My Crystal Radio Projects

Discussion in 'Homebrew and Kit Projects' started by VU2NAN, Aug 18, 2021.

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  1. VU2NAN

    VU2NAN Ham Member QRZ Page

    K0UO, VK4HAT, N8TGQ and 1 other person like this.
  2. KK4NSF

    KK4NSF Ham Member QRZ Page

    Nandu, those are great! I especially like the Razor Blade detector. It's a classic WWII vintage design. I've been playing with home-made semi-conductors for several years, and have found that design to be a great basis for experimentation.

    Crystal radios are excellent for teaching the basics of radio, AND are an interesting field in their own right. Any person interesting in building radios would be well served by building a few crystal sets first. Good work!
     
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  3. W9WQA

    W9WQA Ham Member QRZ Page

    for exotic cr radios find ka9pgc. he is the all time champ at building stuff...
     
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  4. VU2NAN

    VU2NAN Ham Member QRZ Page

    Thank you very much, David.

    But nothing to beat your variocoupler beauty. It's mesmerising!

    73,

    Nandu.
     
    K0UO and VK4HAT like this.
  5. K6BSU

    K6BSU Ham Member QRZ Page

    Many of us have gone through the xtal set phase. I was certain I could design a superior xtal set. Well, it was fun, but not very productive in terms of being able to receive anything above the AM broadcast band. This one sort of worked, but I heard a few stations that were local and running high power. Anyway, it looks good, but that's about all.
     

    Attached Files:

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  6. VU2NAN

    VU2NAN Ham Member QRZ Page

    Hi OM Floyd,

    Superb and real professional!

    73,

    Nandu.
     
  7. W4HAY

    W4HAY XML Subscriber QRZ Page

    It's too bad The Xtal Set Society https://www.midnightscience.com/ is just a shell of it's former self, if it still even exists.
    During its heyday it was a good source of plans and parts for crystal sets.
     
    K0UO likes this.
  8. KK4NSF

    KK4NSF Ham Member QRZ Page

    Quite a few years ago (maybe 20 or so) there used to be a very active Crystal Radio Building Community out there on the Internet. They (we) had contests, built all sorts of very high quality receivers, and published a lot of information to encourage others to try their hand at building. Then as some of the older folks died, the Xtal Radio movement slowly fizzled out. The information is still out there, but very few people use it.... or even understand how much fun it can be

    I'd like to change that.... and offer a challenge: Let's have a contest! Anybody interested?
     
  9. W4HAY

    W4HAY XML Subscriber QRZ Page

    This is one of my crystal sets that covers from ~400 KHz to ~20 MHZ. All the switching is done by clip leads and there are several sets of inductors, including a "spiderweb" set for MW reception. The inductors can be moved to change the coupling. It can be used with either a cat's whisker or germanium diode detector.
    Crystal Set.JPG
     
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  10. KK4NSF

    KK4NSF Ham Member QRZ Page

    Here are a few pics of one of my VERY early Vario-Coupler Sets..... I've built far better ones since then, but even so this little set is one of my favorites. It is extremely simple.... two coils that can be rotated relative to each other (~240uH each) , two 365pF variable caps (w vernier drives), and a variable audio impedance transformer. If you look closely, you will notice that the detector is mounted on an RCA plug so various diodes could be tested. AND the "micro adjustment" on the coils.... made out od old guitar string tighteners! Litz wire would have even made it better, but at the time I didn't even know what litz wire was! The switch in the upper left corner is to shift from series tuning to parrallel tuning.

    As simple as it is., it picked up 125 AM stations, as far away as NYC, El Paso Tx, Miami, and Chicago from Mobile Al. (AND if you hook it up to an amplified speaker, it becomes a TRF receiver, with great audio, too. )


    upload_2021-9-13_11-31-8.jpeg upload_2021-9-13_11-31-32.jpeg
     
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