On Tue, 13 Sep 2005 10:04:56 -0500, Bob Bob wrote:

Err why?

50r to 100r = 122r
50r to 75r = 90r

Cecil already gave you the answer. A 90-degree line is called a
"geometric mean" transformer.

The required impedance is the square root of the product of the
desired R and the load R.

Here's a little tutorial:

http://www.microwaves101.com/encyclo...uarterwave.cfm

Aghaa, Okay tnxs Cec... Too much sun and weird drugs.. (prescription of
course!)

Cheers Bob

Cecil Moore wrote:


Bob Bob wrote:

Err why?
50r to 100r = 122r


SQRT(50*200) = 100

50r to 75r = 90r


SQRT(50*100) = 70.7

Do I have the calcs right?

Wes Stewart wrote:

Okay. 75 ohm is -still- better than 100.


SQRT(50*140) = 84 ohms. Z0=75 ohms is closer to
84 ohms than is Z0=100 ohms. If you had a 200 ohm
feedpoint, Z0=100 ohms would be perfect.

"Bob Bob" wrote in message
...
Hi Roger

Might get around to it today! (Being unemployed is sometimes fun..)


Bob:

If your 100 ohm Q section doesn't work out as expected, I have lots of
RG-71 (93 ohm) coax that might be worth trying. Let me know if you are
interested.

73,

Roger