Re: LF: EbNaut test at 8270.00332 from JN64bw

[Riccardo Zoli <riccardozoli80@gmail.com>]

Hi Paul, Stefan, Jacek, VLF

I'm on air with continuous carrier at the same QRG until 21:30 UTC, then:

f = 8270.00332 Hz
Start time: 21:30:00 UTC
Symbol period: 30 s
Characters: 3 (repeated)
CRC bits: 24
Coding 16K21A
Duration: 8h,16min
Antenna current: 390 mA

Thanks Paul for your explanation.

It's all true! I thought it was so hard to do. But it wasn't! :-)

In my view, VLF are probably the most wonderful experience in my ham activity.

73 de Riccardo IW4DXW

Il 14/Dic/2017 12:47, "DK7FC" <selberdenken@posteo.de> ha scritto:

Am 14.12.2017 09:41, schrieb Paul Nicholson:

Added to the growing list of amateur achievements
at VLF

 http://abelian.org/vlf/amateur-radio/

It has been a very successful season so far.  I hope this
encourages more people to have a go at VLF, we need more
transmitters and receivers.

Indeed!
Recently i thought "VLF is the new LF".
>From the view of a HF amateur, LF is complex because of the large coils, the high voltages, the sepcial narrow band modes, the genaration of stable frequencies, the few number of active stations... Oh and it is sooo deep! Actually it can't work. Oh, and why do these crazy OMs use such low frequencies at all? The 20m band is so much easier ("Youuure 5ee9e", "CQ DX"...)...
VLF is just another step in this direction. The coils are larger, the voltages higher, the ERP lower, the frequency must be even more stable, the modes are even more narrow...
AND, not to forget, like HF->LF, LF->VLF is a few orders of magnitude more fascinating, exciting, exceptional!
I can see only positive tendencies, the lower it goes :-)

Perhaps the perception is that it is difficult?  Surely not.
Don't believe all those stories you hear about how hard it is
to radiate, or how difficult it is to find a location to
receive from!

Let's see -

- Low cost. You don't need expensive SDRs or test equipment.
  Your PC soundcard is signal generator, spectrum analyser,
  and SDR, all in one.  Transmitter is just an audio amplifier,
  even a low quality one.  The most expensive thing you'll buy
  is a load of wire for a loading coil.

- GPS timing?  £18 quid for a NEO-7 module and you know your
  frequency to the micro Hertz.  Buy two, you'll use them!

- Easy to build.  Just audio frequency signals, nothing critical
  about layout.   VLF is great for the homebrew enthusiast.

Indeed!!

- You don't need a huge ERP.  10uW and you're on the air.  Your
  LF antenna will probably do better than you think at VLF.

Uuuh but 10 uW is not so easy. The critical thing is the voltage, not the power. Capacity is needed, and radiation resistance of course.

- UK Notice of Variation?  No problem, a simple application form,
  and if enough apply, maybe the regulators will make that easier.

- Where else can you operate at the cutting edge with such
  simple equipment?

In case you thing my location here is specially good, it certainly
isn't.  The mains here at the top of the Calder Valley is very
rough, terrible sidebands.  All the properties around here get
their power by overhead lines at 12kV and one of the two 33kV
lines feeding Todmorden is only a km away.  The nearest 12kV
line is just 120m from the E-field antenna. 140mV RMS of 50Hz
on the E-field probe and a lot of harmonics.  Reception here is
bad!   You can probably do better in the suburbs.

How many times per century does amateur radio find a green field
to explore?

Currently, about once per week! :-)

  Not just a new band but a whole new frequency range.

Don't miss out on this one!

Exactly!
And the lower we go, the more it makes sense to think in wavelength rather tahn in frequency. Because otherwise a QSY from 2970 Hz to 2470 Hz means a difference of just 500 Hz, which is not much. But it is a difference in wavelength of  20000 m!

73, Stefan

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Paul Nicholson
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