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 Post subject: Re: UHF Crystal Radio
PostPosted: 20 Jan 2016, 22:55 
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Joined: 24 Sep 2014, 08:22
Posts: 69
Location: Bangalore, India
Hi OM Gregg,

Just formed it by hand using nose pliers without teeth and a mandrel.

Many thanks.

73,

Nandu.

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 Post subject: Re: UHF Crystal Radio
PostPosted: 23 Jan 2016, 13:20 
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Joined: 24 Sep 2014, 08:22
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Location: Bangalore, India
Yet another update!

The terminal block arrangement made it convenient to replace the folded dipole with a full wave loop.
Attachment:
1.JPG
UHF Full Wave Loop Crystal Radio

Likewise with an AWX antenna.

Attachment:
2.JPG
UHF AWX Antenna Crystal Radio

Results were as good as with the folded dipole.

Regards,

Nandu.


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 Post subject: Re: UHF Crystal Radio
PostPosted: 23 Jan 2016, 18:16 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
How do you tune the above loop Xtal set?

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 Post subject: Re: UHF Crystal Radio
PostPosted: 23 Jan 2016, 21:29 
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Hi Houston,

I've yet to figure that out!

Right now I am able to receive 2 signals by changing position / antenna orientation.

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Nandu.

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 Post subject: Re: UHF Crystal Radio
PostPosted: 24 Jan 2016, 01:27 
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Joined: 08 Aug 2009, 03:11
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Location: Chilliwack, BC
With UHF, you can do a helical resonator or cavity resonator.

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 Post subject: Re: UHF Crystal Radio
PostPosted: 24 Jan 2016, 05:07 
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Yes, OM Greg, I should have another go at cavity resonators and also try the helical one.

Many thanks.

73,

Nandu.

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 Post subject: Re: UHF Crystal Radio
PostPosted: 30 Jan 2016, 12:45 
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The latest update!

A second Yagi Beam was then rigged up, with another diode providing the return path for the audio, instead of the coil.

The signal strength was not as good. During trials, a chance shorting of the second diode gave a considerable increase in signal strength.
Attachment:
3.JPG
Single-diode UHF Yagi Beam Crystal Radio - Schematic

The diode and capacitor were hence discarded. Performance of this single-diode UHF crystal radio is quite good.

Regards,

Nandu.


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