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Old September 11th 08, 05:29 PM posted to rec.radio.amateur.antenna
Roy Lewallen Roy Lewallen is offline
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First recorded activity by RadioBanter: Jun 2006
Posts: 1,374
Default Translate Smith-Chart statement to English?

Myron A. Calhoun wrote:
I recently bought an automatic tuner (I know, I know; I wasted my
money since manual tuners are so easy to build) which could supposedly
tune "8-1000" ohms resistance. I first asked the manufacturer if
maybe they meant "impedance", and they replied
"Yes, thanks for the correction". That lead to a followup question:

( NOTE: My keyboard doesn't have keys for "plus or minus" or "square
root" so I'll use "#" and "SQRT()", respectively.)

"Does '8-1000 ohms impedance' include ALL COMBINATIONS of #X#jY SUCH
THAT SQRT (Xsquare + Ysquare) is in the range of 8 to 1000 (such as
#8+j0 to #1000+j0 and 0#j8 to 0#j1000), or are there some "holes" in
coverage?"

Their response was:

" We use the polar coordinate system and it covers all phase angles at
14 MHz. Obviously, plotted on a smith chart you would see the range
decrease as you depart from 14 MHz."

I haven't used a Smith Chart since I was first introduced to them in
college (1963!-() Could someone please translate their response to
simple English that I can understand. In particular, what range of
impedances might their tuner cover on 80 meters? 40 meters? 15
meters? 10 meters?


The response translates to: "The range is less at other frequencies than
at 14 MHz."

Roy Lewallen, W7EL