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Re: LF: Some improvements in VLF Rx

To: [email protected]
Subject: Re: LF: Some improvements in VLF Rx
From: DK7FC <[email protected]>
Date: Thu, 11 May 2017 15:40:36 +0200
In-reply-to: <[email protected]cal>
References: <[email protected]cal>
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PS: There are a number of settings you could improve in this wideband spectrogram. If you send me your usr file i would send you one back with some changes, if you like.

Also it may be worth to start a second spectrogram now, centered on 8270 Hz. It could run in 424 uHz which is to 'fast' to display amateur signals (at least the ones which are available these days) but it will give a first impression about the noise background difference between day and night.

73, Stefan

Am 08.05.2017 10:57, schrieb VIGILANT Luis Fernández:
This weekend could fix the QRM problem with the VLF E-probe. There was a ground loop at the 1pps from GPS
The ground of the GPS (and PC via USB) was routed to the audio transformer at the VLF signal side, not soundard side
So, the noise was going up by the VLF cable to the probe and caused a 20dB noise rise in MF/LF in the nearby MiniWhip
The VLF espectrogram has got clearer, but still contaminated. Specially at night, probably due to street led lights in the area
I'm using a separate first Fet at the probe, connected by aprox 15m TV coax. Would it be better to use twisted pair or
keep all the preamp up, close to the probe ?
73 de Luis

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