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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