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Re: VLF: Ground loop improvements and test carrier...

To: [email protected]
Subject: Re: VLF: Ground loop improvements and test carrier...
From: DK7FC <[email protected]>
Date: Wed, 03 Apr 2019 20:24:16 +0200
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PS: Earlier that day, the same test was done at 5170.1 Hz. But there, the antenna current was different:

900m: T2019-03-31_12:31,+19m at I = 2.74 A
1130m: T2019-03-31_12:57,+31m at I = 2.12 A

i.e. the signal was 2.2 dB lower, due to the lower antenna current.

It was a noisy day, but maybe you even catched that signal.

Another thing:
Determined resonance capacities:
8270 Hz: C (measured) L (calculated) delta 1130/900 
900m Ant 0,147 uF 1,82 mH  
1130m Ant 0,1 uF 3,00 mH + 65 %
5170 Hz:      
900m Ant 0,389 uF 1,74 mH  
1130m Ant 0,267 uF 2,85 mH + 64 %
2970 Hz:      
900m Ant 1,147 uF 1,80 mH  
1130m Ant 0,82 uF 2,80 mH + 56 %
970 Hz:      
900m Ant 11 uF 1,75 mH  
1130m Ant 7 uF 3,15 mH + 80 %
(The system includes a 700 uH fixed inductor. This value has been already substracted in the calculated L)

73, Stefan

Am 03.04.2019 18:00, schrieb Paul Nicholson:

Stefan wrote:

> A carrier transmission was done at 8270.1 Hz, using an antenna
> current of 2 A on both antennas.

Received here -

 900m Ant:  T2019-03-31_13:58,+10m: 1.07fT S/N -10.4dB/1Hz

 1130m Ant: T2019-03-31_14:12,+10m: 1.30fT S/N -7.6dB/1Hz

The signal strength hasn't increased as much as the area has
increased.  So maybe the ground return current has remained
at the same depth.  Then the signal would increase as by 1130/900
which is close to what I see here.

Can you compare amplitude and not S/N?

Paul Nicholson

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