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 <[email protected]>
An: rsgb_lf_group <[email protected]>
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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