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Old September 12th 05, 09:39 PM
Bob Bob
 
Posts: n/a
Default Balanced from unbalanced via a 100 ohm Q section

Hi all.

Throwing together a 20m single quad loop (triangular) antenna. In the
past I have fed these with a 75r Q section. Nothing strange here.. I use
to coil up most of it in a 5" coil to help reduce the line radiation
problem - if any... No tuner in use..

This time however I am going to use two pieces of 50 ohm coax in
parallel giving a 100r balanced Q section feeder. This more closely
matches the loop Z. The shields are joined together at each end of the
section and the coax centre conductors become the two antenna connection
points.

Question;

Should I be worried about inbalance in the 50 ohm cable from the radio
to the Q section. ie does the Q section reduce any of that problem? If
that isnt the case I can make up the usual coil of coax before it meets
the Q section.. or can I coil up the Q section instead.

I also wonder about Q section shield grounding as I hadnt intended
grounding either end. Will this be an issue?

Cheers Bob W5/VK2YQA