Is this the same coil as used for the kites stefan?
Laurence in KH6
Lightning storm 29C
> On Dec 15, 2013, at 10:19 AM, "Stefan Schäfer"
> <[email protected]> wrote:
>
> Hi Jay,
>
> Am 15.12.2013 21:09, schrieb [email protected]:
>> Stefan
>>
>> What is the overall antenna R now?
> On VLF? Well, i'm getting 850 mA at 400W, i.e. 550 Ohm. If i remember
> correctly, the coil has 320 Ohm, so the sourrounding losses are 230 Ohm.
>
>> With the kite of years gone by?
> Who knows. At least there are no concrete plans in the moment. But it would
> be nice :-)
> The fixed antenna has some real advantages. But i will never generate a
> signal in the range of 58 mW ERP with that one..
>>
>> Miss reading and seeing the pictures of your escapades in the field.
> :-)
>
> 73, Stefan
>
>
>>
>> Jay W1VD WD2XNS WE2XGR/2 WG2XRS/2
>>
>>
>> ----- Original Message ----- From: "Stefan Schäfer"
>> <[email protected]>
>> To: <[email protected]>; "Paul" <[email protected]>
>> Sent: Sunday, December 15, 2013 11:33 AM
>> Subject: Re: LF: A short VLF experiment at DK7FC
>>
>>
>> Hi Peter, VLF,
>>
>> Did you see a trace on your grabber? Can you show me a link or a screenshot?
>> The signal is well visible on Paul Nicholson's excellent VLF grabber,
>> http://abelian.org/vlf/fbins.shtml#p=1387116000&b=110&s=sp but far from
>> stable. Is instability is due to my signal of course. Distance to Paul
>> is 880 km, http://no.nonsense.ee/qth/map.html?qth=IO83XQ&from=jn49ik00wd
>>
>> You are right, there are many things to optimise. One thing is the
>> housing of the PA. Now it is just mounted on a wooden plate. It is a H
>> bridge using 4x IRFP460, switching directly at 230V*1.41, so the output
>> of the PA is on mains potential! There is no galvanic decoupling
>> transformer on the output (which would allow to use a grounded coax
>> then) because such a transformer would have to be a VERY big ferrite
>> core with many many turns (> 100). So the PA output is directly
>> connected to the primary winding of the loading coil, which couples its
>> field into the resonance winding (1200 turns). So the feed line is
>> floating on an unknown voltage which depends on the capacitive coupling
>> to sourrounding things. In the field experiments 2010/2011 this was no
>> problem. But now it is. I guess this is causing EMC problems to the /2
>> frequency divider, sometimes. Thus, i will put it into a metallic box
>> which is grounded to earth potential.
>>
>> Another problem is the parallel capacitor which i have to add to come on
>> resonance. It's capacity is not high enough and i have to add about 10m
>> or wire hanging arround. This additional wire is moving in the wind
>> blasts and causes further instability of the signal (kind of AM due to
>> modulated resonance peak, i.e. antenna current). Another way would be to
>> add more turns to the coil but this antenna system is voltage limited
>> and it doesn't matter at all if i have to put 400W or 500W into the system.
>>
>> BTW this night/day it was 850 mA antenna current and about 400W RF
>> power. I will plan to do more QRO, when the new capacitor is ready to use.
>>
>> Here is an image of the arrangement, taken 30 minutes ago:
>> https://dl.dropboxusercontent.com/u/19882028/VLF/20131215_165406.jpg
>>
>> As soon as the C of "DK7FC" is finished, i will run some OPDS32
>> sequences for DF6NM and Paul Nicholson and others :-)
>> BTW i have disconnected my VLF grabber antenna since the RX is
>> overloaded anyway. Now it is easier to identify eventual phase glitches
>> (could be on the RX side as well, though).
>>
>> 73 and thanks for watching.
>>
>> Stefan/DK7FC
>>
>>
>>
>> Am 15.12.2013 14:49, schrieb PA1SDB, Peter:
>>> Stefan,
>>> Signal is O.K., but stabillity is'nt :-(
>>> To much spread around center frequency.
>>>
>>> (I know.... I'm complaining about 0.01 Hz drift..........)
>>>
>>> 73's Peter
>>>
>>>
>>> ----- Original Message ----- From: "Stefan Schäfer"
>>> <[email protected]>
>>> To: <[email protected]>; "Paul" <[email protected]>
>>> Sent: Sunday, December 15, 2013 4:14 AM
>>> Subject: Re: LF: A short VLF experiment at DK7FC
>>>
>>>
>>> Since 4:10 UTC, the signal is available without interruptions now on
>>> 8.97000500 kHz.
>>>
>>> 73, Stefan/DK7FC
>>>
>>> Am 14.12.2013 20:50, schrieb Stefan Schäfer:
>>>> Hi all,
>>>>
>>>> Tomorrow the rain probability is just 10% and so i think i can risk to run
>>>> a short VLF experiment on 8970.00500 Hz. I'm using the fixed antenna at
>>>> JN49IK00WD. These days, the QRN is very low for quite a long time! The
>>>> plan is to run about 500W RF power, or more, depending on the voltage
>>>> limit of the antenna. And the plan is to start transmitting tonite, after
>>>> the experiment with VO1NA, i.e. i'll come on air arround 2 UTC, hopefully.
>>>> I will run the test until the late afternoon. First i'm TXing a stable
>>>> frequency until 9 UTC, later some DFCW-600, and then maybe some tests in
>>>> OPDS32.
>>>> Suggestions welcome.
>>>> BUT it all depends on the WX. If it starts to rain then i have to stop.
>>>> Will someone give it a try and watch for me?
>>>>
>>>> 73, Stefan/DK7FC
>>>
>>
>
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