Message-ID: <5C57741B.4020809@posteo.de>
Date: Mon, 04 Feb 2019 00:07:07 +0100
From: DK7FC <selberdenken@posteo.de>
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Subject: Re: LF: TXing WSPR/MF on an indoor loop, part 2
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Hi Markus,

What a surprise, many thanks :-) This was just a short test. I just 
transmitted my call 4 times without an announcement and you picked it 
up. Very attentive :-) I never thought that someone will pick it up :-)
That QRSS was generated by the Raspi using a tool written by VK2COW.

I had a look at http://www.472khz.org/pages/on-the-air/grabbers.php and 
searched for grabberson-line grabbers (excluding my own). DL0AO is not 
yet listed on that page. Just a few MF grabbers that are actually running...

73, Stefan


Am 03.02.2019 23:44, schrieb Markus Vester:
> A little snapshot from the DL0AO LF/MF-grabber...
>
> 73, Markus
>
>
> -----Ursprüngliche Mitteilung-----
> Von: DK7FC <selberdenken@posteo.de>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> Verschickt: So, 3. Feb. 2019 15:00
> Betreff: Re: LF: TXing WSPR/MF on an indoor loop, part 2
>
> ...indeed! Since more than 72 hours i'm running the WSPR transmission 
> in 25% duty cycle (each 8 minutes). First i tuned to 20 A antenna 
> current and the temperature / antenna current changes were much 
> smaller. But there was a certain click, or krrrrkkrt audible from the 
> Cs. It was likely that there were indeed internal voltage 
> breakthroughs, which were self-healing. Now after 3 days the current 
> dropped again to 14 A, meaning that the capacity dropped, so the loop 
> became detuned and so the RF current and voltages dropped to a level 
> which is accepted by the capacitors.
>
> So my conclusion is, the derating curves actually should be considered.
>
> I wonder if the effect is still happening if one keeps the 
> temperatures down at 25 C or even lower. When placing the capacitors 
> in de-ionised iced water, it should be possible to keep the 
> temperatures down, also in the internal of the capacitor.
>
> But all in all this is not a good solution. Fortunately i have another 
> antenna which is more efficient :-)
>
> 73, Stefan
> ...

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Hi Markus, <br>
<br>
What a surprise, many thanks :-) This was just a short test. I just
transmitted my call 4 times without an announcement and you picked it
up. Very attentive :-) I never thought that someone will pick it up :-)<br>
That QRSS was generated by the Raspi using a tool written by VK2COW.<br>
<br>
I had a look at <a class="moz-txt-link-freetext" href="http://www.472khz.org/pages/on-the-air/grabbers.php">http://www.472khz.org/pages/on-the-air/grabbers.php</a> and
searched for grabberson-line grabbers (excluding my own). DL0AO is not
yet listed on that page. Just a few MF grabbers that are actually
running...<br>
<br>
73, Stefan<br>
<br>
<br>
<br>
Am 03.02.2019 23:44, schrieb Markus Vester:
<blockquote cite="mid:515975858.2340956.1549233884518@mail.yahoo.com"
 type="cite">
  <div
 style="font-size: 10pt; font-family: arial,helvetica,sans-serif; color: black;">
  <div
 style="color: black; font-family: arial,helvetica,sans-serif; font-size: 10pt;"
 abp="151">A little snapshot from the DL0AO LF/MF-grabber...<br>
  <br>
73, Markus<br abp="152">
  <br abp="153">
  <br abp="154">
-----Ursprüngliche Mitteilung-----<br abp="155">
Von: DK7FC <a class="moz-txt-link-rfc2396E" href="mailto:selberdenken@posteo.de">&lt;selberdenken@posteo.de&gt;</a><br abp="156">
An: rsgb_lf_group <a class="moz-txt-link-rfc2396E" href="mailto:rsgb_lf_group@blacksheep.org">&lt;rsgb_lf_group@blacksheep.org&gt;</a><br abp="157">
Verschickt: So, 3. Feb. 2019 15:00<br abp="158">
Betreff: Re: LF: TXing WSPR/MF on an indoor loop, part 2<br abp="159">
  <br abp="160">
  </div>
  <div id="yiv6719322957" abp="161">
  <div abp="162">...indeed! Since more than 72 hours i'm running the
WSPR transmission
in 25% duty cycle (each 8 minutes). First i tuned to 20 A antenna
current and the temperature / antenna current changes were much
smaller. But there was a certain click, or krrrrkkrt audible from the
Cs. It was likely that there were indeed internal voltage
breakthroughs, which were self-healing. Now after 3 days the current
dropped again to 14 A, meaning that the capacity dropped, so the loop
became detuned and so the RF current and voltages dropped to a level
which is accepted by the capacitors.<br abp="163" clear="none">
  <br abp="164" clear="none">
So my conclusion is, the derating curves actually should be considered.<br
 abp="165" clear="none">
  <br abp="166" clear="none">
I wonder if the effect is still happening if one keeps the temperatures
down at 25 C or even lower. When placing the capacitors in de-ionised
iced water, it should be possible to keep the temperatures down, also
in the internal of the capacitor.<br abp="167" clear="none">
  <br abp="168" clear="none">
But all in all this is not a good solution. Fortunately i have another
antenna which is more efficient :-)<br abp="169" clear="none">
  <br abp="170" clear="none">
73, Stefan<br abp="171" clear="none">
...</div>
  </div>
  </div>
</blockquote>
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