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Re: LF:QRV Tonight

from [MarkusVester] [Permanent Link][Original]
To: [email protected]
Subject: Re: LF:QRV Tonight
From: [email protected]
Date: Fri, 26 Mar 2004 09:52:36 EST
Reply-to: [email protected]
Sender: [email protected]
Dear Joe and John,

this morning's captures showed VO1NA's signal around 4:30, clear but blurred because my settings (21mHz x 15s /pixel) were way too slow. Above it, there are some traces in the noise which could well be from WD2XES; at least the frequencies and direction (bright blue) seem to match. The Loran line near the top is 137778.370 from Sylt. I also looked around 137789.5, but saw nothing there.

Based on the descriptions of your antenna systems, I have tried to compare radiated powers of the two stations. John's loop (A = 50'x30' =279m^2 above conducting ground) should have a radiation resistance of
Rr = 16/3 * pi^3 * 377ohm * (A / lambda^2)^2 = 0.21 milliohm.
Fed with 11.5 A, it would radiate
EMRP = Rs * I^2 = 27.6mW (or EDRP = 50mW)
towards the direction of maximum gain... quite amazing to see that in Europe.

On the other hand, Joe's 100m vertical would ideally have an effective height of 50m. Assuming some reduction for slantness and E-field shunting by trees, h_eff=30m is probably more realistic. Then we would get
Rr = 4/3 * pi * 377ohm * (h_eff/lambda)^2 = 294 milliohm
and, with 1.6 A,
EMRP = 750mW,
about 14 dB stronger than WD2XES. In addition to that, of course, John's path is significantly longer.

Thanks for transmitting, and good luck to all

Markus
DF6NM in JN59NK


WD2XES will be on 137.7775 sending "XES" in DFCW60 (0.2 Hz shift), starting
at 2330. Power will be around 100 watts to a loop, so the customary Divine
intervention will be required.

John Andrews, W1TAG/WD2XES

>In view of Alan's favourable evaluation of the conditions,
>I will be transmitting QRSS20 on the hour starting at 2200
>and watching on the half hour at QRSS30 centred on 135.922
>kHz.  TX 137.777 kHz 100 watts 1.6 amps to the single 100 metre
>wire aerial.
>Regards
>Joe VO1NA




JPEG image

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