Hello Stefan,
Well, if really necessary one could cool the barrel from inside - not by
filling it with water from the pipe of course; and carrying such an
amount of distilled water to a portable site would be overkill. Better
use a fan which keeps the air inside the barrel (or your tube)
"rotating" while blowing cold air into it (at the bottom) while leaving
the warm air escape at the top. Maybe the furnace effect is sufficient -
experimentation will show.
Good luck winding the coil - hope you have a lathe or somebody else to
help you with that. Reminds me of my tesla coil experiments, but they
are much smaller than your coil.
With some luck, I can get the internet link to the club station (DF0WD /
DK4U) running again soon - if successful, I can put up a temporary
grabber there, or resume my VLF streaming activities (by help of Paul's
VLF streaming server). The question is if the MP3 or Ogg Vorbis
compression will leave the weak signals intact; at the time we started
those activities it was intented for VLF natural radio but not for
hunting extremely weak signals.
Cheers,
Wolf
Stefan Schäfer schrieb:
Hi Wolfgang,
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 ;-)
Yes, here is also snow again, very nerving!! But there is also strong wind :-) But today i will spend time winding the new coil. It makes no sense to use that heavy 50kg coil with bad Q :-(
Maybe the water butt is an idea but... ...but it may be a little expensive, perhaps. Hm, ok, i will think about it... ;-)
73, Stefan
________________________________
Von: [email protected] im Auftrag von Wolfgang Büscher
Gesendet: Sa 06.03.2010 11:35
An: [email protected]
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 grünen oder blauen 200-Liter-Regentonnen, die man in vielen
Baumärkten 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 Schäfer schrieb:
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. Additionally i
have bought 0,4mm diameter enameled copper wire, abt 6km in one piece (i can
give back the rest). So today i try to wind the big L, abt 540mH! 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: [email protected] im Auftrag von Paul Nicholson
Gesendet: Sa 06.03.2010 08:27
An: [email protected]
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
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