[AMPS] Where to read Reflected Power

[Radiodan W7RF]

Hi Pete & Jon, (note for others: antenna and feedline stuff below, if your
amplifier only eyes get burned reading this, please delete to save your self
permanent damage!)

In the ARRL handbook 1998 (probably others, I didn’t check them all) on page
19.6, figure 19.5 there is a chart showing ADDITIONAL loss in transmission
lines as a function of SWR. Very interesting.

Studying this gives a good perspective when trying to figure whether open
wire feedline is needed (a relative statement) for a particular
installation. Shorter runs of cable on lower frequencies may not warrant
open wire feed.

I still love 450 ohm ladder line and use it for my 170 foot dipole for all
bands and lowest additional feedline loss.
Certainly if one wanted to build a dipole for 80 and 75M tuning out SWR for
CW or phone using RG213 would not a be a problem.

73, Dan Magro W7RF, (President WARC 1999, member SCDXC, SCCC)
Manufacturers Rep & Distributor for HENRY RF Power Amplifiers.
RF Applications Power Measuring equipment, See the VFD!
www.radiodan.com <http://www.radiodan.com>     RFpower@radiodan.com
<mailto:RFpower@radiodan.com> A trip to our web site is worth the click!




> -----Original Message-----
> From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On
> Behalf Of Pete Smith
> Sent: Tuesday, September 28, 1999 1:02 PM
> To: Jon Ogden; John Devoldere (ON4UN); Jim Reid; Amps Reflector
> Subject: Re: [AMPS] Where to read Reflected Power
>
>
>
> At 12:49 PM 9/28/1999 -0500, Jon Ogden wrote:
> ...
> >Perhaps buffer isn't the right word.  Yes, it does transform the
> >impedance.  The conjugate match is between the exciter and the tuner.
> >However, a tuner does NOT make a 750 Ohm antenna into a 50 Ohm antenna.
> >That VSWR is still occuring along the feedline of the antenna.
> >
> >A tuner will not make a bad antenna into a good antenna.
>
>
> And here's where I part company with you, Jon.  An antenna with a 750-ohm
> feedpoint impedance, fed with open wire line through a tuner and balun,
> could be a very *good* antenna, indeed.  The real issue is the loss
> performance of the feedline at relatively high VSWRs.
>
> Down boy...bad antenna... down!
>
> 73,  Pete N4ZR
> Sometimes a tower is just a tower
>
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>


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