VLF,
Today i spent several hours just for moving the resonance frequency
from 5.10 to 5.17 kHz. It shounds like an easy job but although i put
more iron powder cores into the coil, which rises the spacing between
the cups, which lowers the L, so it overcompensates the additional
cores, and it rises the Q, the resonance frequency rose to 5.4 kHz and
i didn't get it back. So i had to bring the whole arrangement down to
the lab. Later i managed to bring it accurately on 5.17 kHz and now i'm
back with 225 mA antenna current.
I built an ALC into the conditional actions of SpecLab which hold to
the antenna current into a range between 224 and 226 mA. It seems to
work so far. Of course the tuning range is limited. We will see if the
current stays stable, at least during dry wx...
So now it's time for a new transmission:
f = 5170.000000 Hz
Start time: 04.Jan.2017 08:00:00 UTC
Symbol length: 60 s
Characters: 8
CRC 16
Coding 16K25A
Duration: 12h, 26m, 40s
Antenna current: ~ 225 mA
73, Stefan
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