Message-ID: <4BA8B193.7020203@iup.uni-heidelberg.de>
Date: Tue, 23 Mar 2010 13:18:27 +0100
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: Re: DK7FC's 3rd VLF transmission
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Very nice! 0,8m*0,8m is really practicable and easy to built for 
everyone. Not expensive too... And our distance is 655km, well above the 
garden ;-) I do not even see a too big difference in S/N compared to 
Pauls signal (sure, the distance is 200km less)... So i am very 
confident that there will be some QSOs when further TX stns come up!

Jim, what about the effect of your band filter? Gives this a significant 
S/N improvement on 8,97? Can you show us 2 pics of an overview, say from 
0...20kHz, with and without the filter? Would be interesting!

What do you think about active E-field antennas? I think i will try such 
one the next time using my much liked BF862 and a simple band pass 
filter, just like in your preamp. I got the idea that i can watch my own 
signal receiving here in Heidelberg. Maybe i can even put up such a 
grabber... The distance from my hill to Heidelberg will be a good 50km 
so it is a moderate distance, a good starting point for testing E-field 
antennas...

BTW: The next time i will get my new "office antenna", here in the 7th 
floor of the building of the institute of environmental physics in 
Heidelberg. It will be a horizontal wire, abt 60m long and 25m up! And 
with a good earth! This will be a good antenna for LF :-) I plan to key 
the PA via a laser beam from the roof of my flat, just over the city ;-) 
Maybe going to infrared ;-) There, on this roof of the institute, i can 
arrange such a VLF antenna... Will see :-)

73, Stefan/DK7FC



Am 23.03.2010 11:34, schrieb James Moritz:
> Dear Stefan, LF Group,
>
> ...>Jim, M0BMU is the 2nd best DX distance! Jim, can you describe you 
> RX detailed, pse. Or have i forgotten an older mail? What was the new 
> /p QTH? And what are your observations about the change of QRM?...
>
> I was very pleased to be able to see a signal at my first serious 
> attempt... I have attached the current schematic of the preamp/filter 
> used on Sunday.
>
> The receive site was about 5km east of my normal QTH, I think the 
> locator is IO91WR, but I'll check the exact coordinates.
>
> The /P site had considerably less man-made QRM than my home QTH. The 
> odd 31.5Hz/5Hz spectral lines seen at home were completely absent, but 
> considerable 50Hz harmonics were present, due to nearby overhead power 
> lines. But these did not really cause a problem on Sunday, and I think 
> a noise-cancelling antenna arrangement would be feasible in a future 
> test.
>
> ...>BTW: We could philosophize what is the definition for "DX" on LF 
> and VLF! Or is there a standard definition? In my ham licence i 
> learned that on HF, DX is outside the own continent and on VHF it is 
> above 300km. So, what is it for LF? And what for VLF (by hams)?...
>
> I think on HF nowadays, DX just means stations with unusual callsigns. 
> On VLF, it probably should mean distances beyond those normally 
> achieved - which means just about any distance at all!
>
> Cheers, Jim Moritz
> 73 de M0BMU