>
>Thanks for sharing this interesting paper. Well, the circuit looks quite 
>complex but the image of the final construction looks compact.
>Since we got access to 472 kHz a weeks ago, i need another receive 
>antenna now, since all my front ends are resonanted, i.e. mono band. So 
>the advantage of a single receive antenna becomes more and more 
>convincing to me. Of course it needs a high dynamic range without 
>distortion of the spectrum then..
>
>A question: The DC supply voltage is connected to e.g. C16?
>

     It's connected by way of the output pin, so you send the DC supply right 
up the coax instead of having to run additional wires.  You'll need a bias tee 
down at the receiver end, and I describe one at the end of this paper:

http://www.home.earthlink.net/~christrask/Paper021.html

>
>What might be the lower cutoff frequency if values for the input LP and 
>HP filters are well choosen? It should be possible to extend the circuit 
>to the VLF range (?).
>

     The amplifier itself without the input filter will go down to about 
100-200kHz.  To go lower than that you'll need to increase to capacitor values 
plus change the transformer core material to Fair-Rite 77 or something similar.


Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/