Message-ID: <002001c3f67d$a7795f00$6507a8c0@Main>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
References: <HNEGLMNKFOEMMNHIFAPIIENJCDAA.g4wgt@talkgas.net>
Date: Thu, 19 Feb 2004 00:10:38 -0000
MIME-Version: 1.0
Subject: LF: Re: RF Current meter
Content-Type: text/plain; charset=iso-8859-1; format=flowed
Content-Transfer-Encoding: 8bit
Sender: <owner-rsgb_lf_group@blacksheep.org>
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org

Hi Gary you will just get more volts out of it at higher curent......if that
drives the meter off-scale reduce the number of secondary turns, or use a
potential divider to reduce the voltage.
RF Thermo ammeters can be shunted, but my experiments so far suggest that
the scale does not quite "scale"...even taking care to use a "four terminal"
connection to avoid contact resistances......I'm still working on that one.
I dont think it was you testng this afternoon unless you now have a 1000ft
tower and 10kW :-))

Cheers de Alan G3NYK
alan.melia@btinternet.com


----- Original Message -----
From: "G4WGT - Gary" <g4wgt@talkgas.net>
To: "Rsgb_Lf_Group" <rsgb_lf_group@blacksheep.org>
Sent: 18 February 2004 20:01
Subject: LF: RF Current meter


> Hi all at LF,
>
> I have been conducting tests with QRS & DFCW now that I have completed the
> DDS VFO & the antenna is back up after storm damage & everything seems to
be
> ok.
>
> The main reason for this e-mail is to ask this question,
>
> "When I have looked at designs in amateur radio magazines or internet for
a
> clip on RF Ammeter the designs seem to be limited to 2 ranges (100mA & 1A
> FSD), is there a limit to the range of this type RF Ammeter or can the
> ranges be extented to say 5 Amps maybe? is there a calculation to extend
the
> range ?"
>
> My LF antenna seems to be showing in excess of one Amp so I need an RF
> Ammeter with a greater range than 1A.
>
> 73
>
> Gary - G4WGT
>
>