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Old March 4th 04, 10:33 PM
Steve Nosko
 
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"John Smith" wrote in message
...
Actually, not.
1. the line is mismatched at both ends,


John, You missed something. The problem was stated;

"Isn't a 50 ohm transmitter conjugately matched to a 50 ohm load
when fed through 1/2 wavelength of 450 ohm ladder-line?"


The TRANSMITTER "sees" 50 ohms therefore it is. Some discussion can be made
for the exact phrasing which says, in effect; "...50 ohm transmitter ...to a
50 ohm load". By this I mean using the phrase "to a 50 ohm load" is a bit
misdirecting. In the stated case, the Tx is NOT actually connected *to* the
load. It is connected to a 1/2 wave of line. At the Tx output, there is a
conjugate match.
I believe the intended situation is that a 1/2 wave of ANY line repeats the
load Z at its input. From your comment #2, it appears that you do not know
this.


2. If I have a 50 ohm load at each end, and a line of impedance Z, 1/2
wavelength long, what does Z have to be for max power transfer?


Actually, it IS anything! Yea, Yea there are other *practical*
considerations...balanced...unbalanced....


--
Steve N, K,9;d, c. i My email has no u's.

Nothing
constrains Z to be a value. Z at 50 is great, Z at 500 is not bad (have

to
do some matching)
This problem the way it is stated 50 1/2 line 50 is implying that any

type
of line will do as long as it is 1/2 long, then Z can be 0.01 and Z=20,000

So as long as the matching transformers are in,(assuming the right ones)

it
is matched max power too.
The Tx out 50 ohm unbalanced is matched to the 450 balanced line 1/2
wavelength long and another transformer back down to 50.


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"JDer8745" wrote in message
...
"Isn't a 50 ohm transmitter conjugately matched to a 50 ohm load
when fed through 1/2 wavelength of 450 ohm ladder-line?"

==============

Heck yes, I'm assuming u mean 50 + j 0 Ohms.

73 de Jack, K9CUN





 
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