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From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
References: <CD23FAD2-C25C-4491-B7A6-66370074F9DB@hurontel.on.ca>	<AANLkTi=-0nwKg3SiO683YX4Wo5oq5aQ74aE5pSbbyv02@mail.gmail.com>	<4C51FA69.1030202@iup.uni-heidelberg.de>	<AANLkTi=pxmqqQmySJ=LHuphU+q1ni+jMSczUSp=m8agv@mail.gmail.com>	<AANLkTikOqWtr7wecaXmzjVZauERuNNuFDpBz7uhAEaSw@mail.gmail.com> <AANLkTikUcSDQyzvYm78aDYX5KnRxy91hkh48b4k7LYhm@mail.gmail.com> <4C529C6B.9070908@iup.uni-heidelberg.de> <4C53EB92.4000806@legal-medicine.de> <4C53F284.7070307@iup.uni-heidelberg.de>
In-Reply-To: <4C53F284.7070307@iup.uni-heidelberg.de>
Date: Sat, 31 Jul 2010 14:38:27 +0100
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Subject: Re: VLF: DK7FC's 6th VLF kite experiment
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Dear Stefan, LF Group,

I have been doing some receiving checks <9kHz, and althought the QRN=
 level=20
is quite high, the level of man-made noise at my home QTH seems to be=
 much=20
lower than during the last set of tests. So I should be able to have=
 quite=20
good receiving conditions for DK7FC's tests tomorrow without having to=
 go to=20
a /P location.

Around 6.5kHz there are some weak (n x 50Hz) spectral lines drifting=
 around,=20
and a few more stable lines visible, which may be internal to the PC.=
 This=20
is similar to the situation at 8.97kHz, so I am hopeful that at least=
 the=20
receiver will be reasonably sensitive ;-)

Good luck with the test tomorrow,

Cheers, Jim Moritz
73 de M0BMU

----- Original Message -----=20
From: "Stefan Sch=E4fer" <schaefer@iup.uni-heidelberg.de>
To: <rsgb_lf_group@blacksheep.org>
Sent: Saturday, July 31, 2010 10:53 AM
Subject: Re: VLF: DK7FC's 6th VLF kite experiment


> Hello Peter,
>
> Better say 6,6 +-200 Hz. It is still not certain where the resonance=
 will=20
> be, sorry. There are to many assumtions, estimations and calculation=
s.
>
> On 137 kHz the measured C for 100m is 580pF (measured with a RC brid=
ge and=20
> by measuring the L and calculating C). But EZNEC shows a lower C. Th=
is=20
> could be, since a 100m vertical is not absolutely short against Lamb=
da and=20
> so the sems to occur some impedance transformation which "looks/beha=
ves"=20
> like a higherC.
>
> On <9 kHz the 100m wire IS short against lambda and so i loose this=
=20
> benefit. There, the actual C is present. The L of my variometer part=
 in=20
> the BIG coil is estimated to be 30 mH. Maybe it is even more and the=
=20
> overall L is higher than L(coil)+L(variometer) due to the better mag=
netic=20
> coupling. So maybe i have less C and more L than thought on 8,97.
>
> When doubling the antenna height from 100m to 200m and assuming 5 pF=
/m the=20
> C is doubled as well. So i thought i will come out at 6,34 kHz=20
> (8,97/sqrt(2)). But this may just a rough estimate. EZNEC says the=
 C=20
> factor is not 2 but 1,88 so i would come out some 100 Hz above.
>
> So the question is:
> What is the actual antenna C for 100m
> What is the actual (maximum and average) L
> What is the C factor when going from 100m to 200m
>
> This are many uncertainties and so i didn't want to tap the coil at=
 70% of=20
> the winding to come back to 8,97 kHz but first just to measure out=
 where=20
> the resonance will be, to solve these open Questions. Of course, ano=
ther=20
> important and very interesting issue is propagation in the 46km band=
! :-)
>
> So, sorry for that coarse frequency range. Maybe the actual QRG will=
 be=20
> written here in the reflector and can be seen on my garbber2 but fir=
st=20
> lets hope for proper WX!
>
> 73 and tnx, Stefan/DK7FC
>
>
>
> Am 31.07.2010 11:23, schrieb pws:
>> Hi Stefan,
>>
>> Question: do you have a realistic guess of the frequency window of=
 your
>> transmission around 6.5kHz, e.g. +-100Hz?
>>
>> You wrote:
>>
>>> ....
>>> on *Sunday, the 1. August*, i will make a new kite experiment.
>>> ...
>>> i will transmit at arround *6,5 kHz,
>>> ...
>>> Starting time is* 8 UTC*, maybe some time later
>>> ...
>>> TX QTH is as usual in JN49IS, 49.77647N 8.699525.
>>>
>> Distance is 516km, heading 10deg. to Kiel.
>>
>> Just modified the software running at ~17mHz of resolution. Antenna=
s are
>> two crossed ferrite loops feeding some BC550 in parallel buffered=
 by
>> NE5532. Both amplifiers are connected to a M-Audio Audiophile 192=
 running
>> at 24 kHz on an Intel Atom 330 "shoe-box" under Linux.
>>
>> 73 from Baltic Sea,
>> Peter
>>
>=20