[Lowfer] Wm Beacon "Current" Question

[Neil Klagge]

Hi Mitch. You sent a link that does not work for me.
You said, " I have had great results
using the rf ammeters I have built - for various power ( current ) levels
as shown on John's website, RFAmmeters for LF.  They are very simple to
build - calibrate very easily and never seem to change. The link is:
http://www.w1tag.com/RFA.htm/

I am very interested in that article.
Neil, XSV

w0yse, wg2xsv,now in Vancouver WA
CN85rq

On Sat, Nov 29, 2014 at 11:41 AM, Mitch Powell <ve3ot.mp at gmail.com> wrote:

> Mike:
> This may be a repeat of an earlier email - but I have had great results
> using the rf ammeters I have built - for various power ( current ) levels
> as shown on John's website, RFAmmeters for LF.  They are very simple to
> build - calibrate very easily and never seem to change. The link is:
> http://www.w1tag.com/RFA.htm/
>
> Also - first copy of WM this Saturday morning... attached.
> 73
> Mitch
>
>
> On Thu, Nov 27, 2014 at 12:18 PM, JD <listread at lwca.org> wrote:
>
> > Mike, keep in mind that a current meter for a loop is designed to measure
> > higher current levels because an electrically small loop offers a very
> low
> > resistance if constructed carefully.  A short vertical has inherently
> high
> > capacitive reactance, which you neutralize with the loading coil, plus
> > resistive losses in that coil, the ground system, and nearby
> environmental
> > factors.
> >
> > Thus, from the P= I^2 * R relationship, we see that for the same power
> > level, current in a high impedance circuit must be lower than it would be
> > in
> > a low impedance circuit.  That's why the meter deisgned for the loop
> barely
> > responds in the case of the vertical.
> >
> > LowFER vertical antennas vary widely in their resistive component due to
> > local soil conductivity and coil construction variations.  Most reports
> > I've
> > seen on successful beacons indicate measured RF currents typically in the
> > range of 120-250 mA.  It's hard to get loss factors low enough to exceed
> > 250
> > mA for 1 watt.  Much lower than 120 mA, and the beacon may not get out
> very
> > well...although nowadays with slow modes like QRSS, that's less of a
> > problem
> > than it would have been 15 years ago.
> >
> > John
> > ______________________________________________________________
> > Lowfer mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/lowfer
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Lowfer at mailman.qth.net
> > Post must be less than 50KB total for message plus attachment!
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> >
>
> ______________________________________________________________
> Lowfer mailing list
> Home: http://mailman.qth.net/mailman/listinfo/lowfer
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Lowfer at mailman.qth.net
> Post must be less than 50KB total for message plus attachment!
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>