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. 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!
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?
73, Dimitris VK2COW
Στις Δευ, 4 Φεβ 2019 στις 7:57 μ.μ., ο/η DK7FC <[email protected]> έγραψε:
>
> Hi Dimitris,
>
> Thanks, very kind. If your's is even larger and has just 1 nF, then it
> will be just adequate :-)
> Another radio amateur from Germany offered me two capacitors wich will
> be suitable. They seem to be already on the way in the post.
>
> I wonder how this indoor loop performs as an RX antenna. Of course it
> will depend on the neighbours QRM but maybe it is not as bad as
> expected. Then, i could try to arrange a JT9 QSO or maybe QRSS... If the
> other station is 20 dB stronger, then i could have a higher QRM level...
>
> What about your VLF experiments, what is the next step? What was the
> locator of your 120m antenna? Could you build a longer antenna? Maybe
> you like to try a ground loop? Did you follow the recent experiments
> from my 900m long antenna on 8270 Hz? It is the best experimentation
> field that VLF amateur radio offers these days :-) My recommendation :-)
>
> 73, Stefan
>
>
> Am 04.02.2019 06:54, schrieb Dimitrios Tsifakis:
> > Hi all,
> >
> > I have a few mica capacitors that came from a MW broadcaster, similar
> > to this one (in fact I have one that it bigger than this one).
> >
> > Stefan, I think this is probably your best bet and pity you are not
> > closer otherwise I would be happy to lend you a couple to do your
> > experiments :-)
> >
> > https://rustys.net.au/products/large-ducon-transmitter-honey-pot-capacitor
> >
> > (this is smaller than the ones I have, most are about 1 nF capacitance)
> >
> > 73, Dimitris VK2COW
> >
> > Στις Πέμ, 31 Ιαν 2019 στις 10:01 μ.μ., ο/η dhchurch
> > <[email protected]> έγραψε:
> >
> >> Hello Dimitrios
> >>
> >> Polypropylene capacitors can actually self-heal to such an extent that
> >> there's little left of them. The melting point of polypropylene is not
> >> very high and they can end up as just a liitle blob of plastic.
> >>
> >> Don't worry though, I still use them suitably rated for the frequency in
> >> use and most of them are 600Vac or more.
> >>
> >> 73, Hugh, M0DSZ
> >>
> >> ----- Receiving the following content -----
> >> From: Dimitrios Tsifakis
> >> Receiver: rsgb_lf_group
> >> Time: 2019-01-31, 00:25:55
> >> Subject: Re: LF: TXing WSPR/MF on an indoor loop, part 2
> >>
> >> Hi Stefan,
> >>
> >> In my experience these polypropylene capacitors when they fail, they
> >> just lose some capacitance. I think they call it 'self healing', maybe
> >> they imply that when they fail there is no short circuit?
> >>
> >> I have some really nice silver mica capacitors (ex MW broadcast stuff)
> >> that would be perfect for this task...
> >>
> >> Anyway, I am slowly gearing up for some VLF action over here. The
> >> other day I did some tests at 16.72 kHz into an ugly loop (very
> >> roughly 120 metres by 3 metres, single turn) and I was able to receive
> >> my signals using an unoptimise ferrite antenna at a bit over 2 km from
> >> the TX. I don't think I am in the near field at that distance, am I?
> >> :-)
> >>
> >> 73, Dimitris VK2COW
> >>
> >>
> >>>
> >>
> >
>
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