I recently dissected a commercial (name witheld here) bauln. It failed
due to failure of the enamel coating between the trifilar windings.
It was a 1:1 bauln supposedly covering the ham bands and rated "1.5Kw".
It was air wound with no ferrite. The windings were on a 1" diameter
plastic pipe form (23 trifilar windings of #14 enameled wire)
It had been used on 20-10 meters only.
The last air wound design I saw was a 4:1 Heath-Kit design one. It used
two coils of about 12" long and 3" in diameter.
Question: Is this a legit design? The absence of the ferrite rod makes
me wonder. If this design is an invalid one I will disclose the name of
the manufacturer.
73 de Brian/K3KO
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