I don't disagree with Herb here on the value of that type of loop, but
if the problem is strong local line noise, or any other type of local
noise (the list is long but can include jacuzzi thermostats, low
voltage lighting, bad street lights, battery chargers with switched
supplies - which is about all of them lately, etc. etc.) nothing but a
small, so-called "Magnetic loop" will provide the profound, deep null
needed in the direction of the local crud will do. Local noises can
easily hit S9 plus levels, but on 160, even S3 levels will prevent you
from hearing DX. A noise nulling device can help that too but that's a
whollly different topic with many issues. A 5 ft diameter tuned loop
will provide a very sharp null to null 20 over S9 noise IF you can
orient it in the offending direction AND thats the only direction of
the noise. I have worked VK from NNJ from a 20 over S9 noise
environment using the mag loop when conditions are right.UT It is a
major comprimise rx antenna and will be very underclassed from a
larger, terminated loop for routine DX work.
Pete W2PM
-----Original Message-----
From: Herbert Schoenbohm <herbs@surfvi.com>
To: rick darwicki <n6pe@yahoo.com>
Cc: Group Topband <topband@contesting.com>
Sent: Sun, Dec 20, 2009 6:23 am
Subject: Re: Topband: 160 RX Loops
rick darwicki wrote:
> Hi all,
>
> With high local line noise, is a TUNED LOOP or non-resonant RX loop a
better
option?
>
> I've seen blogs that shielding a loop really doesn't do much.
>
> Comments?
>
>
>
For a quick easy low band low noise antenna I have found that a 20
meter
Delta Loop, corner fed, could hear well with with an in shack pre-amp.
Also the circumference is about right 1005/f for 20 meters that if you
put a 950 ohm resistor in the other corner you end up with a very low
noise K6SE type pennant which give you some nulling in the direction of
the in line resistor. I used to just an insulator at the opposite end
and use two jumpers with alligator clips so I could easily switch
between the Pennant and a 20 meter delta loop.
Try it?
Herb Schoenbohm, KV4FZ
_______________________________________________
160 meters is a serious band, it should be treated with respect. - TF4M
_______________________________________________
160 meters is a serious band, it should be treated with respect. - TF4M
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