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RE: LF: SL settings for EbNaut FFT recording ?

To: "[email protected]" <[email protected]>
Subject: RE: LF: SL settings for EbNaut FFT recording ?
From: VIGILANT Luis Fernández <[email protected]>
Date: Tue, 2 May 2017 08:49:08 +0000
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Thread-topic: LF: SL settings for EbNaut FFT recording ?
Hi Stefan, VLF
And thank you for your all your comments and advices :-)
I was already running an SL instance showing the first 24KHz in a fast way to get an idea of what's going on with QRM and known signals
It is already included in the grabber at 1 min/pixel. Hour changed to UTC just now
As you can see, there is a LOT of noise around. What I'm using is your VLF E-Field probe with the first JFet separated in a 50cm aluminium rod probe
Y placed this antenna in the same pole as MiniWhip. So MiniWhip and the VLF probe are parallel and quite close on top
This increased the noise floor in the MiniWhip and probably is not too good for the VLF probe either. Next is to separate it in an independent isolated mast
As you can see, signals from Alphas are very weak. I will try also with a loop to see if I can get more signal and less noise
Obviously, no clear trace from your last transmission in the 31mHz spectrogram with this Rx conditions
Yes. EbNaut is the last step. But could not resist to try ;-)
Can you generate your own test signal on the MF antenna in 7 km distance? It should be possible to see a few 100V put on the TX antenna, so it is worth to experiment a bit. Maybe a microwave transformer from ebay or so. SpecLab can generate the tone/frequency. Use an available audio PA to drive the transformer, carefully. Could become your first DX on VLF! :-)

At the moment what I did is to use a local generator and could see the trace at 8270 by coupling a wire over the second JFet. An even that was not easy ! :-))))
So, 7Km is an outstanding Dx at this moment. But really challenging 
I do already have a failed microwave oven to use the transformer. And the audio PA too. So you mean to apply the high voltage to the antenna
without resonating coil, right ?
Nice therm. Don't know if the pipe running down to ground would have any issue with this. At the moment 80w at MF didn't show to be harmful
But there can be some noise at 8KHz and this would really be an annoying side effect if that happens :(
The resonating coil for VLF is in the "To-Do" list. Actually found a huge plastic (resin) garden flowerpots which are 60cm diameter by 35cm high
This can be stacked upside down leaving airgap between them for ventilation. Just adding one final on top with no coil serves as rain protection
of the full arrange. But first is the LF PA, which I had postponed for too long, I'm afraid
73 de Luis
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