[TowerTalk] TH7 SWR trouble ... Coax balun question

[Bill Coleman AA4LR]

On 5/4/00 9:51 AM, markku.a.oksanen@nokia.com at 
markku.a.oksanen@nokia.com wrote:

>You may remember that the TH6
>instructions call for a 12-turn balun located at the junction of the boom
>and the mast, couple of feet from the feedpoint with the coax to the
>feedpoint taped to the boom.

To quote from the Ed Gilbert article I cited earlier:

"Don't use too many turns.  For example, the HyGain manuals for my 10
and 15 meter yagis both recommend 12 turns 6 inches in diameter.  At
the very least this is about 3 times as much coax as is needed, and
these dimensions actually give less than the desired choking impedance on 
10 and 15 meters."

Ed recommends a much smaller alternative:

"A 1:1 coaxial balun with excellent choking reactance for 10 through
20 meters can be made by winding 6 turns of RG-213 on inexpensive 4
inch PVC sewer pipe."

See the whole article yourself:
<http://www.contesting.com/_cq-contest/199507/0648.html>

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@radio.org
Quote: "Boot, you transistorized tormentor! Boot!"
            -- Archibald Asparagus, VeggieTales


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