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From: "Tom Boucher" <tom@telemetry.demon.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <005001c7d3fe$e4786d80$6400a8c0@oem17oeylz9on8>  <001901c7d42b$e6fbeaa0$86048351@w4o8m9>  <00a001c7d43c$f4180690$0a7ee150@o>  <Pine.LNX.4.64.0708011456010.10082@lurcher.twatt.local> <1IGMYh-02648G0@fwd31.t-online.de>
Date: Thu, 2 Aug 2007 07:54:34 +0100
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Subject: Re: LF: Re: Re: newbie help
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Status: O

Good point Ha-Jo. When using my antenna impedance analyser, I always leave a 
50 ohm load in parallel with the antenna, using a BNC T-piece. Only when the 
antenna is connected do I remove the 50 ohm terminator, that way hopefully 
any static on the antenna is discharged through it.

73
Tom G3OLB

----- Original Message ----- 
From: <hajo.brandt.dj1zb@t-online.de>
To: <rsgb_lf_group@blacksheep.org>
Sent: Wednesday, August 01, 2007 11:20 PM
Subject: Re: LF: Re: Re: newbie help


> Dear all,
>
> I have heard of a case that a german LF amateur had ruined his
> capacitance meter because of a static loading on the aerial!
>
> Therefore I have always preferred to measure aerial capacitance by
> checking the detuning effect of the aerial to a tuned circuit. The coil
> of this circuit will always ground the aerial for dc.
>
> HW?
>
> 73 Ha-Jo, DJ1ZB
>
>
> "John GM4SLV" <gm4slv@sighthound.demon.co.uk> schrieb:
>>
>> Rog,
>>
>> That's an interesting idea - I've never thought of trying a digital Cap
>> meter. I must try it on the new antenna - and compare it to my homebrew
>> RF bridge, calculations and - more telling - to the valuse of L I
>> eventually need to resonate it.
>>
>>
>> John GM4SLV
>>
>>
>> On Wed, 1 Aug 2007, GW3UEP wrote:
>>
>> > Re ant cap: you can use a DMM [Rapid 328] to gnd - I use 1000pF across
>> > its terminals to decouple RF for a stable reading. Simply subtract its
>> > value. 73, Rog.
>> >
>> > ----- Original Message ----- 
>> > From: James Moritz
>> > To: rsgb_lf_group@blacksheep.org
>> > Sent: Wednesday, August 01, 2007 12:05 PM
>> > Subject: LF: Re: newbie help
>> >
>> >
>> > Dear Paul,
>> >
>> > In a nutshell:
>> >
>> > - You can tune up more or less any bit of wire for reasonable results
>> > on 500kHz. For best results, make it as high up as possible, and
>> > secondarily as long as possible. An HF long wire, or dipole with
>> > feeders strapped would be fine.
>> >
>> > -Work out the capacitance of the wire (see formulas on ON7YD's
>> > antennas pages). and calculate the inductance for resonance around
>> > 502.5kHz. For most HF-sized wire antennas, this will be of the order
>> > of 100s of uH. The resulting coil is
>>
>>
>>
>
>