Jerry Martes wrote:

"Cecil Moore" wrote in message
...
Jerry Martes wrote:
I'm condidering building a slotted line for measuring impedance at 137
MHz. I find no referances to home made lines thru my quick Google
search.
Does anyone know of any publication that show how someone has already
worked
out the problems of contructing one?

Try a Lecher wire system described in 50's ARRL Handbooks.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil
I thought lecher line measurements used a balanced line.
I'm not smart enough to know how to compensate for any irregulariities
associated with open wire measurements of an unbalanced load. And, it seems
that it would be easy enoughto make a 'good enough' slotted line. But,
since I havent found referance to any home built coaxial slotted lines,
maybe its not as easy as I think.

Jerry

About the only difficulty in doing it (besides cost) I can think of is it
would be hard to find a 5 foot long tube you could cut a slot in and not
have it distort due to relieved stress.

Use a square U channel for a bottom and 2 pieces of L to make the top.

Look up the equation for the impedance of square coax, get brass tubing
(which comes in increaments of 1/32") for the center conductor, make 2
end plates for connectors, screw the thing together. Probably should use
plastic screws for the top so they don't have to be flush on the inside.

Thought about making one myself for grins and giggles, but bought a MFJ
analyzer instead; lot more portable.

--
Jim Pennino

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