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Re: LF: Advanced notice of VLF transmission tests

To: [email protected]
Subject: Re: LF: Advanced notice of VLF transmission tests
From: Stefan Schäfer <[email protected]>
Date: Sat, 04 Jun 2011 22:14:45 +0200
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Hello Roger,

Am 04.06.2011 18:49, schrieb Roger Lapthorn:
Stefan, DK7FC, when are you intending to do some tests from your fixed VLF station please? 17dB weaker may be copyable here in 424uHz if continuous carrier. I am really looking forward to this.

Well, some infos about what i plan in then next time and when.
I'll take the TX coil to the antenna in Heidelberg probably next week. Then i will arrange the station and do some first tests to find the resonance frequency. This may be probably a bit above 9 kHz, maybe 10 kHz. Then i have to add some copper rods on HV near a grounded plate on the wall to get some more C. If the signals and ground losses are reasonable good, i shall replace the additional C by some addional L (probably such a bucket as Markus has) to get a better ERP.

I assume the ERP will be about 1 mW. I assume lower earth losses. My TX power is not limited any more! The limit will be the HV withstand voltage of the coil, i estimate about 50 kV rms which is no problem for the antenna, neither for the wire (which is 10mm diameter) nor the insulators (36 kV rms 24/7 under rain or snow). Depending on the earth losses, this limits the maximum power to be applied. But the PA can produce 1...2 kW without problems i think. So i will run as much power as possible.

If all works well and i can find a place in the institute where i can place the coil for a longer time, i'll be QRV regularly, transmitting DFCW-600 to 60000. I will announce that here before, as usual. So, no need to worry to miss anything. I will inform you after the first tests.

I expect to be visible in a radius of 800 km in DFCW-600 on a quiet day in a quiet location, hopefully ;-)

73, Stefan/DK7FC






Thanks Chris G3XIZ for today's test and for the advanced notice. Have a good holiday.

73s
Roger G3XBM

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