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: <[email protected]>
To: <[email protected]>
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" <[email protected]> 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: [email protected]
> 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
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