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 http://w7zoi.net/pvc_bandpass_filters.pdf 73, Wes w7zoi

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
http://w7zoi.net/pvc_bandpass_filters.pdf

73, Wes
w7zoi