Re: VLF: 8970 Hz transmissions, soon again here

[Roger Lapthorn <rogerlapthorn@gmail.com>]

Hi Stefan (and other VLF fans),

The last time I checked, G3XIZ was still awaiting the renewal of his 8.7-9.1kHz band NoV from OFCOM. Mine came through a few weeks ago, although I have yet to radiate other than pW powers with my experiments on TX being earth mode.

My VLF RX system is awaiting your next test Stefan, but please try to give me a few days warning of (weather permitting) activity so that I can dust off the kit and check all is working. It is some months since I have used to loop and preamp with SL on VLF.

By the way, do we know exactly WHAT Paul Nicolson does to detect such weak signals so well? Has anyone heard/read technical details of his super-sensitive and well engineered receiving systems?

73s
Roger G3XBM

2011/11/15 Stefan Schäfer <Stefan.Schaefer@iup.uni-heidelberg.de>

VLF,

Am 15.11.2011 17:03, schrieb DENNIS EASTERLING:

[...] I also have a mini-whip, but this has been extended for

VLF purposes. [...]

...which is good since soon there will be some activity again on 8970 Hz. If you like you can join in to the group of successful listeners on the 33 km band.

Yesterday i carried my TX coil to the fixed antenna here. Also the PA and variometer part of course. I do inted to use the fixed antenna.
I did some calculations about the radiation resistance and losses and power at maximum voltage (50 kV rms on the wire) and found that the ERP will be about 10 dB higher than expected, i.e. i could radiate something in the range of many 100 uW up to 1 mW or theoretically up to 2 mW. We will see and measure.

Paul Nicholsen reported about a very senistive receiver in USA that allows long time integration, i.e. not producing a spectrogram but integrating a given TX time into a single bin, like Paul usually does.
Here on the fixed antenna i could do night transmissions. 500W TX power key down for 24h is no problem (as long as there is no rain).

So i am optimistic and looking forward to some new work on the dreamers band!

Also i would be interested if there is (still) some interest in VLF in this group. For Paul, a endless straight "carrier" would be the optimium while a radio amateur may like to have some true ID and maybe a message to be read and displayed. What about the grabber runners and new prepared VLF receiving stations?

Probably i will start next week but may do some spontaneous tests before...

73, Stefan/DK7FC

PS: I would like to see other VLF transmitting stations as well. What about G3XIZ, DF6NM, OE3GHB, OE5ODL, OK2BVG, DJ8WX? We all could leave some common traces again in the excellent dark spectrogram backgrounds!

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