Message-ID: <4D27752B.1080004@iup.uni-heidelberg.de>
Date: Fri, 07 Jan 2011 21:18:51 +0100
From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= <schaefer@iup.uni-heidelberg.de>
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To: rsgb_lf_group@blacksheep.org
References: <4D25EC9A.6030201@iup.uni-heidelberg.de> <55F29B964A0142EE93CCD0BCFD084EDF@JimPC>
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Subject: Re: LF: Re: adding a L into a 300m LF vertical?
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Jim, Rik,

Thank you for your reply and point of view. So, i'll let the coil on the 
bottom although the wind will be VERY strong tomorrow and on sunday. The 
kite will be strong enough to pull my car if the breaks are not 
fastened! So a coil in 100m wouldn't cause to much sagging even if its 
weight would be 2 kg ;-)

So my signal might be a bit weaker than expected. I hope you can copy a 
trace of my signal ;-)  Hope for a new CW contact, as before 1 year!! :-)

73, Stefan

Am 06.01.2011 22:33, schrieb James Moritz:
> Dear Stefan, LF Group,
>
>> _Questions:_ Is my calculation reasonably useful? Would YOU add that
>> coil in a height of 100m above GND?
>
> I have found with NEC simulations that they give you a reasonable idea 
> of the impedance, but not a precise value. Especially for the 
> resistance, where there are many unknowns - NEC really only sets a 
> lower limit.
>
> On the basis of the calculations, I would first try without the coil, 
> then if results are as expected, I would try it with the coil. 
> Otherwise there are too many variables to make sense of the experiment 
> - if the coil goes up and the impedance is totally different from the 
> calculation, is it because of the coil, the antenna, or the calculation?
>
>>
>> I tend to let it be since the improvement isn't that much and the effort
>> is high. Furthermore the coil losses could be higher since i have to use
>> a thin wire to keep the weight small...
>
> Yes - the 136k coils I have made with Q > 300 have been rather big, 
> either with RF Litz wire or thick solid wire.
>
> Hope to see some signals at the weekend,
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>