Hello Dave and also all the others observing
DI2BO (and the other beacons on 500 kHz),
Today the weather was fine and I took the chance
to drive around and do some ERP field-measurements.
Technically I used the MV-62 Measurement Receiver
that reads the signal strength in dBu. As an antenna I used a simple open loop
with 1 m diameter. To measure the distance to DI2BO I used a Garmin XL-45
handheld GPS system.
Mathematically I used a set of formulas that
Markus, DF6NM helped me to develop (thanks, Markus!). These formuals
come up with the EIRP, the effective radiated power above an isotropic
radiator. For those interested in the forumas, please find attached a samle
XLS file. For techical details, please ask Markus, he is much of an expert in
this than I am ;-)
Next I used some ITU definitions to convert EIRP
to ERP (DEFINITIONS OF RADIATION IN LF, MF AND HF BROADCASTING
BANDS), in which is stated:
The value of the e.r.p. is related to the
e.i.r.p. by the _expression_:
e.r.p. = 0.61 e.i.r.p. (linear
e.r.p. = e.i.r.p. ? 2.2 dB (logarithmic
Here are the results, measured at three
1,02 km distnce: 1,63 mW ERP
distance: 1,85 mW ERP
2,01 km distance: 1,56 mW
The average of these three measurementsis around 1,7 mW
This makes alle your observations even
more astonishing. I would not have guessed that a 500 kHz at that ERP level
signal would span that distance, espeically audiably. With this low power level it also shows the important efect
of QSB from variations in the ionosphere.
Until further notice DI2BO will transmit
on 505,015 kHz with 1,7 Watt ERP day and night (24/7), so please keep watching
and observing and keep thos reports coming in.
Geri, DK8KW / DI2BO
DI2BO: antenna system is a "long wire",
simply about 8 m wire vertically up to a 10m mast, then another 8m wite
horizontally to the roof of my house. OOutpur power is around 10 Watt (DEBEG
7121 on "reduced power").
----- Original Message -----
Sent: Saturday, April 14, 2007 7:39
Subject: Re: LF: DI2BO
> Just to report that when I came back into the shack at 2100z DI2BO
> was clearly audible to my ears, peaking 439 here in Bracknell IO91PJ.
> I was rather amused to clearly hear it send its CW id 'DI2AG' !!
> GI4DPE was also heard beaconing in normal CW around 501.15.
> This maybe highlights the problem with QRSS on 500kHz. I have already
> noted slow and very deep QSB on many signals. While I was watching
> DI2BO on Argo last night I found that it would pop above my noise
> level for only 1 out of 3 or 4 callsign sequences and between that
> there was little more than the odd dot visible. When it appeared most
> but never all of a complete call was visible and it clearly peaked
> quite strong for just a few characters. If I had not known what the
> call was I would have had to listen a long time to postively identify
> it. However when it sent its ID on normal CW when listening without
> Argo later that was copyable in its entirety (admittedly
> 73 Dave G3YMC