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RE: LF: Some improvements in VLF Rx

To: "[email protected]org" <[email protected]>
Subject: RE: LF: Some improvements in VLF Rx
From: VIGILANT Luis Fernández <[email protected]>
Date: Fri, 12 May 2017 15:45:21 +0000
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Thread-topic: LF: Some improvements in VLF Rx
Thank you Stefan
The SL instance is updated with the modified USR file. Non stopped, so you can see the difference
73 de Luis

De: [email protected] [mailto:[email protected]] En nombre de DK7FC
Enviado el: viernes, 12 de mayo de 2017 14:19
Para: [email protected]
Asunto: Re: LF: Some improvements in VLF Rx

Hi Luis,

Am 12.05.2017 11:43, schrieb VIGILANT Luis Fernández:
I can add an SMD ferrite bead (0805) in the gate
Worth to try.

The voltage in the coax down in the shack after the 390R is 6V. Power supply is 14V. So there must be some current trought the FET
Will measure the current
Yes it is 8V/390R = 20 mA. That's a bit much. You could increase that resistor to get about 10 mA, maybe 680 Ohm is a good value.

This is the picture of the 5m mast, which is metal. The last section is a PVC pipe which holds the MiniWhip. The VLF probe is hold in a plastic box
containing the FET and attached to the metal mast using a metal adaptor. So it is quite close to the metal mast, which can provide high capacity ?
Probe lenght is 1m
Looks like a good place. The 1m probe should be fine. The capacity is given by the probe, about 5 pF/m is the rule. 1m should be fine when the antenna is at this location.
The only problem seems to be the contaminated ground. You just need to experiment and find the best results.
Maybe it helps to isolate the probe ground from the mast and feed the cable down to the ground where it has its own earth and an isolation transformer between the TV cable and soundcard... You know...

Yes. Using the battery there was no difference, once the ground loop was removed.
Sounds good!

That will be fine ! File is here
Modified file in attachment.
Will try also a twisted pair instead of the coax
There will be no improvement. I would stay at coax.

Good luck for getting a cleaner background...

73, Stefan
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