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From: John Rabson <john.rabson@numeo.fr>
In-Reply-To: <1313074781.1701.7.camel@gerhard-desktop>
Date: Thu, 11 Aug 2011 17:58:21 +0200
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References: <4E418609.6020500@iup.uni-heidelberg.de> <67A6F7BF45BF4A0193A3DCB53000A283@PcMinto> <008401cc56ce$2f1fb2c0$0401a8c0@xphd97xgq27nyf> <12C475F3F4C84B818461753F2E8A60A6@PcMinto> <4E41AECB.90808@iup.uni-heidelberg.de> <8D68749D37B94275855FDBA46A3F6C97@PcMinto>  <op.vz0iyui5yzqh0k@pc-roelof> <1313033619.1543.20.camel@gerhard-desktop> <4E438B8B.1060800@iup.uni-heidelberg.de> <00c401cc5826$49523e70$71a9c00a@Clemens04> <1313074781.1701.7.camel@gerhard-desktop>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: Re: HB9ASB...
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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!
>=20
> This is exactly the opposite that I experienced with the Mini-Whip.
>=20
> The higher I brought it up (=3D the farther I brought it away from the
> noise source, commonly called "house"), the better the SNR.
>=20
> 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.
>=20
> 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.
>=20
> 73
>=20
> OE3GHB
> Gerhard
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> Am Donnerstag, den 11.08.2011, 13:32 +0200 schrieb Clemens Paul:
>> Hi Stefan,
>>=20
>>> The pole that is on a noisy roof (and its noisy ground) and on the =
other side=20
>>> the pole that is far away in the garden, with its own and clean =
local earth.=20
>>> In the garden a metallic pole should make no difference, as you say.
>>=20
>> 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.
>>=20
>> 73
>> Clemens
>> DL4RAJ
>>=20
>>=20
>>=20
>>=20
>>=20
>> ----- Original Message -----=20
>> From: "Stefan Sch=E4fer" <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...
>>=20
>>=20
>>> Hi Gerhard,
>>>=20
>>> I think one has to compare two different situations:
>>>=20
>>> The pole that is on a noisy roof (and its noisy ground) and on the =
other side=20
>>> the pole that is far away in the garden, with its own and clean =
local earth.=20
>>> In the garden a metallic pole should make no difference, as you say.
>>>=20
>>> 73, Stefan
>>>=20
>>>=20
>>> Am 11.08.2011 05:33, schrieb Gerhard Hickl:
>>>> Roelof!
>>>>=20
>>>> With interest I was following all the discussions about the "Mini
>>>> Whip"-like antennas.
>>>>=20
>>>> 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.
>>>>=20
>>>> 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?
>>>>=20
>>>> 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.
>>>>=20
>>>> Actually it isn't even a true coax cable but a singe shielded =
twisted
>>>> pair where the two inner wires are in parallel....Z=3D? Who =
knows????
>>>>=20
>>>> 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.
>>>>=20
>>>>=20
>>>>=20
>>>> 73
>>>> OE3GHB
>>>> Gerhard
>>>>=20
>>>>=20
>>>>=20
>>>>=20
>>>>=20
>>>>=20
>>>> Am Mittwoch, den 10.08.2011, 21:26 +0200 schrieb Roelof Bakker:
>>>>=20
>>>>> Hello Minto, Stefan,
>>>>>=20
>>>>> Some food for thoughts:
>>>>>=20
>>>>> 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.
>>>>>=20
>>>>> 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.
>>>>>=20
>>>>> 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.
>>>>>=20
>>>>> 73,
>>>>> Roelof, pa0rdt
>>>>>=20
>>>>>=20
>>>>=20
>>>>=20
>>>=20
>>>=20
>>>=20
>>> -----
>>> eMail ist virenfrei.
>>> Von AVG =FCberpr=FCft - www.avg.de
>>> Version: 10.0.1392 / Virendatenbank: 1520/3826 - Ausgabedatum: =
10.08.2011=20
>>=20
>>=20
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