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Re: LF: RE: Summer games / EARTH ANTENNAS

To: [email protected]
Subject: Re: LF: RE: Summer games / EARTH ANTENNAS
From: John Rabson <[email protected]>
Date: Wed, 4 Jul 2018 08:38:05 +0200
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I found this in the files:

"From G4JNT: 1mW (0dBm)  of EIRP on 73kHz got 393km from me to G3PLX way back in 1996.  That was using slow CW (long before someone coined the name QRSSS for it) with a dot period of 40 seconds.”

Andy: did you use an earth current system, or was that a G0 (now SK)?

John F5VLF

On 3 Jul 2018, at 23:41, DK7FC <[email protected]> wrote:

Hi Marcin, 

Keep us informed about your experiments. For you it may be more useful to try kite antennas! Give it a try, it is very easy a nd exciting!

For power generation i used such a cheap generator: https://www.amazon.de/dp/B000QD1EHY/
For 500W it was running quite well, until i made the mistake to mix the oil and fuel BEFORE filling it into the tank. 
It is cheap and not very high quality but it is possible to carry it on your own, which was essential for my kite experiments.
If you want quality, then by a Honda generator...

73, Stefan

Am 03.07.2018 21:26, schrieb Marcin:
Hello Stefan!
From my experience, erth dipole work best on 630m. Unfortunately, in the north of Poland, the soil is well or very conductive. In rocky ground you can get much better results. I am waiting for autumn to continue my experiments. 
I am looking for a power generator for power supply in the field. Can anyone recommend something?
 
73! Marcin SQ2BXI
 
From: [email protected] <[email protected]> On Behalf Of DK7FC
Sent: Tuesday, July 3, 2018 7:50 PM
To: [email protected]
Subject: LF: Summer games / EARTH ANTENNAS
 
Hi Joe, VLF, 

You seem to like to 'play' on the very low frequencies during the sunny days :-) 

Same here! My YL bought a house in JN39XI and we are spending almost each weekend there in the peaceful silence. The forest is really great! I guess you know that, as a Canadian. 
Now i'm planning to receive some signals in JN39XI07 .  BTW a most useful distance for analysing my own signals from Heidelberg (about 55 km QRB).
Oh and i think about playing with earth antennas again, you know! 

BTW did someone (of the group) ever tried to build a full size dipole for 137 kHz? I mean for transmitting! On a stony mountain/hill it could be better than expected. With a Raspi + GPS module one could build up a simple WSPR beacon and a ICL7667, which can be driven by the 3.3 V GPIO output voltage could make a simple and effective 5W PA running at 12V.
The wire just needs to be 1000m long or so. In a low frequented forest it could lay there for some days...

I remeber experimenting with a full size dipole on 630m in 2012, when the band was quite young. It worked well although the antenna was just 4m above the ground and the soil conductivity was not ideal (medium conductivity). A few CW QSOs were done out of a 7 Ah gel battery and just 50W or so, in July!

And what about VLF and ULF using earth antennas? I remember making 45 km distance on 8.97 kHz from the 700m long wire antenna, grounded at each end (250W RF power if i remember correctly). That was about 15 dB in 3.8 mHz. But what would be possible on lower frequencies if the far end of the wire is well grounded?

Time to fill that summer hole (activity)!

73, Stefan


Am 03.07.2018 14:03, schrieb [email protected]:
This was the first time SAQ was heard here using a mobile RX.  It was in a quiet location, a km  from mains lines and other RF pollution.  SAQ became quite weak when 
the RX was in the forest however.  The trees must be good conductors at VLF. 

Is the low-power miniwhip mentioned below the same new one designed with 
help from G4COL with a J310, Rs= 47-270 ohm and the FT-37-43 xfmr?  I'd like 
to try that at VLF. 

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