From: Gerhard Hickl <gerhard.hickl@aon.at>
To: rsgb_lf_group@blacksheep.org
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Date: Thu, 11 Aug 2011 21:14:25 +0200
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Subject: Re: LF: Re: HB9ASB...
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John!

Actually there is no special guying used since the mast is only the
lower (and thus thicker) section of an originally 10m high "cheap"
Fibreglass-Pole like available at http://www.dx-wire.de/fiberglasm.htm

It is tied to the chimney with two tension belts which are commonly used
to fix cargo in a truck. (1 inch wide).

Originally this method of fixing to the chimney was just thought to be
for testing but meanwhile it is up there for more than a year.

The two probes (LF/VLF) on top of the mast are suspended by a string
which enables me to maintain the probes without bringing the pole down.

73
OE3GHB
Gerhard




 




Am Donnerstag, den 11.08.2011, 17:58 +0200 schrieb John Rabson:
> Gerhard,
> 
> What guying arrangements do you use for the 5m mast, please?
> 
> 73
> John F5VLF
> 
> On 11 Aug 2011, at 16:59CEST, Gerhard Hickl wrote:
> 
> > Clemens, LF group!
> > 
> > This is exactly the opposite that I experienced with the Mini-Whip.
> > 
> > The higher I brought it up (= the farther I brought it away from the
> > noise source, commonly called "house"), the better the SNR.
> > 
> > Today I connected the shield of the cable to the lightning protection
> > system up on the roof and couldn't find any difference so far.
> > 
> > I'm using a 5m fibre-glass pole fixed to the chimney as a support for
> > the probe and the shield of the feeder is only grounded in the shack.
> > 
> > 73
> > 
> > OE3GHB
> > Gerhard
> > 
> > 
> > 
> > 
> > 
> > Am Donnerstag, den 11.08.2011, 13:32 +0200 schrieb Clemens Paul:
> >> Hi Stefan,
> >> 
> >>> The pole that is on a noisy roof (and its noisy ground) and on the other side 
> >>> the pole that is far away in the garden, with its own and clean local earth. 
> >>> In the garden a metallic pole should make no difference, as you say.
> >> 
> >> How true.
> >> My miniwhip was completely unusable on the top of my roof,
> >> with or without connecting the coax shield to the lightning
> >> gr.. ehm reference plane.
> >> So I decided to put it in the middle of thegarden where it is only 30cm
> >> above the lawn.
> >> Here connecting the coax braid to a 3m long earth rod was essential
> >> to get rid of the noise.
> >> Now this setup is good enough for receiving SAQ with up to 30dB S/N.
> >> 
> >> 73
> >> Clemens
> >> DL4RAJ
> >> 
> >> 
> >> 
> >> 
> >> 
> >> ----- Original Message ----- 
> >> From: "Stefan Schäfer" <Stefan.Schaefer@iup.uni-heidelberg.de>
> >> To: <rsgb_lf_group@blacksheep.org>
> >> Sent: Thursday, August 11, 2011 9:58 AM
> >> Subject: Re: LF: Re: HB9ASB...
> >> 
> >> 
> >>> Hi Gerhard,
> >>> 
> >>> I think one has to compare two different situations:
> >>> 
> >>> The pole that is on a noisy roof (and its noisy ground) and on the other side 
> >>> the pole that is far away in the garden, with its own and clean local earth. 
> >>> In the garden a metallic pole should make no difference, as you say.
> >>> 
> >>> 73, Stefan
> >>> 
> >>> 
> >>> Am 11.08.2011 05:33, schrieb Gerhard Hickl:
> >>>> Roelof!
> >>>> 
> >>>> With interest I was following all the discussions about the "Mini
> >>>> Whip"-like antennas.
> >>>> 
> >>>> In your description of the "PA0RDT Mini Whip" you suggest to use a non
> >>>> metallic pole for mounting the probe and an (optional) earth-rod to
> >>>> ground (sorry Andy!!) the shield.
> >>>> 
> >>>> I might be completely wrong but isn't it the same when one uses a
> >>>> grounded metallic pole and connect the shield of the coax on top of this
> >>>> pole?
> >>>> 
> >>>> BTW: I have an insulating pole (5m) on top of the roof and yet no
> >>>> grounded shielding of the coax but just in the shack. I will connect the
> >>>> shield to the lightning protection system at the bottom of the pole and
> >>>> see about the difference.
> >>>> 
> >>>> Actually it isn't even a true coax cable but a singe shielded twisted
> >>>> pair where the two inner wires are in parallel....Z=? Who knows????
> >>>> 
> >>>> So considering my "fluffy" set-up, I think my VLF grabber is performing
> >>>> very well but for sure there is room for improvements as well.
> >>>> 
> >>>> 
> >>>> 
> >>>> 73
> >>>> OE3GHB
> >>>> Gerhard
> >>>> 
> >>>> 
> >>>> 
> >>>> 
> >>>> 
> >>>> 
> >>>> Am Mittwoch, den 10.08.2011, 21:26 +0200 schrieb Roelof Bakker:
> >>>> 
> >>>>> 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
> >>>>> 
> >>>>> 
> >>>> 
> >>>> 
> >>> 
> >>> 
> >>> 
> >>> -----
> >>> eMail ist virenfrei.
> >>> Von AVG überprüft - www.avg.de
> >>> Version: 10.0.1392 / Virendatenbank: 1520/3826 - Ausgabedatum: 10.08.2011 
> >> 
> >> 
> > 
> > 
> > 
> > 
> 
>