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Re: Topband: Magnetic Loops

To: "Tom W8JI" <w8ji@w8ji.com>, <topband@contesting.com>
Subject: Re: Topband: Magnetic Loops
From: "ZR" <zr@jeremy.mv.com>
Date: Mon, 27 May 2013 20:53:19 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
Your forgetting that the front end is still broadband and wide open and being blasted into intermod many times. These days not everyone is blessed by the latest gigabuck rig which still is wide open until it hits the roofing filter which wouldnt be there if there werent problems.....

My first experience was with a modified R4C in the early 80's which at least had a front end tuneable preselector. Ive since used it with the various xcvrs here and easily hear the difference plus it can be tuned either side of the wanted signal. Does wonders for BCB rejection also.

Carl
KM1H


Actually a properly designed purpose built loop can offer a reduction in noise from the high Q selectivity offered.


That would only be true if the receiver system noise bandwidth was wider than the loop's bandwidth. If you had a SkyBuddy with 30 kHz noise BW and put a 5 kHz wide loop in front, then you would have a noise BW limited by the loop.

The only way antenna BW reduces noise is if the receiver is overloading from out-of-band signals, or the receiver's ulitmate selectivity is wider than the loop antenna.

While an SX99 or something that terrible might benefit with a high Q loop, even an SX101 would not.
All good topband ops know how to put up a beverage at night.
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All good topband ops know how to put up a beverage at night.
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Topband Reflector

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