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Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47 kHz

To: [email protected]
Subject: Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47 kHz
From: DK7FC <[email protected]>
Date: Wed, 04 May 2016 20:29:58 +0200
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Hi Paul,

R, i understand. Last night the antenna current was 165 mA only because it was a bit detuned. Also the output transformer is quite loud at 6.47 kHz so i had to stop during the working day. I think the core begins to saturate at that frequency and the output voltage is even higher due to the higher total loss resistance (2 additional coils).
A few minutes ago i put some more iron power cores 'into the field'. They are a different type but that doesn't matter.
The WX is perfect see,
The resonance dropped closer to 6.47 kHz, i can and am running 200 mA now, since 18:08 UTC. I will run it for some hours, maybe through the night. The PA power supply shows 23V*3.7A = 85W input power. With 200 mA, i have 10.5 kV rms on the wire.

Last night, the 50s symbols at just 165 mA was quite critical i think. But we can afford to risk something after so much success now. Also, 50s was the longest length to be finished when work starts here in the building.

Now, unfortunately i lost access to my Raspi in the forest. It seems to need a restart. This happens after running a few weeks without a reboot. I have to find the problem...
Will be in the tree again tomorrow if the WX is fine. Then the system will come back on air.

Tell me if you found the best settings so i can start a message. I would assume that 100s symbol length should be no problem on that frequency and 200 mA.

73, Stefan

Am 04.05.2016 09:58, schrieb Paul Nicholson:

> f = 6470.000 Hz
> Start time: 03.05.2016   22:30:02 UTC
> Period: 50 s
> Length: 5

No decode so far but that's no surprise.  I need to find the
right settings for this frequency: calibrating the E and H
rx phase and finding the best pre-blanker filter settings.

The filter settings become more critical down here because
some mains harmonics start to appear in the pass band.

Is it possible to send a few hours of carrier?
Paul Nicholson

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