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LF: [500 kHz] DI2BO has 1.7 mW ERP!

To: <[email protected]>
Subject: LF: [500 kHz] DI2BO has 1.7 mW ERP!
From: "Holger 'Geri', DK8KW" <[email protected]>
Date: Sun, 15 Apr 2007 02:26:56 +0200
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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 scale)

e.r.p. = e.i.r.p. ? 2.2 dB (logarithmic scale)


Here are the results, measured at three different locations:

1,02 km distnce: 1,63 mW ERP
1,57 km distance: 1,85 mW ERP   
2,01 km distance: 1,56 mW ERP

The average of these three measurementsis around 1,7 mW ERP!

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.

Best 73

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 -----
From: "Dave Sergeant" <[email protected]>
Sent: Saturday, April 14, 2007 7:39 AM
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 wrong!).
> 73 Dave G3YMC

Attachment: Field Strength Measurement 505 kHz.xls
Description: MS-Excel spreadsheet

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