Hello group, dear Stefan!
I will participate and change my grabber settings Thursday evening.
73
OE3GHB
Gerhard
Am Dienstag, den 16.11.2010, 21:11 +0100 schrieb Stefan Schäfer:
> Hello Markus, VLF,
>
> Oh, indeed. Well, the earth antenna is a really broad band antenna, as
> seen. But the signal level at 134 kHz is rather small, when regarding
> distance and frequency ;-)
> Anyway funny ;-)
>
> Ok, there seems to be GPS in the forest, even when the GPS antenna is
> behind the car window. The TX power was arround 100W, the last 20
> minutes even at about 200W. Distance to my grabber is 5 km. The
> antenna current was 440 mA at 100W, so the losses have been arround
> 520 Ohm, relatively low. The ground was wet.
> The output transformer remained cold and the SMPS as well, the PA
> anyway. But i noted that the DC plug for my netbook is the wrong one
> so i have to exchange this, otherwise the netbook would shut down
> after some hours... Thus, the test was useful :-)
>
> Ah, BTW, it was on 8970.00000, not on .00500
>
> So, i hope i can do the 24 h transmission starting Thursday arround 16
> UTC at 8970.00500 Hz, running 100W. Here i have attached a new usr
> file for this transmission (just a little change in the time stamp
> display), for those who want to participiate and need a usr file :-)
>
> Well, 35 dB S/N, i just like it, even if its just 5 km :-)
>
> 73, Stefan/DK7FC
>
>
>
>
>
> Am 16.11.2010 18:53, schrieb Markus Vester:
> > Hi Stefan,
> >
> > since 16:54, you are painting a strong 8970 Hz trace on your own VLF
> > grabber, about -69dB (35dB SNR) in the 4.5 mHz window.
> > Interestingly, there is also a 15th harmonic at 134.55 kHz, which
> > appears on your wideband LF grabber at - 80dB (20 dB SNR).
> >
> > Nothing seen on the 0.95 mHz VLF grabber in Nuernberg yet, which may
> > of course be due to me being near the null of your N-S oriented
> > earth antenna.
> >
> > Good luck,
> > Markus
> >
> >
> > -----Ursprüngliche Mitteilung-----
> > Von: Stefan Schäfer <[email protected]>
> > An: [email protected]
> > Cc: Paul <[email protected]>
> > Verschickt: Di., 16. Nov. 2010, 14:50
> > Thema: Re: VLF: Long time transmission on earth antenna
> >
> > Dear VLF,
> >
> > I will do some pre-tests today on the earth antenna (testing if GPS
> > can be received in the forest and if the output transformer becomes
> > warm in steady state when running 100 W RF key-down).
> >
> > Before i will do a (new) short test on 1970 Hz. A loop antenna was
> > built to receive on 1970 Hz. It has still no preamp but is directly
> > fed into the soundcard, anyway... The antenna is now nulling out the
> > strong QRM of the tram line near the institute and i hope for a
> > better S/N.
> >
> > After that about one hour or so on 8970.00500 Hz.
> >
> > Starting time is in about 90 minutes.
> >
> > If someone wants spontaneous to take part, you are invited. The 24 h
> > transmission will then come hopefully in a few days, maybe
> > wednesday/thursday...
> >
> >
> > 73, Stefan/DK7FC
> >
> > PS: Again note that this is a very weak signal test and cannot be
> > compared with a kite antenna transmission. So do not wonder if the
> > signal doesn't appear at 25 dB S/N in 4.5 mHz ;-)
> >
|
