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Old January 6th 04, 07:21 AM
starman
 
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Brian Denley wrote:

starman wrote:

I haven't found this to be so in my case. The coax shield on my low
noise inverted-L is grounded only at the bottom of the antenna's
single wire downlead, which is close to the ground. The coax runs
about 75-ft along the ground to the house, then up one story to the
receiver. There is no ground on the receiver end of the coax. The
noise from home applicances is almostly completely gone now with this
antenna configuration.


Starman:
My random wire coax feedline is also only grounded at one point (the center,
oddly enough) but the fact is that for the feedline to effectively not act
as part of the antenna, the shield must me grounded at BOTH ends. Is one
point better than nothing? Sure.

Like you, I live with it because I find it difficult to implement.


I came to the conclusion that the single ground at the far end of the
coax is 'effectively' preventing the shield from being a common mode
antenna because the noise level is much lower than before I built the
low noise 'Doty-L' antenna system. Another factor is that most of the
coax is laying on the ground. This also helps to reduce common mode
reception on the shield. There's about fifteen feet of coax above the
ground going up to the receiver on the second story. I've also noticed
that the noise level is much higher when I partially remove the antenna
coax connector on the back of the receiver, so that only the center pin
is making contact.


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