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Date: Sun, 7 Feb 2010 10:52:05 +0000
Message-ID: <1f0624b91002070252r24602b60n1ab5d5869350b974@mail.gmail.com>
From: Gary - G4WGT <g4wgt@tiscali.co.uk>
To: rsgb_lf_group@blacksheep.org
DomainKey-Status: good (testing) 
Subject: Re: LF: active ant on metallic mast
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Roelof & All,

Just for your information I am using a PA0RDT Mini-Whip antenna for my
grabbers, it is connected to 2 receivers via a passive 50 ohm splitter. The
antenna size is 30 x 45 mm on the PCB. You can see my results at

http://myweb.tiscali.co.uk/wgtaylor/grabber2.html

<http://myweb.tiscali.co.uk/wgtaylor/grabber2.html>The Mini-Whip is at about
9 metres high on a 1 metre PVC stand off arm attached to my main steel mast.
The mast is 90mm diameter & the coax from the Mini-Whip runs along the stand
off arm & down the side of the mast with my other coax cables from 3 other
antennas & the rotator control cable.

The Mini-Whip coax is grounded at the base of the mast as is the mast
itself. It seems to work very well. I have not compared the results with
running the coax away from the mast straight down from the active antenna,
could be a test I could carry out next time I have to work on the antennas.

73,  Gary - G4WGT.


On 7 February 2010 10:11, Roelof Bakker <roelof@ndb.demon.nl> wrote:

> Hello Alan,
>
> Thank you for the hands up.
> Years ago an old hand told me that it made a lot of difference with the
> coax inside or outside the mast.
> But I don't know if the mast was grounded at the bottom, up on the roof or
> what else.
> So it is time to get a proper metalic mast and do some tests.
>
> Besides my SLM's, I now have a PERSEUS SDR for two years, which is not only
> an excellent receiver, but also a rather sophisticated piece of test gear.
> It has level meter, whith a 0.1 dB resolution, which is not a toy but
> accurate to 0.1 dB for relative measurements. The bandwidth can be set to 5
> Hz if you like, which allows level measurements down to -143 dBm. And a 40
> MHz spectrum analyzer with the noisefloor at -110 dBm, which is great in
> tracking down wide band noise, off air antenna tests etc.
>
> 73,
> Roelof, pa0rdt
>
>

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Roelof &amp; All,<div><br></div><div>Just for your information I am using=
 a PA0RDT Mini-Whip antenna for my grabbers, it is connected to 2 receiver=
s via a passive 50 ohm splitter. The antenna size is 30 x 45 mm on the PCB=
. You can see my results at</div>
<div><br></div><div><a href=3D"http://myweb.tiscali.co.uk/wgtaylor/grabber=
2.html">http://myweb.tiscali.co.uk/wgtaylor/grabber2.html</a></div><div><b=
r></div><div><a href=3D"http://myweb.tiscali.co.uk/wgtaylor/grabber2.html"=
></a>The Mini-Whip is at about 9 metres high on a 1 metre PVC stand off ar=
m attached to my main steel mast. The mast is 90mm diameter &amp; the coax=
 from the Mini-Whip runs along the stand off arm &amp; down the side of th=
e mast with my other coax cables from 3 other antennas &amp; the rotator=
 control cable.</div>
<div><br></div><div>The Mini-Whip coax is grounded at the base of the mast=
 as is the mast itself. It seems to work very well. I have not compared th=
e results with running the coax away from the mast straight down from the=
 active antenna, could be a test I could carry out next time I have to wor=
k on the antennas.</div>
<div><br></div><div>73, =A0Gary - G4WGT.</div><div><br></div><div><br><div=
 class=3D"gmail_quote">On 7 February 2010 10:11, Roelof Bakker <span dir=
=3D"ltr">&lt;<a href=3D"mailto:roelof@ndb.demon.nl">roelof@ndb.demon.nl</a=
>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1=
px #ccc solid;padding-left:1ex;">Hello Alan,<br>
<br>
Thank you for the hands up.<br>
Years ago an old hand told me that it made a lot of difference with the co=
ax inside or outside the mast.<br>
But I don&#39;t know if the mast was grounded at the bottom, up on the roo=
f or what else.<br>
So it is time to get a proper metalic mast and do some tests.<br>
<br>
Besides my SLM&#39;s, I now have a PERSEUS SDR for two years, which is not=
 only an excellent receiver, but also a rather sophisticated piece of test=
 gear. It has level meter, whith a 0.1 dB resolution, which is not a toy=
 but accurate to 0.1 dB for relative measurements. The bandwidth can be se=
t to 5 Hz if you like, which allows level measurements down to -143 dBm.=
 And a 40 MHz spectrum analyzer with the noisefloor at -110 dBm, which is=
 great in tracking down wide band noise, off air antenna tests etc.<br>

<br>
73,<br>
Roelof, pa0rdt<br>
<br>
</blockquote></div><br></div>

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