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Re: [TowerTalk] 160 RX antenna. What kind of choke?

To: Dan Zimmerman N3OX <>
Subject: Re: [TowerTalk] 160 RX antenna. What kind of choke?
From: Colman Ahern <>
Date: Mon, 31 Dec 2007 09:56:12 -0800
List-post: <>
Can you give some details about the choke which you added to the 
feedline?  Ferrite mix, number of turns, size of core?  At my 
receive-only location I have a very high level of RFI/EMI to deal with.

Colman Ahern.


> With the flag, I've taken great care to isolate it from the ground
> because I know common mode pickup can totally destroy such a low gain
> antenna's utility. The transformer is an isolated winding type on a
> binocular core as described in Low Band DXing, and I added a *second*
> 1:1 isolation transformer near the base of the mast the flag is on,
> and yesterday I added a several thousands-of-ohms choke on that
> feedline back near the shack.  The whole time I was trying to reduce
> the noise I heard on an AM portable radio with it's ferrite stick
> antenna coupling to the magnetic field around the coax feeding the
> flag.  The new choke helped quite a bit and it seemed to help the
> noise level on the flag as well.


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