Gerhard,
Many thanks.
73
John F5VLF
On 11 Aug 2011, at 21:14CEST, Gerhard Hickl wrote:
> 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" <[email protected]>
>>>> To: <[email protected]>
>>>> 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
>>>>
>>>>
>>>
>>>
>>>
>>>
>>
>>
>
>
>
>
|
