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From: "Dave Sergeant" <dave@davesergeant.com>
To: rsgb_lf_group@blacksheep.org
Date: Sun, 15 Apr 2007 13:29:00 +0100
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Subject: Re: LF: [500 kHz] DI2BO has 1.7 mW ERP!
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Thanks for the update Geri, it perhaps shows that all the magic 
formulas we are using to estimate our ERP are somewhat wide of the 
mark. It also gives me some comfort that my vertical, estimated to 
have 1% efficiency on a good day, will put out something others can 
copy. When I have built the transmitter of course, at least I now 
have my UK NOV.

I may have been confusing DJ2BO with DI2AG the other night and was 
actually listening to AG audible above the noise. Last night SM6BHZ 
was on, he is incredibly strong here, peaking 599 on the S meter. So 
I was unable to repeat the test to see if I could hear either by ear 
as BHZ was a little too close for my 400Hz filter. But will do so 
tonight or tomorrow.

Must dash.
73 Dave G3YMC

On 15 Apr 2007 at 2:26, Holger 'Geri', DK8KW wrote:

> 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" <dave@davesergeant.com>
> To: <rsgb_lf_group@blacksheep.org>
> 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
> > 
> > 
> > 
> > http://www.davesergeant.com
> > 
> > 


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