On Feb 23, 2007, at 9:29 AM, Darrell Bellerive wrote:
On February 22, 2007 09:44 am, Don Wilhelm wrote:
Look at the Elecraft BL2 for a switchable 1:1/4:1 balun, it will
handle up
to 250 watts. If you do not need the switchable arrangement, the
BL1 can
be constructed for either a 1:1 or a 4:1 configuration and its
power rating
is 150 watts. A convenient ground lug is located on the balun
output side.
How can a balun be switchable from 1:1 or 4:1? Surely the
characteristic
impedance of the windings will be missmatched at one of the settings.
Actually the characteristic impedance of the windings will ideally be
2*Z0. For a 1:1 balun they will appear in parallel, while for 4:1
they will appear to be in parallel at one port and in series at the
other.
Bob, N7XY
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