ve finished below.  Also, I’ve been updating the graphic from a previous post to improve readability and reflect not only boards that are “complete” but complete and tested.  Almost all the modules of the analyzer have been built, but they haven’t been integrated or tested.  On the graphic below, I’ve highlighted the modules that are integrated and tested in green.

Analyzer Master Layout

The graphic above not only functions as a scoreboard, of sorts, for the status of my analyzer, It’s also the physical layout of the modules.  I’ve included space for some optional modules that I don’t have yet.  These include the PDM, Mixer 4, and both the filter and 1G-2G mode switches.  I figured that if I plan for them now, I won’t be disappointed later.  The boxes in yellow are those that I’ll use removable SMA connectors on, while the white ones will be direct-soldered coax.  The number in the boxes are the port number on each module.  I’ve omitted the control board from this diagram because it will be installed on the rear panel, and this frame will be installed near the front panel.  Also left out of this diagram is the cavity filter.  The filter needs to be made of copper pipe and sheet brass.  It’s large at 4″x4″x1″, so I’ll have to buy an enclosure with adequate internal space.  Another decision that I’ll have to make is whether I want to include a power transformer (taking A/C from the wall) inside the case.

Mounting Frame

Master Oscillator mounted

Coaxial wiring

Coaxial wiring

Digital Wiring

Completed module harness

Master Oscillator

Master Oscillator Board

Finished Master Oscillator

Control Board

Finished control board

Analog Digital Converter

Completed analog digital converter

Log detector

(almost) complete Log Detector

I.F. Amplifier

Completed IF Amplifier

DDS 1 & 3

Completed DDS module


(almost) complete PLO 1

Cavity Filter

Hairpin installation

  1. #1 by Paul on May 3, 2010 - 1:12 am

    Just started building my boards up, so your in depth comments and pictures are much appreciated. Thank you for your significant efforts.

  2. #2 by admin on May 3, 2010 - 6:06 am

    You’re welcome!

  3. #3 by patrick murphy on September 16, 2010 - 11:32 am

    hi i am quite interested in building the analyser and desire some further info.
    you’re obviously quite busy with the project and i would not wish to impose.
    some info re the eventual cost……….will i be able to resolve sigs at 1.5 ghz …
    is there an information document i can download

    i thank you for your consideration……………de ea5ei9eh………….in downtown spain

  4. #4 by admin on September 16, 2010 - 12:17 pm

    I’m certainly not the designer of this project. I’m building this off these designs: http://scottyspectrumanalyzer.com/
    If you’re interested in building one, I recommend joining the Yahoo Group: http://groups.yahoo.com/group/spectrumanalyzer/

    Expect to spend the equivalent of a few hundred US dollars: http://scottyspectrumanalyzer.com/msaslim.html#Cost_of_the_MSA_using_SLIMs

    This device can operate in 3 bands:
    (close to) 0 to 1Ghz,
    1Ghz to 2Ghz,
    2Ghz to 3Ghz.

    Good luck!

  5. #5 by Scotty Sprowls on March 1, 2011 - 8:08 pm

    Hi William,
    I love your “scoreboard” idea. I was admiring your pictures when I noticed your Master Oscillator. Both R1 and R3 are resistors marked “3300”. Normally, a 4 digit resistor would tell me that those are 330 ohms. You really want 33 ohmers, and mine are marked 33R0. I can’t read R3, but it is obviously different than the other two.

  6. #6 by hpux735 on March 1, 2011 - 8:17 pm

    Thanks scotty! I had better check that, I’ve always had somewhat weak output from my oscillator!

  7. #7 by Sam Wetterlin on March 2, 2011 - 5:43 am

    William–Nice work. You may want to reserve room for the video switch (single SLIM) and the recently discussed Mixer 3 amps (single SLIM). I see your 1G/2G switch space is a double SLIM; this can actually be done with a single SLIM–the SPDT with PE4251. I think Scotty is right on the MO resistors. Also, C7 on the MO looks like it is unsoldered on one end.

    Good Luck
    Sam W.

  8. #8 by hpux735 on March 2, 2011 - 9:46 am

    Thanks Sam,
    I designed the layout back when the switches were double slims and the video switch and mixer 3 amp didn’t exist. As I haven’t built either switch yet, I’ll probably massage the extra slims in to the opened space. I’ll add C7 to my list of stuff to check 🙂

  9. #9 by Steve_W on May 29, 2012 - 1:54 am

    have you finished yet?

    if not please update your scorecard 🙂

    Looks good so far, did you make the base from copper plate? looks like its a couple of Millimeters thick, I’ll bet that was not cheap!!


    Steve W

  10. #10 by mane on September 22, 2014 - 9:31 am

    Why you used SMA connector more.
    Means what is reason.

  11. #11 by Bojan on September 29, 2015 - 12:37 pm

    Hi All,
    Please, where can I buy the set of PCBs for spectrum analyser project???

    regards Bojan

  12. #12 by Bojan on October 3, 2015 - 1:53 am

    I am trying to get complette PCBs for MSA.
    Can You maybe help me???

    best regards Bojan, Slovenia

  13. #13 by hpux735 on October 3, 2015 - 10:21 am

    I can’t really, I’m sorry. The best advice I have is to check on Github for eagle files: https://github.com/xdadman/msa_eagle and https://github.com/hpux735/MSA Also, on the mailing list, but I see you’ve asked there, as well.

  14. #14 by Carsten on May 8, 2019 - 6:01 am

    Hey William
    My building will now be continued after a break of 3 years. After stumbling over your page, I made the mounting frame.
    I am not sure how to manage the switch boards, but I’ll find a way.
    Which final Crystal filter do you use and where did you get it? It’s quite difficult to find and order a proper MCF for 10.965 MHz.
    Maybe it is possible you could provide a photo of your finished device?
    Thank you for sharing your experiences.
    Regards Carsten

  15. #15 by hpux735 on May 8, 2019 - 6:08 am

    I’m embarrassed to admit that I have not finished it! 🙁

    I got as far as doing some traces, and measuring the zero hump, tuning the cavity filter, stuff like that. Then life got in the way. Then Rigol had the indecency to release a $1000 spectrum analyzer! Anyway, I’m starting to get back into the hobby, and I’m hitting the limitations of the Rigol (because it only goes to about 1ghz). What I’m thinking about is using the MSA kit in conjunction with my Rigol, but that’s another story.

    For the 10 MHZ filter: I scoured eBay, and bought a few of them, and selected the one that seemed to work the best.

    Which switch board do you mean?

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