View single post by sparks

Posted: Nov 9th, 2011 06:39 PM

Joined:	Jan 15th, 2008
Location:	New Zealand
Posts:	77
Status:	Offline

I mentioned 4.7mH as this would resonate below medium wave and avoid clear pickup of medium wave stations. But, as I said this simple design will always be somewhat prone to broadband pickup. That is why I suggested the ferrite rod antennas, as 2 of these in series would be more selective at rejecting medium wave signals.

Yes the raudive design uses a choke that would make it resonant at approx 800kHz, so in the middle of MW band.

Yes, you can series connect the black chokes to get a higher inductance.

A radio tuned to an unused medium wave channel will be receiving the varying mixture of brown, white and impulse noise spectra I mentioned. Thats why I suggested it as a better alternative to the raudive diode at receiving a suitable noise source. It gives the advantage that if tuned correctly, there will be no radio station voices breaking through - as is often the case with broadband devices such as the raudive diode.

I dont see any real advantage in trying to build the raudive diode, when a radio on an unused channel can give you approx the same noise output. There is however some speculation that the crystal diode has properties that may promote the formation of evp voices, but I havent any evidence of this. There are some other members of this forum that are looking at this concept, and are better able to comment than me. perhaps they can offer some comments please?
JEFF