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Author Topic: Crystal radio Experimentation with the oscilloscope and signal tracer  (Read 2710 times)
KJ4TLB
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Posts: 31




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« on: January 29, 2018, 05:31:54 AM »

In this video I break out the Tektronix 2235 oscilloscope and the Heathkit IT 12 to take a close look at a crystal radio I picked up many years ago in Switzerland. The Heathkit will be used so that the radio can be heard in the video itself.

This includes an internal inspection as well as an observation of the waveforms at each stage.

Enjoy!

https://www.youtube.com/watch?v=2f2nQ9yDAIA
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WA8ZTZ
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Posts: 282




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« Reply #1 on: January 29, 2018, 06:11:36 PM »

Interesting, tnx for posting.
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AA4HA
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Posts: 2626




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« Reply #2 on: January 29, 2018, 06:22:33 PM »

Those caps underneath do not look to be period-appropriate (much much more modern) but still a very pretty radio.

I love those coils; That is really a lost art. It makes me want to get out the spools of Litz wire that are somewhere under my desk and wind some like that.

thanks for the video.
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
WI8P
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Posts: 678




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« Reply #3 on: January 31, 2018, 04:01:54 AM »

Nice video and a great looking radio!
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WA8ZTZ
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Posts: 282




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« Reply #4 on: February 09, 2018, 05:55:29 AM »

Had not bothered with my crystal set for several years...  straining to hear with that tiny earpiece.  However, obtained and assembled a signal tracer kit (Velleman K7000) and hooked it to a 3" speaker... WOW, a whole room full of audio.  Heard a half dozen stations booming out of the speaker just casually tuning across the dial.  TNX for the great idea !   Smiley  
« Last Edit: February 09, 2018, 06:01:42 AM by WA8ZTZ » Logged
N8YX
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Posts: 1294




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« Reply #5 on: February 09, 2018, 06:11:29 AM »

One of the experimenter magazines of the late 70s/early 80s had an article which details construction of a "Spider-Web Receiver". That is, the coils are wound on forms which give the appearance of a spider's web. Phenolic board was used for the forms.

I have some fairly high-end equipment in the shack, but nostalgia makes me want to go fishing through the junk box for a spare 1N34...maybe a CK722 as the follower/audio amp.
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WA8ZTZ
Member

Posts: 282




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« Reply #6 on: February 09, 2018, 02:48:24 PM »

One of the experimenter magazines of the late 70s/early 80s had an article which details construction of a "Spider-Web Receiver". That is, the coils are wound on forms which give the appearance of a spider's web. Phenolic board was used for the forms.

I have some fairly high-end equipment in the shack, but nostalgia makes me want to go fishing through the junk box for a spare 1N34...maybe a CK722 as the follower/audio amp.

My crystal set has a spider web coil.  So do my LW and AM band antenna tuners.  My experience has been better performance with the spider web type coil.  It takes some experimentation getting the turns count right but, IMHO, the results are worth it.  Coil forms and other goodies are available from the Xtal Set Society  www.midnightscience.net.
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