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Old October 3rd 05, 11:20 PM
Reg Edwards
 
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"Bob Bob" wrote in message
...
Hi Reg

The two pieces of coax are only meant to be a 100 ohm balanced Q

section
to translate the antenna Z to close to that of the main feedline

(50r).
I could do the same if I had some 100r open/ribbon feedline.

The outer conductors/shield should be at zero potential and as such
preserve the Z between the two inner conductors. This is handy in

that
the coaxes dont have to be bound close together and could be fed

through
a non metallic conduit without problems.

Have I made any sense?

Yes, that works OK. You have acheived your objective.

My only comment is that the inner coaxial conductors are very thin and
depending on length they may be a little lossy. You could use a
twisted pair of thicker wires insulated with thin plastic which would
have approximately the same 100-ohm impedance. The actual impedance is
not very critical.

This would also eliminate stray capacitance of the coax outer
conductors to their surroundings. Although that is not likely to
cause much trouble anyway.
----
Reg.