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Re: [RFI] Link-coupled loop - more.

To: rfi@contesting.com
Subject: Re: [RFI] Link-coupled loop - more.
From: <n0tt1@juno.com>
Date: Tue, 1 Apr 2014 23:26:20 +0000
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
> We carefully plotted the bearings we took on a map of our area of 
> the city.
 
I've often thought about attaching, say, a boat or auto compass to 
the loop support....might make the plotting easier.
 
Does anyone know of a "good" model of compass that would
work for that purpose?
 
73,
Charlie, N0TT
 
On Tue, 01 Apr 2014 15:24:23 -0700 "Kenneth G. Gordon"
<kgordon2006@frontier.com> writes:
> OK. My son, Brendan KB7QEU and I went out after lunch and took 8 more 
> 
> bearings with one of Tom Thompson's loops which I had constructed 
> over 
> the past few days. 
> 
> Tom's loop tunes VERY sharply. I intend to add a bandswitch, a large 
> scale, 
> and a vernier dial to it to make it both easier to peak and easier 
> to take down 
> a data point.
> 
> We carefully plotted the bearings we took on a map of our area of 
> the city.
> 
> I connected the loop to the FT-890 in AM mode (BW 6 KHz), tuned to 
> 3573.5 
> KHz where "my" noise peaks, and used the FT-890's "S" meter to take 
> 
> readings.
> 
> First of all, the nulls are not quite as sharp, nor as deep, as 
> those I get with a 
> shielded loop, but they suffice. (The shielded loop I was using 
> would 
> commonly show a difference from null to peak of over 30 db, while 
> the 
> unshielded loop most often provides a difference of only about 10 
> db).
> 
> The results we plotted are somewhat confusing to me as three of the 
> 
> bearings did not result in anything common to the other five.
> 
> 4 of the bearings definitely converge on an area that appears to be 
> around 
> an area of about 1 square block which is 4 blocks east of us.
> 
> A 5th is close, but outside the convergence zone of the other 4.
> 
> Signal strengths became greater as we got up on a hill to the east 
> of my 
> station which is also nearer to that 1 block area than some other 
> bearings.
> 
> Those three bearings that gave confusing results were the weakest 
> ones, 
> and the differences between the null and a peak were only about 1 
> "S" unit.
> 
> However, one odd thing is that two of those three bearings, if I 
> take a 90 
> degree normal bearing to those, both show up in the same area as the 
> 4 
> "good" bearings. One, in fact, is exactly coincident at its end with 
> two of the 
> other "good" bearings.
> 
> I don't know how to read those odd ones, but I am not in the habit of 
> 
> throwing out data points just because they don't "fit" either. So I 
> don't know 
> what to do about them right now.
> 
> I suppose I should drive over to that spot 4 blocks east of us and 
> take a look 
> around, then take some more bearings.
> 
> Probably tomorrow...
> 
> Ken W7EKB.
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