I never said that driven element tuning will have any effect on any?other
parameters.
Quick enough?
-John, N9RF
-----Original Message-----
From: Carl <km1h@jeremy.mv.com>
To: John <jmltinc@aol.com>; amps@contesting.com
Sent: Fri, 24 Apr 2009 11:51 am
Subject: Re: [Amps] High SWR
Please explain how driven element tuning will affect the other parameters.?
?
Keep it quick and simple as the moderator gets upset when topics drift off
amps.?
?
Carl?
KM1H?
?
?
----- Original Message ----- From: "John" <jmltinc@aol.com>?
To: <amps@contesting.com>?
Sent: Friday, April 24, 2009 12:29 PM?
Subject: Re: [Amps] High SWR?
?
>?
> Design of a Yagi is a comprimise of SWR, gain, and F/B as they are >
> interdependent. If you optimize for one, the others will change. For >
> low-band beam, F/B is usually most important, but at the expense of > gain,
> SWR or both. If you were to optimize a beam for lowest SWR, you > would
> comprimise gain and/or F/B.?
>?
> I don't think it would be a valid statement "that because a Yagi has > high
> SWR it has poor F/B". I think it would be fair to say that if you > had LOW
> SWR, you are lacking in the gain or F/B department.?
>?
> -John, N9RF?
> ----- Original Message ----- > From: Gary Smith?
> To: amps@contesting.com?
> Sent: Friday, April 24, 2009 11:02 AM?
> Subject: Re: [Amps] High SWR?
>?
>?
> A comment: I have been told that a high swr on a yagi antenna reduces > the
> front to back ratio. Any truth (facts?) to support this info??
> 73,?
> Gary...wa6fgi?
> ----- Original Message ----- > From: Gary Schafer?
> To: 'Scott McGrath' ; amps@contesting.com?
> Sent: Thursday, April 23, 2009 9:26 AM?
> Subject: Re: [Amps] High SWR?
>?
>?
>?
>?
> > -----Original Message-----?
> > From: amps-bounces@contesting.com > [mailto:amps-bounces@contesting.com] On?
> > Behalf Of Scott McGrath?
>?
> > In reality and especially with a tube amplifier and a Pi output > tank the?
> > antenna system can be brought into resonance at a wide range of?
> > impedances and resonance is what we are looking for and it really > is?
> > Antenna System Goodness in MOST cases. As the reflected power > is?
> > definitely real but it is best expressed as the reactive power in > a?
> > system which effectively is lost. With ladder line if long > enough will?
> > re-radiate some of this 'lost' power.?
>?
> Reflected power is not best expressed as reactive power. It is real > power?
> and it is not lost power just because it is reflected. when > reflected power?
> sees the matching network in the final amp or antenna tuner it then > gets?
> re-reflected back toward the antenna to be ultimately radiated > along with?
> the rest of the power. The only "lost power" is that due to the > feed line?
> loss on both the forward and reflected power.?
>?
> With ladder line the loss is normally very low and very little > forward
> power?
> is lost and very little reflected power is lost. There can be very > high swr?
> (high reflected power) on the line and most all of the reflected > power will?
> end up getting back to the antenna to be radiated by the antenna.?
>?
> Ladder line will not re_radiate reflected power any more than it > will?
> radiate forward power. If the line is well balanced it will not > radiate?
> either forward or reflected power that may be on it.?
>?
> 73?
> Gary K4FMX?
>?
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