G'day Stefan and Edgar,
My house is on QF44OX00OR and the property extends to QF44NX (50 acres
or 200,000 m^2). I do have permission from some neighbours to lay
wires into their properties, so an extra large (over 1km) ground wire
is entirely doable but not at this point in time. The reference loop
is from the shed, about 100 metres south of the house, to the tractor
shed. I have mains in the shed and I also have a 200 W audio linear
amplifier to get things started. I can build a class-E kilowatt if
necessary later. I like the roughly north-south loop configuration as
it favours many large cities (Melbourne, Sydney, Brisbane and Tassie)
and most importantly Canberra which is only 30 km to the South. I will
try to get some signals received in Canberra before I start asking
people further away to have a listen. I currently have assembled an XO
clocked DDS controlled by an arduino to do the initial tests but later
when I decide to go QRSSSSSI can dig out and use the old rubidium
clock as a reference for extra stability. For receiving I use a 24
bit, 192 kHz USB sound card and spectrum lab (thanks Wolf!). The
antenna I will use for receive is one of those monster ferrite rods.
Amplification may not even be necessary, the signals I get when the
antenna is tuned seem to be already quite good. Once I have a decent
RX antenna I think I will start gifting these rods (I have a few) to
interested amateurs in the region and help them get started with
receiving on VLF. Make a small army of receivers, that would make life
much easier when evaluating antennas!
Hey, you should document your experiments even if it is a summary of
the activities and nothing more. The list is great but perhaps we are
missing out on many other potentially interested people that may have
not discovered the list. You are clearly not lazy having achieved so
much on MF and below :-)
I have played with ground loops before and had some good results in
LF. Once I establish a reference system, I can compare antennas
including ground loops. Unlike Europe where you have plenty of people
around you, I have to do both the TXing and the RXing and that
requires effort and time. The latter is a very scarce resource!
Anyway, looks like a nice day today to do some more outdoor work. We
had lightning storms and plenty of rain the past few days, so I
haven't made any progress.
73, Dimitris VK2COW
Στις Τρί, 5 Φεβ 2019 στις 8:09 μ.μ., ο/η DK7FC <[email protected]> έγραψε:
>
> Hi Dimitris,
>
> Am 04.02.2019 06:54, schrieb Dimitrios Tsifakis:
> > [...] and pity you are not
> > closer otherwise [...]
> Indeed. Otherwise we could do some VLF experiments together, maybe in
> that desert close to the sea:
> https://www.youtube.com/watch?v=XfR9iY5y94s :-)
>
>
> Am 05.02.2019 01:16, schrieb Dimitrios Tsifakis:
> > Hi Stefan,
> >
> > I am working on both making a portable VLF magnetic field antenna
> > (tuned) and a transmit antenna which perhaps will be better than the
> > existing 120 m by 3 m (average height) loop. The resistance of this
> > loop isn't stellar (about 11 ohm DCR) and half of it is aluminium
> > welding wire. Anyway, it's there and it is my reference antenna.
> It could be a good RX antenna for VLF. Did you try to connect a
> soundcard of a notebook and record something or produce a spectrogram?
> You know there is Edgar from Tasmania, most probably already following
> the conversation and hoping to receive something of you :-)
>
> > The
> > new loop antenna will be better but it is still under construction.
> > Heavy copper cabling is surprisingly difficult to put up in the air
> > with limited resources. Anyway, once all that is in place, I will do
> > some local tests (without rubidium or GPS locked oscillators) and
> > we'll take it from there. My QTH locator is QF44OX (very close to
> > QF44nx). I have plenty of space but it's undulating and kangaroos
> > always make a mess with low hanging wires!
> >
> Wow, exciting! So the RX is in QF44OX and the TX is in QF44NX?
> If you have plenty of space, it may be easier to improve the ERP by
> building a larger loop out of thin wire instead of a 'small' one out of
> heavy wire. Maybe you can even bury the wire to avoid collisions with
> kangaroos.
>
> > Is there a web page with your 8270 Hz experiments? I'd love to read up
> > a bit of inspiring material of what others have achieved as it can be
> > quite lonely doing experiments like that where I am. How much radiated
> > power have you achieved?
> >
> I must admit that i do not have my own homepage with up to date overview
> of my VLF experiments. There is a list maintained by Paul Nicholson
> giving an impression of what has been done lately on VLF/ULF:
> http://abelian.org/vlf/amateur-radio/
> A web page of these experiments would be very large and you could read
> for hours. But i'm rather lazy writing it up, unfortunately. I'm rather
> the one who puts time into winding coils!!! ;-)
> Actually the whole story of all experiments is spread over the emails of
> this reflector.
>
> Your next well prepared VLF RX station is Edgar J.T. in QE37PD, see
> http://k7fry.com/grid/?qth=QF44OX&from=QE37PD
> With a well prepared loop, it is not unlikely at all to leave a trace on
> his site! The distance is just like the distance between me and Paul
> Nicholson.
>
> But at the moment you are doing some first steps and there are some more
> to be done until you reach that distance. But it is really doable!
> At the transmitter site, do you have electricity or do you transmit from
> batteries?
> What is the power level?
> Can you (temporarely) lay out a wire from here to there:
> http://k7fry.com/grid/?qth=QF44NX86FC&from=QF44NX73XQ :-) This is a good
> length and if configured to a loop, it would point perfectly towards
> Edgar. A simple loudspeaker cable of 0.75mm2 would be fine. And you will
> need some ground rods at the ends.
>
> Sorry, that was maybe a bit much of input :-)
> What do you think?
>
> 73, Stefan
>
>
>
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