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Re: VLF: Earth antenna transmissions on a guide rail?!?? NOW on the air

To: [email protected]
Subject: Re: VLF: Earth antenna transmissions on a guide rail?!?? NOW on the air...
From: Roman <[email protected]>
Date: Sun, 29 Jul 2018 14:59:37 +0300
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Hi Stefan!

Whats you TX? Ebnaut or carier?
Wait an other results.


> Hi Roman,
> Here are two spectrum peaks from 8270 Hz and 5170 Hz. I integrated the
> complete transmission time into one bin. I also produced a wav file from
> the recorded data (already resampled, mixed, filtered, blanked) and
> postprocess this into SpecLab now, so we get a usual spectrogram
> demonstrating that there was no trace before and after the transmission
> on that frequency. The file starts 2 hours earlier and ends 2 hours later...
> More tomorrow...
> 73, Stefan
> Am 28.07.2018 15:54, schrieb Roman:
>> Congrats, Stefan!
>> Pse inform us with screens as possible!
>> 73!
>> Roman
>>> And another update: The 5170 Hz carrier was running from 10:13...11:19
>>> UTC. The current was constant at about 555 mA.
>>> Now my last transmission for today is on 2970.005 Hz, running 590 mA,
>>> on air since 11:22 UTC, running for at least 1 hour...
>>> 73, Stefan
>>> Am 28.07.2018 12:50, schrieb DK7FC:
>>>> Update: Since 10:13 UTC i'm TXing on 5170 Hz. The antenna current is
>>>> 556 mA and the phase looks a bit less inductive but still inductive.
>>>> Despite beeing in the center of the Pfälzer Wald, i have mobile
>>>> internet access and so i reached my Linux PC recording the VLF stream
>>>> (both loop antennas). Using vlfrx-tools i managed to produce a spectrum
>>>> peak of 17 dB SNR after just 30 minutes!!!! (More later) So it is
>>>> possible with this ground loop TX antenna to transmit on 5170 Hz and
>>>> beeing detected in about 55 km distance! :-) These are two new
>>>> records for the TX earth antenna league :-)
>>>> I'm going to continue transmitting on 5170.000 Hz until 11:13 UTC, then
>>>> i'll do QSY to 2970.005 Hz which simply means i change the frequency in
>>>> SpecLabs signal generator driving my PA! :-)
>>>> 73, Stefan
>>>> Am 28.07.2018 11:43, schrieb DK7FC:
>>>>> Hi VLF,
>>>>> I'm sitting in my car while writing this email. I'm in JN39WI96GX and i
>>>>> transmit on 8270.000 Hz with a GPS locked signal generator into an
>>>>> about 450 m long earth antenna using two guide rails as the earth
>>>>> electrodes on both ends. On each end there are 16 (18) massive T-T
>>>>> poles holding the guide rail, providing a super good earth coupling. I
>>>>> measured that they are connected to each other.
>>>>> The transmitter is on the air since 9:08 UTC running 550 mA with just
>>>>> 75 W DC inout power into my hand warm lossy linear mode VLF PA!
>>>>> I'm amazed about the low losses! At DC i got 447 mA at 50.9 V. The wire
>>>>> is 0.4 mm diameter so it has 63 Ohm. That means the ground loss is just
>>>>> 50 Ohm !!!! Amazing! And i have no efforts to build up a ground
>>>>> connection here, i just need to connect the wire. Since the wire losses
>>>>> are higher than the ground losses, i can get maybe 2 dB more signal
>>>>> when buying some better wire. I already found a source that offers 0.75
>>>>> mm^2 100 m loudspeaker cable (i.e. 200m wire)for just 13 EUR....
>>>>> BTW i even have an ugly old scope here which is battery powered. I can
>>>>> see that the phase of voltage and current is slightly inductive, maybe
>>>>> 30 deg or so. So i could series resonate the antenna with some C. This
>>>>> is for the next experiment...
>>>>> The signal becomes visible on my grabber now, in 424 uHz and also some
>>>>> bright pixels in the 3.8 mHz window.
>>>>> I'm going to stop the carrier at 10:08 UTC, after 1 hour. Then i'll
>>>>> continue on 5.17 kHz!
>>>>> BTW the antenna , if it works like a real loop, is beaming directly to
>>>>> Paul Nicholson ;-)
>>>>> 73, Stefan
>>>>> Am 26.07.2018 17:19, schrieb DK7FC:
>>>>>> ...i just searched in the old emails and also on G3XBM's blog and found
>>>>>> this entry: 
>>>>>> So that is the best distance on a transmit earth antenna (or ground
>>>>>> loop) so far, at VLF, by amateurs.
>>>>>> I had a much lower earth resistance in mind but actually i just got
>>>>>> 0.53 A at 250 W RF power, so the losses were rather 890 Ohm!
>>>>>> Will it be possible to make 55 km distance at 8.27 kHz, maybe in a
>>>>>> lower bandwidth like 424 uHz, with power levels in the range of 50 W
>>>>>> only?
>>>>>> 73, Stefan
>>>>>> Am 22.07.2018 20:28, schrieb DK7FC:
>>>>>>> Hi all,
>>>>>>> During the weekend i am in the Pfälzer Wald again which is such a nice
>>>>>>> place to be! I already installed a fixed E field antenna for VLF/ULF
>>>>>>> reception in JN39XI06 :-)
>>>>>>> Now i have the idea to use a guide rail (attachment!) as an electrode
>>>>>>> for a earth electrode antenna! There is a perfect road which is not
>>>>>>> much frequented and where no way is crossing so i could temporary
>>>>>>> install a long wire on the ground between two of these guide rails. I
>>>>>>> would assume they provide a good grounding. They are located on a
>>>>>>> relatively high hill/mountain with stony ground. The mountain is very
>>>>>>> steep there and in some distance, 200m deeper, there is a brook..
>>>>>>> With some luck the ground losses can be near 200 Ohm? Maybe rather 300
>>>>>>> Ohm. I'm going to prepare things and plan to transmit for some time
>>>>>>> next weekend. If the ground loop actually acts like a loop, the bearing
>>>>>>> should be 135 deg, so it will be in a 45 deg angle towards my QTH where
>>>>>>> my grabber is listening in 55 km distance. That's quite a good distance
>>>>>>> for testing! I'd like to try LF and VLF, maybe ULF it all works well.
>>>>>>> A BTW the wire length will be 860 m! However there are two guide rails
>>>>>>> in a shorther distance, about 450 m. I will try the shorter length
>>>>>>> first, to get an impression of the loss resistance and to see if
>>>>>>> something is visible at all :-)
>>>>>>> 73, Stefan
Roman, RW3ADB

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