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Sunday, February 4, 2024

Scott KQ4AOP Successfully BUILDS a Receiver (Video) -- This is the Homebrew Spirit at its Maximum

This is just so cool.  Scott KQ4AOP has successfully homebrewed a ham radio receiver.  He used the circuit Dean and I developed (with a lot of input from Farhan and others) for the High School receiver project.  But Scott has had more success than any of our students.  And I think he has had -- in a certain sense -- more success than any of us.  After all, how many of us can say -- as Scott can -- that he used a homebrew receiver that he made to listen -- for the very first time -- to amateur radio signals?  Scott writes:  "Those first sounds were my first time ever hearing any Amateur Radio first hand!" 

In the email below, you can see Scott's deep commitment to homebrew: "I want to build my own gear for 40m. I want to learn morse code. I want my first contact to be on my own gear."  Wow Scott, the building of the receiver is the hard part, and you have already done that.  I think you are well on your way.  

In the video above you can watch Scott tune the entire 40 meter band and a bit beyond. You hear CW at the low end.  Then FT-8.  Then SSB.  Up just above the top of the band I think you can hear our old nemesis Radio Marti.  And this powerful broadcaster is NOT breaking through on the rest of the band.  FB Scott.  Congratulations.  



Thank you for the quick response, direction, and pointers. I won't give up, and I am not in a rush. 

I have wanted my amateur radio license since the early-to-mid-80s. I got my Technician and General in May of 2022 and completed my Extra in May 2023. I always wanted to understand how to design circuits, and I wanted to build them. I share that background to say that I have this impractical goal that I am stubborn enough to stick to (all due respect to you and Pete's advice on the topic of getting on the air). I want to build my own gear for 40m. I want to learn morse code. I want my first contact to be on my own gear. So, your blog and podcast really resonates with me. 

I am only teaching myself at this point. It was the perfect project for my goals. I thought that if all these high school kids in Virginia, Canada, and Germany can do it, it was the sweet spot I was looking for. 

The only transceiver I have was recently gifted to me. It is a Sommerkamp TS-788DX CB radio that allegedly works on 10m in addition to CB. I haven't connected it up because I wanted to stay focused on the HSR. I have a mentor who has gear that I can use to test the oscillator. I am not involved with the nearby ham club, but I know they would help if needed. 

Thanks again and I will keep you posted,

73 Scott KQ4AOP

Bill and Dean - Thank you for sharing and documenting this receiver. I greatly appreciate you publishing the circuit, class notes, and build videos. That got me 75% to completion.
I feel blessed that both of you chipped in and encouraged me through the troubleshooting to finally getting the receiver to start “breathing RF”.
Those first sounds were my first time ever hearing any Amateur Radio first hand!


  1. Dear Scott,
    Congratulations to your fine build! Truely Truely beautifully carried out.
    Soon we have to thing about an accompanying transmitter!
    73 de,

  2. Thank you Andrea! I agree 100%!

    Thanks again Bill, Dean, Farhan, Walter, and Rick. I am honored to be in such great company. The high school students and their project pictures get some credit too.

    If anyone is on the fence about taking on a project like this, you can do it and it is wildly rewarding! There are plenty of folks out there that will encourage you and want you to succeed at this! My advice: Take your time, be patient, and seek help when you get stuck.

    If you are younger than 25 years of age and you loved Legos or putting things together, you will get a ton of enjoyment out of building this receiver. You will learn things about electronics and build critical thinking skills in a hands-on way! I learned much by just measuring voltage at different points of the circuits and thinking about why the circuit was behaving (or not) the way it was!

  3. This is great! The round "islands of connectivity" floating in a sea of discontinuity look like conductive push pins. The sound is good for just a transformer output? And the 3D printed 9v holder with the floating potentiometer give it that "homebrew" feel. There is nothing as much (well almost) fun as starting with little doodads and ending with something alive. Well done.


    1. Thank you Dontay - it is wild that all those little bits do so much! Turning that knob and hearing those whistles and sounds is so cool. I can’t see where it will ever get old!

  4. This is my dad, he has been working on this for a while, I’m pretty proud of him, and so is Collin. Good one pops!

    1. My son and his friends tel me what I am doing is cool. If I could just talk them into getting their tickets before they graduate!!!

  5. Scott, great work! Welcome to the brotherhood of homebrewers. Nothing beats that feeling you get when you hear those first signals coming from a receiver you built with your own hands. You have achieved something that's very rare among hams indeed. Keep building and look to the Soldersmoke community and other resources for inspiration and help. A word of caution about something I learned the hard way; if you ever build a receiver and it seems to be dead, remember that HF conditions are variable depending on atmospheric conditions, the time of day, the placement and size of your antenna - there may be no signals to be heard when you power up your new creation for the first time. If this happens don't give up, check your work and if everything is wired correctly try again later that day, or over several days. The on-line SDRs (http://rx.linkfanel.net/) are a tremendous help where you can see if there are signals to be heard. I remember when I built my very first receiver, when I completed the build it was receiving signals from everywhere very loud, the next day when I attempted to demonstrate my creation to friends the receiver was dead! I was so frustrated I was almost ready to tear it apart and give up. What I didn't realize was that the day I completed the build a contest was going on, but the next day conditions were lousy and the contest was over so there was nothing to be heard at that time. I wish you good success in all your homebrew endeavors. 73 Rick N3FJZ

    1. Thank you Rick! Your schematic had some detail I needed when troubleshooting some feedback issues in the amplifier. Thank you for building those diagrams.

      Thank you for the advice. I think I hit a few of those walls and the SolderSmoke community did kick in and lift me up to a working receiver!

  6. Great job on that receiver. Good stable signals coming through, shows that you did a great job on your VFO! And that you have tuned your band pass filter! Very good job!


    What is the transformer ratio or where did you get the transformer for the audio out?


    1. Thank you. I am still very happy with the finished product and ready to experiment with it some.

      I think the answer to your question is:
      810 Turns Primary / 80 Turns Secondary

      If I missed what you are asking, maybe the spec sheet has it. Let me know if you wanted something else.


      Look for: 42TL003-RC

      Xicon Audio Transformers / Signal Transformers
      US HTS:8504314035 ECCN:EAR99 COO:TW

  7. Mike - here is a link to the Bill of Materials. I think I got the Mouser link from the BOM.


  8. Mike - here is a link to the Bill of Materials. I think I got the Mouser link from the BOM.



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