I use a 'scope and signal generator in series with the loading coil and
antenna to resonate. It works fb, spot on every time
mal/g3kev
----- Original Message -----
From: "Stefan Schäfer" <[email protected]>
To: <[email protected]>
Sent: Tuesday, June 26, 2012 12:26 PM
Subject: Re: LF: Re: New VLF Grabber in Darmstadt
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
>>>>>
>>>>>
>>>>>
>>>>
>>>
>
>
|
