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From: John Rabson <john.rabson@numeo.fr>
In-Reply-To: <1313090065.1579.46.camel@gerhard-desktop>
Date: Sun, 14 Aug 2011 10:13:12 +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> <25D9CE8E-70C7-4FB5-8A10-0ED6B94255EE@numeo.fr> <1313090065.1579.46.camel@gerhard-desktop>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: Re: HB9ASB...
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Gerhard,

Many thanks.

73
John F5VLF

On 11 Aug 2011, at 21:14CEST, Gerhard Hickl wrote:

> John!
>=20
> 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
>=20
> It is tied to the chimney with two tension belts which are commonly =
used
> to fix cargo in a truck. (1 inch wide).
>=20
> 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.
>=20
> 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.
>=20
> 73
> OE3GHB
> Gerhard
>=20
>=20
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> Am Donnerstag, den 11.08.2011, 17:58 +0200 schrieb John Rabson:
>> Gerhard,
>>=20
>> What guying arrangements do you use for the 5m mast, please?
>>=20
>> 73
>> John F5VLF
>>=20
>> On 11 Aug 2011, at 16:59CEST, Gerhard Hickl wrote:
>>=20
>>> 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
>>>=20
>>>=20
>>>=20
>>>=20
>>>=20
>>> 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
>>>=20
>>>=20
>>>=20
>>>=20
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