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eHam Forums => HomeBrew => Topic started by: VU2NAN on January 21, 2017, 05:10:55 AM



Title: Portable AM Crystal Radio
Post by: VU2NAN on January 21, 2017, 05:10:55 AM
May be viewed at

https://nandustips.blogspot.in/2017/01/portable-am-crystal-radio.html

73,

Nandu.


Title: RE: Portable AM Crystal Radio
Post by: ONAIR on January 21, 2017, 01:25:06 PM
May be viewed at

https://nandustips.blogspot.in/2017/01/portable-am-crystal-radio.html

73,

Nandu.
   Nice!  I used to use something similar to that to monitor my AM transmitted audio.


Title: RE: Portable AM Crystal Radio
Post by: VU2NAN on January 21, 2017, 05:51:29 PM
Thanks, OM!

73,

Nandu.


Title: RE: Portable AM Crystal Radio
Post by: AC6AN on January 22, 2017, 09:52:23 AM
Nandu, the circuit makes no sense.
Try a counterpoise and couple in the middle with a transformer.
The secondary will have a tuning capacitor in parallel and one Ge diode and headphones in series.
Since the antenna is so short, you might want to look into using a zero-threshold mosfet instead of the Ge diode.
A good reference is this article: http://www.arrl.org/files/file/Technology/tis/info/pdf/culter.pdf (http://www.arrl.org/files/file/Technology/tis/info/pdf/culter.pdf).


Title: RE: Portable AM Crystal Radio
Post by: VU2NAN on January 22, 2017, 06:38:26 PM
Hi OM Ori,

I suppose stray capacitance, between headphone leads, body and ground and that between telescopic and nearby overhead cables, does the trick!

73,

Nandu.


Title: RE: Portable AM Crystal Radio
Post by: VK4FFAB on January 22, 2017, 07:54:31 PM
Thanks for sharing Nandu, I always enjoy seeing your projects.

Rob.


Title: RE: Portable AM Crystal Radio
Post by: VU2NAN on January 22, 2017, 09:02:15 PM
Thanks, OM Rob.

Your blog / projects carry the marks of a true professional!

73,

Nandu.


Title: RE: Portable AM Crystal Radio
Post by: VU2NAN on January 22, 2017, 09:31:57 PM
Thanks, OM Rob.

Your blog / projects bear the mark of a true professional!

73,

Nandu.


Title: RE: Portable AM Crystal Radio
Post by: VU2NAN on January 25, 2017, 09:00:07 PM
There's been an update.

https://nandustips.blogspot.in/2017/01/portable-am-crystal-radio.html

73,

Nandu.


Title: RE: Portable AM Crystal Radio
Post by: VU2NAN on March 07, 2019, 09:01:25 AM
Here's another update.

(https://lh3.googleusercontent.com/mMbzjjfvC4Ab-A2q364svB4G1LU7MMHOetj83WUsjRPofe75BG9w2DcdKNkIZ0XOR4cHeLILJWXcmWWvpQ=w293-h220-rw)

https://nandustips.blogspot.in/2017/01/portable-am-crystal-radio.html

73,

Nandu.