[time-nuts] Subject: Re: Don't use cheap cables -- a cautionary tale

Brucekareen at aol.com Brucekareen at aol.com
Tue Mar 5 18:54:05 EST 2013

I would like to add to Bob Camp's comment about twisted pair.
In the past I used to provide one-turn resonant loop antennas for AM  
broadcasters who needed to monitor signals from their transmitters at studio  
facilities in electrically noisy urban buildings.  The three-foot diameter  
resonant-loops were grounded at the centerpoint and provided low noise  
reception, but this was degraded if a coaxial lead-in was used.  A workable  
solution turned out to be shielded audio cables.  These seemed to have a  
characteristic impedance of about 150 ohms.  At the receiving end we used  ferrite 
150-ohm balanced to 50-ohm unbalanced transformers.  With the  balanced 
circuit and shielded audio cable, very long runs could be employed with  little 
noise pickup.
Bruce, KG6OJI

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