Re: LF: Re: Mini-Whip Antenna

["DENNIS EASTERLING" <dennis.easterling@btinternet.com>]

> 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.
> ...