Hi Marco and Stefan,
Competing with NWC Harold Holt would be insanity, regardless of the
regulation, that's a frequency to certainly avoid :-)
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! 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). You know the
addiction!
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! :-)
73, Dimitris VK2COW
Στις Πέμ, 7 Φεβ 2019 στις 7:21 μ.μ., ο/η DK7FC <[email protected]> έγραψε:
>
> Hi Dimitris,
>
> Interesting, theat LIPD class. So you could even try higher frequencies
> than 8.3 kHz. Here we are not allowed to transmit above 8.3 kHz.
> However, i have a special licence to transmit arround 17.47 kHz, with 5
> mW ERP. On that frequency i have been received by Edgar and we
> transferred a 3 character message successfully some months ago. A 5
> character message almost decoded but in the end we failed.
>
> Why is there is a gap between 19.95...20.05 kHz? No idea but i would
> have expected a gap arround 19.8 kHz, because of NWC
> https://en.wikipedia.org/wiki/Naval_Communication_Station_Harold_E._Holt
>
> 200 uW on 8.27 kHz is a good signal but with the space you have, you
> could get up to 20 dB more so it is a pity. But anyway, many people
> could detect you at 200 uW, at least in a radius a few 1000 km.
>
> 73, Stefan
>
>
>
> Am 07.02.2019 01:52, schrieb Dimitrios Tsifakis:
> > Ciao Marco,
> >
> > yes, the grass is indeed greener on the other side but I am not
> > complaining about that! If there is no time now, perhaps there will be
> > later! More things to do when I retire, there is nothing worse that
> > people that retire and do nothing...By the way I do look at the legal
> > aspects. We are lucky in Australia our local spectrum authority has
> > made it clear how much we can radiate in the various parts of the
> > spectrum. There is a class licence known as LIPD (low interference
> > potential devices) which tell you how many microwatts you can radiate
> > on VLF and below and it is very generous I think. Here is what we are
> > allowed to do:
> >
> > 0 kHz to 14 kHz 200 uW EIRP
> > 14 kHz to 19.95 kHz 50 uW EIRP
> > 20.05 kHz to 70 kHz 7.5 uW EIRP
> >
> > (note I cannot transmit between 19.95 kHz and 20.05 kHz, not sure why
> > there is that gap)
> >
> > I can live with that!
> >
> > 73, Dimitris VK2COW
> >
> >
> > Στις Πέμ, 7 Φεβ 2019 στις 5:46 π.μ., ο/η [email protected]
> > <[email protected]> έγραψε:
> >
> >> Hi Stefan, Dimitris,
> >>
> >> room is sure a thing that is not missing in VK :-)
> >> I remember a vacation I had there some years ago ... a lot of km between
> >> "adiacent places".. so ideal place for LF, VLF and even close to DC
> >> frequencies!
> >> During my travel, just for fate, I drove close to Holt Navy Base sporting
> >> an antenna just a bit larger than your loop ;-)
> >> Anyway you know the grass of the neighbor is more green...
> >> Dimitris has room but not a lot of time..
> >> I have more time but less room
> >> somebody else has room and time but no money...
> >> What an hard life!
> >> But... we all have fun!
> >>
> >> 73 Marco IK1HSS
> >>
> >> P.S. who's looking the legal aspects?? ;-)
> >>
> >> ----Messaggio originale----
> >> Da: [email protected]
> >> Data: 5-feb-2019 23.40
> >> A:<[email protected]>
> >> Ogg: Re: VLF: in VK?
> >>
> >> Dimitris,
> >>
> >> Am 05.02.2019 21:14, schrieb Dimitrios Tsifakis:
> >>
> >> 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.
> >>
> >> Wow, i'm envious and happy that you have such possibilities!!!!!!!!!!!!!!
> >> Not at this time, ok. I would suggest to start in small steps anyway, then
> >> you can be happy about many improvements, not just a single big one :-)
> >> I often imagine to live in Canada or Australia and do such experiments
> >> exactly!
> >>
> >> The reference loop
> >> is from the shed, about 100 metres south of the house, to the tractor
> >> shed.
> >>
> >> 100m is very close, the far field begins at about 5.7 km distance at 8.27
> >> kHz. A RX in that distance is only useful to check and observe the signal
> >> stability and compare levels. A feedback monitor like my tree which is 3.5
> >> km distant from my INV-L antenna in the city. From my ground loop antenna
> >> in JN39WI it is 57.6 km distant, which is already an interesting distance
> >> and can be challenging below 3 kHz.
> >>
> >> I have mains in the shed and I also have a 200 W audio linear
> >> amplifier to get things started.
> >>
> >> Excellent, just excellent! Your signal could be the stongest of the radio
> >> amateurs! 200W is just fine for the first steps. But be careful with those
> >> audio amplifiers, they do not seem to like to much reactive power.
> >> For tuning the antenna you will only need a capacitor in series. For my
> >> portable VLF system i built a current transformer to produce a small
> >> voltage that goes to the soundcard. Then, using SpecLab, i can calculate
> >> the antenna current directly and even keep the phase of the current
> >> stable, even if there should be a soundcard glitch. For the signal
> >> generation i also use SpecLab and a cheap GPS module. It all works very
> >> reliable, there were no problems so far.
> >> With a house at one of the ends of the antenna you are in a very
> >> comfortable situation! You may already have a ground system there, so the
> >> effort is at one end only.
> >>
> >> 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.
> >>
> >> Yes, this is a very good distance to observe your own signal. If you have
> >> internet access there and can leave a small PC/notebook/tablet ... then
> >> you could build up a webpage and run a grabber from there like i do from
> >> my tree (still under maintenance). That would be ideal and it just feels
> >> good to see the own signal very clearly on a real RX in a short distance.
> >> You are then independent.
> >>
> >>
> >> 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!
> >>
> >>
> >> Oh yes! Fortunately there are a few arround here. These days this is
> >> (sorted by distance to my VLF loop): DK7FC, DF6NM, DL0AO, DL4YHF, IK1QFK,
> >> Paul Nicholson, SQ5BPF and RN3AUS. Oh and W1VD, K3SIW and Edgar J.T. This
> >> is about the complete VLF group worldwide, at least those who prooved to
> >> detect narrow band (sub mHz) signals close to the limits, in the last 3
> >> years until now.
> >>
> >> 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.
> >>
> >> Yes, you are right. I had the same thought sometimes. Certainly there are
> >> many amateurs who would feel like having a new life when starting at VLF,
> >> It is an unknown spectrum for 99.9 % of the amateurs. Actually it is not
> >> even amateur radio because it is not a spectrum allocated to amateur
> >> radio. So everyone could operate there.
> >> But there is a risk, you know. There are those people who do not simply
> >> start to transmit/receive there and feel good. There are those who prefer
> >> to ask if this is legal at all. And then they ask here and there, as long
> >> as they find someone who triggers their fears and phobs, and then they do
> >> nothing at all! Beware of such people, they are contaminating your free
> >> mind. Concentrate on ideas and wishes, like for example detecting your own
> >> signal in Canberra. And then the question "Will this also work on lower
> >> frequencies", for example.
> >> When writing an article in a radio magazine, what will be the result? Will
> >> it actually lead to more active people on the band, who transmit and/or
> >> receive for a longer time, say at least 5 to 10 years? Or will it rise a
> >> short interest only, dominated by people telling it is not legal and so
> >> on... I'm not sure about that. It could be even better to stay in a
> >> smaller group who can do what it wants instead causing a decision /
> >> regulation by an 'authority'.
> >>
> >> You are clearly not lazy having achieved so
> >> much on MF and below :-)
> >>
> >>
> >> Thanks but i'm lazy into a certain spectrum. On the other side, there are
> >> people who write many articles over the years but it is simply impossible
> >> for them to even imagine to wind a coil which has more than 100 turns.
> >> Maybe it is good that there is a variety of people, the article writers
> >> and the coil winders and something inbetween :-) Oh, and the programmers!
> >> Very important. Without Wolfgang and Paul and Markus we would do nothing
> >> at all!
> >> Oh BTW maybe i'll transmit on my loop again the next weekend. I can't
> >> await it, it is more than 2 weeks ago, a very long time!!
> >>
> >> I have played with ground loops before and had some good results in
> >> LF.
> >>
> >> On VLF it should work much better (relative to a vertical E field
> >> antenna). The idea is that the current runs back in a deep layer (skin
> >> depth), depending on the ground conductivity. So it should work better on
> >> poor conducting ground.
> >>
> >> 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.
> >>
> >>
> >> RR, good luck and fun with the new challenges.
> >> Looking forward to your next steps and reports.
> >>
> >> 73, Stefan
> >>
> >>
> >>
> >> 73, Dimitris VK2COW
> >>
> >>
> >>
> >>
> >>
> >
>
|
