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PostPosted: 25 Apr 2016, 09:11 
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Location: Bangalore, India
This series-tuned, shunt-fed crystal radio was built using parts salvaged from a vintage / battered SCR - 578 lifeboat radio (popularly referred to as 'Gibson Girl').
Attachment:
2.JPG
'Gibson Girl' Crystal Radio - Schematic

It consists of a baseplate, antenna tuning coil, antenna tuning capacitor and a terminal strip modified to suit.
Attachment:
1.JPG
'Gibson Girl' Crystal Radio

The only part required to be fished out from the junkbox was a Schottky diode SB 860. It was mounted underneath the terminal strip.

The local 612 kHz, 200 kW AM broadcast station comes in real loud using a 60' long wire antenna and sound-powered phones. Headphone current, measured using a 1mA FSD 60 Ω meter, is 600 μA.

Regards,

Nandu.


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PostPosted: 12 Aug 2016, 06:41 
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Joined: 05 Aug 2016, 14:35
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Pretty neat! And an interesting source.

Now, for your next trick, how about an FM Crystal radio? Many think it cannot be done. In point of fact, they work quite nicely if you are in good 'seeing' range of a station.

NOTE: These are NOT my radios linked - and with thanks to the sources:

http://solomonsmusic.net/FM_CrystalRadio.html


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PostPosted: 15 Aug 2016, 14:24 
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Peter W. wrote:
Pretty neat! And an interesting source.

Now, for your next trick, how about an FM Crystal radio? Many think it cannot be done. In point of fact, they work quite nicely if you are in good 'seeing' range of a station.

NOTE: These are NOT my radios linked - and with thanks to the sources:

http://solomonsmusic.net/FM_CrystalRadio.html


Great link,

I must admit its the first I have heard of FM crystal radios..

Regards
M. Gregg

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PostPosted: 15 Aug 2016, 16:10 
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Joined: 08 Aug 2009, 03:11
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Location: Chilliwack, BC
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I have heard, even from a physicist, that it is impossible to build FM crystal radios.


Obviously that "physicist" has never heard of slope-detection ;)

With modern hot-carrier diodes, it's actually easier to build a crystal set as the frequency goes up! Radio-Electronics magazine even had crystal Ka band radar detector projects that worked as good as some of the superhets at the time because active device NF up there was hideous without cryogenic cooling back in the early 1980's.

Cheers!

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PostPosted: 01 Sep 2016, 05:48 
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Peter W. wrote:
Pretty neat! And an interesting source.

Now, for your next trick, how about an FM Crystal radio? Many think it cannot be done. In point of fact, they work quite nicely if you are in good 'seeing' range of a station.

NOTE: These are NOT my radios linked - and with thanks to the sources:

http://solomonsmusic.net/FM_CrystalRadio.html


Thanks, Peter.

Not yet successful with FM Crystal radios!

Regards,

Nandu.

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PostPosted: 01 Sep 2016, 09:18 
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I am planning to make an FM Crystal radio as demo at the next Kutztown meet. The nice thing about these beasts is that there are remarkably few and very inexpensive parts. If I get one going, I will send it you you via your website.

Noting, however, Mr. Burns comment about "the best laid plans...".


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PostPosted: 02 Sep 2016, 01:45 
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vu2nan wrote:
Not yet successful with FM Crystal radios!


MORE ANTENNA! :idea: :D :smoking:

73's

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PostPosted: 02 Sep 2016, 13:36 
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Geek wrote:
vu2nan wrote:
Not yet successful with FM Crystal radios!


MORE ANTENNA! :idea: :D :smoking:

73's



Funny, unlike SW, LW or MW (AM), FM tends not to respond well to Longer Antenna. And an amplified antenna would very likely overload the 'front end' on these beasts, such as it is.... ;)


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PostPosted: 02 Sep 2016, 22:05 
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I take it you've never built a FM colinear or J-pole? ;)

Cheers!

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PostPosted: 03 Sep 2016, 00:34 
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Joined: 24 Sep 2014, 08:22
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Hi Gregg, Hi Peter,

The main hurdle is my self-enforced limitation (strictly no amplifier!).

Then to build a real high Q circuit for successful slope detection.

Lastly, the absence of a nearby high power FM station.

Many thanks.

Regards,

Nandu.

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