Message-ID: <4DFB7B90.8070205@iup.uni-heidelberg.de>
Date: Fri, 17 Jun 2011 18:06:40 +0200
From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= <schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: Re: LF RX loop
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Hello Peter,

Tnx for confirmation.
Today i bought a new copper tube, circular, 1m diameter and 18mm tube 
diameter and 1mm thickness (16 EUR). This time i realized excellent 
contact of the caps dieectly to the tube. The first version used about 
8cm (in sum) 1mm dia silver wire which may have caused some Q loss. 
Addionally i want to use WIMA FKP-1 types now, 100nF/1250V. The new 
version is very mechanically stable, i am glad and will show a photo later.
The Q measurement isn't done yet.
Now i have to concentrate on VLF...
So next week i'll give a new report.

73, Stefan/DK7FC

Am 17.06.2011 15:47, schrieb pws:
> Hi Stefan,
>
> You wrote:
>    
>> ...
>> I found the Q of the
>> loop is just 8! Is this normal? Which Q do others achieve, with a
>> similar antenna for 137 kHz?
>> ...
>>      
> Confirming your findings. In the late 90th I built a 2m-loop from 1"
> coax ("Flexwell") for nulling out Loran-C splatter. I remember a
> bandwidth of ~12-15 kHz =>  Q ~= 10 with 8.2uH/165nF.
> http://www.qsl.net/df3lp/projects/lfloop/index.html
>
>    
>> ...
>> It is fascinating to null out s signal, which i have done the first
>> time now. I can reduce the signal of DCF39 by 25 dB by turning the
>> loop...
>>      
> That's somewhat different to what could be found here. I observed very
> sharp Nulls well>40dB below main lobes. May be due do the orthodox
> "screened" design including the usual gap. But as you suggested that's only
> true for pure groundwave reception. At VLF I'm observing the deepest null
> of DHO38 (~200km; noon) at ~30deg. of elevation.
>
> Good luck for tomorrow,
> Peter, df3lp
>