Towertalk
[Top] [All Lists]

Re: [TowerTalk] SWR is what SWR meter measures

To: "Ian White GM3SEK" <g3sek@ifwtech.co.uk>,<towertalk@contesting.com>
Subject: Re: [TowerTalk] SWR is what SWR meter measures
From: "Tom Rauch" <w8ji@contesting.com>
Reply-to: Tom Rauch <w8ji@contesting.com>
Date: Fri, 13 May 2005 09:48:10 -0400
List-post: <mailto:towertalk@contesting.com>
> I agree with your bottom line, Tom... but not completely
with your
> reasoning.
>
> The problem is that the so-called "directional wattmeters"
don't
> actually measure forward or reflected power. They sample
RF voltage and
> current on the line, run the current through a resistor to
get a
> voltage, and then  add or subtract those voltages in
vector form.
> Finally they detect the resultant RF signal, and the DC
current pushes a
> meter up-scale. Nothing at all in this process is
responding to RF power
> as such, only to  RF voltages and currents.

If you read my last response to Martin you'll see we agree
even on that point!!

I'm not saying the meters actually MEASURE reflected and
forward power, what I'm saying is if we want true power
subtract the reflected power from forward power reading.

Hey, I can't help it what the meter scales say! It isn't my
fault they use those words! ;-)

73 Tom

_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather 
Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions 
and ask for Sherman, W2FLA.

_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>