Hi Stefan, VLF
>Special congrats to IW4DXW who made his first amateur VLF reception at all (i
>think)!
Yes, it's my first time :-)
>Riccardo, is that spectrogram really set to 3.8 mHz FFT bin width, as stated
>in the text field?
No, it was my mistake. In fact my spectrogram is set to 424uHz FFT bin width.
>Your simple antenna matching schmatic is apprechiated. It may be helpful for
>further stations. I note that no special preamp is needed.
Thanks, dear Stefan. Mic boost (+20dB) activated in last reception on
my Creative SB X-Fi (see attachement).
Now, very strong here in JN64: peak @ 13/15dB.
All the best
73 de Riccardo IW4DXW
2017-11-30 13:50 GMT+01:00 DK7FC <[email protected]>:
> Hello VLF freinds,
>
> I spent some day in Berlin, thus the late reply, sorry.
> The carrier is actually running since 25.Nov 23 UTC witout any interruption!
> I have/had control over the TX via the samrtphone. I can follow the antenna
> current and can access the PC to stop the transmission if something would be
> wrong. Also there is the safety function that stops the transmission as soon
> as the antenna current drops by more than 30 mA under the target level of
> 700 mA.
>
> Thanks to all stations who gave a feedback and RX report of the first
> amateur transmission on 17.47 kHz.
> Special congrats to IW4DXW who made his first amateur VLF reception at all
> (i think)!
>
> Riccardo, is that spectrogram really set to 3.8 mHz FFT bin width, as stated
> in the text field?
> Your simple antenna matching schmatic is apprechiated. It may be helpful for
> further stations. I note that no special preamp is needed.
>
> Luis, your few bright pixels look most promising. But maybe it is better to
> wait until tomorrow before claiming that new distance record on the 17 km
> band. It would be a first amateur detection on VLF between DL and EA! This
> evening i will finally rise the ERP by 3 dB, going from 700 mA to 1 A
> antenna current... With 3 dB more, the few pixels should become a solid
> line.
> BTW all this helps to see how 'far' you are away from getting a detection on
> 8270 and below..
>
> Sq5BPF has set up a grabber but didn't see a trace so far. I started a
> grabber window at RC4HAA running at 212 uHz. There is no trace at all! I did
> expect much better results over that distance.
> Also KL7L has set up a grabber window, without results so far.
> My first impression is that the band offers less better propagation than
> expected! So let's hope that QRO will help :-)
>
> Before loosing these informations i set up a small list containing
> informations about RX stations and SNR reports, see attachment. Tell me if
> there is something wrong or if i forgot something.
>
> I will inform when the signal level has changed or when interruptions
> happened. So far the transmission is still running. Ah yes the antenna
> current ca be followed at
> http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.png Quite unspectacular
> but some kind of feedback...
>
> 73, Stefan
>
>
>
>
> Am 29.11.2017 22:46, schrieb Riccardo Zoli:
>>
>> Hi Stefan, VLF
>>
>> I got your signal in JN64bw, dear Stefan. Depending on the QSB and/or
>> QRN, you're peaking 15dB over noise. Fantastic! :-))
>> I'm using my LF antenna tuned on your QRG with a (approx.) 200mH coil.
>> The 17470.5 signal (locally generated by a GPS disciplined DDS) is
>> used for Spectrum Lab SR correction.
>> Schematic and capture attached.
>>
>>
>> Congrats, Stefan, and keep up the good work!
>>
>> All the best,
>>
>> 73 de Riccardo IW4DXW
>>
>>
>>
>> 2017-11-26 0:40 GMT+01:00 DK7FC<[email protected]>:
>>
>>>
>>> Hi VLF,
>>>
>>> Since 23 UTC a 700 mA carrier is running on 17.4701 kHz!
>>>
>>> It is a little surprise to the VLF community i think ;-)
>>>
>>> Legal? Yes:
>>>
>>> http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/17,47kHz_Sonderlizenz.jpg
>>> Actually the document has 3 pages but the other ones are no so relevant.
>>> My ERP is limited to 5 mW. I did not request more because more isn't
>>> possible anyway with this antenna.
>>>
>>> I wound a big single layer coil with 0.5 mm enameled wire on a PVC tube
>>> with
>>> 315 mm outher diameter.
>>>
>>> 0.7 A is just a first careful step. The coil is designed to hold 1.5 A
>>> 'key
>>> down'.
>>>
>>> The carrier will run the whole night and even tomorrow at daytime.
>>>
>>> Worldwide reports are welcome ;-)
>>>
>>> It is not sub-9-kHz but still VLF, the 17 km band!! So give it chance :-)
>>>
>>> The tree has still some solar power to stream the signal from the EW loop
>>> down to the city, so there is a feedback spectrogram at
>>> http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
>>>
>>>
>>> 73, Stefan
>>>
>>> PS: I still can hear that tone of the coil. It is terrible! Be happy when
>>> you are older than me!
>>>
capt171201231242.jpg
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