Hi Stefan,


> This is what i use on my grabber:
> http://www.iup.uni-heidelberg.de/schaefer_vlf/8,97kHz%20active%20E%20field%20antenna%20by%20DK7FC.jpg

That looks simple enough and from what I see, there are other happy
customers (4x1RF, G3XBM and TF3HZ) so I'll make one. :-)

Don't have the BF862 FETs but may have something similar, maybe J310
or MPF102? Need to look at the datasheets.

> Mostly they are locked internally, i.e. by SpecLab. You have to lock on a
> reference frequency to correct the soundcard xtal drift. This can be done by
> using a small GPS module (running from the 5V of the USB) that has a 10 khz
> output. You can see the 10 kHz line in my wideband spectrogram on the bottom
> of the grabber site.
> Alternatively you can lock on a MSK transmitter (military) if one is
> available. In VK, there is NWC on 19.8 kHz which is in OG78BE (locator). You
> should have good reception of that transmitter since we can see it here in 1
> Hz as well.

Oh yes, the Exmouth station is very very strong here, very strong,
audible signal. That makes things simple. The other option is to use a
soundcard that has a 10 MHz clock input and connect it to my Rb
reference. There are a couple of friends that experiment with these,
but to be honest, I like the simplicity of using SL to lock to a known
good signal.

73, Dimitris VK1SV