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Re: [RFI] RFI cured with 1/4 wave wire

To: <RFI@contesting.com>
Subject: Re: [RFI] RFI cured with 1/4 wave wire
From: "David Harmon" <k6xyz@sbcglobal.net>
Date: Sun, 21 Feb 2016 13:31:31 -0600
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Years ago....this is how I resolved a TV raster problem on 80mtrs from my own 
TV.
I used RG-6 and laid it on the floor....it was much less than 1/4 wave though.


73

David Harmon
K6XYZ
Sperry, OK


-----Original Message-----
From: RFI [mailto:rfi-bounces@contesting.com] On Behalf Of JW via RFI
Sent: Sunday, February 21, 2016 12:07 PM
To: rfi@contesting.com
Subject: Re: [RFI] RFI cured with 1/4 wave wire


Has anyone said it yet - laying a 1/4 wavelength of wire out 'on the ground' 
creates an (albeit somewhat lossy) open-endedquarter wave 'stub' of somewhat 
indeterminate Z.
Recall, a quarter length away from the *open* end of a QW stubthe Z exhibits a 
low Z value. This is tantamount to 'walking' halfway around the perimeter of 
the Smith Chart (Z transformationor inversion in this case) and is the simple 
application of "The Quarter Wave Rule" that any RF savvy engineer should 'take 
tohis or her grave.

This is, BTW, a common trick (open-ended QW stub or microstrip 'line') used on 
uWave MMICs to decouple Vgg and Vdd DC supply lines at millimeter wave lengths.
73,
Jim WB5WPA


      From: Gerald Wolczanski <jerrywolczanski@earthlink.net>
 To: rfi@contesting.com 
 Sent: Sunday, February 21, 2016 10:21 AM
 Subject: [RFI] RFI cured with 1/4 wave wire
   

"RF ground"

OK - I get your point.  When I say "RF ground" I mean a place for
antenna return currents to flow

Back to my original question:
"Why did the installation of a 1/4 wave wire attached to ground, at/near
the coupler, cure my 30 meter noise problem?"

My guess:  It provided a low-Z ground at that frequency, not unlike a
"tuned ground"

as for:
http://www.k9yc.com/GroundingAndAudio.pdf

I see I have a "pin 1" problem (Elecraft K2) and probably numerous other
grounding/bonding things I need to look at.  I will do that in the weeks
ahead, but right now, I'm clean as a whistle.

Jerry
KI4IO
Warrenton, VA

 


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