My comment was specifically directed towards the issue that this person
may have an interaction problem. Please read my post again if you doubt
it. As such I am correct to suggest TowerTalk.
As to the effect of high VSWR on "forward" power measurements, AMPS is
the place.
Mike N2MG
n2mg@contesting.com
On Thursday, September 09, 1999 12:41 PM, Jon Ogden
[SMTP:jono@enteract.com] wrote:
>
> Jonathan Kaplan wrote:
>
> >>> In other words, when I tune the AMP
> >>> the power meter (a RS model) will either show greater power at
> >>> a high SWR or low power at low SWR. But not high power at low
> >>> SWR! What does this mean is wrong? Does it neccessarily
> >>> mean the final output into the air is limited, and that the
antenna
> >>> system is out of tune?
> >>
> >>If you mean that the meter shows extra high power on frequencies for
which
> >the
> >>SWR is high, this is an inaccurate power reading caused by the
meter's being
> >>designed to work properly only on a relatively flat (low-swr) line.
> >
> >Not EXTRA high power. The maximum power showing in any case is about
1Kw,
> >which I am told is about expected for 100w drive from a Yeasu Ft-840.
>
> Someone suggested this belongs on Tower Talk - NOT! It's an amplifier
> related question.
>
> If you have a high SWR, your power meter WILL very likely read higher
> power than would be read under a "normal" SWR condition. In other
words,
> if you are transmitting 1KW and are getting 50% of your power
reflected
> back to you (SWR: ~6:1), this "reflected" power will reach your amp,
> tuner, etc and will be reflected back up the line towards the antenna.
> So your power meter will end up reading around 1500 Watts out. The
best
> thing to do is subtract reflected power from forward power. But then
> again, as others have pointed out, the power meter is not really
accurate
> in environs far away from 50 Ohms.
>
> Also, you neglected to tell us what "low power at low SWR" means. Is
> "low" 1000 Watts? Or is "low" 100 Watts??
>
> 73,
>
> Jon
> KE9NA
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