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Date: Thu, 26 Dec 2013 18:32:43 +0100
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: VLF: 8969.99
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Hi Bob,

Of course, if the coil is protected against rain, then it is no problem. 
But the coil is quite large and due to the high voltage, the housing 
should ideally have a distance of 30cm or more to the coil. So the 
housing must be quite large, even more. And that makes it dangerous 
because of wind blasts on the to of the building in 35m AGL...
Anyway it would be nice and i also thought about using a simple foil 
across the coil, without additional distance.
However on LF, there are partial discharges on the top of the coil which 
burns holes into the protecting foil. And the VLF winding is 2000m long. 
It is a lot of effort to repair it after a short cut between some turns 
due to arcing. So it is a high risk.
I think i will make a test in the near future and see if 9 kHz partial 
discharges are as agressive as 137 kHz partial discharges :-)
73, Stefan/DK7FC

Am 26.12.2013 16:32, schrieb Bob Raide:
> Stefan;
> Even if you have your coils in weather proof housing rain is no good 
> to transmit on 9 kHz? Bob
>
> ------------------------------------------------------------------------
> Date: Thu, 26 Dec 2013 13:55:11 +0100
> From: Stefan.Schaefer@iup.uni-heidelberg.de
> To: rsgb_lf_group@blacksheep.org
> Subject: Re: VLF: 8969.99
>
> Hi Uwe, Tom, VLF,
>
> Best signal ever from Tom, capture attached. Is it due to the 
> propagation or did it improve your signal?
> What about some tests in OPDS32 or maybe JT9-30? Unfortunately there 
> is permanent rain here so i have to wait some days longer.
>
> 73, Stefan/DK7FC

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Hi Bob, <br>
<br>
Of course, if the coil is protected against rain, then it is no
problem. But the coil is quite large and due to the high voltage, the
housing should ideally have a distance of 30cm or more to the coil. So
the housing must be quite large, even more. And that makes it dangerous
because of wind blasts on the to of the building in 35m AGL... <br>
Anyway it would be nice and i also thought about using a simple foil
across the coil, without additional distance. <br>
However on LF, there are partial discharges on the top of the coil
which burns holes into the protecting foil. And the VLF winding is
2000m long. It is a lot of effort to repair it after a short cut
between some turns due to arcing. So it is a high risk. <br>
I think i will make a test in the near future and see if 9 kHz partial
discharges are as agressive as 137 kHz partial discharges :-)<br>
73, Stefan/DK7FC<br>
<br>
Am 26.12.2013 16:32, schrieb Bob Raide:
<blockquote cite="mid:BLU180-W62F434A4CCA435DECB293EACC20@phx.gbl"
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  <div dir="ltr">Stefan;<br>
Even if you have your coils in weather proof housing rain is no good to
transmit on 9 kHz? Bob<br>
&nbsp;<br>
  <div>
  <hr id="stopSpelling">Date: Thu, 26 Dec 2013 13:55:11 +0100<br>
From: <a class="moz-txt-link-abbreviated" href="mailto:Stefan.Schaefer@iup.uni-heidelberg.de">Stefan.Schaefer@iup.uni-heidelberg.de</a><br>
To: <a class="moz-txt-link-abbreviated" href="mailto:rsgb_lf_group@blacksheep.org">rsgb_lf_group@blacksheep.org</a><br>
Subject: Re: VLF: 8969.99<br>
  <br>
Hi Uwe, Tom, VLF,<br>
  <br>
Best signal ever from Tom, capture attached. Is it due to the
propagation or did it improve your signal?<br>
What about some tests in OPDS32 or maybe JT9-30? Unfortunately there is
permanent rain here so i have to wait some days longer.<br>
  <br>
73, Stefan/DK7FC</div>
  </div>
</blockquote>
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