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Re: VLF: Back on 5.17 kHz / 58 km...

To: [email protected]
Subject: Re: VLF: Back on 5.17 kHz / 58 km...
From: DK7FC <[email protected]>
Date: Wed, 04 Jan 2017 02:26:04 +0100
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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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