OK. I recommend to use an RF amperemeter to find the resonance. An
analog one of course. That makes resonating a fun, very comfortable.
Also you can easily calculate the losses if the RF power is known.
Remember: https://dl.dropbox.com/u/19882028/VLF/VLFcoil.jpg
73, Stefan
Am 26.06.2012 12:10, schrieb mal hamilton:
Stefan
I have calculated that I need 150 mH loading coil for 9 Khz. I have already
resonated the antenna using some ferrite core inductors and can hear it
singing at 9 khz with the low power signal generator.
I have started a big TX coil but need to finish it. I can RX well on the
band.
73 de mal/g3kev
----- Original Message -----
From: "Stefan Schäfer"<[email protected]>
To:<[email protected]>
Sent: Monday, June 25, 2012 11:11 PM
Subject: Re: LF: Re: New VLF Grabber in Darmstadt
Yes, in any way it would be nice again to put some focus on VLF. It's a
long time ago i regularly monitored my own VLF grabber
(http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html).
Looks like SAQ has tuned up today for a time arround 10 UTC. The Alphas
are OFF again and the noise is maybe 10 dB higher than in winther, as a
maximum. I do not change the brightness between summer and winther.
Opera 4 H, what the hell is that?
How long does it take to get a full decode in that mode and what is the
content of the decoded message? If 4 H means 4 hours and the content is
a full callsign and locator (about like in WOLF) then maybe it can be
compared with DFCW-120? If so, i guess the range of a 1 mW ERP station
will be below 100 km, if conds are good (i.e. no QRN and during the gap
in the morning which is arround 8...11 UTC) and the RX is is typical.
We know that no digimode can do miracles. However we often saw stations
just transmitting a few dashes. If these dashes will satisfy all, it
would be fine.
Due to other projects (ah, i remember, it was the LF DX to VK times) i
stopped the local VLF experiments with the LOPT transformer. Also is
showed me that there is no real alternative to an air coil if a serious
ERP is goal. That was clear in advance but the proof was clearer than i
thought.
As i write these lines, a small VLF flame starts to burn again. But
there is the MF project on the table as well...
What about all the other VLF transmitting stations? We have been 7
(OK2BVG, OE3GHB, DF6NM, G3XIZ, DJ8WX, OE5ODL, PA3CPM, DK7FC) who passed
distances above 1 Lambda. Did i forget someone?
73, Stefan/DK7FC
Am 26.06.2012 00:39, schrieb Graham:
Would be the first with Opera 4 H decode over this side of
the UK as well !
--------------------------------------------------
From: "Stefan Schäfer"<[email protected]>
Sent: Monday, June 25, 2012 11:20 PM
To:<[email protected]>
Subject: Re: LF: Re: New VLF Grabber in Darmstadt
Mal,
Am 25.06.2012 20:08, schrieb mal hamilton:
Stefan
This sounds interesting and given time I might get Transmitting on the
Dreamers band.
Yes, give it a try! You know how it is done and need less effort due
to your higher antenna C and mains availability.
You can surely be the first who will be visible in EU from the UK.
I have all the equipment suitable plus antennas but I am busy with
other
persuits at present.
Take care and the time to carefully wind a suitable coil on a large
tube. 60 cm, rather 80 cm diameter is recommended. You have Paul
Nicholsons grabber in a not to far distance, which will be very
helpful for the first tests!
73, Stefan
----- Original Message -----
From: "Stefan Schäfer"<[email protected]>
To:<[email protected]>
Cc: "Paul"<[email protected]>; "Christoph Maurer"
<[email protected]>
Sent: Monday, June 25, 2012 1:18 PM
Subject: LF: New VLF Grabber in Darmstadt
VLF,
It's a long time ago that we put the focus on VLF. Today i want to
inform you about a new VLF Grabber at the Technical University of
Darmstadt,
http://skmail.ikp.physik.tu-darmstadt.de/gvw/grabber.html run
by Christoph Maurer who is working in the nuclear science institute.
Seems they want to observe the VLF spectrum and try to make some
earthquake precursors.
I've been in contact with Christoph some month ago and convinced
him to
share the received spectrum with us by running such a grabber :-) He
even runs a "DFCW-6000" window on that site. There are no CPU
resources
for that at the moment though.
The distance to Heidelberg is 51.3 km,
http://no.nonsense.ee/qthmap/?qth=JN49HV80ST&from=jn49ik00wd so it
should be easy to get a reception on 8970 Hz (Dreamers band :-) ) even
in summer.
If i find the time in the coming weeks i'm planning a summer VLF
event.
BTW my special permission to fly a kite in 300m AGL expires in June
2012
:-( These days, i'm not sure whether it makes sense to try to
extend it.
73, Stefan/DK7FC
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