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Message-ID: <3A587A0873B342658A282BE1766C0DED@DennisPC>
From: "DENNIS EASTERLING" <dennis.easterling@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <F34AE1C11C9F44D2950EC49C5A2196A6@gmc.net> <op.vpan5am6yzqh0k@pc-roelof> <4D7062BE2D504CA4A55BDE1C7103CF31@gmc.net> <op.vpat3gvlyzqh0k@pc-roelof> <04DC6D14A81F4542B1D2189A5440F3D5@DennisPC> <015d01cbb57f$1feb9d00$0201a8c0@Clemens04>
In-Reply-To: <015d01cbb57f$1feb9d00$0201a8c0@Clemens04>
Date: Sun, 16 Jan 2011 16:46:37 -0000
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Subject: Re: LF: Re: Mini-Whip Antenna
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>Clemens

Thank you for your information.   My homebrew untuned loops used adjacent 
balanced pre-amplifiers, but still suffered from local qrm.   Papers I have 
read suggest that at lower frequencies, nearby metal objects effect the 
balance of unscreened loops.   The screened loop I made of low loss coax, 
although less sensitive, enabled me to read stations on mf which were 
otherwise impossible, though in this case the amplifier was a grounded base 
followed by a grounded collector arrangement.   The Wellbrook is better 
engineered of course, and is now steerable, so I benefit both ways.

73 Dennis M0JXM

----- Original Message ----- 
From: "Clemens Paul" <cpaul@gmx.net>
To: <rsgb_lf_group@blacksheep.org>
Sent: Sunday, January 16, 2011 1:13 PM
Subject: Re: LF: Re: Mini-Whip Antenna


> Dennis,
>
> if the loop-preamp system is well balanced the loop doesn't need
> screening.
> E.g. the Wellbrook ALA1530 broadband loop is unshielded.
> Therefore its preamp is a push-pull design.
>
> 73
> Clemens
> DL4RAJ
>
>
> ----- Original Message ----- 
> From: "DENNIS EASTERLING" <dennis.easterling@btinternet.com>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Sunday, January 16, 2011 11:15 AM
> Subject: Re: LF: Re: Mini-Whip Antenna
>
>
>> Dear Roelof and Petr
>>
>> When I first tried the mini-whip I was very sceptical of its performance,
>> but in my circumstances, living surrounded by houses and near a main line
>> electric railway ((25kV) it has performed very well indeed.
>>
>> I tried tuned loops of various sizes but the qrm is overwhelming in such
>> close quarters to the switched mode power units and machines operating in
>> nearby houses.   Out of various loops, the wide band untuned screened 
>> loop
>> seemed the best option, with a simple 1m loop of co-ax cable and 
>> amplifier
>> tied to the back fence and the Wellbrook ALA1530 giving similar 
>> performance
>> at MF, although the Welbrook is better engineered and mounted on a 
>> rotator.
> ...
>