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
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>>
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>>> 10.08.2011
>>
>>
>
>
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