UHF Crystal Radio

[vu2nan]

May be viewed at

http://nandustips.blogspot.in/2015/12/uhf-crystal-radio.html

73,

Nandu.

 

[vu2nan]

Here's an update.

................Later on, another Yagi Beam was rigged up with a second OA85 providing the return path for the audio instead of the coil.

UHF Yagi Beam Crystal Radio
with 2 diodes - Schematic

Signal strength was as good on that one too.



Two UHF Yagi Beam Crystal Radios

73,

Nandu.

 

[vu2nan]

Another update.

A folded dipole version, mounted on a terminal block.



It obviates the need for a coil / additional diode and works quite well too.

http://nandustips.blogspot.in/2015/12/uhf-crystal-radio.html

73,

Nandu

 

[vu2nan]

Yet another update!

The terminal block arrangement made it convenient to replace the folded dipole with a full wave loop.


UHF Full Wave Loop Crystal Radio

Likewise with an AWX antenna.


UHF AWX Antenna Crystal Radio

Results were as good as with the folded dipole.

73,

Nandu.

 

[vu2nan]

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.


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.

73,

Nandu.

 

[vu2nan]

Broken link rectified.

https://nandustips.blogspot.com/2015/12/uhf-crystal-radio.html

73,

Nandu.