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Date: Sat, 06 Mar 2010 12:31:56 +0100
From: =?ISO-8859-1?Q?Wolfgang_B=FCscher?= <dl4yhf@freenet.de>
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Subject: Re: AW: AW: AW: LF: Re: 9kHz noise level
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Hello Stefan,

Well, if really necessary one could cool the barrel from inside - not by=
=20
filling it with water from the pipe of course; and carrying such an=20
amount of distilled water to a portable site would be overkill. Better=20
use a fan which keeps the air inside the barrel (or your tube)=20
"rotating" while blowing cold air into it (at the bottom) while leaving=20
the warm air escape at the top. Maybe the furnace effect is sufficient -=
=20
experimentation will show.

Good luck winding the coil - hope you have a lathe or somebody else to=20
help you with that. Reminds me of my tesla coil experiments, but they=20
are much smaller than your coil.

With some luck, I can get the internet link to the club station (DF0WD /=
=20
DK4U) running again soon - if successful, I can put up a temporary=20
grabber there, or resume my VLF streaming activities (by help of Paul's=20
VLF streaming server). The question is if the MP3 or Ogg Vorbis=20
compression will leave the weak signals intact; at the time we started=20
those activities it was intented for VLF natural radio but not for=20
hunting extremely weak signals.

Cheers,
  Wolf



Stefan Sch=E4fer schrieb:
> Hi Wolfgang,
> =20
> Yes, i know about the optimum L/d ratio but i haven't such a Wasserfass=
 ;-) Cooling the coil by water inside is rather a joke i assume? :-P The=
 high epsilon r (81) would slightly decrease the Q. But it would be a good=
 indicator if the water in the water butt is boiling, than i should do a=
 TX break ;-)
> =20
> Yes, here is also snow again, very nerving!! But there is also strong wi=
nd :-) But today i will spend time winding the new coil. It makes no sense=
 to use that heavy 50kg coil with bad Q :-(
> =20
> Maybe the water butt is an idea but... ...but it may be a little expensi=
ve, perhaps. Hm, ok, i will think about it... ;-)
> =20
> 73, Stefan
>
> ________________________________
>
> Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Wolfgang B=FCsche=
r
> Gesendet: Sa 06.03.2010 11:35
> An: rsgb_lf_group@blacksheep.org
> Betreff: Re: AW: AW: LF: Re: 9kHz noise level
>
>
>
> Hi Stefan, Paul, and the group;
>
> Nice to hear about the progress, and hope to catch some signals here
> (one fine day) in JO42FD near Bielefeld.
>
> Stefan, just one suggestion:
> A 2 m long 25 cm diameter tube as coil form will tolerate high voltages,
> no doubt. But it's not the optimum L/D ratio for maximum coil 'Q'.
> Did you consider other 'plastic objects' like plastic barrels (in
> German: Die gr=FCnen oder blauen 200-Liter-Regentonnen, die man in viele=
n
> Baum=E4rkten findet) ?
> I have one of those things here, and iirc the material is polyethylene,
> which is quite a good dielectric.. better than some PVC.
> You could even cool it from the inside wall with water, if necessary ;-)
>
> Greetings from snowy Westphalia,
>    Wolf  DL4YHF .
>
>
> Stefan Sch=E4fer schrieb:
>  =20
>> Very nice Paul!
>> I hope i can generate a peak outcoming of the noise in the picture ;-)
>> Yesterday i have got a PVC tube with 25cm diameter and 2m long. Additio=
nally i have bought 0,4mm diameter enameled copper wire, abt 6km in one pi=
ece (i can give back the rest). So today i try to wind the big L, abt 540m=
H! Than, the internal R will be abt 350 Ohm, not less but no problem. As=
 said, the limiting factor will be the voltage at the wire...
>>
>> 73, Stefan/DK7FC
>>
>> ________________________________
>>
>> Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Paul Nicholson
>> Gesendet: Sa 06.03.2010 08:27
>> An: rsgb_lf_group@blacksheep.org
>> Betreff: Re: AW: LF: Re: 9kHz noise level
>>
>>
>>
>> Stefan wrote:
>>  > I plan to transmit on 8,9700 kHz...
>>
>>  > during the test i make QSY of some Hz if the RXing station
>>  > has a carrier/line on this QRG.
>>
>> Here's a live spectrum for 8970 +/- 1Hz - resolution is 5mH.
>> Amplitude calibration is only within a factor of two or so.
>>
>>   http://abelian.org/vlf/nb.shtml
>>
>>  > do you know other members in the VLF group who live near
>>  > frankfurt?
>>
>> Ich habe die Frage gestellt.
>> --
>> Paul Nicholson
>> --
>>
>>
>>
>> =20
>>    =20
>
>
>
>
>  =20