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Re: LF: Re: HB9ASB...

To: [email protected]
Subject: Re: LF: Re: HB9ASB...
From: "Roelof Bakker" <[email protected]>
Date: Wed, 10 Aug 2011 21:26:44 +0200
In-reply-to: <8D68749D37B94275855FDBA46A3F6C97@PcMinto>
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Hello Minto, Stefan,

Some food for thoughts:

When I tested a mini-whip in the garden with battery feed and also with a battery fed SLM, I found the noise lower than when used inside and operated from the mains.

The coax cable from the house station was connected in parallel with the mini-whip by means of a BNC T-piece. The noise increased by 9 dB. My assumption is that this noise is received on the shield of the coax inside the house.

Without connecting the shield to a separate radio earth, the noise received on the shield inside the house will travel over the shield all the way to the antenna. There the noise will be received by the sensitive probe. This will be by means of capacitively coupling, I guess. Many people have reported a large drop in local noise by connecting the shield at the bottom of the mast.
This also applies to normal active whips of course.

73,
Roelof, pa0rdt


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