[Milsurplus] Re: Milsurplus Digest, Vol 44, Issue 19

[Bob Camp]

Hi

My guess is that they have pre-amps on the loops. An OP-37 or similar  
will do a pretty good job without a lot of hassle at 15 to 20 KHz, if  
the loop is fairly low impedance. If the tuned loop is high inductance  
you may have to go to a lower noise current amp.

Bob
KB8TQ


On Dec 9, 2007, at 9:29 PM, Brooke Clarke wrote:

> Hi:
>
> Buried somewhere within 6 feet of me is a military manual that  
> describes the antenna used on subs to pickup VLF.  It consists of a  
> large amount of transformer laminations and a huge number of turns.
>
> The Cubic 3030 is an excellent VLF receiver.  One of the key design  
> considerations is to block any A.C. line noise.  That's not at all  
> simple to do.  The AMRAD active whip suffers from line noise, see:
> http://www.prc68.com/I/LF-Ant.shtml
>
> I don't see how a PC sound card can get around the line noise, let  
> alone internally generated noise.
>
> Have Fun,
>
> Brooke Clarke, N6GCE
> http://www.PRC68.com
> http://www.precisionclock.com
> http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam
>
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