Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]

Re: VLF: DF6NM kite activity June 19

To: [email protected]
Subject: Re: VLF: DF6NM kite activity June 19
From: Stefan Schäfer <[email protected]>
Date: Wed, 22 Jun 2011 14:22:44 +0200
In-reply-to: <DB1AF20F204E4F89964218DC6B852003@White>
References: <[email protected]> <9B4318767B6849FFB89F8294D336ACEC@White> <[email protected]> <[email protected]> <DB1AF20F204E4F89964218DC6B852003@White>
Reply-to: [email protected]
Sender: [email protected]
User-agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3
Hello Markus, VLF,

Am 21.06.2011 00:00, schrieb Markus Vester:
Total resistance of the antenna circuit was around 280 ohms (including 140 ohms for the coil). This is about half of that when I used the same kite antenna in Bamberg with only a few short ground pegs.
Excellent! I wish to have such a low earth resistance. Also 140 Ohms for the coil is very good. Mine has 185 Ohm for 190 mH but therefore no HV problems so far, even at 1.7 A antenna current (in the 10th exp during the CW transmissions)
 
BTW all seven buckets connected to 900 pF resonate at about 4.6 kHz - Stefan, how about a 65 km band ;-)
65 km sounds good! ;-) Would be the lowest frequency ever. You should be the first one to transmit there. If you early announce such a test i would run a "DFCW-2400" window on 4600 Hz.
But as we planned, we should think about coupling our coils in a common meeting, maybe on my 12th experiment. You seem to have 1.3 H. Coupling with my 550 mH coil may achieve 2 H. If we would use my 300m vertical which has about 1650 pF we could transmit on 2.77 kHz, ULF, the 108 km band! :-) What do you think? We could generate about 7 mW ERP!
On my own grabber, I attempted to compare signal levels from DK7FC (-71 dB, 180 km) and myself (-43 dB, 4.5 km). Correcting this difference (28 dB) by the EMRP ratio (26 mW / 1.2 mW = 13 dB), distance ratio (1/r = 32 dB) plus an additional nearfield correction (1/r³ instead of 1/r from 4.5 to 5.3 km = 3 dB), we find that Stefan was 28+13-35 dB = 6 dB weaker than we would expect by pure groundwave. This corresponds very well to the earlier experience that there is a midday skywave cancellation effect for about 200 km.
Interesting!

73, Stefan/DK7FC

<Prev in Thread] Current Thread [Next in Thread>