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From: Dimitrios Tsifakis <dtsifakis@gmail.com>
Date: Sat, 9 Feb 2019 09:01:47 +1100
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To: rsgb_lf_group@blacksheep.org
Subject: Re: VLF: in VK?
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Hi Stefan and VLF,

well, I am now officially hooked! My signal on 29.5 kHz (VLF's edge)
has been detected 22.3 km away in Canberra by Dale VK1DSH. Only
casualty is the russian mica capacitors (K31-11-3) which got really
hot (I was focusing on the amplifier and neglected the poor caps). I
had 4 of them in parallel, each 4700 pF.  Maybe they will recover if I
let them cool down :-)

That's probably a first for Australia, I haven't heard anyone else
doing tests like this.

I now have to wait for properly sized caps that should be coming in
the mail.. Then we can continue the exploration of VLF :-)

73, Dimitris VK2COW


Στις Σάβ, 9 Φεβ 2019 στις 1:20 π.μ., ο/η DK7FC <selberdenken@posteo.de> έγραψε:
>
> Hi Dimitris,
>
> Am 07.02.2019 22:59, schrieb Dimitrios Tsifakis:
>
> You must have a much larger antenna than me as in my current 140 m^2,
> 3-turn loop, I can reach a bit over a 1 uW with a 1 kW input!
>
> On which frequency? Didn't you tell about a 120m x 3m single turn loop?
>
>  There
> are many physical limitation that cannot be exceeded that will never
> allow me 200 uW with this antenna. Of course, that's just the start,
> once I get some success, I will be looking for larger antennas (and I
> do have some ideas which extend past my fence).
>
> One of the first steps could also be to place a receiver in the far field, a good receiver. You are working in Canberra, right? So you can place a RX there and make a webpage showing spectrograms?
> Ah BTW are you skilled with Linux or do you arlready know that you'll never give it a try?
>
>  You know the
> addiction!
>
>
> Hehe, yes!
> I already looked arround in your location. It is a QTH for dreamers! You know the history about the 'DREAMERS'? ;-)
> What is that stuff in QF44OX02XI ? Is it water? Or there in QF44OX01US ? Water, that is water! Horray!! There you could throw some wire into, your aluminium wire.
> Oh and here in QF44NW99XV  That's excellent! There is just a little effort and you will be able to leave a trace on Edgars RX, TXing with 200 uW.
> If you can lay a wire from here to there, see http://k7fry.com/grid/?qth=QF44OX01US&from=QF44NW99XV that's 1000m already and you can get a good conductivity. Try to find metallic plates, maybe 1 sqare metre. That could work fine. 1 km is not so much, you could even roll it up again after transmitting.
> It would be interesting to see how much current you can get at DC or at various frequencies up to 30 kHz.
>
> Anyway, my plan is to start at 29.999 kHz (the entrance to VLF!)
> first. My antenna works a lot better on that frequency. I will them
> move down in frequency. For the legal limit of 7.5 uW, what distance
> would you expect a QRSS10 signal to cover at 29.99 kHz? We'll find out
> this weekend but I can start taking bets today! :-)
>
>
> If you have a well working RX, sensitive antenna, both H field, the right position and 'no' nearby QRM sources, it think you can make 10 km. That's my guess, without doing calculations.
> If you run 50 uW on 17.47 kHz (Edgar is skilled on that frequency!) you will reach Edgar, if your loop points into his direction. If you can run just 500 mA into that 1 km long wire, on that frequency, you will be there!
> Do you have enough wire for the weekend? :-) I use that cheap CCA loudspeaker cable which has 0.75 mm2. A 100m ring (i.e. 2x 100m) costs about 13 EUR here, quite affordable.
>
> 73, Stefan
>
> 73, Dimitris VK2COW
>
>