Topband: Receiving loops

[W2PM]

If you are referring to a magnetic loop the problem is not the pickup from the shield - that is the conductor for picking up the signals - all signals including noise. The issue with a magnetic loop would be imbalance and that would be due to improper construction where the sides of the loop either way of the gap would not be equal or how you connect or install the tuning capacitor. Close proximity to a conducting surface would also affect the directivity. But even with a poorly constructed mag loop you should still get the null but it may not be symetrical or as deep as it should be. 

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On Jun 16, 2012, at 10:36, Arthur Delibert <radio75a3 at msn.com> wrote:

> 
> Tim -- If the suggestions from others don't entirely do the trick, here's another thing to consider:  The outer conductor on your coax might be picking up local noise and/or destroying the pattern of your receiving antenna.  I DX the AM broadcast band with whatever antennas I can fit into my suburban backyard.  I was getting poor results with a pennant until I put Radio Works T-4 line isolators at both ends of the coax.  Suddenly the antenna began to behave as expected. Hope this helps. Art DelibertKB3FJO
>> From: tshoppa at wmata.com
>> To: topband at contesting.com
>> Date: Sat, 16 Jun 2012 13:28:38 +0000
>> Subject: Topband: Receiving loops
>> 
>> I want to try a new receiving antenna for the summer Stew Perry. Last winter was my first foray onto 160M and I really felt like an alligator. I could work everyone I could hear, with just 100W. I think that means I need a better receive antenna. If you look at my score in the winter Stew Perry I think I did great QSO-number wise, but my average distance was very poor, I'm guessing typical alligator.
>> 
>> I have tried pennants and K9AY's over the winter with little success. Compared to my transmitting antenna (A "T" with a poor radial system) most signals were still better, S/N wise, on my transmitting antenna. I feel like I must've been doing something wrong. Still the fact that a few signals came in on the loop with by ear much better S/N, maybe I was on the right track and just didn't try hard enough.
>> 
>> I will be trying a small tuned magnetic loop tonight (e.g. the last one at http://www.w8ji.com/magnetic_receiving_loops.htm with the 9:1 transformer) . And maybe a terminated beverage but I'm limited to about 150'... well maybe I could run something longer down the driveway as long as I clean it up before the sun comes up and the neighbors see.
>> 
>> I was fairly impressed with small tuned magnetic loops when I was doing some BCB DX'ing several years ago. I wasn't comparing with beverages or anything.
>> 
>> Tim N3QE
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>> UR RST IS ... ... ..9 QSB QSB - hw? BK
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> UR RST IS ... ... ..9 QSB QSB - hw? BK