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LF: Re: Activity from Deutschlandfunk Antenna

To: [email protected], [email protected], [email protected], "Reg Edwards" <[email protected]>
Subject: LF: Re: Activity from Deutschlandfunk Antenna
From: "James Moritz" <[email protected]>
Date: Wed, 24 Jul 2002 16:18:18 +0100
In-reply-to: <[email protected]>
Reply-to: [email protected]
Sender: <[email protected]>
Dear Walter, Markus and friends, Reg, LF Group,

Very pleased to work DJ2LF/P this morning, both on 136k and cross-band 40m/136k. I was running the usual 1200W + inverted L at 9m on LF, plus an IC718 with a dipole on 40m.Their signal was 579 even when running 1W TX power, and was obviously very strong when running the full 200W.

I also measured the field strength using a 4m^2 single turn loop antenna with an SPM-19 selective level meter. Running full power, DJ2LF/P measured between 35dBuV/m and 36.5dBuV/m, about 60uV/m on average, in IO91VR. At a distance of 705km, this works out to 36W ERP over perfect, flat ground - using G4FGQ's grndwav3 program, and assuming "type 4" ground (this seemed the best compromise of the several choices available), ground & diffraction losses account for an additional 6.7dB, making the actual ERP 167W - this is within 0.5dB of the figure obtained by PA0SE.

If my ERP is about 400mW, turning the above calculations around gives my field strength in JN49ON as about 3uV/m, so reception there is actually not too bad.

For comparison, DCF39 on the same antenna measures as 57dBuV/m, at a distance of 828km, an ERP over perfect ground of 7.0kW. And assuming the same ground type as before, ground loss is 9dB, giving an actual ERP of 55kW. I believe the usual figure quoted is 40kW, so agreeing within 1.5dB.

I calculated the antenna calibration factor simply from the area of the loop and the impedance levels, so as a further cross-check I also measured DCF39 using my ferrite rod measuring antenna, previously calibrated using a Helmholz coil set-up. This measured DCF 39 at 56.4dBuV/m, so only 0.6dB difference between two completely different measuring antennas, calibrated in different ways, which inspires a good degree of confidence.

So thanks to all in Donnebach; It looks like the DLF mast, our measurements, and Reg's software are all working well today. I look forward to hearing how things were at the TX end!

Cheers, Jim Moritz
73 de M0BMU



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