EMRFD Message Archive 2246

Message Date From Subject
2246 2008-10-14 19:55:11 Wes Hayward Simple bandpass filters
Hi All,

Those of us in the much of the world had ready access to powered iron
toroids and use them regularly for constructing bandpass filters. But
there are parts of the world where a toroid is a rare thing indeed.
But there are still radio amateurs and experimenters in those areas.
In an attempt to help some of these folks with some design chores, I
took a look at a HF bandpass filter that used air core coils. I wound
the coils on some PVC pipe, measured L and Q with the coil in air, then
measured L and Q with the coil in a shield. Then a bandpass filter
was designed, based upon the measurement results. It was then built
and measured.

I have posted this on my own web site. It's at

73, Wes